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TPS54331: 5.1 Volt Output instead of 5 Volt

Mohammed Khan
Prodigy 10 points
Part Number: TPS54331

In the previous version of the board, I'm getting 5.068 volts as output voltage which is also designed using TPS. The newer version of the board has also the same components, but I'm getting 5.1111 volts as output voltage.

VDM=Vin=8.084V(Older Version)

VDM=Vin=8.606V(Newer Version).

I removed L4 so that the circuit is isolated from the rest of the board, still, I'm getting 5.111 V as output. Could it be something to do with the design of P.C.B? I asked the P.C.B designer, he said both versions have a similar layout. No changes. Can anyone suggest what might be happening?

  • Former Member
    0 Former Member

    Hi Mohammed,

    The difference between 5.068V and 5.111V is only 43mV(0.1%), and the input voltage is different. 

    Many factors may lead the output difference: 

    1.Line Regulation(Datasheet page 23):

    Line regulation is the ability of the power supply to maintain its specified output voltage over changes in the input line voltage. It is expressed as percent of change in the output voltage relative to the change in the input line voltage.

    2.Load Regulation(Datasheet page 23):

    Load regulation is the ability of the power supply to maintain its specified output voltage given changes in the load. This does not mean the tolerance applies when there are sudden changes in load, it means over the permissible load range the regulation can change by this amount.

    3.Feedback Resistors' accuracy:

    There are 1%, 0.1%, 10% accuracy resistors.

    4.Reference voltage accuracy:
              You can check the reference voltage accuracy as below:

    Thanks.