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AN1376 APPLICATION NOTE

16 OVER VOLTAGE PROTECTION

A dangerous fault that could happen in case is the failure of the feedback circuitry. If this oc-

curs, the SMPS output voltages can get high values, depending on the load by each output

and the transformer coupling between the windings. Consequently, the rectifiers and the out-

put capacitors are overstressed and can be destroyed. To avoid the SMPS failure a suitable

protection circuit has been added. Then the circuit has been tested opening the loop, giving

the following results:

3.3V OUTPUT: @ full load

3.3V OUTPUT: @ No load

@115V – 50Hz

@220V – 50Hz

@115V – 50Hz

@220V – 50Hz