SG3525

The SG3525 is a highly versatile and popular integrated circuit (IC) primarily used as a Pulse Width Modulator (PWM) controller for designing all types of switching power supplies (SMPS), DC-DC converters, and DC-AC inverters.

It is a 16-pin IC that offers improved performance and a reduced external parts count compared to earlier designs.²It operates in voltage-mode control.

Key Features and Characteristics

• Operating Voltage: 8.0 V to 35 V.

• Reference Voltage: A precise on-chip +5.1V reference trimmed to 1% accuracy.

• Oscillator Range: Adjustable frequency from 100Hz to 400kHz using external timing resistors (R_T) and a capacitor (C_T).

• Outputs: Features dual totem-pole outputs (Output A and Output B) that are complementary and capable of sourcing and sinking up to 400mA peak current, often enough to directly drive MOSFETs or IGBTs in low to medium power applications.

• Deadtime Control: Has an adjustable deadtime programmed by an external resistor (R_D) connected between the C_T and Discharge pins, which is crucial for preventing "shoot-through" in push-pull or half-bridge output stages.

• Soft-Start: Includes a built-in soft-start circuitry requiring only an external timing capacitor. This slowly ramps up the duty cycle at startup to limit inrush current.

• Protection: Features pulse-by-pulse shutdown via a dedicated pin (pin 10) and an Undervoltage Lockout (UVLO) which inhibits the outputs when the supply voltage is too low.

• Synchronization: ASYNC input allows synchronization with an external system clock, useful when multiple units are used.