AN3011 datasheet(28/37 Pages) STMICROELECTRONICS

Part #	AN3011

Description	In certain applications such as LCD or plasma TVs

PDF	37 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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Efficiency

AN3011

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Doc ID 16043 Rev 1

Figure 29.

Second overcurrent protection - protection tripping

In Figure 29, when the board is working in full-load condition with an input voltage of 115

VAC, the secondary winding is shorted. If the converter runs with the secondary winding

shorted, there is a very high current flowing through the transformer windings, the

secondary diode, and the VIPer power section. The second over-current protection, which

stops the converter operation after two switching cycles, prevents the flow of these high

currents. Figure 30 shows the situation when a permanent short-circuit is applied on the

secondary winding. Most of the time the power section of the VIPer is off, eliminating any

risk of overheating.

Figure 30.

Operating with the secondary winding shorted. Restart mode

AN3011 Datasheet(PDF) 28 Page - STMicroelectronics