P R O D U C T H I G H L I G H T
D
UAL
O
UTPUT
PWM C
ONTROLLERS
WITH
5-B
IT
DAC
P
R O D U C T I O N
D
A T A
S
H E E T
T
H E
I
N F I N I T E
P
O W E R
O F
I
N N O V A T I O N
LX1664/64A, LX1665/65A
P A C K A G E O R D E R I N F O R M AT I O N
T
A
(C)
Plastic DIP
16-pin
0 to 70
LX1664CN
LX1665CN
LX1664CD
LX1665CDW
LX1664ACN
LX1665ACN
LX1664ACD
LX1665ACDW
N
Note: All surface-mount packages are available in Tape & Reel. Append the letter "T" to part number. (e.g. LX1664CDT)
Plastic DIP
18-pin
N
Plastic SOIC
16-pin
D
Plastic SOIC Wide
18-pin
DW
SS
TDRV
V
CC
INV
V
CC_CORE
VID0
VID1
VID2
VID3
OV
C
T
BDRV
GND
V
C1
U1
LX1665
VID3
C
5
1F
12V
R
1
V
OUT
5V
18-pin
Wide-Body SOIC
Q
1
IRL3102
2.5H
6.3V, 1500F x 3**
14
13
12
11
10
1
2
3
4
5
6
7
C
8
680pF
VID2
VID1
VID0
VID4
C
3
0.1F
0.0025
Supply Voltage
for CPU Core
6.3V
1500F x3
** Three capacitors for Pentium
Four capacitors for Pentium II
VID4
L
DRV
Supply Voltage
For I/O Chipset or GTL+ Bus
8
16
15
L
FB
PWRGD
9
PWRGD
OV
17
18
Q
2
IRL3303
Q
4
IRLZ44
C
7
330F
R
5
R
6
L
1
C
2
C
1
C
9
330F
F
1
20A
L
2
1H
LX1665
I N
A
P
E N T I U M
II S
I N G L E
-C
H I P
P
O W E R
S
U P P LY
S
O L U T I O N
Copyright 1999
Rev. 1.2 11/99
1
11861 W
ESTERN
A
VENUE
, G
ARDEN
G
ROVE
, CA. 92841, 714-898-8121, F
AX
: 714-893-2570
L
I N
F
I N I T Y
M
I C R O E L E C T R O N I C S
I
N C
.
D E S C R I P T I O N
K E Y F E AT U R E S
The LX1664/64A and LX1665/65A are
monolithic switching regulator con-
troller IC's designed to provide a low cost,
high performance adjustable power supply
for advanced microprocessors and other
applications requiring a very fast transient
response and a high degree of accuracy.
Short-circuit Current Limiting with-
out Expensive Current Sense Resistors.
Current-sensing mechanism can use PCB
trace resistance or the parasitic resistance of
the main inductor. The LX1664A and
LX1665A have reduced current sense com-
parator threshold for optimum perfor-
mance using a sense resistor. For applica-
tions requiring a high degree of accuracy, a
conventional sense resistor can be used to
sense current.
Programmable Synchronous Recti-
fier Driver for CPU Core. The main
output is adjustable from 1.3V to 3.5V using
a 5-bit code. The IC can read a VID signal
I 5-bit Programmable Output For CPU Core
Supply
I Adjustable Linear Regulator Driver Output
I No Sense Resistor Required For Short-
Circuit Current Limiting
I Designed To Drive Either Synchronous Or
Non-Synchronous Output Stages
I Soft-Start Capability
I Modulated, Constant Off-Time Architecture
For Fast Transient Response And Simple
System Design
I Available Over-Voltage Protection (OVP)
Crowbar Driver And Power Good Flag
(LX1665 only)
set by a DIP switch on the motherboard, or
hardwired into the processor's package (as
in the case of Pentium
Pro and Pentium II
processors). The 5-bit code adjusts the
output voltage between 1.30 and 2.05V in
50mV increments and between 2.0 and 3.5V
in 100mV increments, conforming to the
Intel Corporation specification. The device
can drive dual MOSFET's resulting in typical
efficiencies of 85 - 90% even with loads in
excess of 10 amperes. For cost sensitive
applications, the bottom MOSFET can be
replaced with a Schottky diode (non-syn-
chronous operation).
Linear Regulator Driver. The LX1664/
65 family of devices have a secondary
regulator output. This can drive a MOSFET
or bipolar transistor as a pass element to
construct a low-cost adjustable linear regu-
lator suitable for powering a 1.5V GTL+ bus
or 2.5V clock supply.
