High Performance Current Mode PWM Controller

AP3842/3/4/5

This datasheet contains new product information. Anachip Corp. reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of

this product. No rights under any patent accompany the sale of the product.

Rev.1.0 Oct.11, 2004

1/8

Features

•

Optimized for Off-Line and DC to DC Converters

•

Low Start-Up Current (≦0.5mA)

•

Automatic Feed Forward Compensation

•

Pulse-by-Pulse Current Limiting

•

Enhanced Load Response Characteristics

•

Under-Voltage Lockout (UVLO) with Hysteresis

•

Double Pulse Suppression

•

High Current Totem Pole Output

•

Internally Trimmed Bandgap Reference

•

Current Mode Operation to 500KHZ

•

Low Ro Error Amplifier

Pin Connections

PDIP-8L, SOP-8L

1

2

3

4

COMP.

V

FB

V

REF

5

6

7

8

I

SENSE

R

OUTPUT

GROUND

V

I

Top View

General Description

The AP3842/3/4/5 family of control ICs provides the

necessary features to implement off-line or DC to

DC fixed frequency current mode control schemes

with a minimal external parts count. Internally

implemented circuits include under voltage lockout

featuring start-up current less than 0.5 mA, a

precision reference trimmed for accuracy at the

error amp input, logic to insure latched operation, a

PWM comparator which also provides current limit

control, and a totem pole output stage designed to

source or sink high peak current. The output stage,

suitable for driving N-Channel MOSFETs, is low in

the off-state.

Differences between members of this family are the

under-voltage lockout thresholds and maximum

duty cycle ranges. The AP3842 and AP3844 have

UVLO thresholds of 16V(on) and 10V(off), ideally

suited for off-line applications. The corresponding

thresholds for the AP3843 and AP3845 are 8.5V

and 7.6V. The AP3842 and AP3843 can operate to

duty cycles approaching 100%. A range of the zero

to < 50% is obtained by the AP3844 and AP3845

by the addition of an internal toggle flip flop which

blanks the output off every other clock cycle.

Ordering Information

AP 384X X X X

Package

S8:SOP-8L

N8:PDIP-8L

Packing

Blank: Tube

Part No.

2:3842

3:3843

4:3844

5:3845

Lead Free

Blank : Normal

L : Lead Free Package A : Taping