INTEL CORPORATION, 1997
December 1997
Order Number: 272731-002
EMBEDDED ULTRA-LOW POWER
Intel486
TM
SX PROCESSOR
Figure 1. Embedded Ultra-Low Power Intel486TM SX Processor Block Diagram
s
Ultra-Low Power Version of the Intel486TM
SX Processor
-- 32-Bit RISC Technology Core
-- 8-Kbyte Write-Through Cache
-- Four Internal Write Buffers
-- Burst Bus Cycles
-- Dynamic Bus Sizing for 8- and 16-bit
Data Bus Devices
-- Intel System Management Mode (SMM)
-- Boundary Scan (JTAG)
s
176-Lead Thin Quad Flat Pack (TQFP)
s
Separate Voltage Supply for Core Circuitry
s
Fast Core-Clock Restart
s
Auto Clock Freeze
s
Ideal for Embedded Battery-Operated and
Hand-Held Applications
A5850-01
Paging
Unit
Prefetcher
32-Byte Code
Queue
2x16 Bytes
Code
Stream
Barrel
Shifter
Cache Unit
Burst Bus
Control
Bus Control
Write Buffers
4 x 32
64-Bit Interunit Transfer Bus
Register
File
ALU
Segmentation
Unit
Descriptor
Registers
Limit and
Attribute PLA
32
Base/
Index
Bus
Translation
Lookaside
Buffer
20
8 Kbyte
Cache
Clock
Control
Control &
Protection
Test Unit
Control
ROM
Address
Drivers
CLK Input
Core
Clock
Data Bus
Transceivers
Request
Sequencer
Bus Size
Control
Cache
Control
Boundary
Scan
Control
Bus Interface
D31-D0
A31-A2
BE3#- BE0#
ADS# W/R# D/C# M/IO#
PCD PWT RDY# LOCK#
PLOCK# BOFF# A20M#
BREQ HOLD HLDA
RESET SRESET INTR
NMI SMI# SMIACT#
STPCLK#
BRDY# BLAST#
BS16# BS8#
KEN# FLUSH#
AHOLD EADS#
TCK TMS
TDI TD0
Instruction
Decode
32
Decoded
Instruction
Path
PCD
PWT
2
Physical
Address
32-Bit Data Bus
32-Bit Data Bus
Linear Address
Micro-
Instruction
Displacement Bus
32
32
32
32
32
32
128
24
Information in this document is provided in connection with Intel products. No license, express or implied, by
estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in
Intel's Terms and Conditions of Sale for such products, Intel assumes no liability whatsoever, and Intel
disclaims any express or implied warranty, relating to sale and/or use of Intel products including liability or
warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright
or other intellectual property right. Intel products are not intended for use in medical, life saving, or life
sustaining applications.
Intel may make changes to specifications and product descriptions at any time, without notice.
Designers must not rely on the absence or characteristics of any features or instructions marked "reserved" or
"undefined." Intel reserves these for future definition and shall have no responsibility whatsoever for conflicts or
incompatibilities arising from future changes to them.
The Embedded Ultra-Low Power Intel486TM SX processor may contain design defects or errors known as
errata which may cause the product to deviate from published specifications. Current characterized errata are
available on request.
Contact your local Intel sales office or your distributor to obtain the latest specifications and before placing your
product order.
Copies of documents which have an ordering number and are referenced in this document, or other Intel
literature may be obtained by calling 1-800-548-4725 or by visiting Intel's website at http://www.intel.com.
Copyright Intel Corporation, 1997
*Third-party brands and names are the property of their respective owners.
Contents
iii
Embedded Ultra-Low Power
Intel486
TM
SX Processor
1.0 INTRODUCTION ........................................................................................................................................ 1
1.1 Features ............................................................................................................................................. 1
1.2 Family Members ................................................................................................................................. 2
2.0 HOW TO USE THIS DOCUMENT ............................................................................................................. 3
3.0 PIN DESCRIPTIONS ................................................................................................................................. 3
3.1 Pin Assignments ................................................................................................................................. 3
3.2 Pin Quick Reference ........................................................................................................................... 7
4.0 ARCHITECTURAL AND FUNCTIONAL OVERVIEW ............................................................................. 15
4.1 Separate Supply Voltages ................................................................................................................ 15
4.2 Fast Clock Restart ............................................................................................................................ 17
4.3 Level-Keeper Circuits ....................................................................................................................... 18
4.4 Low-Power Features ........................................................................................................................ 19
4.4.1 Auto Clock Freeze ................................................................................................................. 19
4.5 CPUID Instruction ............................................................................................................................. 19
4.5.1 Operation of the CPUID Instruction ....................................................................................... 19
4.6 Identification After Reset .................................................................................................................. 20
4.7 Boundary Scan (JTAG) .................................................................................................................... 21
4.7.1 Device Identification ............................................................................................................... 21
4.7.2 Boundary Scan Register Bits and Bit Order ........................................................................... 21
5.0 ELECTRICAL SPECIFICATIONS ........................................................................................................... 22
5.1 Maximum Ratings ............................................................................................................................. 22
5.2 DC Specifications ............................................................................................................................. 22
5.3 AC Specifications ............................................................................................................................. 25
5.4 Capacitive Derating Curves .............................................................................................................. 32
6.0 MECHANICAL DATA .............................................................................................................................. 33
6.1 Package Dimensions ........................................................................................................................ 33
6.2 Package Thermal Specifications ...................................................................................................... 34
FIGURES
Figure 1.
Embedded Ultra-Low Power Intel486TM SX Processor Block Diagram ...................................... i
Figure 2.
Package Diagram for 176-Lead TQFP Package Embedded ULP Intel486TM SX Processor .... 4
Figure 3.
Example of Supply Voltage Power Sequence ......................................................................... 16
Figure 4.
Stop Clock State Diagram with Typical Power Consumption Values ...................................... 17
Figure 5.
CLK Waveform ........................................................................................................................ 28
Figure 6.
Input Setup and Hold Timing ................................................................................................... 28
Figure 7.
Input Setup and Hold Timing ................................................................................................... 29
Figure 8.
Output Valid Delay Timing ....................................................................................................... 29
Figure 9.
Maximum Float Delay Timing .................................................................................................. 30
Contents
iv
Figure 10.
TCK Waveform ........................................................................................................................ 30
Figure 11.
Test Signal Timing Diagram ..................................................................................................... 31
Figure 12.
Typical Loading Delay versus Load Capacitance under Worst-Case Conditions
for a Low-to-High Transition ..................................................................................................... 32
Figure 13.
Typical Loading Delay versus Load Capacitance under Worst-Case Conditions
for a High-to-Low Transition ..................................................................................................... 32
Figure 14.
Package Mechanical Specifications for the 176 Lead TQFP Package .................................... 33
TABLES
Table 1.
The Embedded Ultra-Low Power Intel486
TM
SX Processor ....................................................... 2
Table 2.
Pin Assignment for 176-Lead TQFP Package Embedded ULP Intel486TM SX Processor ........ 5
Table 3.
Pin Cross Reference for 176-Lead TQFP Package Embedded ULP
Intel486TM SX Processor ............................................................................................................ 6
Table 4.
Embedded ULP Intel486TM SX Processor Pin Descriptions ...................................................... 7
Table 5.
Output Pins .............................................................................................................................. 12
Table 6.
Input/Output Pins ..................................................................................................................... 13
Table 7.
Test Pins .................................................................................................................................. 13
Table 8.
Input Pins ................................................................................................................................. 14
Table 9.
CPUID Instruction Description ................................................................................................. 19
Table 10.
Boundary Scan Component Identification Code ...................................................................... 21
Table 11.
Absolute Maximum Ratings ..................................................................................................... 22
Table 12.
Operating Supply Voltages ...................................................................................................... 22
Table 13.
DC Specifications ..................................................................................................................... 23
Table 14.
Active I
CC
Values ..................................................................................................................... 24
Table 15.
Clock Stop, Stop Grant, and Auto HALT Power Down I
CC
Values .......................................... 24
Table 16.
AC Characteristics ................................................................................................................... 25
Table 17.
AC Specifications for the Test Access Port ............................................................................. 27
Table 18.
Thermal Resistance ................................................................................................................. 34
Table 19.
Maximum Ambient Temperature (T
A
) ...................................................................................... 34
Embedded Ultra-Low Power Intel486TM SX Processor
1
1.0
INTRODUCTION
This data sheet describes the embedded Ultra-Low
Power (ULP) Intel486TM SX processor. It is intended
for embedded battery-operated and hand-held appli-
cations. The embedded ULP Intel486 SX processor
provides all of the features of the Intel486 SX
processor except for the external data-bus parity
logic and the processor-upgrade pin. The processor
typically uses 20% to 50% less power than the
Intel486 SX processor. Additionally, the embedded
ULP Intel486 SX processor external data bus has
level-keeper circuitry and a fast-recovery core clock
which are vital for ultra-low-power system designs.
The processor is available in a Thin Quad Flat
Package (TQFP) enabling low-profile component
implementation.
The embedded ULP Intel486 SX processor consists
of a 32-bit integer processing unit, an on-chip cache,
and a memory management unit. The design
ensures full instruction-set compatibility with the
8086, 8088, 80186, 80286, Intel386TM SX, Intel386
DX, and all versions of Intel486 processors.
1.1
Features
The embedded ULP Intel486 SX processor offers
these features of the Intel486 SX processor:
32-bit RISC-Technology Core -- The embedded
ULP Intel486 SX processor performs a complete
set of arithmetic and logical operations on 8-, 16-,
and 32-bit data types using a full-width ALU and
eight general purpose registers.
Single Cycle Execution -- Many instructions
execute in a single clock cycle.
Instruction Pipelining -- Overlapped instruction
fetching, decoding, address translation and
execution.
On-Chip Cache with Cache Consistency
Support -- An 8-Kbyte, write-through, internal
cache is used for both data and instructions.
