Microsemi Corporation LX1661CN, LX1660CD, LX1661CD, LX1660CN Datasheet

A

DVANCED

PWM C

ONTROLLER

P RODUCTION DAT A SHEET

THE INFINITE POWER OF INNOVATION

LX1660/1661

LIN DOC #:

1660

DESCRIPTION KEY FEATURES

■ Designed To Drive A Synchronous Rectifier

Stage — Can Also Be Used In Non­Synchronous 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

The LX1660 and LX1661 Are Mono­lithic 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

®

or other micropro-

cessors.

Synchronous Rectifier Driver For

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 applica­tions.

Short-Circuit Current Limiting

Without Expensive Current Sense Re­sistors. The current sensing mechanism

can use a PCB trace resistance or the para­sitic resistance of the main inductor. For
applications requiring a high degree of
accuracy, a conventional sense resistor
can be used.

Hiccup Mode Fault Protection. The
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.

Ultra-Fast Transient Response Re­duces 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 ca­pacitors to meet stringent transient over­and under-shoot specifications.

PRODUCT HIGHLIGHT

PACKAGE ORDER INFORMATION

T

A

(°C)

Plastic DIP
16-pin

0 to 70 LX166xCN LX166xCD

N

Plastic SOIC
16-pin

D

LX1661 IN SOCKET 7
P

ROCESSOR SUPPLY

APPLICATION

APPLICATIONS

■ Pentium Processor Supplies

■ AMD-K6

TM

Supplies

■ Cyrix

®

6x86TM Supplies

■ Voltage Regulator Modules

■ General Purpose DC:DC Supplies

Note: All surface-mount packages are available in Tape & Reel.

Append the letter "T" to part number. (i.e. LX166xCDT)

EN

C

T

C8
390pF

TDRV

V

CC

CS-

OT

ADJ

SGND
V

REF

INV
NINV
HICCUP CS+

SYNCEN

BDRV

PGND

V

C1

LX1661

R16
10k

C3

0.1µF

C4
390pF

R15

2.0k
1%

R14, 1%
See Table 5

C9
1µF

12V

L1

R1, 5m

16V, 1000µF

Sanyo MV-GX or

equivalent

V

OUT

16V, 1000µF

Sanyo MV-GX or equivalent

VIN 5V

16-pin SOIC

C1
390pF

Q1

IRL3103

5µH Toroid

D1

C5

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

C2 C7

C6

OUTEN

U1

R5, 1k

R6, 1k

Copyright © 1998
Rev. 1.1 7/98

1

11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841, 714-898-8121, FAX: [phone]

L INFINITY MICROELECTRONICS INC.

IMPORTANT: For the most current data, consult LinFinity's web site: http://www.linfinity.com.

A

DVANCED

PWM C

ONTROLLER

LX1660/1661

PRODUCT DATABOOK 1996/1997

Copyright © 1998

Rev. 1.1 7/98

2

P

RODUCTION DATA SHEET

ABSOLUTE MAXIMUM RATINGS (Note 1)

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 at T

A

= 25°C

N Package ............................................................................................................... 1.5W

D Package........................................................................................................... 830mW

Operating Junction Temperature

Plastic (N, D Packages) ......................................................................................... 150°C

Storage Temperature Range .................................................................... -65°C to +150°C

Lead Temperature (Soldering, 10 Seconds) ............................................................. 300°C

PACKAGE PIN OUTS

1 16

215

314

413

512

611

710

89

D PACKAGE

(Top View)

N PACKAGE:

THERMAL RESISTANCE-JUNCTION TO AMBIENT,

θθ

θθ

θ

JA

65°C/W

D PACKAGE:

THERMAL RESISTANCE-JUNCTION TO AMBIENT,

θθ

θθ

θ

JA

120°C/W

Junction Temperature Calculation: TJ = TA + (P

D

x θ

JA

).

The θ

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
PGND
BDRV
V

CC

SYNCEN
CS+
CS-

EN

OT

ADJ

SGND

V

REF

INV

NINV/SS

HICCUP

C

T

1 16

215

314

413

512

611

710

89

N PACKAGE

(Top View)

V

C1

TDRV
PGND
BDRV
V

CC

SYNCEN
CS+
CS-

EN

OT

ADJ

SGND

V

REF

INV

NINV/SS

HICCUP

C

T

A

DVANCED

PWM C

ONTROLLER

LX1660/1661

PRODUCT DATABOOK 1996/1997

3

Copyright © 1998
Rev. 1.1 7/98

P RODUCTION DAT A SHEET

ELECTRICAL CHARACTERISTICS

(

Unless otherwise specified, 10.8 < V

CC

< 13.2, 0°C ≤ TA ≤ 85°C. Test conditions: V

CC

= 12V, T = 25°C.

)

Reference Section

Parameter

Symbol

Test Conditions

Initial Output Voltage VCC = 12V, IL = 100µA

Load Regulation V

CC

= 12V, IL = 10µA to 5mA

Short Circuit Current I

SH

V

REF

= 1.96V

LX1661

Units

Min. Typ. Max. Min. Typ. Max.