(continued next page)
A P P L I C AT I O N S
I Socket 7 (Pentium Class) Microprocessor
Supplies (including Intel Pentium Processor,
AMD-K6
TM
And Cyrix
6x86
TM
, Gx86
TM
and
M2
TM
Processors)
I Pentium II and Deschutes Processor & L2-
Cache Supplies
I Voltage Regulator Modules
IMPORTANT: For the most current data, consult LinFinity's web site: http://www.linfinity.com.
See next page
for
Selection
Guide
D
UAL
O
UTPUT
PWM C
ONTROLLERS
WITH
5-B
IT
DAC
LX1664/64A, LX1665/65A
P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7
Copyright 1999
Rev. 1.2 11/99
2
P
R O D U C T I O N
D
A T A
S
H E E T
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Supply Voltage (V
C1
) .................................................................................................... 25V
Supply Voltage (V
CC
) .................................................................................................... 15V
Output Drive Peak Current Source (500ns) ............................................................... 1.5A
Output Drive Peak Current Sink (500ns) ................................................................... 1.5A
Input Voltage (SS, INV, V
CC_CORE
, C
T
, VID0-VID4) ........................................... -0.3V to 6V
Operating Junction Temperature
Plastic (N, D & DW Packages) ............................................................................. 150C
Storage Temperature Range .................................................................... -65C to +150C
Lead Temperature (Soldering, 10 Seconds) ............................................................. 300C
PACKAGE PIN OUTS
N (16-PIN DIP) PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
JA
65C/W
N (18-PIN DIP) PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
JA
60C/W
D PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
JA
120C/W
DW PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
JA
90C/W
Junction Temperature Calculation: T
J
= T
A
+ (P
D
x
JA
).
The
JA
numbers are guidelines for the thermal performance of the device/pc-board system.
All of the above assume no ambient airflow
THERMAL DATA
Note 1. Exceeding these ratings could cause damage to the device. All voltages are with respect
to Ground. Currents are positive into, negative out of the specified terminal. Pin
numbers refer to DIL packages only.
V
C1
TDRV
GND
BDRV
V
CC
C
T
L
DRV
L
FB
SS
INV
V
CC_CORE
VID0
VID1
VID2
VID3
VID4
1
16
2
15
3
14
4
13
5
12
6
11
7
10
8
9
N PACKAGE -- 16-Pin
LX1664/1664A (Top View)
V
C1
TDRV
GND
BDRV
V
CC
C
T
L
DRV
L
FB
SS
INV
V
CC_CORE
VID0
VID1
VID2
VID3
VID4
1
16
2
15
3
14
4
13
5
12
6
11
7
10
8
9
D PACKAGE -- 16-Pin
LX1664/1664A (Top View)
V
C1
TDRV
GND
BDRV
V
CC
C
T
OV
L
DRV
PWRGD
SS
INV
V
CC_CORE
VID0
VID1
VID2
VID3
VID4
L
FB
1
18
2
17
3
16
4
15
5
14
6
13
7
12
8
11
9
10
N PACKAGE -- 18-Pin
LX1665/1665A (Top View)
V
C1
TDRV
GND
BDRV
V
CC
C
T
OV
L
DRV
PWRGD
SS
INV
V
CC_CORE
VID0
VID1
VID2
VID3
VID4
L
FB
1
18
2
17
3
16
4
15
5
14
6
13
7
12
8
11
9
10
DW PACKAGE -- 18-Pin
LX1665/1665A (Top View)
D E V I C E S E L E C T I O N G U I D E
OVP and
Current-Sense
DEVICE
Packages
Power Good
Comp. Thresh. (mV) Optimal Load
LX1664
16-pin SOIC
No
100
Pentium-class (<10A)
LX1664A
& DIP
60
Pentium II (> 10A)
LX1665
18-pin SOIC
Yes
100
Pentium-class (<10A)
LX1665A
& DIP
60
Pentium II (> 10A)
D E S C R I P T I O N
(con't.)
Smallest Package Size. The LX1664 is
available in a narrow body 16-pin surface
mount IC package for space sensitive appli-
cations. The LX1665 provides the additional
functions of Over Voltage Protection (OVP)
and Power Good (PWRGD) output drives
for applications requiring output voltage
monitoring and protection functions.
Ultra-Fast Transient Response re-
duces system cost. The modulated off-
time architecture results in the fastest tran-
sient response for a given inductor, reduc-
ing output capacitor requirements, and re-
ducing the total regulator system cost.