Cache hits provide zero wait-state access times
for data within the cache. Bus activity is tracked to
detect alterations in the memory represented by
the internal cache. The internal cache can be
invalidated or flushed so that an external cache
controller can maintain cache consistency.
External Cache Control -- Write-back and flush
controls for an external cache are provided so the
processor can maintain cache consistency.
On-Chip Memory Management Unit -- Address
management and memory space protection
mechanisms maintain the integrity of memory in a
multitasking and virtual memory environment. Both
segmentation and paging are supported.
Burst Cycles -- Burst transfers allow a new
double word to be read from memory on each bus
clock cycle. This capability is especially useful for
instruction prefetch and for filling the internal
cache.
Write Buffers -- The processor contains four
write buffers to enhance the performance of
consecutive writes to memory. The processor can
continue internal operations after a write to these
buffers, without waiting for the write to be
completed on the external bus.
Bus Backoff -- When another bus master needs
control of the bus during a processor initiated bus
cycle, the embedded ULP Intel486 SX processor
floats its bus signals, then restarts the cycle when
the bus becomes available again.
Instruction Restart -- Programs can continue
execution following an exception generated by an
unsuccessful attempt to access memory. This
feature is important for supporting demand-paged
virtual memory applications.
Dynamic Bus Sizing -- External controllers can
dynamically alter the effective width of the data
bus. Bus widths of 8, 16, or 32 bits can be used.
Boundary Scan (JTAG) -- Boundary Scan
provides in-circuit testing of components on
printed circuit boards. The Intel Boundary Scan
implementation conforms with the IEEE Standard
Test Access Port and Boundary Scan Architecture.
Intel System Management Mode (SMM) -- A
unique Intel architecture operating mode provides
a dedicated special purpose interrupt and address
space that can be used to implement intelligent
power management and other enhanced functions
in a manner that is completely transparent to the
operating system and applications software.
I/O Restart -- An I/O instruction interrupted by a
System Management Interrupt (SMI#) can
automatically be restarted following the execution
of the RSM instruction.
Stop Clock -- The embedded ULP Intel486 SX
processor has a stop clock control mechanism that
provides two low-power states: a Stop Grant state
(4085 mW typical, depending on input clock
frequency) and a Stop Clock state (~60 W typical,
with input clock frequency of 0 MHz).
2
Embedded Ultra-Low Power Intel486TM SX Processor
Auto HALT Power Down -- After the execution of
a HALT instruction, the embedded ULP Intel486
SX processor issues a normal Halt bus cycle and
the clock input to the processor core is automati-
cally stopped, causing the processor to enter the
Auto HALT Power Down state (4085 mW typical,
depending on input clock frequency).
The embedded ULP Intel486 SX processor differs
from the Intel486 SX processor in the following
areas:
Processor Upgrade Removed -- The UP# signal
is not provided.
Parity Signals Removed -- The DP3-DP0 and
PCHK# signals are not provided.
Separate Processor-Core Power -- While the
embedded ULP Intel486 SX processor requires a
supply voltage of 3.3 V, the processor core has
dedicated V
CC
pins and operates with a supply
voltage as low as 2.4 V.
Small, Low-Profile Package -- The 176-Lead
Thin Quad Flat Pack (TQFP) package is approxi-
mately 26 mm square and only 1.5 mm in height.
This is approximately the diameter and thickness
of a U.S. quarter. The embedded ULP Intel486 SX
processor is ideal for embedded hand-held and
battery-powered applications.
Level Keeper Circuits -- The embedded ULP
Intel486 SX processor has level-keeper circuits for
its 32-bit external data bus signals. They retain
valid high and low logic voltage levels when the
processor is in the Stop Grant and Stop Clock
states. This is a power-saving improvement from
the floating data bus of the Intel486 SX processor.
Auto Clock Freeze -- The embedded ULP
Intel486 SX processor monitors bus events and
internal activity. The Auto Clock Freeze feature
automatically controls internal clock distribution,
turning off clocks to internal units when they are
idle. This power-saving function is transparent to
the embedded system.
Fast Clock Restart -- The embedded ULP
Intel486 SX processor requires only eight clock
periods to synchronize its internal clock with the
CLK input signal. This provides for faster transition
from the Stop Clock State to the Normal State. For
33-MHz operation, this synchronization time is
only 240 ns compared with 1 ms (PLL startup
latency) for the Intel486 processor.
1.2
Family Members
Table 1 shows the embedded ULP Intel486 SX
processor and briefly describes its characteristics.
Table 1. The Embedded Ultra-Low Power Intel486
TM
SX Processor
Product
Supply
Voltage
(V
CCP
)
Processor
Core Supply
Voltage
(V
CC
)
Processor
Frequency
(MHz)
Package
FA80486SXSF-33
3.3 V
2.4 V to 3.3 V
25
176-Lead
TQFP
2.7 V to 3.3 V
33
Embedded Ultra-Low Power Intel486TM SX Processor
3
2.0
HOW TO USE THIS DOCUMENT
The embedded ULP Intel486 SX processor has
characteristics similar to the Intel486 SX processor.
This document describes the new features of the
embedded ULP Intel486 SX processor. Some
Intel486 SX processor information is also included to
minimize the dependence on the reference
documents.
For a complete set of documentation related to the
embedded ULP Intel486 SX processor, use this
document in conjunction with the following reference
documents:
Embedded Intel486TM Processor Family
Developer's Manual
-- Order No. 273021
Embedded Intel486TM Processor Hardware
Reference Manual
-- Order No. 273025
Intel Application Note AP-485 --
Intel Processor
Identification with the CPUID Instruction
--
Order No. 241618
3.0
PIN DESCRIPTIONS
3.1
Pin Assignments
The following figures and tables show the pin assign-
ments for the 176-pin Thin Quad Flat Pack (TQFP)
package of the embedded ULP Intel486 SX
processor. Included are:
Figure 2, Package Diagram for 176-Lead TQFP
Package Embedded ULP Intel486TM SX Processor
(pg. 4)
Table 2, Pin Assignment for 176-Lead TQFP
Package Embedded ULP Intel486TM SX Processor
(pg. 5)
Table 3, Pin Cross Reference for 176-Lead TQFP
Package Embedded ULP Intel486TM SX Processor
(pg. 6)
Table 4, Embedded ULP Intel486TM SX Processor
Pin Descriptions (pg. 7)
Table 5, Output Pins (pg. 13)
Table 6, Input/Output Pins (pg. 13)
Table 7, Test Pins (pg. 14)
Table 8, Input Pins (pg. 14)
The tables and figures show "no-connects" as "N/C."
These pins should always remain unconnected.
Connecting N/C pins to V
CC
, V
CCP
, V
SS
, or any other
signal pin can result in component malfunction or
incompatibility with future steppings of the
embedded ULP Intel486 SX processor.
Embedded Ultra-Low Power Intel486TM SX Processor
4
Figure 2. Package Diagram for 176-Lead TQFP Package Embedded ULP Intel486TM SX Processor
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
BLAST#
VCC
PLOCK#
LOCK#
VSS
VCCP
N/C
BRDY#
BOFF#
BS16#
BS8#
VCC
N/C
RDY#
KEN#
VCC
VSS
HOLD
AHOLD
TCK
VCC
VCC
VSS
VCC
VCC
VSS
CLK
HLDA
W/R#
VSS
VCCP
BREQ
BE0#
BE1#
BE2#
BE3#
VCC
M/IO#
D/C#
PWT
PCD
VCCP
VSS
VCC
176-Lead TQFP
(top view)
45
46
47
48
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
49
50
51
52
53
EADS#
A2
0
M
#
R
ESET
VSS
F
L
USH#
IN
T
R
NM
I
SRESE
T
SM
IACT
#
VC
C
VSS
VCCP
SM
I#
TD
O
VC
C
ST
PCL
K
#
D3
1
D3
0
D2
9
D2
8
VC
C
VCCP
VSS
D2
7
D2
6
D2
5
D2
4
VCCP
VSS
D2
3
D2
2
D2
1
VCCP
VSS
D2
0
D1
9
D1
8
VC
C
D1
7
VSS
VSS
VCCP
D1
6
VSS
132
131
130
129
128
127
126
125
124
123
122
121
120
119
118
117
116
115
114
113
112
111
110
109
108
107
106
105
104
103
102
101
100
99
98
97
96
95
94
93
92
91
90
89
VSS
VSS
VCCP
A25
A26
A27
A28
VCCP
A29
A30
A31
VSS
D0
D1
D2
D3
D4
VCC
VSS
VCC
VCC
VSS
VCC
VCC
VSS
VCCP
D5
D6
VCCP
N/C
D7
VSS
D8
D9
VSS
VCC
D10
D11
D12
D13
VSS
VCCP
D14
D15
ADS#
A2
VSS
VCCP
VSS
VSS
VCCP
A3
A4
A5
RESERV
E
D#
A6
A7
A8
