REV 1.1 2/1/01
Characteristics subject to change without notice.
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256K
X28HC256
32K x 8 Bit
5 Volt, Byte Alterable EEPROM
FEATURES
Access time: 70ns
Simple byte and page write
--Single 5V supply
--No external high voltages or V
PP
control circuits
--Self-timed
--No erase before write
--No complex programming algorithms
--No overerase problem
Low power CMOS
--Active: 60mA
--Standby: 500A
Software data protection
--Protects data against system level inadvertent
writes
High speed page write capability
Highly reliable Direct Write
TM
cell
--Endurance: 1,000,000 cycles
--Data retention: 100 years
Early end of write detection
--DATA polling
--Toggle bit polling
DESCRIPTION
The X28HC256 is a second generation high perfor-
mance CMOS 32K x 8 EEPROM. It is fabricated with
Xicor's proprietary, textured poly floating gate technol-
ogy, providing a highly reliable 5 Volt only nonvolatile
memory.
The X28HC256 supports a 128-byte page write opera-
tion, effectively providing a 24s/byte write cycle, and
enabling the entire memory to be typically rewritten in
less than 0.8 seconds. The X28HC256 also features
DATA Polling and Toggle Bit Polling, two methods of
providing early end of write detection. The X28HC256
also supports the JEDEC standard Software Data Pro-
tection feature for protecting against inadvertent writes
during power-up and power-down.
Endurance for the X28HC256 is specified as a mini-
mum 1,000,000 write cycles per byte and an inherent
data retention of 100 years.
BLOCK DIAGRAM
X Buffers
Latches and
Decoder
I/O Buffers
and Latches
Y Buffers
Latches and
DECODER
Control
Logic and
Timing
256Kbit
EEPROM
Array
I/O
0
I/O
7
Data Inputs/Outputs
CE
OE
V
CC
V
SS
A
0
A
14
WE
Address
Inputs
X28HC256
Characteristics subject to change without notice.
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PIN CONFIGURATION
A
14
A
12
A
7
A
6
A
5
A
4
A
3
A
2
A
1
A
0
I/O
0
I/O
1
I/O
2
V
SS
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
V
CC
WE
A
13
A
8
A
9
A
11
OE
A
10
CE
I/O
7
I/O
6
I/O
5
I/O
4
I/O
3
X28HC256
Plastic DIP
CERDIP
Flat Plastic
SOIC
A
6
A
5
A
4
A
3
A
2
A
1
A
0
NC
I/O
0
A
8
A
9
A
11
NC
OE
A
10
CE
I/O
7
I/O
6
4 3 2 1 32 31
30
14 15 16 17 18 19 20
5
6
7
8
9
10
11
12
13
29
28
27
26
25
24
23
22
21
LCC
PLCC
A
7
I/O
1
I/O
2
V
SS
I/O
3
I/O
4
I/O
5
(Top View)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
A 3
A 4
A 5
A 6
A 7
A 12
A 14
NC
VCC
NC
WE
A13
A 8
A 9
A11
OE
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
A 2
A 1
A 0
I/O0
I/O1
I/O2
NC
VSS
NC
I/O3
I/O4
I/O5
I/O6
I/O7
CE
A10
A
12
A
14
NC
V
CC
WE
A
13
NC
X28HC256
X28HC256
11
I/O
0
10
A
0
14
V
SS
9
A
1
8
A
2
7
A
3
6
A
4
5
A
5
2
A
12
28
V
CC
12
I/O
1
13
I/O
2
15
I/O
3
4
A
6
3
A
7
1
16
I/O
4
20
CE
22
OE
24
A
9
17
I/O
5
27
WE
19
I/O
7
21
A
10
23
A
11
25
A
8
18
I/O
6
26
A
13
(Bottom View)
PGA
A
14
X28HC256
TSOP
PIN DESCRIPTIONS
Addresses (A
0
A
14
)
The Address inputs select an 8-bit memory location
during a read or write operation.
Chip Enable (CE)
The Chip Enable input must be LOW to enable all read/
write operations. When CE is HIGH, power consump-
tion is reduced.
Output Enable (OE)
The Output Enable input controls the data output buff-
ers, and is used to initiate read operations.
Data In/Data Out (I/O
0
I/O
7
)
Data is written to or read from the X28HC256 through
the I/O pins.
Write Enable (WE)
The Write Enable input controls the writing of data to
the X28HC256.
