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AS2208

Primary Side PWM Controller

Unspecified 

AS2208

Primary Side PWM Controller

Preliminary Specification

Features

• Low Startup Current

• Single-start or auto-restart

modes

• Oscillator trimmed for precision

duty cycle clamp

• Standard temperature range

extended to 105°C

• Remote on / off control

• Self limiting supply Voltage

• Standard current mode control

Description

The AS2208 is a simplified pulse width modulation control-

ler, offering similar functionality as that of the AS3842.

Based on the AS2214, the AS2208 provides the additional

features of low startup current and overvoltage latching,

making it a good solution for adapter applications.

The PWM function is controlled by the current sense com-

parator for normal current mode control. The COMP pin,

which serves as an input to the current sense comparator,

provides a 1 mA current source which can be tied directly to

the control loop optocoupler. The output stage is a high

current totem pole output that sees only 85 ns delay from the

PWM comparator.

The AS2208 requires only 100 µA of startup current. The

undervoltage lockout (UVLO) thresholds are nominally 14V

for turn on and 8 V for turn off. The VREG pin, based on a

trimmed bandgap reference, provides a temperature com-

pensated 5 V to loads of up to 50 mA. The oscillator

discharge current is trimmed to provide guaranteed duty

cycle clamping.

Pin Configuration — Top view

PDIP (N)

COMP 1

ISNS 2

RT/CT 3

OV 4

8 VREG

7 VCC

6 OUT

5 GND

8L SOIC (D)

COMP 1

ISNS 2

RT/CT 3

OV 4

8 VREG

7 VCC

6 OUT

5 GND

Ordering Information

Package

8-Pin Plastic DIP

8-Pin Plastic SOIC

ASTEC Semiconductor

Temperature Range

0 to 105° C

0 to 105° C

77

Order Code

AS2208N

AS2208D

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