VSS
VCC
A9
A1
0
VCCP
VSS
VCC
A1
1
A1
2
VCC
A1
3
A1
4
VCCP
VSS
A1
5
A1
6
A1
7
VSS
VCCP
TD
I
TM
S
A1
8
A1
9
A2
0
VCCP
VCCP
A2
1
A2
2
A2
3
A2
4
17
6
17
5
17
4
17
3
17
2
17
1
17
0
16
9
16
8
16
7
16
6
16
5
16
4
16
3
16
2
16
1
16
0
15
9
15
8
15
7
15
6
15
5
15
4
15
3
15
2
15
1
15
0
14
9
14
8
14
7
14
6
14
5
14
4
14
3
14
2
14
1
14
0
13
9
13
8
13
7
13
6
13
5
13
4
13
3
Embedded Ultra-Low Power Intel486TM SX Processor
5
Table 2. Pin Assignment for 176-Lead TQFP Package
Embedded ULP Intel486TM SX Processor
Pin #
Description
Pin #
Description
Pin #
Description
Pin #
Description
1
BLAST#
45
EADS#
89
D15
133
A24
2
V
CC
46
A20M#
90
D14
134
A23
3
PLOCK#
47
RESET
91
V
CCP
135
A22
4
LOCK#
48
V
SS
92
V
SS
136
A21
5
V
SS
49
FLUSH#
93
D13
137
V
CCP
6
V
CCP
50
INTR
94
D12
138
V
CCP
7
N/C
51
NMI
95
D11
139
A20
8
BRDY#
52
SRESET
96
D10
140
A19
9
BOFF#
53
SMIACT#
97
V
CC
141
A18
10
BS16#
54
V
CC
98
V
SS
142
TMS
11
BS8#
55
V
SS
99
D9
143
TDI
12
V
CC
56
V
CCP
100
D8
144
V
CCP
13
N/C
57
SMI#
101
V
SS
145
V
SS
14
RDY#
58
TDO
102
D7
146
A17
15
KEN#
59
V
CC
103
N/C
147
A16
16
V
CC
60
STPCLK#
104
V
CCP
148
A15
17
V
SS
61
D31
105
D6
149
V
SS
18
HOLD
62
D30
106
D5
150
V
CCP
19
AHOLD
63
D29
107
V
CCP
151
A14
20
TCK
64
D28
108
V
SS
152
A13
21
V
CC
65
V
CC
109
V
CC
153
V
CC
22
V
CC
66
V
CCP
110
V
CC
154
A12
23
V
SS
67
V
SS
111
V
SS
155
A11
24
V
CC
68
D27
112
V
CC
156
V
CC
25
V
CC
69
D26
113
V
CC
157
V
SS
26
V
SS
70
D25
114
V
SS
158
V
CCP
27
CLK
71
D24
115
V
CC
159
A10
28
HLDA
72
V
CCP
116
D4
160
A9
29
W/R#
73
V
SS
117
D3
161
V
CC
30
V
SS
74
D23
118
D2
162
V
SS
31
V
CCP
75
D22
119
D1
163
A8
32
BREQ
76
D21
120
D0
164
A7
33
BE0#
77
V
CCP
121
V
SS
165
A6
34
BE1#
78
V
SS
122
A31
166
RESERVED#
35
BE2#
79
D20
123
A30
167
A5
36
BE3#
80
D19
124
A29
168
A4
37
V
CC
81
D18
125
V
CCP
169
A3
38
M/IO#
82
V
CC
126
A28
170
V
CCP
39
D/C#
83
D17
127
A27
171
V
SS
40
PWT
84
V
SS
128
A26
172
V
SS
41
PCD
85
V
SS
129
A25
173
V
CCP
42
V
CCP
86
V
CCP
130
V
CCP
174
V
SS
43
V
SS
87
D16
131
V
SS
175
A2
44
V
CC
88
V
SS
132
V
SS
176
ADS#
Embedded Ultra-Low Power Intel486TM SX Processor
6
Table 3. Pin Cross Reference for 176-Lead TQFP Package
Embedded ULP Intel486TM SX Processor
Address
Pin #
Data
Pin #
Control
Pin #
N/C
V
CCP
V
CC
V
SS
A2
175
D0
120
AHOLD
19
7
6
2
5
A3
169
D1
119
BE0#
33
13
31
12
17
A4
168
D2
118
BE1#
34
103
42
16
23
A5
167
D3
117
BE2#
35
56
21
26
A6
165
D4
116
BE3#
36
66
22
30
A7
164
D5
106
BLAST#
1
72
24
43
A8
163
D6
105
BOFF#
9
77
25
48
A9
160
D7
102
BRDY#
8
86
37
55
A10
159
D8
100
BREQ
32
91
44
67
A11
155
D9
99
BS16#
10
104
54
73
A12
154
D10
96
BS8#
11
107
59
78
A13
152
D11
95
CLK
27
125
65
84
A14
151
D12
94
D/C#
39
130
82
85
A15
148
D13
93
HLDA
28
137
97
88
A16
147
D14
90
HOLD
18
138
109
92
A17
146
D15
89
KEN#
15
144
110
98
A18
141
D16
87
LOCK#
4
150
112
101
A19
140
D17
83
M/IO#
38
158
113
108
A20
139
D18
81
PCD
41
170
115
111
A21
136
D19
80
PLOCK#
3
173
153
114
A22
135
D20
79
PWT
40
156
121
A23
134
D21
76
RESERVED#
166
161
131
A24
133
D22
75
RDY#
14
132
A25
129
D23
74
TCK
20
145
A26
128
D24
71
W/R#
29
149
A27
127
D25
70
A20M#
46
157
A28
126
D26
69
EADS#
45
162
A29
124
D27
68
FLUSH#
49
171
A30
123
D28
64
INTR
50
172
A31
122
D29
63
NMI
51
174
D30
62
RESET
47
D31
61
SMI#
57
SMIACT#
53
SRESET
52
STPCLK#
60
TDO
58
ADS#
176
TDI
143
TMS
142
W/R#
29
Embedded Ultra-Low Power Intel486TM SX Processor
7
3.2
Pin Quick Reference
The following is a brief pin description. For detailed signal descriptions refer to Appendix A, "Signal Descrip-
tions," in the
Embedded Intel486TM Processor Family Developer's Manual,
order No. 273021.
Table 4. Embedded ULP Intel486TM SX Processor Pin Descriptions (Sheet 1 of 6)
Symbol
Type
Name and Function
CLK
I
Clock
provides the fundamental timing and internal operating frequency for the
embedded ULP Intel486 SX processor. All external timing parameters are
specified with respect to the rising edge of CLK.
ADDRESS BUS
A31-A4
A3A2
I/O
O
Address Lines A31A2, together with the byte enable signals, BE3#BE0#,
define the physical area of memory or input/output space accessed. Address lines
A31A4 are used to drive addresses into the embedded ULP Intel486 SX
processor to perform cache line invalidation. Input signals must meet setup and
hold times t
22
and t
23
. A31A2 are not driven during bus or address hold.
BE3#
BE2#
BE1#
BE0#
O
O
O
O
Byte Enable
signals indicate active bytes during read and write cycles. During the
first cycle of a cache fill, the external system should assume that all byte enables
are active. BE3#BE0# are active LOW and are not driven during bus hold.
BE3# applies to D31D24
BE2# applies to D23D16
BE1# applies to D15D8
BE0# applies to D7D0
DATA BUS
D31D0
I/O
Data Lines. D7D0 define the least significant byte of the data bus; D31D24
define the most significant byte of the data bus. These signals must meet setup
and hold times t
22
and t
23
for proper operation on reads. These pins are driven
during the second and subsequent clocks of write cycles.
Embedded Ultra-Low Power Intel486TM SX Processor
8
BUS CYCLE DEFINITION
M/IO#
D/C#
W/R#
O
O
O
Memory/Input-Output
,
Data/Control
and Write/Read
lines are the primary bus
definition signals. These signals are driven valid as the ADS# signal is asserted.
M/IO#
D/C#
W/R#
Bus Cycle Initiated
0
0
0
Interrupt Acknowledge
0
0
1
HALT/Special Cycle (see details below)
0
1
0
I/O Read
0
1
1
I/O Write
1
0
0
Code Read
1
0
1
Reserved
1
1
0
Memory Read
1
1
1
Memory Write
HALT/Special Cycle
Cycle Name
BE3# - BE0#
A4-A2
Shutdown 1110 000
HALT 1011
000
Stop Grant bus cycle
1011
100
LOCK#
O
Bus Lock
indicates that the current bus cycle is locked. The embedded ULP
Intel486 SX processor does not allow a bus hold when LOCK# is asserted
(address holds are allowed). LOCK# goes active in the first clock of the first locked
bus cycle and goes inactive after the last clock of the last locked bus cycle. The
last locked cycle ends when Ready is returned. LOCK# is active LOW and not
driven during bus hold. Locked read cycles are not transformed into cache fill
cycles when KEN# is returned active.
PLOCK#
O
Pseudo-Lock indicates that the current bus transaction requires more than one
bus cycle to complete. For the embedded ULP Intel486 SX processor, examples of
such operations are segment table descriptor reads (64 bits) and cache line fills
(128 bits).
The embedded ULP Intel486 SX processor drives PLOCK# active until the
addresses for the last bus cycle of the transaction are driven, regardless of
whether RDY# or BRDY# have been returned.
PLOCK# is a function of the BS8#, BS16# and KEN# inputs. PLOCK# should be
sampled only in the clock in which Ready is returned. PLOCK# is active LOW and
is not driven during bus hold.
BUS CONTROL
ADS#
O
Address Status
output indicates that a valid bus cycle definition and address are
available on the cycle definition lines and address bus. ADS# is driven active in the
same clock in which the addresses are driven. ADS# is active LOW and not driven
during bus hold.
Table 4. Embedded ULP Intel486TM SX Processor Pin Descriptions (Sheet 2 of 6)
Symbol
Type
Name and Function
Embedded Ultra-Low Power Intel486TM SX Processor
9
RDY#
I
Non-burst Ready
input indicates that the current bus cycle is complete. RDY#
indicates that the external system has presented valid data on the data pins in
response to a read or that the external system has accepted data from the
embedded ULP Intel486 SX processor in response to a write. RDY# is ignored
when the bus is idle and at the end of the first clock of the bus cycle.
RDY# is active during address hold. Data can be returned to the embedded ULP
Intel486 SX processor while AHOLD is active.
RDY# is active LOW and is not provided with an internal pull-up resistor. RDY#
must satisfy setup and hold times t
16
and t
17
for proper chip operation.
BURST CONTROL
BRDY#
I
Burst Ready
input performs the same function during a burst cycle that RDY#
performs during a non-burst cycle. BRDY# indicates that the external system has
presented valid data in response to a read or that the external system has
accepted data in response to a write. BRDY# is ignored when the bus is idle and at
the end of the first clock in a bus cycle.