PIN NAMES
Symbol
Description
A
0
A
14
Address Inputs
I/O
0
I/O
7
Data Input/Output
WE
Write Enable
CE
Chip Enable
OE
Output Enable
V
CC
+5V
V
SS
Ground
NC
No Connect
X28HC256
Characteristics subject to change without notice.
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DEVICE OPERATION
Read
Read operations are initiated by both OE and
CE
LOW.
The read operation is terminated by either CE or OE
returning HIGH. This two line control architecture elimi-
nates bus contention in a system environment. The
data bus will be in a high impedance state when either
OE or CE is HIGH.
Write
Write operations are initiated when both CE and WE
are LOW and OE is HIGH. The X28HC256 supports
both a CE and WE controlled write cycle. That is, the
address is latched by the falling edge of either CE or
WE, whichever occurs last. Similarly, the data is
latched internally by the rising edge of either CE or
WE, whichever occurs first. A byte write operation,
once initiated, will automatically continue to comple-
tion, typically within 3ms.
Page Write Operation
The page write feature of the X28HC256 allows the
entire memory to be written in typically 0.8 seconds.
Page write allows up to one hundred twenty-eight
bytes of data to be consecutively written to the
X28HC256, prior to the commencement of the internal
programming cycle. The host can fetch data from
another device within the system during a page write
operation (change the source address), but the page
address (A
7
through A
14
) for each subsequent valid
write cycle to the part during this operation must be the
same as the initial page address.
The page write mode can be initiated during any write
operation. Following the initial byte write cycle, the host
can write an additional one to one hundred twenty-
seven bytes in the same manner as the first byte was
written. Each successive byte load cycle, started by
the WE HIGH to LOW transition, must begin within
100s of the falling edge of the preceding WE. If a sub-
sequent WE HIGH to LOW transition is not detected
within 100s, the internal automatic programming
cycle will commence. There is no page write window
limitation. Effectively the page write window is infinitely
wide, so long as the host continues to access the
device within the byte load cycle time of 100s.
Write Operation Status Bits
The X28HC256 provides the user two write operation
status bits. These can be used to optimize a system
write cycle time. The status bits are mapped onto the
I/O bus as shown in Figure 1.
Figure 1. Status Bit Assignment
DATA Polling (I/O
7
)
The X28HC256 features DATA Polling as a method to
indicate to the host system that the byte write or page
write cycle has completed. DATA Polling allows a sim-
ple bit test operation to determine the status of the
X28HC256. This eliminates additional interrupt inputs
or external hardware. During the internal programming
cycle, any attempt to read the last byte written will pro-
duce the complement of that data on I/O
7
(i.e., write
data = 0xxx xxxx, read data = 1xxx xxxx). Once the
programming cycle is complete, I/O
7
will reflect true
data.
Toggle Bit (I/O
6
)
The X28HC256 also provides another method for
determining when the internal write cycle is complete.
During the internal programming cycle I/O
6
will toggle
from HIGH to LOW and LOW to HIGH on subsequent
attempts to read the device. When the internal cycle is
complete the toggling will cease, and the device will be
accessible for additional read and write operations.
5
TB
DP
4
3
2
1
0
I/O
Reserved
Toggle Bit
DATA Polling
X28HC256
Characteristics subject to change without notice.
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DATA POLLING I/O
7
Figure 2. DATA Polling Bus Sequence
CE
OE
WE
I/O
7
X28HC256
Ready
Last
Write
HIGH Z
V
OL
V
IH
A
0
A
14
An
An
An
An
An
An
V
OH
An
Figure 3. DATA Polling Software Flow
DATA Polling can effectively halve the time for writing to
the X28HC256. The timing diagram in Figure 2 illus-
trates the sequence of events on the bus. The software
flow diagram in Figure 3 illustrates one method of
implementing the routine.
Write Data
Save Last Data
and Address
Read Last
Address
IO
7
Compare?
X28HC256
No
Yes
Writes
Complete?
No
Yes
Ready
X28HC256
Characteristics subject to change without notice.
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THE TOGGLE BIT I/O
6
Figure 4. Toggle Bit Bus Sequence
CE
OE
WE
X28C512/513
Last
Write
I/O
6
HIGH Z
*
*
V
OH
V
OL
Ready
* I/O
6
Beginning and ending state of I/O
6
will vary.
