L6565_ quasi-resonant controller

The L6565 is a current mode master controller IC designed specifically for building off-line quasi-resonant ZVS (zero voltage switching when switched on) flyback converters. The quasi resonance operation is realized by the transformer demagnetization induction input that triggers the MOSFET to turn on.

The power capacity of the converter varies with the grid voltage and is compensated by line voltage feedforward. Under light load, the equipment has a special function to automatically reduce the operating frequency, while maintaining the operating status as close to the zero voltage switch as possible. In addition to extremely low start current and static current, this feature helps to maintain low power consumption of the main power supply under light loads and complies with Blue Angel and Energy Star standards.

The integrated circuit also includes a disable function, an on-chip current detection filter, an error amplifier with a precise reference voltage for primary regulation, and an effective two-stage overcurrent protection.

L6565_ quasi-resonant controller

All functions

Switching power supply for TV/monitor
Blue Angel, Energy Star, Energy 2000
Digital consumer
Ac-dc adapter/charger
Printers, fax machines, copiers and scanners
1% accuracy (@TJ =25˚C) internal reference voltage
Disable function (on/off control)
Quasi resonant (QR) zero voltage switch (ZVS) topology
Frequency folding achieves optimal standby efficiency
The line is fed forward, providing constant power instead of power variation
Ultra-low start (<70µA) and static current (<3.5mA)
±400mA totem pole gate driver with UVLO pull-down
Pulse by pulse and burp mode OCP

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