SG6105A controller is designed for switching-mode power supplies for desktop PCs. It provides all the functions necessary to monitor and control the output of the power supply. Remote ON/OFF control, power-good circuitry, and protection features against over-voltage and over-power are implemented. It directly senses all the output rails for OVP without the need for external dividers. An innovative AC-signal sampling circuitry provides a sufficient power-down warning signal for PG.

A built-in timer generates accurate timing for the control circuit, including the PS-off delay. The cycle-by-cycle PWM switching prevents the power transformer from saturation and ensures the fastest response for the short-circuit protection, which greatly reduces stress for power transistors. Two internal precision TL431 shunt regulators provide stable reference voltage and a driver for 3.3V and 5V standby regulation.

Utilizing minimum external components, the SG6105A includes the functions for push-pull and/or half-bridge topology, decreasing production cost and PCB space, and increasing the MTBF for power supply.

• PC Half-Bridge (or 494) Power Supply Supervisor + two 431 + PWM
• High Integration with Few External Components
• Over-Voltage Protection for 3.3V, 5V, and 12V
• Under-Voltage Protection for 3.3V, 5V, and 12V
• Under-Voltage Protection for –12V and/or –5V
• Over-Power and Short-Circuit Protection
• Power-Down Warning Circuitry
• Power-Good Circuitry
• Delay Time for PSON and PG Signal
• Remote ON/OFF Function
• On-Chip Oscillator and Error Amplifier
• Two Shunt Regulators for 3.3V and 5V-Standby
• Latching PWM for Cycle-by-Cycle Switching
• Push-Pull PWM Operation and Totem Pole Outputs
• Soft-start and Maximum 93% Duty Cycle

Switching mode power supply for computers:

• AT
• NLX
• SFX (micro-ATX)