SG3525AES

Integrates a 5.1V reference voltage source, a 100Hz–500KHz wide-frequency oscillator, soft-start circuit, error amplifier, PWM comparator, undervoltage lockout circuit, and power transistor output driver circuit. Features a synchronous clock function, capable of operating in master/slave mode or synchronizing with an external system clock signal. Dead-time adjustment can be achieved by inserting a resistor between the CT pin and the Discharge pin. The internally integrated soft-start circuit requires only an external timing capacitor on pin 8 to enable PWM soft-start functionality. During power-up, the timing capacitor voltage is charged by an internal 50uA constant current source, rising gradually from zero to Vref, while the PWM output simultaneously ramps up from zero to the maximum duty cycle required for voltage regulation; the soft-start process ends when the timing capacitor voltage reaches Vref. When the fault circuit asserts a Shutdown signal, this signal affects both the output stage and the soft-start circuit. When the signal on Shutdown (pin 10) goes high, the output is disabled and the soft-start capacitor begins to discharge. If the high level persists, the soft-start capacitor will fully discharge; the soft-start sequence will not reinitiate until the shutdown signal is deasserted. The Shutdown pin must not be left floating and should be reliably connected to ground through a pull-down resistor to prevent external interference signals from coupling in and disrupting normal operation.

Applications

• Inverter power supplies
• High-power high-frequency switching power supplies
• DC pulse-width modulation speed control systems
• UPS power supplies
• DC/DC converters
• High-power chargers

Key features

• Wide operating voltage range: +8V~+35V
• Built-in 5.1V reference voltage, ±1% accuracy
• Wide oscillator frequency range: 100Hz~500KHz
• Oscillator external synchronization
• Adjustable dead time
• Built-in soft-start circuit
• Input undervoltage lockout
• PWM latch function, inhibits multiple pulses
• Dual-channel sink and source current drive capability