Figure 5. Toggle Bit Software Flow
The Toggle Bit can eliminate the chore of saving and
fetching the last address and data in order to implement
DATA Polling. This can be especially helpful in an array
comprised of multiple X28HC256 memories that is
frequently updated. The timing diagram in Figure 4
illustrates the sequence of events on the bus. The soft-
ware flow diagram in Figure 5 illustrates a method for
polling the Toggle Bit.
HARDWARE DATA PROTECTION
The X28HC256 provides two hardware features that
protect nonvolatile data from inadvertent writes.
Default V
CC
Sense--All write functions are inhibited
when V
CC
is 3.5V typically.
Write Inhibit--Holding either OE LOW, WE HIGH, or
CE HIGH will prevent an inadvertent write cycle during
power-up and power-down, maintaining data integrity.
SOFTWARE DATA PROTECTION
The X28HC256 offers a software-controlled data pro-
tection feature. The X28HC256 is shipped from Xicor
with the software data protection NOT ENABLED; that
is, the device will be in the standard operating mode. In
this mode data should be protected during power-up/
down operations through the use of external circuits.
The host would then have open read and write access
of the device once V
CC
was stable.
The X28HC256 can be automatically protected during
power-up and power-down (without the need for exter-
nal circuits) by employing the software data protection
feature. The internal software data protection circuit is
enabled after the first write operation, utilizing the soft-
ware algorithm. This circuit is nonvolatile, and will
remain set for the life of the device unless the reset
command is issued.
Once the software protection is enabled, the X28HC256 is
also protected from inadvertent and accidental writes in the
powered-up state. That is, the software algorithm must be
issued prior to writing additional data to the device.
Compare
X28C256
No
Yes
ok?
Compare
Accum with
Addr n
Load Accum
From Addr n
Last Write
Ready
Yes
X28HC256
Characteristics subject to change without notice.
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SOFTWARE ALGORITHM
Selecting the software data protection mode requires
the host system to precede data write operations by a
series of three write operations to three specific
addresses. Refer to Figure 6 and 7 for the sequence.
The three-byte sequence opens the page write window,
enabling the host to write from one to one hundred
twenty-eight bytes of data. Once the page load cycle
has been completed, the device will automatically be
returned to the data protected state.
SOFTWARE DATA PROTECTION
Figure 6. Timing Sequence--Byte or Page Write
CE
WE
(V
CC
)
Write
Protected
V
CC
0V
Data
Address
AAA
5555
55
2AAA
A0
5555
t
BLC MAX
Writes
ok
Byte
or
Age
t
WC
Figure 7. Write Sequence for Software Data
Protection
Regardless of whether the device has previously been
protected or not, once the software data protection
algorithm is used and data has been written, the
X28HC256 will automatically disable further writes
unless another command is issued to cancel it. If no
further commands are issued the X28HC256 will be
write protected during power-down and after any sub-
sequent power-up.
Note:
Once initiated, the sequence of write operations
should not be interrupted.
Write Last
Write Data XX
to Any
Write Data A0
to Address
5555
Write Data 55
to Address
2AAA
Write Data AA
to Address
5555
After t
WC
Re-Enters Data
Protected State
Byte to
Last Address
Address
Optional
Byte/Page
Load Operation
Byte/Page
Load Enabled
X28HC256
Characteristics subject to change without notice.
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RESETTING SOFTWARE DATA PROTECTION
Figure 8. Reset Software Data Protection Timing Sequence
CE
WE
Standard
Operating
Mode
V
CC
Data
Address
AAA
5555
55
2AAA
80
5555
t
WC
AA
5555
55
2AAA
20
5555
Figure 9. Write Sequence for resetting Software
Data Protection
In the event the user wants to deactivate the software
data protection feature for testing or reprogramming in
an EEPROM programmer, the following six step algo-
rithm will reset the internal protection circuit. After t
WC
,
the X28HC256 will be in standard operating mode.
Note:
Once initiated, the sequence of write operations
should not be interrupted.
SYSTEM CONSIDERATIONS
Because the X28HC256 is frequently used in large
memory arrays, it is provided with a two line control
architecture for both read and write operations. Proper
usage can provide the lowest possible power dissipa-
tion, and eliminate the possibility of contention where
multiple I/O pins share the same bus.
To gain the most benefit, it is recommended that CE be
decoded from the address bus and be used as the pri-
mary device selection input. Both OE and WE would
then be common among all devices in the array. For a
read operation, this assures that all deselected devices
are in their standby mode, and that only the selected
device(s) is/are outputting data on the bus.
