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Alliance Semiconductor

AS80M1800/1801 Product Brief

2003 (c) Copyright Alliance Semiconductor Corporation. All rights reserved.

January 2003

Key Features

• Compatible with most PWM controllers

Works with both current mode and voltage mode

PWM controllers.

• Input frequency ranges:

50 KHz to 400 KHz (AS80M1800)

400 KHz to 1 MHz (AS80M1801)

This is the input frequency range the device can

accommodate from the external PWM controller.

• Wide input PWM duty cycle range of 10% to 90%

Supports an extremely wide range of line and load

regulation conditions.

• Output drive current of 200 mA

Drives most popular power MOSFETs used in

SMPS designs.

• Supply voltage range of 7 V to 20 V

• Under voltage lockout

• Spread spectrum modulation with adjustable spread

• Output short circuit sense with adjustable level and

automatic recovery

• No-load condition sense

• Power savings feature

Frequency skip at no-load allows implementation

of Energy Star and other next generation power

savings modes

• Loss of input detect

Protects SMPS from catastrophic failure by shut-

ting off the output driver if the input PWM signal is

lost

• Under voltage lock-out

Protects SMPS from catastrophic failure by shut-

ting off the output drive if the supply voltage drops

below input VCC range

• Available in 8-pin SOIC package

Device Block Diagram

AS80M1800: 50 KHz to 400 KHz

AS80M1801: 400 KHz to 1 MHz

UVLO

SS

modulator

200 mA

buffer

Loss of

drive detect

Load monitor

&

recovery

Gate drive

Current sense

Current adjust

Modulation rate

Spread range

PWM_in