Pin Description

PIN

NAME

DESCRIPTION

APPLICATION INFORMATION

1

Vin

Source Input Voltage

Input to start-up regulator. Input range

13V to 100V.

2

FB

Feedback Signal

Inverting input of the internal error

amplifier. The non-inverting input is

internally connected to a 1.25V

reference.

3

COMP

The output of the error

amplifier and input to the

Pulse Width Modulator

COMP pull-up is provided by an

internal 5K resistor which may be

used to bias an opto-coupler

transistor.

4V

CC

Output of the internal high

voltage series pass regulator.

Regulated output voltage 7.7V

If an auxiliary winding raises the

voltage on this pin above the

regulation set point, the internal series

pass regulator will shutdown, reducing

the controller power dissipation.

5

OUT

Output of the PWM controller

Gate driver output with a 1A peak

current capability

6

GND

Ground return

7

UVLO

Line Under-Voltage Shutdown An external resistor divider from the

power converter source sets the

shutdown levels. The threshold of

operation equals 1.25V. Hysteresis is

set by a switched internal 20µA

current source.

8

CS

Current Sense input

Current sense input for current mode

control and over-current protection.

Current limiting is accomplished using

a dedicated current sense comparator.

If the CS comparator input exceeds

0.5V the OUT pin switches low for

cycle-by-cycle current limiting. CS is

held low for 50ns after OUT switches

high to blank leading edge current

spikes.

9

RT / SYNC

Oscillator timing resistor pin

and synchronization input

An external resistor connected from

RT to GND sets the oscillator

frequency. This pin will also accept

synchronization pulses from an

external clock.

10

SS

Softstart Input

An external capacitor and an internal

10µA current source set the soft-start

ramp rate.

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