Because the X28HC256 has two power modes,
standby and active, proper decoupling of the memory
array is of prime concern. Enabling CE will cause tran-
sient current spikes. The magnitude of these spikes is
dependent on the output capacitive loading of the l/Os.
Therefore, the larger the array sharing a common bus,
the larger the transient spikes. The voltage peaks
associated with the current transients can be sup-
pressed by the proper selection and placement of
decoupling capacitors. As a minimum, it is recommended
Write Data 55
to Address
2AAA
Write Data 55
to Address
2AAA
Write Data 80
to Address
5555
Write Data AA
to Address
5555
Write Data 20
to Address
5555
Write Data AA
to Address
5555
After t
WC
,
Re-Enters
Unprotected
State
X28HC256
Characteristics subject to change without notice.
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that a 0.1F high frequency ceramic capacitor be used
between V
CC
and V
SS
at each device. Depending on
the size of the array, the value of the capacitor may
have to be larger.
In addition, it is recommended that a 4.7F electrolytic
bulk capacitor be placed between V
CC
and V
SS
for
each eight devices employed in the array. This bulk
capacitor is employed to overcome the voltage droop
caused by the inductive effects of the PC board traces.
X28HC256
Characteristics subject to change without notice.
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ABSOLUTE MAXIMUM RATINGS
Temperature under bias
X28HC256 ...................................... 10C to +85C
X28HC256I, X28HC256M............. 65C to +135C
Storage temperature ........................ 65C to +150C
Voltage on any pin with
respect to V
SS
........................................1V to +7V
D.C. output current ............................................. 10mA
Lead temperature (soldering, 10 seconds)........ 300C
COMMENT
Stresses above those listed under "Absolute Maximum
Ratings" may cause permanent damage to the device.
This is a stress rating only; functional operation of the
device (at these or any other conditions above those indi-
cated in the operational sections of this specification) is
not implied. Exposure to absolute maximum rating condi-
tions for extended periods may affect device reliability.
RECOMMENDED OPERATING CONDITIONS
Temperature
Min.
Max.
Commercial
0C
+70C
Industrial
40C
+85C
Military
55C
+125C
Supply Voltage
Limits
X28HC256
5V 10%
D.C. OPERATING CHARACTERISTICS (Over recommended operating conditions unless otherwise specified.)
Notes: (1) Typical values are for T
A
= 25C and nominal supply voltage.
(2) V
IL
min. and V
IH
max. are for reference only and are not tested.
POWER-UP TIMING
Note:
(3) This parameter is periodically sampled and not 100% tested.
Symbol
Parameter
Limits
Unit
Test Conditions
Min.
Typ.
(7)
Max.
I
CC
V
CC
active current
(TTL Inputs)
30
60
mA
CE = OE = V
IL
, WE = V
IH
, All I/O's = open,
address inputs = .4V/2.4V levels @ f = 10MHz
I
SB1
V
CC
standby current
(TTL Inputs)
1
2
mA
CE = V
IH
, OE = V
IL
, All I/O's = open, other
inputs = V
IH
I
SB2
V
CC
standby current
(CMOS Inputs)
200
500
A
CE = V
CC
0.3V, OE = GND, All I/Os = open,
other inputs = V
CC
0.3V
I
LI
Input leakage current
10
A
V
IN
= V
SS
to V
CC
I
LO
Output leakage current
10
A
V
OUT
= V
SS
to V
CC
, CE = V
IH
V
lL
(2)
Input LOW voltage
1
0.8
V
V
IH
(2)
Input HIGH voltage
2
V
CC
+ 1
V
V
OL
Output LOW voltage
0.4
V
I
OL
= 6mA
V
OH
Output HIGH voltage
2.4
V
I
OH
= 4mA
Symbol
Parameter
Max.
Unit
t
PUR
(3)
Power-up to read
100
s
t
PUW
(3)
Power-up to write
5
ms
X28HC256
Characteristics subject to change without notice.
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CAPACITANCE T
A
= +25C, f = 1MHz, V
CC
= 5V
ENDURANCE AND DATA RETENTION
Symbol
Test
Max.
Unit
Conditions
C
I/O
(9)
Input/output capacitance
10
pF
V
I/O
= 0V
C
IN
(9)
Input capacitance
6
pF
V
IN
= 0V
Parameter
Min.