Over-Voltage Protection and Power
Good Flag. The OVP output in the LX1665
& LX1665A can be used to drive an SCR
crowbar circuit to protect the load in the
event of a short-circuit of the main MOSFET.
The LX1665 & LX1665A also have a logic-
level Power Good Flag to signal when the
output voltage is out of specified limits.
D
UAL
O
UTPUT
PWM C
ONTROLLERS
WITH
5-B
IT
DAC
LX1664/1664A, LX1665/65A
P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7
3
Copyright 1999
Rev. 1.2 11/99
P
R O D U C T I O N
D
A T A
S
H E E T
E L E C T R I C A L C H A R A C T E R I S T I C S
(Unless otherwise specified, 10.8 < V
CC
< 13.2, 0C
T
A
70C. Test conditions: V
CC
= 12V, T = 25C. Use Application Circuit.)
Reference & DAC Section
(See Table 1 - Next Page)
Parameter
Symbol
Test Conditions
Regulation Accuracy
(See Table 1)
(Less 40mV output adaptive positioning)
, V
CC
= 12V, I
LOAD
= 6A
Regulation Accuracy
1.8V
V
OUT
2.8V
Timing Section
Off Time Initial
OT
V
CC_CORE
= 1.3V, C
T
= 390pF
V
CC_CORE
= 3.5V, C
T
= 390pF
Off Time Temp Stability
V
CC_CORE
= 1.3V to 3.5V
Discharging Current
I
DIS
V
CC_CORE
= 1.3V, V
CT
= 1.5V
Ramp Peak
V
P
Ramp Peak-Valley
V
RPP
V
CC_CORE
= 1.3V
V
CC_CORE
= 3.5V
Ramp Valley Delay to Output
10% Overdrive
Input Bias Current (V
CC_CORE
Pin)
I
B
1.3V < V
INV
= V
CC_CORE
< 3.5V
Pulse By Pulse C
L
LX1664/1665
V
CLP
Initial Accuracy
LX1664A/1665A
Initial Accuracy
C
S
Delay to Output
10% Overdrive
Error Comparator Section
Input Bias Current
I
B
1.3V < V
SS
= V
INV
< 3.5V
Input Offset Voltage
V
IO
E
C
Delay to Output
10% Overdrive
Output Drivers Section
Drive Rise Time
T
R
V
C1
= V
CC
= 12V, C
L
= 3000pF
Drive Fall Time
T
F
V
C1
= V
CC
= 12V, C
L
= 3000pF
Drive High
V
DH
V
CC
= V
CC
= 12V, I
SOURCE
= 20mA
V
CC
= V
CC
= 12V, I
SINK
= 200mA
Drive Low
V
DL
V
CC
= V
CC
= 12V, I
SOURCE
= 20mA
V
CC
= V
CC
= 12V, I
SINK
= 200mA
Output Pull Down
V
PD
V
CC
= V
C
= 0, I
PULL UP
= 2mA
UVLO and S.S. Section
Start-Up Threshold
V
ST
Hysteresis
V
HYST
SS Sink Current
I
SD
V
C1
= 10.1V
SS Sat Voltage
V
OL
V
C1
= 9V, I
SD
= 200A
Supply Current Section
Dynamic Operating Current
I
CD
V
CC
= V
C1
= 12V, Out Freq = 200kHz, C
L
= 0
Power Good / Over-Voltage Protection Section (LX1665 Only)
Lower Threshold
(V
CC_CORE
/ DAC
OUT
)
Hysteresis
Power Good Voltage Low
I
PWRGD
= 5mA
Over-Voltage Threshold
(V
CC_CORE
/ V
DAC
)
OVP Sourcing Current
V
OV
= 5V
Units
-30
30
mV
-1
1
%
LX1664/1665 (A)
Min.
Typ.
Max.
2
s
1
s
40
ppm
180
210
240
A
2
V
0.9
1
1.1
V
0.37
0.42
0.47
V
100
ns
0.8
2
A
36
41
46
mV
200
ns
27
35
A
85
100
115
mV
50
60
70
mV
200
ns
70
ns
70
ns
11
V
10
V
0.06
0.1
V
0.8
1.2
V
0.8
1.4
V
9.9
10.1
10.4
V
0.31
V
2
5.5
mA
0.15
0.6
V
27
mA
88
90
92
%
1
%
0.5
0.7
V
110
117
125
%
30
45
mA
Linear Regulator Section
Output Voltage
Set by external resistors
Setpoint Accuracy
I
L
= 0.5A using 0.5% resistors
Output Temperature Drift
Load Regulation
Cummulative Accuracy
Op-Amp Output Current
Open Loop
1.5
3.6
V
-1.5
1.5
%
40
ppm
1.5
%
3
%
50
70
mA
Current Sense Section
D
UAL
O
UTPUT
PWM C
ONTROLLERS
WITH
5-B
IT
DAC
LX1664/64A, LX1665/65A
P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7
Copyright 1999
Rev. 1.2 11/99
4
P
R O D U C T I O N
D
A T A
S
H E E T
E L E C T R I C A L C H A R A C T E R I S T I C S
Table 1 - Adaptive Transient Voltage Output
(Output Voltage Setpoint Typical)
0A
5A/Div.
