In detail :

a - The Primary Side :

The VIPER20 stands as a PWM circuit with integrated Power MOSFET after the Rectifying-Filtering stage

(F01 fuse, R03 NTC, L02 and C04 filtering coil and capacitor, D03 diode bridge and C03 front bulk

capacitor).

R01 and D01 ensure the correct supplying of the VIPer20 device during normal operation thanks to the

auxiliary winding of the transformer. C05 is in charge of filtering this output, and provides also the needed

energy at start up thanks to the integrated start up current source of the VIPer20 device. The PWM function

is determined by R02, D06 (frequency of operation) and the collector and emmitor of the photocoupler

(linear width modulation). The couple R04, C07 is a compensation network.

b - The Secondary side :

Figure 3b : Secondary Side of Battery Charger

AN1051 - APPLICATION NOTE

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