Max.
Unit
Endurance
1,000,000
Cycles
Data retention
100
Years
A.C. CONDITIONS OF TEST
MODE SELECTION
EQUIVALENT A.C. LOAD CIRCUIT
SYMBOL TABLE
Input pulse levels
0V to 3V
Input rise and fall times
5ns
Input and output timing levels
1.5V
CE
OE
WE
Mode
I/O
Power
L
L
H
Read
D
OUT
active
L
H
L
Write
D
IN
active
H
X
X
Standby and
write inhibit
High Z
standby
X
L
X
Write inhibit
--
--
X
X
H
Write inhibit
--
--
5V
1.92K
30pF
OUTPUT
1.37K
WAVEFORM
INPUTS
OUTPUTS
Must be
steady
Will be
steady
May change
from LOW
to HIGH
Will change
from LOW
to HIGH
May change
from HIGH
to LOW
Will change
from HIGH
to LOW
Don't Care:
Changes
Allowed
Changing:
State Not
Known
N/A
Center Line
is High
Impedance
X28HC256
Characteristics subject to change without notice.
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A.C. CHARACTERISTICS (Over the recommended operating conditions, unless otherwise specified.)
Read Cycle Limits
Read Cycle
Notes: (4) t
LZ
min., t
HZ
, t
OLZ
min. and t
OHZ
are periodically sampled and not 100% tested, t
HZ
and t
OHZ
are measured with CL = 5pF, from the
point when CE, OE return HIGH (whichever occurs first) to the time when the outputs are no longer driven.
(5) For faster 256K products, refer to X28VC256 product line.
Symbol
Parameter
X28HC256-70 X28HC256-90 X28HC256-12 X28HC256-15
Unit
Min.
Max.
Min.
Max.
Min. Max.
Min.
Max.
t
RC
(5)
Read cycle time
70
90
120
150
ns
t
CE
(5)
Chip enable access time
70
90
120
150
ns
t
AA
(5)
Address access time
70
90
120
150
ns
t
OE
Output enable access time
35
40
50
50
ns
t
LZ
(4)
CE LOW to active output
0
0
0
0
ns
t
OLZ
(4)
OE LOW to active output
0
0
0
0
ns
t
HZ
(4)
CE HIGH to high Z output
35
40
50
50
ns
t
OHZ
(4)
OE HIGH to high Z output
35
40
50
50
ns
t
OH
Output hold from address change
0
0
0
0
ns
t
CE
t
RC
Address
CE
OE
WE
Data Valid
t
OE
t
LZ
t
OLZ
t
OH
t
AA
t
HZ
t
OHZ
Data I/O
V
IH
HIGH Z
Data Valid
X28HC256
Characteristics subject to change without notice.
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Write Cycle Limits
Notes: (6) Typical values are for T
A
= 25C and nominal supply voltage.
(7) t
WC
is the minimum cycle time to be allowed from the system perspective unless polling techniques are used. It is the maximum
time the device requires to automatically complete the internal write operation.
(8) t
WPH
and t
DW
are periodically sampled and not 100% tested.
WE Controlled Write Cycle
Symbol
Parameter
Min.
Typ.
(6)
Max.
Unit
t
WC
(7)
Write cycle time
3
5
ms
t
AS
Address setup time
0
ns
t
AH
Address hold time
50
ns
t
CS
Write setup time
0
ns
t
CH
Write hold time
0
ns
t
CW
CE pulse width
50
ns
t
OES
OE HIGH setup time
0
ns
t
OEH
OE HIGH hold time
0
ns
t
WP
WE pulse width
50
ns
t
WPH
(8)
WE HIGH recovery (page write only)
50
ns
t
DV
Data valid
1
s
t
DS
Data setup
50
ns
t
DH
Data hold
0
ns
t
DW
(8)
Delay to next write after polling is true
10
s
t
BLC
Byte load cycle
0.15
100
s
Address
t
AS
t
WC
t
AH
t
OES
t
DS
t
DH
t
OEH
CE
WE
OE
Data In
Data Out
HIGH Z
Data Valid
t
CS
t
CH
t
WP
X28HC256
Characteristics subject to change without notice.
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CE Controlled Write Cycle
Page Write Cycle
Notes: (9) Between successive byte writes within a page write operation, OE can be strobed LOW: e.g. this can be done with CE and WE
HIGH to fetch data from another memory device within the system for the next write; or with WE HIGH and CE LOW effectively per-
forming a polling operation.