BRDY# is sampled in the second and subsequent clocks of a burst cycle. Data
presented on the data bus is strobed into the embedded ULP Intel486 SX
processor when BRDY# is sampled active. If RDY# is returned simultaneously with
BRDY#, BRDY# is ignored and the burst cycle is prematurely aborted.
BRDY# is active LOW and is provided with a small pull-up resistor. BRDY# must
satisfy the setup and hold times t
16
and t
17
.
BLAST#
O
Burst Last
signal indicates that the next time BRDY# is returned, the burst bus
cycle is complete. BLAST# is active for both burst and non-burst bus cycles.
BLAST# is active LOW and is not driven during bus hold.
INTERRUPTS
RESET
I
Reset input forces the embedded ULP Intel486 SX processor to begin execution at
a known state. The processor cannot begin executing instructions until at least
1 ms after V
CC
, V
CCP
, and CLK have reached their proper DC and AC specifica-
tions. The RESET pin must remain active during this time to ensure proper
processor operation. However, for warm resets, RESET should remain active for at
least 15 CLK periods. RESET is active HIGH. RESET is asynchronous but must
meet setup and hold times t
20
and t
21
for recognition in any specific clock.
INTR
I
Maskable Interrupt
indicates that an external interrupt has been generated. When
the internal interrupt flag is set in EFLAGS, active interrupt processing is initiated.
The embedded ULP Intel486 SX processor generates two locked interrupt
acknowledge bus cycles in response to the INTR pin going active. INTR must
remain active until the interrupt acknowledges have been performed to ensure
processor recognition of the interrupt.
INTR is active HIGH and is not provided with an internal pull-down resistor. INTR is
asynchronous, but must meet setup and hold times t
20
and t
21
for recognition in
any specific clock.
NMI
I
Non-Maskable Interrupt
request signal indicates that an external non-maskable
interrupt has been generated. NMI is rising-edge sensitive and must be held LOW
for at least four CLK periods before this rising edge. NMI is not provided with an
internal pull-down resistor. NMI is asynchronous, but must meet setup and hold
times t
20
and t
21
for recognition in any specific clock.
Table 4. Embedded ULP Intel486TM SX Processor Pin Descriptions (Sheet 3 of 6)
Symbol
Type
Name and Function
Embedded Ultra-Low Power Intel486TM SX Processor
10
SRESET
I
Soft Reset pin duplicates all functionality of the RESET pin except that the
SMBASE register retains its previous value. For soft resets, SRESET must remain
active for at least 15 CLK periods. SRESET is active HIGH. SRESET is
asynchronous but must meet setup and hold times t
20
and t
21
for recognition in any
specific clock.
SMI#
I
System Management Interrupt input invokes System Management Mode (SMM).
SMI# is a falling-edge triggered signal which forces the embedded ULP Intel486
SX processor into SMM at the completion of the current instruction. SMI# is
recognized on an instruction boundary and at each iteration for repeat string
instructions. SMI# does not break LOCKed bus cycles and cannot interrupt a
currently executing SMM. The embedded ULP Intel486 SX processor latches the
falling edge of one pending SMI# signal while it is executing an existing SMI#. The
nested SMI# is not recognized until after the execution of a Resume (RSM)
instruction.
SMIACT#
O
System Management Interrupt Active, an active LOW output, indicates that the
embedded ULP Intel486 SX processor is operating in SMM. It is asserted when the
processor begins to execute the SMI# state save sequence and remains active
LOW until the processor executes the last state restore cycle out of SMRAM.
STPCLK#
I
Stop Clock Request input signal indicates a request was made to turn off or
change the CLK input frequency. When the embedded ULP Intel486 SX processor
recognizes a STPCLK#, it stops execution on the next instruction boundary (unless
superseded by a higher priority interrupt), empties all internal pipelines and write
buffers, and generates a Stop Grant bus cycle. STPCLK# is active LOW. Though
STPCLK# has an internal pull-up resistor, an external 10-K
pull-up resistor is
needed if the STPCLK# pin is not used. STPCLK# is an asynchronous signal,
but must remain active until the embedded ULP Intel486 SX processor issues
the Stop Grant bus cycle. STPCLK# may be de-asserted at any time after the
processor has issued the Stop Grant bus cycle.
BUS ARBITRATION
BREQ
O
Bus Request
signal indicates that the embedded ULP Intel486 SX processor has
internally generated a bus request. BREQ is generated whether or not the
processor is driving the bus. BREQ is active HIGH and is never floated.
HOLD
I
Bus Hold Request allows another bus master complete control of the embedded
ULP Intel486 SX processor bus. In response to HOLD going active, the processor
floats most of its output and input/output pins. HLDA is asserted after completing
the current bus cycle, burst cycle or sequence of locked cycles. The embedded
ULP Intel486 SX processor remains in this state until HOLD is de-asserted. HOLD
is active HIGH and is not provided with an internal pull-down resistor. HOLD must
satisfy setup and hold times t
18
and t
19
for proper operation.
HLDA
O
Hold Acknowledge
goes active in response to a hold request presented on the
HOLD pin. HLDA indicates that the embedded ULP Intel486 SX processor has
given the bus to another local bus master. HLDA is driven active in the same clock
that the processor floats its bus. HLDA is driven inactive when leaving bus hold.
HLDA is active HIGH and remains driven during bus hold.
Table 4. Embedded ULP Intel486TM SX Processor Pin Descriptions (Sheet 4 of 6)
Symbol
Type
Name and Function
Embedded Ultra-Low Power Intel486TM SX Processor
11
BOFF#
I
Backoff
input forces the embedded ULP Intel486 SX processor to float its bus in
the next clock. The processor floats all pins normally floated during bus hold but
HLDA is not asserted in response to BOFF#. BOFF# has higher priority than RDY#
or BRDY#; if both are returned in the same clock, BOFF# takes effect. The
embedded ULP Intel486 SX processor remains in bus hold until BOFF# is
negated. If a bus cycle is in progress when BOFF# is asserted the cycle is
restarted. BOFF# is active LOW and must meet setup and hold times t
18
and t
19
for
proper operation.
CACHE INVALIDATION
AHOLD
I
Address Hold
request allows another bus master access to the embedded ULP
Intel486 SX processor's address bus for a cache invalidation cycle. The processor
stops driving its address bus in the clock following AHOLD going active. Only the
address bus is floated during address hold, the remainder of the bus remains
active. AHOLD is active HIGH and is provided with a small internal pull-down
resistor. For proper operation, AHOLD must meet setup and hold times t
18
and t
19
.
EADS#
I
External Address - This signal indicates that a
valid
external address has been
driven onto the embedded ULP Intel486 SX processor address pins. This address
is used to perform an internal cache invalidation cycle. EADS# is active LOW and
is provided with an internal pull-up resistor. EADS# must satisfy setup and hold
times t
12
and t
13
for proper operation.
CACHE CONTROL
KEN#
I
Cache Enable
pin is used to determine whether the current cycle is cacheable.
When the embedded ULP Intel486 SX processor generates a cycle that can be
cached and KEN# is active one clock before RDY# or BRDY# during the first
transfer of the cycle, the cycle becomes a cache line fill cycle. Returning KEN#
active one clock before RDY# during the last read in the cache line fill causes the
line to be placed in the on-chip cache. KEN# is active LOW and is provided with a
small internal pull-up resistor. KEN# must satisfy setup and hold times t
14
and t
15
for proper operation.
FLUSH#
I
Cache Flush
input forces the embedded ULP Intel486 SX processor to flush its
entire internal cache. FLUSH# is active LOW and need only be asserted for one
clock. FLUSH# is asynchronous but setup and hold times t
20
and t
21
must be met
for recognition in any specific clock.
PAGE CACHEABILITY
PWT
PCD
O
O
Page Write-Through
and Page Cache Disable pins reflect the state of the page
attribute bits, PWT and PCD, in the page table entry, page directory entry or
control register 3 (CR3) when paging is enabled. When paging is disabled, the
embedded ULP Intel486 SX processor ignores the PCD and PWT bits and
assumes they are zero for the purpose of caching and driving PCD and PWT pins.
PWT and PCD have the same timing as the cycle definition pins (M/IO#, D/C#, and
W/R#). PWT and PCD are active HIGH and are not driven during bus hold. PCD is
masked by the cache disable bit (CD) in Control Register 0.
Table 4. Embedded ULP Intel486TM SX Processor Pin Descriptions (Sheet 5 of 6)
Symbol
Type
Name and Function
Embedded Ultra-Low Power Intel486TM SX Processor
12
BUS SIZE CONTROL
BS16#
BS8#
I
I
Bus Size 16
and Bus Size 8
pins (bus sizing pins) cause the embedded ULP
Intel486 SX processor to run multiple bus cycles to complete a request from
devices that cannot provide or accept 32 bits of data in a single cycle. The bus
sizing pins are sampled every clock. The processor uses the state of these pins in
the clock before Ready to determine bus size. These signals are active LOW and
are provided with internal pull-up resistors. These inputs must satisfy setup and
hold times t
14
and t
15
for proper operation.
ADDRESS MASK
A20M#
I
Address Bit 20 Mask pin, when asserted, causes the embedded ULP Intel486 SX
processor to mask physical address bit 20 (A20) before performing a lookup to the
internal cache or driving a memory cycle on the bus. A20M# emulates the address
wraparound at 1 Mbyte, which occurs on the 8086 processor. A20M# is active
LOW and should be asserted only when the embedded ULP Intel486 SX processor
is in real mode. This pin is asynchronous but should meet setup and hold times t
20
and t
21
for recognition in any specific clock. For proper operation, A20M# should
be sampled HIGH at the falling edge of RESET.