LX1660

1.98 2 2.02 1.98 2 2.02 V

22mV

24 24 mA

Timing Section

Off Time Initial OT OT

ADJ

= 1.8V, CT = 390pF

OT

ADJ

= 3.5V, CT = 390pF

Off Time Temp Stability OT

ADJ

= 1.8V to 3.5V

Discharging Current I

DISVNINV

= 1.8V, VCT = 1.5V

V

NINV

= 3.5V, VCT = 1.75V

Ramp Peak V

P

Ramp Peak-Valley V

RPP

OT

ADJ

= 1.8V

OT

ADJ

= 3.5V

Ramp Valley Delay to Output 10% Overdrive
Turn Off Threshold V

OFF

(Voltage at OT

ADJ

Pin)

22µS
11µS

22%
180 210 240 180 210 240 µA
180 210 240 180 210 240 µA

22V

0.8 0.9 1.0 0.8 0.9 1.0 V

0.475 0.5 0.525 0.475 0.5 0.525 V
100 100 nS

0.6 0.9 1.2 0.6 0.9 1.2 V

Input Bias Current I

B

1.8V < VCS+ = VCS < 3.5V

Pulse By Pulse C

L

V

CLP

Initial Accuracy

C

S

Delay to Output 10% Overdrive

Error Comparator Section

Synchronous Control Section

Synchronous Enable Threshold S

YCEN

Current Sense Section

0.1 1.0 0.1 1.0 µ A
2 364248 mV

150 150 nS

0.5 0.7 0.9 0.5 0.7 0.9 V

0.1 1 0.1 1 µA

80 90 100 80 90 100 mV

150 150 nS

Input Bias Current I

B

VFB = V

SET

Input Offset Voltage V

IO

EC Delay to Output 10% Overdrive

Output Drivers Section

Output Rise Time TRVCL = VC2 = 12V, CL = 3000pF

Output Fall Time T

F

VCL = VC2 = 12V, CL = 3000pF

Output Pull Down V

PDVCC

= VC = 0, I

PULL UP

= 2mA

Peak Current I

PKtPULSE

= 500ns

70 70 nSec

70 70 nSec

11V

1.0 1.0 A

UVLO and S.S. Section

Start-Up Threshold V

ST

Hysteresis V

HYST

S.S. Sink Current I

SD

V

CL

= 10.1V

S.S. Sat Voltage V

OLVCL

= 9V, ISD = 20µA

Enable Shutdown Threshold V

EN

Enable Bias Current I

ENIEN

(Low), VEN = 0V

I

EN

(High), VEN = 2V

Enable Hysteresis

9.85 10.15 10.45 9.85 10.15 10.45 V

0.31 0.31 V

23 23 mA

0.2 0.6 0.2 0.6 V

1.3 1.4 1.5 1.3 1.4 1.5 V

-0.5 -1 -0.5 -1 µA

0.5 1 0.5 1 µA

0.14 0.16 0.18 0.14 0.16 0.18 V

Supply Current Section

Dynamic Operating Current I

CD

VCC = VC = 12V, Out Freq = 200kHz, CL = 0

Start-Up Current I

ST

VCL = 10V

25 25 mA

500 1000 500 1000 µ A

Hiccup Section

Hiccup Factor “ON” Time (C

HICCUP

= 0.1µF typ.)

Hiccup Duty Cycle

100 100 mS/µF

10 10 %

A

DVANCED

PWM C

ONTROLLER

LX1660/1661

PRODUCT DATABOOK 1996/1997

Copyright © 1998

Rev. 1.1 7/98

4

P

RODUCTION DATA SHEET

BLOCK DIAGRAM

1

EN

INTERNAL

V

CC

2

OT

ADJ

2V REF

EN

UVLO

10.6/10.1

2V OUT

V

CC

1.4V
VREG 5V

3

SGND

4

V

REF

5

INV

6

NINV/SS

7

HICCUP

OFFTIME CONTROL

8

C

T

SRQ

Q

R DOM

BREAK

BEFORE

MAKE

16

V

C1

15

TDRV

14

PGND

12

V

CC

11

SYNCEN

10

CS+

9

CS-

SYNC EN

COMP

I

MAX

PWM LATCH

ENABLE

ERROR
COMP

O

TADJ

V

PEAK

= 2V

V

VAL

= 1V

SRQ

Q

V

CC

HICCUP

90mV

10

I

I

UPGRADE

VREG GOOD

0.7V

HICCUP LATCH

13

BDRV

40mV (1661 only)

1.5V

FIGURE 1 — Block Diagram

A

DVANCED

PWM C

ONTROLLER

LX1660/1661

PRODUCT DATABOOK 1996/1997

5

Copyright © 1998
Rev. 1.1 7/98

P RODUCTION DAT A SHEET

EN 1 A low voltage at this pin puts the IC in sleep-mode.

OT

ADJ

2 The purpose of this pin is to allow modulation of the OFF-time relative to the reference voltage. The OFF-time is

inversely proportional to the reference voltage. The inverting input of the upgrade voltage comparator is also
connected to this pin, when the voltage at this pin is below 0.7V, the controller shuts down.

SGND 3 This pin is the signal ground of the IC.

V

REF

4 2V reference.

INV 5 This pin is the inverting input of the error comparator.

NINV/SS 6 This pin is the non-inverting input of the error comparator (LX1661 only: 40mV offset between this pin and error

comparator). This pin is pulled low during sleep-mode to allow soft-start function during start up.

HICCUP 7 A hiccup-mode capacitor connected to this pin adjusts duty cycle.

C

T

8 The OFF-time is programmed by connecting a capacitor from this pin to ground.

CS- 9 This is the inverting input of the pulse-by-pulse current comparator.

CS+ 10 This is the non-inverting input of the pulse-by-pulse current comparator.

SYNCEN 11 This pin enables the synchronous (bottom) driver. A high voltage at this pin disables the synchronous driver.

V

CC

12 This is the IC supply voltage as well as the supply to the bottom MOSFET.

BDRV 13 This is the gate drive to the bottom MOSFET

PGND 14 This is a separate ground for the top and bottom MOSFET.

TDRV 15 This is the gate drive to the top MOSFET.

V

C1

16 This pin is a separate power supply input for the top drive.

Pin # Description

FUNCTIONAL PIN DESCRIPTION