(10)The timings shown above are unique to page write operations. Individual byte load operations within the page write must conform to
either the CE or WE controlled write cycle timing.
Address
t
AS
t
OEH
t
WC
t
AH
t
OES
t
CS
t
DS
t
DH
t
CH
CE
WE
OE
Data In
Data Out
HIGH Z
Data Valid
t
CW
WE
OE
(9)
Last Byte
Byte 0
Byte 1
Byte 2
Byte n
Byte n+1
Byte n+2
t
WP
t
WPH
t
BLC
t
WC
CE
Address
(10)
I/O
*For each successive write within the page write operation, A
7
A
15
should be the same or
writes to an unknown address could occur.
X28HC256
Characteristics subject to change without notice.
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DATA Polling Timing Diagram
(11)
Toggle Bit Timing Diagram
(11)
Note:
(11)Polling operations are by definition read cycles and are therefore subject to read cycle timings.
Address
A
n
D
IN
= X
t
WC
t
OEH
t
OES
CE
WE
OE
I/O
7
t
DW
A
n
A
n
D
OUT
= X
D
OUT
= X
CE
OE
WE
I/O
6
t
OES
t
DW
t
WC
t
OEH
HIGH Z
*
*
* I/O
6
beginning and ending state will vary, depending upon actual t
WC
.
X28HC256
Characteristics subject to change without notice.
15 of 23
REV 1.1 2/1/01
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PACKAGING INFORMATION
28-Lead Ceramic Flat Pack Type F
NOTE: ALL DIMENSIONS IN INCHES (IN PARENTHESES IN MILLIMETERS)
0.740 (18.80)
Max.
0.019 (0.48)
0.015 (0.38)
0.050 (1.27) BSC
0.045 (1.14) Max.
Pin 1 Index
1
28
0.130 (3.30)
0.090 (2.29)
0.045 (1.14)
0.025 (0.66)
0.180 (4.57)
Min.
0.006 (0.15)
0.003 (0.08)
0.030 (0.76)
Min.
0.370 (9.40)
0.250 (6.35)
Typ. 0.300 2 Plcs.
0.440 (11.18)
Max.
X28HC256
Characteristics subject to change without notice.
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REV 1.1 2/1/01
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PACKAGING INFORMATION
0.561 (14.25)
0.541 (13.75)
28-Lead Ceramic Pin Grid Array Package Type K
NOTE: ALL DIMENSIONS IN INCHES (IN PARENTHESES IN MILLIMETERS)
0.020 (0.51)
0.016 (0.41)
12
13
15
17
18
11
10
14
16
19
9
8
20
21
7
6
22
23
5
2
28
24
25
4
3
1
27
26
Typ. 0.100 (2.54)
All Leads
0.080 (2.03) 4 Corners
0.070 (1.78)
Pin 1 Index
0.660 (16.76)
0.640 (16.26)
0.110 (2.79)
0.090 (2.29)
0.072 (1.83)
0.062 (1.57)
0.185 (4.70)
0.175 (4.44)
0.050 (1.27)
0.008 (0.20)
A
A
A
A
NOTE: LEADS 4,12,18 & 26
0.080 (2.03)
0.070 (1.78)
X28HC256
Characteristics subject to change without notice.
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REV 1.1 2/1/01
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PACKAGING INFORMATION
NOTE:
1. ALL DIMENSIONS IN INCHES (IN PARENTHESES IN MILLIMETERS)
2. PACKAGE DIMENSIONS EXCLUDE MOLDING FLASH
0.022 (0.56)
0.014 (0.36)
0.160 (4.06)
0.120 (3.05)
0.625 (15.88)
0.590 (14.99)
0.110 (2.79)
0.090 (2.29)
1.470 (37.34)
1.400 (35.56)
1.300 (33.02)
Ref.
Pin 1 Index
0.160 (4.06)
0.125 (3.17)
0.030 (0.76)
0.015 (0.38)
Pin 1
Seating
Plane
0.065 (1.65)
0.040 (1.02)
0.557 (14.15)
0.510 (12.95)
0.085 (2.16)
0.040 (1.02)
0
15
28-Lead Plastic Dual In-Line Package Type P
Typ. 0.010 (0.25)
X28HC256
Characteristics subject to change without notice.
