LX1664/1664A, LX1665/65A

PRODUCT DA T ABOOK 1996/1997

7

Copyright © 1999

Rev. 1.2 11/99

SS

1

1

INV

2

2

V

CC_CORE

33

VID0

4

4

VID1

5

5

VID2

6

6

VID3

7

7

VID4

8

8

L

FB

99

PWRGD

N.C.

10

L

DRV

10

11

OV

N.C.

12

C

T

11

13

V

CC

12

14

BDRV

13

15

GND

14

16

TDRV

15

17

V

C1

16

18

Soft-Start pin, internally connected to the non-inverting input of the error comparator.

Inverting input of the error comparator.

Output voltage. Connected to non-inverting input of the current-sense comparator.

Voltage Identification pin (LSB) input used to set output voltage.

Voltage Identification pin (MSB) input. This pin is also the range select pin — when low

(CLOSED), output voltage is set to between 1.30 and 2.05V in 0.05V increments. When high

(OPEN), output is adjusted from 2.0 to 3.5V in 0.1V increments.

Linear regulator feedback pin. 1.5V reference is connected to a resistor divider to set desired

output voltage.

Open collector output pulls low when the output voltage is out of limits.

Linear regulator drive pin. Connect to gate of MOSFET for linear regulator function.

SCR driver goes high when the processor's supply is over specified voltage limits.

The off-time is programmed by connecting a timing capacitor to this pin.

This is the (12V) supply to the IC, as well as gate drive to the bottom FET.

This is the gate drive to the bottom FET. Leave open in non-synchronous operation (when bottom

FET is replaced by a Schottky diode).

Both power and signal ground of the device.

Gate drive for top MOSFET.

This pin is a separate power supply input for the top drive. Can be connected to a charge pump

when only 12V is available.

Pin

LX1664

LX1665

Name

Pin #

Pin #

Description

FUNCTIONAL PIN DESCRIPTION