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TPS54340B: prevent Vout to reach Vin in case of resistor feedback failure?

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Part Number: TPS54340B

Team,

Regarding FMECA analysis in power supply:
Looking at the TPS54340B diagram if there is a failure with one of the feedback resistors connected to FB then the Output VOUT reaches the Input level VIN:

What do we advise in general to prevent VOUT to reach VIN in this case?
Are there some simple changes to implement in the basic application circuit that could prevent it?

Thanks in advance!

A.

  • Hi Anber,

    Vout will reaches Vin if Rfbt is open, or Rfbb is short. 

    One simple solution is: add 1k between FB pin and mid point of feedback resistor divider, add one zener between Vout and FB pin, Rfbb should be 1K level to reduce DC offset by Zener leakage current  

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