TEST ACCESS PORT
TCK
I
Test Clock, an input to the embedded ULP Intel486 SX processor, provides the
clocking function required by the JTAG Boundary scan feature. TCK is used to
clock state information (via TMS) and data (via TDI) into the component on the
rising edge of TCK. Data is clocked out of the component (via TDO) on the falling
edge of TCK. TCK is provided with an internal pull-up resistor.
TDI
I
Test Data Input is the serial input used to shift JTAG instructions and data into the
processor. TDI is sampled on the rising edge of TCK, during the SHIFT-IR and
SHIFT-DR TAP controller states. During all other Test Access Port (TAP) controller
states, TDI is a "don't care." TDI is provided with an internal pull-up resistor.
TDO
O
Test Data Output is the serial output used to shift JTAG instructions and data out
of the component. TDO is driven on the falling edge of TCK during the SHIFT-IR
and SHIFT-DR TAP controller states. At all other times TDO is driven to the high
impedance state.
TMS
I
Test Mode Select is decoded by the JTAG TAP to select test logic operation. TMS
is sampled on the rising edge of TCK. To guarantee deterministic behavior of the
TAP controller, TMS is provided with an internal pull-up resistor.
RESERVED PINS
RESERVED#
I
Reserved is reserved for future use. This pin MUST be connected to an external
pull-up resistor circuit. The recommended resistor value is 10 kOhms.
Table 4. Embedded ULP Intel486TM SX Processor Pin Descriptions (Sheet 6 of 6)
Symbol
Type
Name and Function
Embedded Ultra-Low Power Intel486TM SX Processor
13
Table 5. Output Pins
Name
Active Level
Output Signal
Floated During
Address Hold
Floated During
Bus Hold
During Stop Grant and
Stop Clock States
1
BREQ
HIGH
Previous State
HLDA
HIGH
As per HOLD
BE3#-BE0#
LOW
Previous State
PWT, PCD
HIGH
Previous State
W/R#, M/IO#, D/C#
HIGH/LOW
Previous State
LOCK#
LOW
HIGH (inactive)
PLOCK#
LOW
HIGH (inactive)
ADS#
LOW
HIGH (inactive)
BLAST#
LOW
Previous State
A3-A2
HIGH
Previous State
SMIACT#
LOW
Previous State
NOTES:
1. The term "Previous State" means that the processor maintains the logic level applied to the signal pin just before the pro-
cessor entered the Stop Grant state. This conserves power by preventing the signal pin from floating.
Table 6. Input/Output Pins
Name
Active Level
Output Signal
Floated During
Address Hold
Floated During
Bus Hold
During Stop Grant and
Stop Clock States
1,2
D31-D0
HIGH
Level-Keeper
A31-A4
HIGH
Previous State
NOTES:
1. The term "Level-Keeper" means that the processor maintains the most recent logic level applied to the signal pin. This con-
serves power by preventing the signal pin from floating. If a system component, other than the processor, temporarily drives
these signal pins and then floats them, the processor forces and maintains the most recent logic levels that were applied by
the system component.
2. The term "Previous State" means that the processor maintains the logic level applied to the signal pin just before the pro-
cessor entered the Stop Grant state. This conserves power by preventing the signal pin from floating.
Embedded Ultra-Low Power Intel486TM SX Processor
14
Table 7. Test Pins
Name
Input or Output
Sampled/ Driven On
TCK
Input
N/A
TDI
Input
Rising Edge of TCK
TDO
Output
Failing Edge of TCK
TMS
Input
Rising Edge of TCK
Table 8. Input Pins
Name
Active Level
Synchronous/
Asynchronous
Internal Pull-Up/
Pull-Down
CLK
RESET
HIGH
Asynchronous
SRESET
HIGH
Asynchronous
Pull-Down
HOLD
HIGH
Synchronous
AHOLD
HIGH
Synchronous
Pull-Down
EADS#
LOW
Synchronous
Pull-Up
BOFF#
LOW
Synchronous
Pull-Up
FLUSH#
LOW
Asynchronous
Pull-Up
A20M#
LOW
Asynchronous
Pull-Up
BS16#, BS8#
LOW
Synchronous
Pull-Up
KEN#
LOW
Synchronous
Pull-Up
RDY#
LOW
Synchronous
BRDY#
LOW
Synchronous
Pull-Up
INTR
HIGH
Asynchronous
NMI
HIGH
Asynchronous
RESERVED#
SMI#
LOW
Asynchronous
Pull-Up
STPCLK#
LOW
Asynchronous
Pull-Up
1
TCK
HIGH
Pull-Up
TDI
HIGH
Pull-Up
TMS
HIGH
Pull-Up
NOTE:
1. Though STPCLK# has an internal pull-up resistor, an external 10-K
pull-up resistor is needed if the STPCLK# pin is not
used.
Embedded Ultra-Low Power Intel486TM SX Processor
15
4.0
ARCHITECTURAL AND
FUNCTIONAL OVERVIEW
The embedded ULP Intel486 SX processor archi-
tecture is essentially the same as the 3.3 V Intel486
SX processor with a 1X clock (CLK) input. Refer to
the Embedded Intel486TM Processor Family
Developer's Manual, order number 273032, for a
description of the ULP Intel486 SX processor. The
following notes supplement the information in the
manual.
The information pertaining to parity signals for the
external data bus does not apply. The embedded
ULP Intel486 SX processor does not have DP0#,
DP1#, DP2#, DP3# and PCHK# signal pins.
References to the Upgrade Power Down Mode do
not apply. The embedded ULP Intel486 SX
processor does not have the UP# signal pin and
does not support the Intel OverDrive
processor.
References to "V
CC
" are called "V
CCP
" by the
embedded ULP Intel486 SX processor when the
supply voltage pertains to the processor's external
interface drivers and receivers. The term "V
CC
"
pertains only to the processor core supply voltage
of the embedded ULP Intel486 SX processor.
Information about the split-supply voltage is
provided in this datasheet.
The Phase-Locked Loop (PLL) of the 1X clock
(CLK) input has been replaced by a proprietary
Differential Delay Line (DDL) that has a faster
startup and recovery time. Datasheet references to
the PLL and its 1 ms recovery time are replaced
with the DDL circuit and its eight-CLK recovery
time. Information about the DDL and startup and
recovery latency is provided in this datasheet.
The embedded ULP Intel486 SX processor has
level-keeper circuits for its external 32-bit data bus
signals (D31-D0). The Intel486 SX processor
floats its data bus instead. More information about
the level-keeper circuitry is provided in this
datasheet.
The datasheet describes the processor supply-
current consumption for the Auto HALT Power
Down, Stop Grant, and Stop Clock states. This
supply-current consumption for the embedded
ULP Intel486 SX processor is much less than that
of the Intel486 SX processor. Information about
power consumption and these states is provided in
this datasheet.
The CPU ID, Boundary-Scan (JTAG) ID, and
boundary-scan register bits for the embedded ULP
Intel486 SX processor are in this datasheet.
The embedded ULP Intel486 SX processor has
one pin reserved for possible future use. This pin
is an input signal, pin 166. It is called
RESERVED# and must be connected to a 10-K
pull-up resistor.
4.1
Separate Supply Voltages
The embedded ULP Intel486 SX processor has
separate voltage-supply planes for its internal core-
processor circuits and its external driver/receiver
circuits. The supply voltage for the internal core
processor is named V
CC
and the supply voltage for
the external circuits is named V
CCP
.
For a single-supply voltage design, the embedded
ULP Intel486 SX processor is functional at
3.3 V 0.3 V. In this type of system design, the
processor's V
CC
and V
CCP
pins must be tied to the
same power plane.
Even though V
CCP
must be 3.3 V 0.3 V, the
processor's external-output circuits can drive TTL-
compatible components. However, the processor's
external-input circuits do not allow connection to
TTL-compatible components. Section 5.2, DC Speci-
fications (pg. 22) contains the DC specifications for
the processor's input and output signals.
For lower-power operation, a separate, lower voltage
for V
CC
can be chosen, but V
CCP
must be
3.3 V 0.3 V. Any voltage value between 2.4 V and
3.3 V can be chosen for V
CC
for guaranteed
processor operation up to 25 MHz. The embedded
ULP Intel486 SX processor can also operate at
33 MHz, provided the V
CC
value chosen is between
2.7 V and 3.3 V. Section 5.2, DC Specifications (pg.
22) defines supply voltage specifications.
In systems with separate V
CC
and V
CCP
power
planes, the processor-core voltage supply must
always be less than or equal to the processor's
external-interface voltage supply; e.g., the system
design must guarantee:
V
CC
V
CCP
Violating this relationship causes excessive power
consumption. Limited testing has shown no
component damage when this relationship is
violated. However, prolonged violation is not recom-
mended and component integrity is not guaranteed.
16
Embedded Ultra-Low Power Intel486TM SX Processor
The V
CC
V
CCP
relationship must also be
guaranteed by the system design during power-up
and power-down sequences. Refer to Figure 3.
Even though V
CC
must be less than or equal to
V
CCP
, it is recommended that the system's power-on
sequence allows V
CC
to quickly achieve its opera-
tional level once V
CCP
achieves its operational level.
Similarly, the power-down sequence should allow
V
CCP
to power down quickly after V
CC
is below the
operational voltage level. These recommendations
are given to keep power consumption at a minimum.
Deviating from the recommendations does not
create a component reliability problem, but power
consumption of the processor's external interface
circuits increases beyond normal operating values.
Figure 3. Example of Supply Voltage Power Sequence
TIME
V
CCP
V
CC
0 V
V
CC
min
V
CCP
min
V
CC
and V
CCP
(V)
POWER OFF
POWER ON
17
Embedded Ultra-Low Power Intel486TM SX Processor
4.2
Fast Clock Restart
The embedded ULP Intel486 SX processor has an
integrated proprietary differential delay line (DDL)
circuit for internal clock generation. The DDL is
driven by the CLK input signal provided by the
external system. During normal operation, the
external system must guarantee that the CLK signal
maintains its frequency so that the clock period
deviates no more than 250 ps/CLK. This state,
called the Normal State, is shown in Figure 4.
