lx1660 Microsemi Corporation, lx1660 Datasheet

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lx1660

Manufacturer Part Number
lx1660
Description
Advanced Pwm Controller
Manufacturer
Microsemi Corporation
Datasheet
T
Copyright © 1998
Rev. 1.1
H E
LX1661 I
P
A
ROCESSOR
The LX1660 and LX1661 Are Mono-
lithic Switching Regulator Controller
ICs designed to provide low-cost, high-
performance adjustable power supply for
microprocessors and other applications
requiring a fast transient response and a
high degree of accuracy. They provide
an adjustable synchronous Pulse Width
Modulator output suitable for a power
supply for Pentium
cessors.
CPU Core. The devices can drive dual
MOSFETs resulting in typical efficiencies
of 85 - 90%, even with loads in excess of
10A. Synchronous shutdown results in
increased efficiency in light load applica-
tions.
IMPORTANT: For the most current data, consult LinFinity's web site: http://www.linfinity.com.
PPLICATION
Synchronous Rectifier Driver For
7/98
I
R14, 1%
See Table 5
R15
2.0k
1%
N F I N I T E
N
S
R16
10k
C3
0.1µF
S
UPPLY
OCKET
11861 W
P
®
7
or other micropro-
O W E R
C4
390pF
ESTERN
D E S C R I P T I O N
O F
C8
390pF
L
OUTEN
A
I N
Note: All surface-mount packages are available in Tape & Reel.
VENUE
T
0 to 70
I
P A C K A G E O R D E R I N F O R M A T I O N
A
Append the letter "T" to part number. (i.e. LX166xCDT)
F
N N O V A T I O N
1
2
3
4
5
6
7
8
(°C)
I N I T Y
EN
OT
SGND
V
INV
NINV
HICCUP
C
, G
REF
T
ADJ
Without Expensive Current Sense Re-
sistors. The current sensing mechanism
can use a PCB trace resistance or the para-
sitic resistance of the main inductor. For
applications requiring a high degree of
accuracy, a conventional sense resistor
can be used.
hiccup mode is programmable and with
pulse-by-pulse current limiting will help
protect the power supply system and load
in the even of a short circuit.
duces System Cost. The fixed frequency
modulated off-time architecture results in
the fastest transient response for a given
inductor. Adaptive voltage positioning
(LX1661 only) requires fewer low-ESR ca-
pacitors to meet stringent transient over-
and under-shoot specifications.
ARDEN
16-pin SOIC
Short-Cir cuit Current Limiting
Hiccup Mode Fault Protection. The
Ultra-Fast Transient Response Re-
P R O D U C T H I G H L I G H T
LX1661
N
U1
M
G
Plastic DIP
16-pin
ROVE
SYNCEN
LX166xCN
I C R O E L E C T R O N I C S
PGND
BDRV
TDRV
CS+
CS-
, CA. 92841, 714-898-8121, F
V
V
CC
C1
16
15
14
13
12
11
10
9
12V
C9
1µF
D
P
A
R O D U C T I O N
Plastic SOIC
16-pin
IRL3103
D V A N C E D
LX166xCD
Q1
C1
390pF
5µH Toroid
D1
I
N C
L1
R5, 1k
R6, 1k
AX
P W M C
Sanyo MV-GX or equivalent
: 714-893-2570
.
Designed To Drive A Synchronous Rectifier
Stage — Can Also Be Used In Non-
Synchronous Applications
Soft-Start Capability
Hiccup-Mode Fault Protection
No Current-Sense Resistor Required For
Current Limiting
Modulated Constant Off-Time Control
Mechanism For Fast Transient Response And
Simple System Design
2V, 0.5% Internal Voltage Reference Brought
Out
Pentium Processor Supplies
AMD-K6
Cyrix
Voltage Regulator Modules
General Purpose DC:DC Supplies
16V, 1000µF
®
LX1660/1661
K E Y F E A T U R E S
A P P L I C A T I O N S
D
C2
6x86
TM
R1, 5m
A T A
O N T R O L L E R
Supplies
TM
Supplies
LIN D
C7
S
H E E T
Sanyo MV-GX or
16V, 1000µF
O C
equivalent
C5
#: 1660
V
IN
V
OUT
5V
C6
1

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lx1660 Summary of contents

Page 1

... The LX1660 and LX1661 Are Mono- lithic Switching Regulator Controller ICs designed to provide low-cost, high- performance adjustable power supply for microprocessors and other applications requiring a fast transient response and a high degree of accuracy ...

