Microsemi

Linfinity Microelectronics Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

Page 2

Copyright

© 2000

Rev. 1.1b,2005-03-09

LX1681/1682

Voltage-Mode PWM Controllers

TM

®

ABSOLUTE MAXI MUM RATI NGS ( NOTE 1)

Output Drive Peak Current Source (500ns) ................................................................. 1.0A

Output Drive Peak Current Sink (500ns) ..................................................................... 1.0A

Input Voltage (SS/ENABLE Pin) ........................................................................-0.3 to 6V

Operating Junction Temperature................................................................................150°C

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

RoHS / Pb-free Peak Package Solder Reflow Temp (40 second max. exposure) ........... 260°C (+0, -5)

Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to

Ground. Currents are positive into, negative out of specified terminal.

TH ERM A L DATA

THERMAL RESISTANCE

θ

JA

165

°C/W

system. All of the above assume no ambient airflow.

PACKAGE PI N OUT

1

2

4

3

5

6

8

7

V

FB

SS

N.C.

GND

V

CC

CS

V

C1

TDRV

LX1681

(Top View)

1

2

4

3

5

6

8

7

V

FB

SS

GND

BDRV

V

CC

CS

V

C1

TDRV

LX1682

(Top View)

RoHS / Pb-free 100% Matte Tin Lead Finish

FUNCTIONAL PIN DESCRIPTION

Voltage Feedback. A 1.25V reference is connected to a resistor divider to set desired output voltage.

SS

Soft-Start And Hiccup Capacitor Pin. During start up the voltage of this pin controls the output voltage. An

internal 20k

Ω resistor and the external capacitor set the time constant for soft-startup. Soft-start does not begin

until the supply voltage exceeds the UVLO threshold. When over-current occurs, this capacitor is used for timing

hiccup. The PWM can be disabled by pulling the SS pin below 0.3V

GND

Ground for IC.

TDRV

Gate Drive For Upper MOSFET.

BDRV

Gate Drive For Lower MOSFET.

Separate Supply For MOSFET Gate Drive. Connect to 12V.

CS

Over-Current Set. Connect resistor between CS pin and the source of the upper MOSFET to set current-limit

point.

IC Supply Voltage (nominal 5V) And High Side Drain Sense Voltage.