Time - 100s/Div.
2.8V
100mV/Div.
Output Load
0 to 14A
Output Voltage
FIGURE 1 -- Output Transient Response
(using 5m
sense resistor and 5H output inductor)
Note:
Adaptive Transient Voltage Output
In order to improve transient response a 40mV
offset is built into the Current Sense comparator.
At high currents, the peak output voltage will be
lower than the nominal set point, as shown in
Figure 1. The actual output voltage will be a
function of the sense resistor, the output current
and output ripple.
0
1
1
1
1
1.34V
1.30V
0
1
1
1
0
1.39V
1.35V
0
1
1
0
1
1.44V
1.40V
0
1
1
0
0
1.49V
1.45V
0
1
0
1
1
1.54V
1.50V
0
1
0
1
0
1.59V
1.55V
0
1
0
0
1
1.64V
1.60V
0
1
0
0
0
1.69V
1.65V
0
0
1
1
1
1.74V
1.70V
0
0
1
1
0
1.79V
1.75V
0
0
1
0
1
1.84V
1.80V
0
0
1
0
0
1.89V
1.85V
0
0
0
1
1
1.94V
1.90V
0
0
0
1
0
1.99V
1.95V
0
0
0
0
1
2.04V
2.00V
0
0
0
0
0
2.09V
2.05V
1
1
1
1
1
2.04V
2.00V
1
1
1
1
0
2.14V
2.10V
1
1
1
0
1
2.24V
2.20V
1
1
1
0
0
2.34V
2.30V
1
1
0
1
1
2.44V
2.40V
1
1
0
1
0
2.54V
2.50V
1
1
0
0
1
2.64V
2.60V
1
1
0
0
0
2.74V
2.70V
1
0
1
1
1
2.84V
2.80V
1
0
1
1
0
2.94V
2.90V
1
0
1
0
1
3.04V
3.00V
1
0
1
0
0
3.14V
3.10V
1
0
0
1
1
3.24V
3.20V
1
0
0
1
0
3.34V
3.30V
1
0
0
0
1
3.44V
3.40V
1
0
0
0
0
3.54V
3.50V
VID4
VID3
VID2
VID1
VID0
Processor Pins
Output Voltage (V
CC_CORE
)
0 = Ground, 1 = Open (Floating)
0.0A
Nominal Output*
* Nominal = DAC setpoint voltage with no adaptive output voltage positioning.
D
UAL
O
UTPUT
PWM C
ONTROLLERS
WITH
5-B
IT
DAC
LX1664/1664A, LX1665/65A
P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7
5
Copyright 1999
Rev. 1.2 11/99
P
R O D U C T I O N
D
A T A
S
H E E T
C H A R A C T E R I S T I C S C U R V E S
70
75
80
85
90
95
1
2
3
4
5
6
7
8
9
10
11
12
13
14
I
OUT
(A)
EFFICIENCY (%)
__
EFFICIENCY AT 3.1V
EFFICIENCY AT 2.8V
EFFICIENCY AT 1.8V
Output Set Point
70
75
80
85
90
95
100
1
2
3
4
5
6
7
8
9
10
11
12
13
14
I
OUT
(A)
EFFICIENCY (%)
__
EFFICIENCY AT 3.1V
EFFICIENCY AT 2.8V
EFFICIENCY AT 1.8V
Output Set Point
FIGURE 2 -- Efficiency Test Results:
Non-Synchronous Operation, V
IN
= 5V
FIGURE 3 -- Efficiency Test Results:
Synchronous Operation, V
IN
= 5V
FIGURE 4 -- Efficiency Test Results: Synchronous Operation, V
IN
= 12V.
Note: Non-synchronous operation not recommended for 12V operation, due to power loss in Schottky diode.
60
65
70
75
80
85
90
1
2
3
4
5
6
7
8
9
10
11
12
13
14
I
OUT
(A)
1.8V EFFICIENCY
2.8V EFFICIENCY
3.3V EFFICIENCY
Output Set Point
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