To increase or decrease the CLK frequency more
quickly than this, the system must interrupt the
processor with the STPCLK# signal. Once the
processor indicates that it is in the Stop Grant State,
the system can adjust the CLK signal to the new
frequency, wait a minimum of eight CLK periods,
then force the processor to return to the normal
operational state by deactivating the STPCLK#
interrupt. This wait of eight CLK periods is much
faster than the 1 ms wait required by earlier Intel486
SX processor products.
While in the Stop Grant State, the external system
may deactivate the CLK signal to the processor. This
forces the processor to the Stop Clock State -- the
state in which the processor consumes the least
power. Once the system reactivates the CLK signal,
the processor transitions to the Stop Grant State
within eight CLK periods.
Normal operation can be resumed by deactivating
the STPCLK# interrupt signal. Here again, the
embedded ULP Intel486 SX processor recovers
from the Stop Clock State much faster than the 1 ms
PLL recovery of earlier Intel486 SX processors.
Figure 4. Stop Clock State Diagram with Typical Power Consumption Values
4 Auto HALT
Power Down State
CLK Running
40 - 85 mWatts
5 Stop Clock Snoop State
1 Normal State
2 Stop Grant State
3 Stop Clock State
EADS#
One Clock PowerUp
Perform Cache Invalidation
Normal Execution
CLK Running
40 - 85 mWatts
Internal Powerdown
CLK Stopped
~ 60 Watts
STPCLK#
deasserted
Stop CLK
Start CLK
plus DDL Startup
Latency
STPCLK# asserted
and Stop Grant bus
cycle generated
STPCLK# asserted and
Stop Grant bus cycle generated
STPCLK# deasserted and
HALT bus cycle generated
HALT asserted and
HALT bus cycle
generated
INTR, NMI, SMI#
RESET, SRESET
EADS#
Embedded Ultra-Low Power Intel486TM SX Processor
18
4.3
Level-Keeper Circuits
To obtain the lowest possible power consumption
during the Stop Grant and Stop Clock states, system
designers must ensure that:
input signals with pull-up resistors are not driven
LOW
input signals with pull-down resistors are not
driven HIGH
See Table 8, Input Pins (pg. 14) for the list of signals
with internal pull-up and pull-down resistors.
All other input pins except A31-A4 and D31-D0 must
be driven to the power supply rails to ensure lowest
possible current consumption.
During the Stop Grant and Stop Clock states, most
processor output signals maintain their previous
condition, which is the level they held when entering
the Stop Grant state. In response to HOLD driven
active during the Stop Grant state when the CLK
input is running, the embedded ULP Intel486 SX
processor generates HLDA and floats all output and
input/output signals which are floated during the
HOLD/HLDA state. When HOLD is deasserted,
processor signals which maintain their previous state
return to the state they were in prior to the
HOLD/HLDA sequence.
The data bus (D31-D0) also maintains its previous
state during the Stop Grant and Stop Clock states,
but does so differently, as described in the following
paragraphs.
The embedded ULP Intel486 SX processor's data
bus pins (D31-D0) have level keepers which
maintain their previous states while in the Stop Grant
and Stop Clock states. In response to HOLD driven
active during the Stop Grant state when the CLK
input is running, the embedded ULP Intel486 SX
processor generates HLDA and floats D31-D0
throughout the HOLD/HLDA cycles. When HOLD is
deasserted, the processor's D31-D0 signals return to
the states they were in prior to the HOLD/HLDA
sequence.
At all other times during the Stop Grant and Stop
Clock states, the processor maintains the logic
levels of D31-D0. When the external system circuitry
drives D31-D0 to different logic levels, the processor
flips its D31-D0 logic levels to match the ones driven
by the external system. The processor maintains
(keeps) these new levels even after the external
circuitry stops driving D31-D0.
For some system designs, external resistors may not
be required on D31- D0 (they are required on
previous Intel486 SX processor designs). System
designs that never request Bus Hold during the Stop
Grant and Stop Clock states might not require
external resistors. If the system design uses Bus
Hold during these states, the processor disables the
level-keepers and floats the data bus. This type of
design would require some kind of data bus termi-
nation to minimize power consumption. It is strongly
recommended that the D31-D0 pins do not have
network resistors connected. External resistors used
in the system design must be of a sufficient
resistance value to "flip" the level-keeper circuitry
and eliminate potential DC paths.
The level-keeper circuit is designed to allow an
external 27-K
pull-up resistor to switch the D31-D0
circuits to a logic-HIGH level even though the level-
keeper attempts to keep a logic-LOW level. In
general, pull-up resistors smaller than 27 K
can be
used as well as those greater than or equal to 1 M
.
Pull-down resistors, when connected to D31-D0,
should be least 800 K
.
Embedded Ultra-Low Power Intel486TM SX Processor
19
4.4
Low-Power Features
As with other Intel486 processors, the embedded
ULP Intel486 SX processor minimizes power
consumption by providing the Auto HALT Power
Down, Stop Grant, and Stop Clock states (see
Figure 4). The embedded ULP Intel486 SX
processor has an Auto Clock Freeze feature that
further conserves power by judiciously deactivating
its internal clocks while in the Normal Execution
Mode. The power-conserving mechanism is
designed such that it does not degrade processor
performance or require changes to AC timing specifi-
cations.
4.4.1
Auto Clock Freeze
To reduce power consumption, during the following
bus cycles -- under certain conditions -- the
processor slows-up or freezes some internal clocks:
Data-Read Wait Cycles (Memory, I/O and Interrupt
Acknowledge)
Data-Write Wait Cycles (Memory, I/O)
HOLD/HLDA Cycles
AHOLD Cycles
BOFF Cycles
Power is conserved during the wait periods in these
cycles until the appropriate external-system signals
are sent to the processor. These signals include:
READY
NMI, SMI#, INTR, and RESET
BOFF#
FLUSH#
EADS#
BS8#, BS16# and KEN# transitions
The embedded ULP Intel486 SX processor also
reduces power consumption by temporarily freezing
the clocks of its internal logic blocks. When a logic
block is idle or in a wait state, its clock is frozen.
4.5
CPUID Instruction
The embedded ULP Intel486 SX processor supports
the CPUID instruction (see Table 9). Because not all
Intel processors support the CPUID instruction, a
simple test can determine if the instruction is
supported. The test involves the processor's ID Flag,
which is bit 21 of the EFLAGS register. If software
can change the value of this flag, the CPUID
instruction is available. The actual state of the ID
Flag bit is irrelevant and provides no significance to
the hardware. This bit is cleared (reset to zero) upon
device reset (RESET or SRESET) for compatibility
with Intel486 processor designs that do not support
the CPUID instruction.
CPUID-instruction details are provided here for the
embedded ULP Intel486 SX processor. Refer to Intel
Application Note AP-485
Intel Processor Identifi-
cation with the CPUID Instruction
(Order No.
241618) for a description that covers all aspects of
the CPUID instruction and how it pertains to other
Intel processors.
4.5.1
Operation of the CPUID Instruction
The CPUID instruction requires the software
developer to pass an input parameter to the
processor in the EAX register. The processor
response is returned in registers EAX, EBX, EDX,
and ECX.
Table 9. CPUID Instruction Description
OP CODE
Instruction
Processor
Core Clocks
Parameter passed in
EAX
(Input Value)
Description
0F A2
CPUID
9
0
Vendor (Intel) ID String
14
1
Processor Identification
9
> 1
Undefined (Do Not Use)
Embedded Ultra-Low Power Intel486TM SX Processor
20
Vendor ID String - When the parameter passed in EAX is 0 (zero), the register values returned upon
instruction execution are shown in the following table.
The values in EBX, EDX and ECX indicate an Intel processor. When taken in the proper order, they decode to
the string "
GenuineIntel
."
Processor Identification - When the parameter passed to EAX is 1 (one), the register values returned upon
instruction execution are:
4.6
Identification After Reset
Processor Identification - Upon reset, the EDX register contains the processor signature:
31-------------24
23-----------16
15--------------8
7--------------0
High Value (= 1)
EAX
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 1
Vendor ID String
EBX
u
(75)
n
(6E)
e
(65)
G
(47)
(ASCII
EDX
I
(49)
e
(65)
n
(6E)
i
(69)
Characters)
ECX
l
(6C)
e
(65)
t
(74)
n
(6E)
31---------------------------14
13,12
11----8
7----4
3----0
Processor
Signature
EAX
(Do Not Use)
Intel Reserved
0 0
Processor
Type
0 1 0 0
Family
0 0 1 0
Model
XXXX
Stepping
(Intel releases information about stepping numbers as needed)
31--------------------------------------------------------------------------------------------------0
Intel Reserved
EBX
Intel Reserved
(Do Not Use)
ECX
Intel Reserved
31----------------------------------------------------------------------------2
1
0
Feature Flags
EDX
0------------------------------------------------------------------------------0
1
VME
0
FPU
31---------------------------14
13,12
11----8
7----4
3----0
Processor
Signature
EDX
(Do Not Use)
Intel Reserved
0 0
Processor
Type
0 1 0 0
Family
0 0 1 0
Model
XXXX
Stepping
(Intel releases information about stepping numbers as needed)
Embedded Ultra-Low Power Intel486TM SX Processor
21
4.7
Boundary Scan (JTAG)
4.7.1
Device Identification
Table 10 shows the 32-bit code for the embedded ULP Intel486 SX processor which is loaded into the Device
Identification Register.