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REV 1.1 2/1/01
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PACKAGING INFORMATION
28-Lead Plastic Small Outline Gull Wing Package Type S
0.299 (7.59)
0.290 (7.37)
0.419 (10.64)
0.394 (10.01)
0.020 (0.508)
0.014 (0.356)
0.0200 (0.5080)
0.0100 (0.2540)
0.050 (1.270)
BSC
0.713 (18.11)
0.697 (17.70)
0.012 (0.30)
0.003 (0.08)
0.105 (2.67)
0.092 (2.34)
X 45
NOTES:
1. ALL DIMENSIONS IN INCHES (IN PARENTHESES IN MILLIMETERS)
2. FORMED LEAD SHALL BE PLANAR WITH RESPECT TO ONE ANOTHER WITHIN 0.004 INCHES
Seating Plane
Base Plane
0.42" Max.
0.030" Typical
28 Places
0.050" Typical
0.050"
Typical
FOOTPRINT
0.0350 (0.8890)
0.0160 (0.4064)
0.013 (0.32)
0.008 (0.20)
0 8
X28HC256
Characteristics subject to change without notice.
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REV 1.1 2/1/01
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PACKAGING INFORMATION
0.620 (15.75)
0.590 (14.99)
Typ. 0.614 (15.60)
0.110 (2.79)
0.090 (2.29)
Typ. 0.100 (2.54)
1.690 (42.95)
Max.
0.023 (0.58)
0.014 (0.36)
Typ. 0.018 (0.46)
0.232 (5.90) Max.
0.060 (1.52)
0.015 (0.38)
Pin 1
0.200 (5.08)
0.125 (3.18)
0.065 (1.65)
0.033 (0.84)
Typ. 0.055 (1.40)
0.610 (15.49)
0.500 (12.70)
0.100 (2.54) Max.
0
15
32-Lead Hermetic Dual In-Line Package Type D
NOTE: ALL DIMENSIONS IN INCHES (IN PARENTHESES IN MILLIMETERS)
0.005 (0.13) Min.
0.150 (3.81) Min.
0.015 (0.38)
0.008 (0.20)
Seating
Plane
X28HC256
Characteristics subject to change without notice.
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REV 1.1 2/1/01
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PACKAGING INFORMATION
0.150 (3.81) BSC
0.458 (11.63)
0.458 (11.63)
0.442 (11.22)
Pin 1
0.020 (0.51) x 45 Ref.
0.095 (2.41)
0.075 (1.91)
0.022 (0.56)
0.006 (0.15)
0.055 (1.39)
0.045 (1.14)
TYP. (4) PLCS.
0.040 (1.02) x 45 Ref.
Typ. (3) Plcs.
0.050 (1.27) BSC
0.028 (0.71)
0.022 (0.56)
(32) Plcs.
0.200 (5.08)
BSC
0.558 (14.17)
0.088 (2.24)
0.050 (1.27)
0.120 (3.05)
0.060 (1.52)
Pin 1 Index Corner
32-Pad Ceramic Leadless Chip Carrier Package Type E
NOTE:
1. ALL DIMENSIONS IN INCHES (IN PARENTHESES IN MILLIMETERS)
2. TOLERANCE: 1% NLT 0.005 (0.127)
0.300 (7.62)
BSC
0.015 (0.38)
Min.
0.400 (10.16)
BSC
0.560 (14.22)
0.540 (13.71)
DIA.
0.015 (0.38)
0.003 (0.08)
X28HC256
Characteristics subject to change without notice.
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REV 1.1 2/1/01
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PACKAGING INFORMATION
0.021 (0.53)
0.013 (0.33)
0.420 (10.67)
0.050 (1.27) Typ.
Typ. 0.017 (0.43)
0.045 (1.14) x 45
0.300 (7.62)
Ref.
0.453 (11.51)
0.447 (11.35)
Typ. 0.450 (11.43)
0.495 (12.57)
0.485 (12.32)
Typ. 0.490 (12.45)
Pin 1
0.400
(10.16)
Ref.
