I am using MPS171AGS as Flyback Converter

DC-DC Power Converters
1

I am using MPS171AGS as Flyback Converter. Since it is self powered supply I didnt connect any external Vcc. But i see Vcc is fluctuating from 3V to 4.5V. IC is not turning on & I dont see Auxiliary & Secondary outputs

2

Hello @sunil.bhattad,

Welcome to MPS Forum. What is the nature of the input source at the drain? Can you also share your schematic?

3

It is DC Bus voltage from Full Bridge rectifier

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4

I am getting Vcc as attached

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5

Hello @sunil.bhattad,

Thank you for sharing the schematic. What is the VBUS voltage applied? The recommended VCC range is 5.5 to 5.7 V but here it only steps up to 4.5 V. As the desired output voltage is 10 V, the IC would require an external VCC supply to reduce the overall power consumption. Please refer to the following section in the DS.

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6

Thanks for this information.
We are giving DC Bus min 70V to 300V
Can i use 5V Auxiliary & directly give to Vcc? 5V would be sufficient?

7

Hello @sunil.bhattad,

I believe 5 V might be a bit low as the EC stable in the DS mentions Vccon minimum value as 5.1 V.

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