Table 10. Boundary Scan Component Identification Code
Version
Part Number
Mfg ID
009H = Intel
1
V
CC
0=5V
1=3.3 V
Intel
Architecture
Type
Family
0100 = Intel486
CPU Family
Model
00010 =
embedded ULP
Intel486 SX
processor
31----28
27
26-----------21
20----17
16--------12
11------------1
0
XXXX
1
000001
0100
00010
00000001001
1
(Intel releases information about version numbers as needed)
Boundary Scan Component Identification Code = x828 2013 (Hex)
4.7.2
Boundary Scan Register Bits and Bit
Order
The boundary scan register contains a cell for each
pin as well as cells for control of bidirectional and
three-state pins. There are "Reserved" bits which
correspond to no-connect (N/C) signals of the
embedded ULP Intel486 SX processor. Control
registers WRCTL, ABUSCTL, BUSCTL, and
MISCCTL are used to select the direction of bidirec-
tional or three-state output signal pins. A "1" in these
cells designates that the associated bus or bits are
floated if the pins are three-state, or selected as
input if they are bidirectional.
WRCTL controls D31-D0
ABUSCTL controls A31-A2
BUSCTL controls ADS#, BLAST#, PLOCK#,
LOCK#, W/R#, BE0#, BE1#, BE2#, BE3#, M/IO#,
D/C#, PWT, and PCD
MISCCTL controls HLDA, and BREQ
The following is the bit order of the embedded ULP
Intel486 SX processor boundary scan register:
TDO
A2, A3, A4, A5, RESERVED#, A6,
A7, A8, A9, A10, A11, A12, A13,
A14, A15, A16, A17, A18, A19,
A20, A21, A22, A23, A24, A25,
A26, A27, A28, A29, A30, A31,
Reserved, D0, D1, D2, D3, D4,
D5, D6, D7, Reserved, D8, D9,
D10, D11, D12, D13, D14, D15,
Reserved, D16, D17, D18, D19,
D20, D21, D22, D23, Reserved,
D24, D25, D26, D27, D28, D29,
D30, D31, STPCLK#, Reserved,
Reserved, SMI#, SMIACT#,
SRESET, NMI, INTR, FLUSH#,
RESET, A20M#, EADS#, PCD,
PWT, D/C#, M/IO#, BE3#, BE2#,
BE1#, BE0#, BREQ, W/R#,
HLDA, CLK, Reserved, AHOLD,
HOLD, KEN#, RDY#, BS8#,
BS16#, BOFF#, BRDY#,
Reserved, LOCK#, PLOCK#,
BLAST#, ADS#, MISCCTL,
BUSCTL, ABUSCTL, WRCTL
TDI
22
Embedded Ultra-Low Power Intel486TM SX Processor
5.0
ELECTRICAL SPECIFICATIONS
5.1
Maximum Ratings
Table 11 is a stress rating only. Extended exposure
to the Maximum Ratings may affect device reliability.
Furthermore, although the embedded ULP Intel486
SX processor contains protective circuitry to resist
damage from electrostatic discharge, always take
precautions to avoid high static voltages or electric
fields.
Functional operating conditions are given in Section
5.2, DC Specifications and Section 5.3, AC Speci-
fications.
5.2
DC Specifications
The following tables show the operating supply
voltages, DC I/O specifications, and component
power consumption for the embedded ULP Intel486
SX processor.
Table 11. Absolute Maximum Ratings
Case Temperature under
Bias
-65 C to +110 C
Storage Temperature
-65 C to +150 C
DC Voltage on Any Pin
with Respect to Ground
-0.5 V to V
CCP
+ 0.5 V
Supply Voltage V
CC
with
Respect to V
SS
-0.5 V to +4.6 V
Supply Voltage V
CCP
with Respect to V
SS
-0.5 V to +4.6 V
Table 12. Operating Supply Voltages
Product
V
CCP
Range
1
Max. CLK
Frequency
V
CC
Range
2
V
CC
Fluctuation
FA80486SXSF-33
3.3 V
0
.
3 V
25
2.4 V min
3.3 V max
0.2 V
+0.3 V/-0.2 V
0.3 V
at 2.4 V
V
CC
2.7 V
at 2.7 V
<
V
CC
< 3.0 V
at 3.0 V
V
CC
3.3 V
33
2.7 V min
3.3 V max
NOTES:
1. In all cases, V
CCP
must be
V
CC
.
2. V
CC
may be set to any voltage within the V
CC
Range. The setting determines the allowed V
CC
Fluctuation.
Embedded Ultra-Low Power Intel486TM SX Processor
23
Table 13. DC Specifications
T
CASE
=0 C to +85 C
Symbol
Parameter
Min.
Max.
Unit
Notes
V
IL
Input LOW Voltage
-0.3
+0.8
V
V
IH
Input HIGH Voltage
2.0
V
CCP
+0.3
V
Note 1
V
IHC
Input HIGH Voltage of CLK
V
CCP
-0.6
V
CCP
+0.3
V
V
OL
Output LOW Voltage
I
OL
= 2.0 mA
I
OL
= 100 A
0.4
0.2
V
V
V
OH
Output HIGH Voltage
I
OH
= -2.0 mA
I
OH
= -100 A
2.4
V
CCP
-0.2
V
V
I
LI
Input Leakage Current
15
A
Note 2
I
IH
Input Leakage Current
200
A
Note 3
I
IL
Input Leakage Current
400
A
Note 4
I
LO
Output Leakage Current
15
A
C
IN
Input Capacitance
10
pF
Note 5
C
OUT
I/O or Output Capacitance
10
pF
Note 5
C
CLK
CLK Capacitance
6
pF
Note 5
NOTES:
1. All inputs except CLK.
2. This parameter is for inputs without pull-up or pull-down resistors and 0V
V
IN
V
CCP
.
3. This parameter is for inputs with pull-down resistors and V
IH
= 2.4V, and for level-keeper pins at V=0.4V.
4. This parameter is for inputs with pull-up resistors and V
IL
= 0.4V, and for level-keeper pins at V=2.4V.
5. F
C
=1 MHz. Not 100% tested.
Embedded Ultra-Low Power Intel486TM SX Processor
24
Table 14. Active I
CC
Values
T
CASE
=0 C to +85 C
Symbol
Parameter
Frequency
Supply Voltage
Typical I
CC
Max. I
CC
Notes
I
CC1
I
CC
Active
(V
CC
pins)
25 MHz
V
CC
= 2.4
0.2 V
120 mA
195 mA
V
CC
= 3.3
0.3 V
165 mA
260 mA
33 MHz
V
CC
= 2.7
0.2 V
180 mA
280 mA
V
CC
= 3.3
0.3 V
220 mA
345 mA
I
CC2
I
CC
Active
(V
CCP
pins)
25 MHz
V
CCP
= 3.3
0.3 V
9 mA
30 mA
1
33 MHz
V
CCP
= 3.3
0.3 V
12 mA
40 mA
1
NOTES:
1. These parameters are for C
L
= 50 pF
Table 15. Clock Stop, Stop Grant, and Auto HALT Power Down I
CC
Values
T
CASE
= 0 C to +85 C
Symbol
Parameter
Frequency
Supply Voltage
Typical I
CC
Max. I
CC
Notes
I
CCS0
I
CC
Stop Clock
(V
CC
pins)
0 MHz
V
CC
= 2.4
0.2 V
4
A
120
A
Note 1
V
CC
= 2.7
0.2 V
4
A
130
A
V
CC
= 3.3
0.3 V
5
A
150
A
I
CCS2
I
CC
Stop Clock
(V
CCP
pins)
0 MHz
V
CCP
= 3.3
0.3 V
3
A
80
A
I
CCS1
I
CC
Stop Grant,
Auto HALT
Power Down
(V
CC
pins)
25 MHz
V
CC
= 2.4
0.2 V
14 mA
25 mA
V
CC
= 3.3
0.3 V
20 mA
30 mA
33 MHz
V
CC
= 2.7
0.2 V
20 mA
30 mA
V
CC
= 3.3
0.3 V
25 mA
35 mA
I
CCS3
I
CC
Stop Grant,
Auto HALT
Power Down
(V
CCP
pins)
25 MHz
V
CCP
= 3.3
0.3 V
425
A
1.5 mA
33 MHz
V
CCP
= 3.3
0.3 V
610
A
2.0 mA
NOTES:
1. The I
CC
Stop Clock specification refers to the I
CC
value once the processor enters the Stop Clock state. For all input signals,
the V
IH
and V
IL
levels must be equal to V
CCP
and 0V, respectively, to meet the I
CC
Stop Clock specifications.
Embedded Ultra-Low Power Intel486TM SX Processor
25
5.3
AC Specifications
The AC specifications for the embedded ULP Intel486 SX processor are given in this section.
Table 16. AC Characteristics (Sheet 1 of 2)
valid over the operating supply voltages listed in Table 12, Operating Supply Voltages (pg. 22).
