VIPER53-E STMicroelectronics, VIPER53-E Datasheet - Page 18
VIPER53-E
Manufacturer Part Number
VIPER53-E
Description
Fixed frequency off line converter
Manufacturer
STMicroelectronics
Datasheet
1.VIPER53-E.pdf
(36 pages)
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Secondary feedback configuration example
18/36
Since the dynamic characteristics of the converter are set on the secondary side through
components associated to U3, the compensation network has only a role of gain
stabilization for the optocoupler, and its value can be freely chosen. R5 can be set to a fixed
value of 1k , offering the possibility of using C7 as a soft start capacitor: When starting up
the converter, the VIPer53 device delivers a constant current of 0.6 mA on the COMP pin,
creating a constant voltage of 0.6V in R5 and a rising slope across C7. This voltage shape,
together with the operating range of 0.5V to 4.5V provides a soft start-up of the converter.
The rising speed of the output voltage can be set through the value of C7. The C4 and C6
values must be adjusted accordingly in order to ensure a correct start-up.
VIPer53 - E