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TPS23755EVM-894: About load regulation spec

Tsukui Yusuke
Guru 21930 points
Part Number: TPS23755EVM-894
Other Parts Discussed in Thread: TPS23755

Hi,

Could you tell me about TPS23755 EVM load regulation spec in light load condition.
The following graph is described in User's Guide.
At light load, customers think that regulation is bad.

1.Please tell me the reason why the voltage rises.

2.Is there a way to improve regulation?
   Customer's target is about 12.6V.



Best Regards,
Yusuke

  • 0
    TI__Mastermind 41760 points

    Hi Yusuke-san,

    1. This is normal behavior for primary side regulated converter. At no loads, there is no way for the output caps to discharge so the voltage will increase. In this case ~13.5V.

    2.Typically there is already a load on the output to keep the output voltage well regulated; otherwise, a dummy load can be added like 50m ohm if you want to stay within your 12.6V spec. This is what's commonly done. If your design does not allow this, then a secondary side regulated flyback can be used; it could still have a similar problem at no load, but it won't be as high as a PSR topology because you have a divider on the secondary and the opto biasing currents that help discharge the output cap.

    Regards,

    Darwin