T
CASE
= 0 C to +85 C; C
L
= 50 pF
Symbol
Parameter
2.4V
V
CC
<
2.7V
2.7V
V
CC
3.3V
Min
Max
Min
Max
Unit
Notes
Frequency
0
25
0
33
MHz
Note 1
t
1
CLK Period
40
30
ns
Note 1
t
1a
CLK Period Stability
250
250
ps/CLK
Note 2
t
2
CLK High Time
14
11
ns
at 2V
t
3
CLK Low Time
14
11
ns
at 0.8V
t
4
CLK Fall Time
4
3
ns
2V to 0.8V
Note 3
t
5
CLK Rise Time
4
3
ns
0.8V to 2V
Note 3
t
6
A2-A31, PWT, PCD, BE0#-
BE3#, M/IO#, D/C#, W/R#,
ADS#, LOCK#, BREQ, HLDA,
SMIACT# Valid Delay
3
19
3
16
ns
t
7
A2-A31, PWT, PCD, BE0#-
BE3#, M/IO#, D/C#, W/R#,
ADS#, LOCK#, BREQ, Float
Delay
28
20
ns
Note 3
t
8a
BLAST#, PLOCK# Valid Delay
3
24
3
20
ns
t
9
BLAST#, PLOCK# Float Delay
28
20
ns
Note 3
t
10
D0-D31 Write Delay
3
20
3
19
ns
t
11
D0-D31 Float Delay
28
20
ns
Note 3
t
12
EADS# Setup Time
8
6
ns
t
13
EADS# Hold Time
3
3
ns
t
14
BS16#, BS8#, KEN# Setup
Time
8
6
ns
t
15
BS16#, BS8#, KEN# Hold
Time
3
3
ns
t
16
RDY#, BRDY# Setup Time
8
6
ns
t
17
RDY#, BRDY# Hold Time
3
3
ns
t
18
HOLD, AHOLD Setup Time
10
6
ns
t
18a
BOFF# Setup Time
10
9
ns
Embedded Ultra-Low Power Intel486TM SX Processor
26
t
19
HOLD, AHOLD, BOFF# Hold
Time
3
3
ns
t
20
FLUSH#, A20M#, NMI, INTR,
SMI#, STPCLK#, SRESET,
RESET Setup Time
10
6
ns
t
21
FLUSH#, A20M#, NMI, INTR,
SMI#, STPCLK#, SRESET,
RESET Hold Time
3
3
ns
t
22
D0-D31, A4-A31 Read Setup
Time
6
6
ns
t
23
D0-D31, A4-A31 Read Hold
Time
3
3
ns
NOTES:
1. 0 Hz operation is tested and guaranteed by the STPCLK# and Stop Grant bus cycle protocol. 0 Hz < CLK < 8 MHz opera-
tion is confirmed by design characterization, but not 100% tested in production.
2. Specification t1a is applicable only when CLK frequency is changed without STPCLK# / STOP GRANT bus cycle protocol.
3. Not 100% tested, guaranteed by design characterization.
4. CLK reference voltage for timing measurement is 1.5 V except t2 through t5. Other signals are measured at 1.5 V.
Table 16. AC Characteristics (Sheet 2 of 2)
valid over the operating supply voltages listed in Table 12, Operating Supply Voltages (pg. 22).
T
CASE
= 0 C to +85 C; C
L
= 50 pF
Symbol
Parameter
2.4V
V
CC
<
2.7V
2.7V
V
CC
3.3V
Min
Max
Min
Max
Unit
Notes
Embedded Ultra-Low Power Intel486TM SX Processor
27
.
Table 17. AC Specifications for the Test Access Port
Symbol
Parameter
2.2 V
Vcc
<
3.0 V
Vcc = 3.3 0.3 V
Unit
Figure
Notes
Min
Max
Min
Max
t
24
TCK Frequency
5
8
MHz
10
t
25
TCK Period
200
125
ns
10
Note 1
t
26
TCK High Time
65
40
ns
10
@ 2.0V
t
27
TCK Low Time
65
40
ns
10
@0.8V
t
28
TCK Rise Time
15
8
ns
10
Note 2
t
29
TCK Fall Time
15
8
ns
10
Note 2
t
30
TDI, TMS Setup Time
16
8
ns
11
Note 3
t
31
TDI, TMS Hold Time
20
10
ns
11
Note 3
t
32
TDO Valid Delay
3
46
3
30
ns
11
Note 3
t
33
TDO Float Delay
52
36
ns
11
Notes 3, 4
t
34
All Outputs (except
TDO) Valid Delay
3
80
3
30
ns
11
Note 3
t
35
All Outputs (except
TDO) Float Delay
88
36
ns
11
Notes 3, 4
t
36
All Inputs (except TDI,
TMS, TCK) Setup Time
16
8
ns
11
Note 3
t
37
All Inputs (except TDI,
TMS, TCK) Hold Time
35
15
ns
11
Note 3
NOTES:
1. TCK period
CLK period.
2. Rise/Fall Times are measured between 0.8 V and 2.0 V. Rise/Fall times can be relaxed by 1 ns per 10 ns increase in TCK
period.
3. Parameter measured from TCK.
4. Not 100% tested, guaranteed by design characterization.
Embedded Ultra-Low Power Intel486TM SX Processor
28
Figure 5. CLK Waveform
Figure 6. Input Setup and Hold Timing
1.5 V
t
1
t
5
t
2
t
4
t
3
0.8 V
CLK
2.0 V
t
x
t
y
1.5 V
t
x
= input setup times
t
y
= input hold times, output float, valid and hold times
1.5 V
0.8 V
2.0 V
T
x
T
x
T
x
T
x
CLK
EADS#
BS8#, BS16#, KEN#
BOFF#, AHOLD, HOLD
RESET, FLUSH#,
A4-A31
(READ)
A20M#, INTR, NMI,
SMI#, STPCLK#, SRESET
t
12
t
14
t
13
t
15
t
18
t
19
t
20
t
21
t
22
t
23
Embedded Ultra-Low Power Intel486TM SX Processor
29
Figure 7. Input Setup and Hold Timing
Figure 8. Output Valid Delay Timing
T
2
T
x
CLK
RDY#, BRDY#
D0-D31
T
x
1.5 V
1.5 V
t
16
t
17
t
22
t
23
BLAST#,
PLOCK#
T
x
T
x
T
x
T
x
CLK
A2-A31, PWT, PCD,
D0-D31
VALID n+1
MAX
t
6
VALID n
t
10
t
8a
BE0-3#, M/IO#,
D/C#, W/R#, ADS#,
LOCK#, BREQ, HLDA,
VALID n+1
MIN
MAX
VALID n
VALID n+1
MIN
MAX
VALID n
MIN
SMIACT#
Embedded Ultra-Low Power Intel486TM SX Processor
30
Figure 9. Maximum Float Delay Timing
Figure 10. TCK Waveform
T
x
T
x
T
x
CLK
A2-A31, PWT, PCD,
D31-D0
BLAST#,
MIN
t
6
VALID
BE0-3#, M/IO#,
D/C#, W/R#, ADS#,
LOCK#, BREQ
PLOCK#
t
7
t
10
t
11
t
8a
t
9
MIN
VALID
MIN
VALID
0.8 V
t
26
t
25
2.0 V
TCK
t
27
t
28
t
29
0.8 V
2.0 V
Embedded Ultra-Low Power Intel486TM SX Processor
31
Figure 11. Test Signal Timing Diagram
t
31
t
30
TCK
TMS
TDI
TDO
OUTPUT
INPUT
VALID
t
32
t
33
VALID
t
35
VALID
VALID
VALID
t
34
t
37
t
36
1.5 V
Embedded Ultra-Low Power Intel486TM SX Processor
32
5.4
Capacitive Derating Curves
The following graphs are the capacitive derating curves for the embedded ULP Intel486 SX processor.
Figure 12. Typical Loading Delay versus Load Capacitance under Worst-Case Conditions for a Low-to-
High Transition
Figure 13. Typical Loading Delay versus Load Capacitance under Worst-Case Conditions for a High-
to-Low Transition
nom+7
nom+6
nom+5
nom+4
nom+3
nom+2
nom+1
nom
nom-1
nom-2
25
50
75
100
125
150
Capacitive Load (pF)
Del
ay (ns)
NOTE: This graph will not be linear outside of the capacitive range shown.
nom = nominal value from the AC Characteristics table.
nom+5
nom+4
nom+3
nom+2
nom+1
nom
nom-1
nom-2
25
50
75
100
125
150
Capacitive Load (pF)
Delay (ns)
NOTE: This graph will not be linear outside of the capacitive range shown.
nom = nominal value from the AC Characteristics table.
Embedded Ultra-Low Power Intel486TM SX Processor
33
6.0
MECHANICAL DATA
This section describes the packaging dimensions and thermal specifications for the embedded ULP Intel486
SX processor.
6.1
Package Dimensions
Figure 14. Package Mechanical Specifications for the 176-Lead TQFP Package
176
133
45
132
0.10 0.10
0
Min
10
Max
0.50 0.10
0.10 0.10
1.50 0.20
0.16 Min
o.28 Max
0.60 0.20
24.0 0.10
26.0 0.40
1
44
88
89
NOTES:
Height measurements same as width measurements
Units: mm
A4586-01
34
Embedded Ultra-Low Power Intel486TM SX Processor
6.2
Package Thermal Specifications
The embedded ULP Intel486 SX processor is
specified for operation when the case temperature
(T
C
) is within the range of 0C to 85C. T
C
may be
measured in any environment to determine whether
the processor is within the specified operating range.
The ambient temperature (T
A
) can be calculated
from
JC
and
JA
from the following equations:
T
J
= T
C
+ P *
JC
T
A
= T
J
- P *
JA
T
C
= T
A
+ P * [
JA
-
JC
]
T
A
= T
C
- P * [
JA
-
JC
]
Where T
J
, T
A
, T
C
equals Junction, Ambient and
Case Temperature respectively.
JC
,
JA
equals
Junction-to-Case and Junction-to-Ambient thermal
Resistance, respectively. Maximum Power
Consumption (P) is defined as
P =
V (typ) * I
CC
(max)
P =
[V
CC
(typ) * I
CC1
(max)] +
[V
CCP
(typ) * I
CC2
(max)]
where:
I
CC1
is the V
CC
supply current
I
CC2
is the V
CCP
supply current
Values for
JA
and
JC
are given in the following
tables for each product at its maximum operating
frequencies.
The following table shows maximum ambient temperatures of the embedded ULP Intel486 SX processor for
each product and maximum operating frequencies. These temperatures are calculated using I
CC1
and I
CC2
values measured during component-validation testing using V
CCP
=3.6 V and worst-case V
CC
values.
Table 18. Thermal Resistance
(C/W)
JC
and
JA
for the 176-Lead TQFP Package
JC
(C/W)
JA
(C/W) with no airflow
4.3
33.6
Table 19. Maximum Ambient Temperature (T
A
)
176-Lead TQFP Package
Frequency
V
CC
T
A
(C) with no airflow
25 MHz
2.4 V
76
3.3 V
65
33 MHz
2.7 V
69
3.3 V
59
PDF 
ZIP