ST8411 3~6V Synchronous Rectifier Controller
Specifications
Product details
Overview
The ST8411 is a high-performance secondary-side synchronous rectification driver chip. By driving an internal low on-resistance N-channel MOSFET, it replaces the freewheeling diode on the secondary side of a conventional flyback power supply, improving system efficiency and simplifying thermal design. The ST8411 detects the internal SR MOSFET drain voltage to control the SR MOSFET gate turn-on and turn-off, and can be applied in DCM and QR mode flyback systems. The ST8411 features an output-voltage detection function: when the output voltage is above 3V the device starts operating; when it rises above 5.45V an internal 3mA pull-down current prevents the system output voltage from drifting up under no-load conditions; and when an output voltage above 6V is detected, a strong pull-down current is applied, providing an efficient, safe and simple solution for 5V power supplies.
Features
- Supports system operation in DCM or QR mode
- Built-in fixed turn-on/turn-off delay eliminates resonant ringing interference
- Built-in 5.45V voltage clamp pull-down prevents output overshoot under no-load
- Built-in 6V over-voltage protection with strong pull-down above 6V
- 3V startup voltage
- 2.9V undervoltage protection
- Minimum on-time programmable via an external resistor for excellent transient response
- Simple peripheral circuitry
Typical Applications
- Adapters, single-cell lithium battery chargers, cordless phones
- ADSL modems, MP3 players and other portable devices
- Backup power supplies and auxiliary power supplies