0.553 (14.05)
0.547 (13.89)
Typ. 0.550 (13.97)
0.595 (15.11)
0.585 (14.86)
Typ. 0.590 (14.99)
3 Typ.
0.048 (1.22)
0.042 (1.07)
0.140 (3.56)
0.100 (2.45)
Typ. 0.136 (3.45)
0.095 (2.41)
0.060 (1.52)
--
0.015 (0.38)
Seating Plane
0.004 Lead
CO Planarity
32-Lead Plastic Leaded Chip Carrier Package Type J
NOTES:
1. ALL DIMENSIONS IN INCHES (IN PARENTHESES IN MILLIMETERS)
2. DIMENSIONS WITH NO TOLERANCE FOR REFERENCE ONLY
0.510"
Typical
0.050"
Typical
0.050"
Typical
0.300"
Ref.
FOOTPRINT
0.400"
0.410"
0.030" Typical
32 Places
X28HC256
Characteristics subject to change without notice.
22 of 23
REV 1.1 2/1/01
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PACKAGING INFORMATION
8.02 (0.315)
7.98 (0.314)
1.18 (0.046)
1.02 (0.040)
0.17 (0.007)
0.03 (0.001)
0.26 (0.010)
0.14 (0.006)
0.50 (0.0197) BSC
0.58 (0.023)
0.42 (0.017)
14.15 (0.557)
13.83 (0.544)
12.50 (0.492)
12.30 (0.484)
Pin #1 Ident.
O 0.76 (0.03)
Seating
Plane
See Note 2
See Note 2
0.50 0.04
(0.0197 0.0016)
0.30 0.05
(0.012 0.002)
14.80 0.05
(0.583 0.002)
1.30 0.05
(0.051 0.002)
0.17 (0.007)
0.03 (0.001)
Typical
32 Places
15 Eq. Spc. 0.50 0.04
0.0197 0.016 = 7.50 0.06
(0.295 0.0024) Overall
Tol. Non-Cumulative
Solder Pads
FOOTPRINT
NOTE:
1. ALL DIMENSIONS ARE SHOWN IN MILLIMETERS (INCHES IN PARENTHESES).
32-Lead Thin Small Outline Package (TSOP) Type T
X28HC256
Characteristics subject to change without notice.
23 of 23
LIMITED WARRANTY
Devices sold by Xicor, Inc. are covered by the warranty and patent indemnification provisions appearing in its Terms of Sale only. Xicor, Inc. makes no warranty,
express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement.
Xicor, Inc. makes no warranty of merchantability or fitness for any purpose. Xicor, Inc. reserves the right to discontinue production and change specifications and prices
at any time and without notice.
Xicor, Inc. assumes no responsibility for the use of any circuitry other than circuitry embodied in a Xicor, Inc. product. No other circuits, patents, or licenses are implied.
TRADEMARK DISCLAIMER:
Xicor and the Xicor logo are registered trademarks of Xicor, Inc. AutoStore, Direct Write, Block Lock, SerialFlash, MPS, and XDCP are also trademarks of Xicor, Inc. All
others belong to their respective owners.
U.S. PATENTS
Xicor products are covered by one or more of the following U.S. Patents: 4,326,134; 4,393,481; 4,404,475; 4,450,402; 4,486,769; 4,488,060; 4,520,461; 4,533,846;
4,599,706; 4,617,652; 4,668,932; 4,752,912; 4,829,482; 4,874,967; 4,883,976; 4,980,859; 5,012,132; 5,003,197; 5,023,694; 5,084,667; 5,153,880; 5,153,691;
5,161,137; 5,219,774; 5,270,927; 5,324,676; 5,434,396; 5,544,103; 5,587,573; 5,835,409; 5,977,585. Foreign patents and additional patents pending.
LIFE RELATED POLICY
In situations where semiconductor component failure may endanger life, system designers using this product should design the system with appropriate error detection
and correction, redundancy and back-up features to prevent such an occurrence.
Xicor's products are not authorized for use in critical components in life support devices or systems.
1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to
perform, when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user.
2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life
support device or system, or to affect its safety or effectiveness.
Xicor, Inc. 2000 Patents Pending
REV 1.1 2/1/01
www.xicor.com
Ordering Information
Device
Access Time
70 = 70ns
90 = 90ns
12 = 120ns
15 = 150ns
Temperature Range
Blank = Commercial = 0C to +70C
I = Industrial = 40C to +85C
M = Military = 55C to +125C
MB = MIL-STD-883
Package
P = 28-Lead Plastic DIP
D = 28-Lead CERDIP
J = 32-Lead PLCC
S = 28-Lead plastic SOIC
E = 32-Pad LCC
K = 28-Pin grid array
F = 28-Lead flat pack
T = 32-Lead TSOP
X28HC256
X
X
-X
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