Page 2

... LX1660/1661 Supply Voltage ............................................................................................................. 25V Output Peak Current Source (500ns) ......................................................................... 1.5A Output Peak Current Sink (500ns) ............................................................................. 1.5A Analog Inputs ................................................................................................... -0.3 to +6V Power Dissipation 25° Package ...

Page 3

... I (High 12V, Out Freq = 200kHz 10V 0.1µF typ.) HICCUP LX1660/1661 LX1660 LX1661 Min. Typ. Max. Min. Typ. Max. 1.98 2 2.02 1. 180 210 240 180 210 240 180 ...

Page 4

... LX1660/1661 V CC ENABLE ADJ SGND REF 40mV (1661 only) ERROR COMP INV 5 O TADJ NINV/ PEAK VAL HICCUP 7 UPGRADE 0. ...

Page 5

... This pin is a separate power supply input for the top drive. C1 Copyright © 1998 Rev. 1.1 7/ LX1660/1661 5 ...

Page 6

... LX1660 Only: The INV pin is connected to the negative side of the sense resistor (i.e. the actual voltage supplied to the load) — See Figure 2. The LX1660 will achieve a high DC set- point accuracy, since it regulates at the load, but it will have greater transient voltage over- and under-shoots than the LX1661. ...

Page 7

... The number of capacitors in the output filter bank may be reduced by two in a typical application; more may be removed for systems with lesser transient requirements pulse-by-pulse current limiting is desired, remove C7 and short LX1660 pin 7 to ground Motorola MBR1035 for 10A capability; downsize as per required current. ...

Page 8

... LX1660/1661 C10 0.1µF LX1670 VIDO CC 10K 2 13 D4B V SENSE PWRGD P VID4 GOOD VID3 OUT 0.1µF OUTEN ENABLE VID2 BLKEN VID1 GND VID0 Note 1 ...

Page 9

... VID code can be set by means of a jumper or DIP switch. For 2.2V low or ‘0’ signal, connect the VID pin to ground (DIP switch 2.3V ON). For high or ‘1’, leave open (DIP switch OFF). 2.4V 2.5V 2.6V 2.7V 2.8V 2.9V 3.0V 3.1V 3.2V 3.3V 3.4V 3.5V LX1660/1661 16V, 1000µF Sanyo MV-GX or equivalent V Q1 IRL3103 L1 R1, 5m 5µH Toroid C5 D1 16V, 1000µF Sanyo MV-GX or ...

Page 10

... SELECTING BETWEEN THE LX1660 AND THE LX1661 In order to provide maximum user versatility, the Advanced PWM Controller is offered in two versions: the LX1660 and the LX1661. The LX1661 has a 40mV offset built-in which compensates for the current sense resistor voltage drop. This allows optimal transient response for high-speed systems, such as Pentium Pro processor power supplies ...

Page 11

... Product Highlight on the first page 7 of this data sheet. TIMING CAPACITOR SELECTION The frequency of operation of the LX1660 / 1661 is a function of the duty cycle and OFF-time. The OFF-time is proportional to the timing capacitor (connected to Pin 8, C minimize frequency variations with duty cycle. The frequency is constant, during steady-state operation, due to the modulation of the OFF-time ...

Page 12

... S Again, select (R C4 ERROR COMPARATOR INPUT BYPASS CAPACITOR The LX1660/61 device has a unique topology which results in extremely fast response to transient disturbances. Actual loop closure is around a comparator. A capacitor should be placed between the INV and NINV Error Comparator inputs to eliminate jitter and noise. This capacitor value should be ½ the timing capacitor ...

Page 13

... DS(ON) sourcing/sinking could occur. If synchronization is not practical, the next best alternative is to disable the synchronous (bottom) switch. This is easily accomplished with the LX1660/61 by pulling the SYNCEN pin HIGH. In most applications reduction in efficiency will result when the synchronous driver is disabled ...

Page 14

... LX1660/1661 USING THE LX1660/1661 IN PROGRAMMABLE APPLICATIONS The LX1660/61 device may be used in conjunction with the LX1670 Programmable Reference to implement a high-perfor- mance, digitally-controlled switched-mode power supply suitable for Pentium Pro Processors and other advanced microprocessor- based designs. The LX1670 incorporates a 5-bit equivalent DAC, which can be programmed by the microprocessor’ ...

Page 15

... LX1662/1663 LX1664/1665 Dual Output PWM for µProcessor Applications LX1668 Triple Output PWM for µProcessor Applications LX1553 PWM for 5V - 3.3V Conversion LX1670 Programmable Reference & Voltage Monitor Pentium is a registered trademark of Intel Corporation. LX1660/1661 ...

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