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TPS54060: error in UVLO limits

Horacio R DRUT
Prodigy 20 points
Part Number: TPS54060

Hi,

I have a DC DC converter design using TPS54060. Input voltage is 37V nominal, 30-42 range. I have set UVLO limits for STOP @ 30V and for START @ 31.5V.

Resistor values are accordingly: 499k and 20k.

However I am verifying important deviations from these limits (sometimes STOP goes as low as 27V).

Is there anything else I should check to achieve consistent results on these limits?


Vout = 5V
Fsw = 700kHz

Thanks, rgds,

Richard

  • 0
    TI__Mastermind 26520 points
    Hello Horacio,

    Unfortunately the Enable pin threshold is not precise enough from two perspectives. Please note the following

    1. the Enable voltage threshold can vary from 0.9V to 1.55V with 1.25V being the typical.
    2. the Ihsy current specification is only a typical value this too can vary by some degree and is not guaranteed.

    Please check the voltage on the Enable pin as you vary the input voltage, rising and falling.

    if you are seeing variation in part to part, this is due to the above variations. If you need something accurate you will need to implement external circitry to provide accurate enable/disable.

    Hope this helps?
  • 0 in reply to David Baba
    Prodigy 20 points
    Thanks David,

    I was suspecting Ihys was not being completely accurate.
    It would be nice to add this info to the datasheet!

    Rgds,

    HR DRUT