PRODUCT NAME

ICF SG3525

FUNCTIONAL DESCRIPTION

Pulse Width Modulator Control Circuit

APPLICATIONS

Regulating Pulse Width Modulators

AC controller

GENERAL DESCRIPTION

The ICF SG3525 pulse width modulator control circuit offers improved performance and lower external parts count when implemented for controlling all types of switching power supplies.

The on−chip +5.1 V reference is trimmed to ± 1% and the error amplifier has an input common−mode voltage range that includes the reference voltage, thus eliminating the need for external divider resistors. A sync input to the oscillator enables multiple units to be slaved or a single unit to be synchronized to an external system clock. A wide range of deadtime can be programmed by a single resistor connected between the C_T and Discharge pins. This device also

features built−in soft−start circuitry, requiring only an external timing capacitor. A shutdown pin controls both the soft−start circuitry and the output stages, providing instantaneous turn off through the PWM latch with pulsed shutdown, as well as soft−start recycle with longer shutdown commands. The under voltage lockout inhibits the outputs and the changing of the soft−start capacitor when VCC is below nominal. The output stages are totem−pole design capable of sinking and sourcing in excess of 200 mA. The output stage of the ICF SG3525 features NOR logic resulting in a low output for an off−state.

FEATURES

8.0 V to 35 V Operation

5.1 V ± 1.0% Trimmed Reference

100 Hz to 400 kHz Oscillator Range

Separate Oscillator Sync Pin

Adjustable Deadtime Control

Input Undervoltage Lockout

Latching PWM to Prevent Multiple Pulses

Pulse−by−Pulse Shutdown

Dual Source/Sink Outputs: ±400 mA Peak

Pb−Free Packages are Available

BLOCK DIAGRAM

ORDERING INFORMATION