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AN1729

APPLICATION NOTE

June 2003

QR ZVS Flyback topology

well as other contributions reflected from the secondary side.

Figure 1. Flyback topology

Llk

Lm

Ls

Lp

Cin

Rp

Vin

Vout

Cd

D03IN1462

by: R.D. Stracquadaini, C. Leonardi

L6565-BASED LOW COST SMPS FOR TV WITH

LESS THEN 1W STANDBY CONSUMPTION

The need for energy consumption reduction brings to the design of more and more efficient power sup-

plies. High efficiency is required not only when the system supplied is fully operating but also when it is

in standby condition and absorbs very little power. A common design target for many home appliances

is that their power consumption in standby mode be less than 1W.

In this paper a cost-effective solution for the power supply of a 60W 14" TV, with a standby power con-

sumption of less then 1W is presented.

The topology used for this Switch Mode Power Supply is a Quasi-resonant Flyback Converter (See

AN1326) in order to reduce the switching losses (ZVS at turn-on) and then to increase efficiency. In or-

der to increase the performance in standby condition the start up network was designed with particular

burst mode operation of the power supply when the system is in standby condition. The power MOS