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About TPS65070 15s TIMER

YUAN LIN
Prodigy 80 points
Other Parts Discussed in Thread: TPS65070

Hi:

I have a problem about TPS65070: My product need push down to ground always for PB_IN pin when the product is used.But the PGOOD will send a low pluse signal to reset CPU after the system is powered on about 15s.

I found that the PGOOD will be low after the PB_IN is kept 15s in the datasheet and descript that this is optional.So i think this function isn't fixed for TPS65070.I think the TPS65070 has different version. Isn't it ? And I have tested the TPS65070EVM board supplied by TI,this problem will not current,that is to say,the PGOOD hasn't low signal after the PB_IN pin is pushed low above 15s.And i have modified the TPS65070EVM board circuit same to my product circuit,the EVM board has not the low signal for PGOOD pin. So i think the TPS65070 has the different version chip, has not it? thanks!

  • 0
    TI__Genius 16870 points

    Hi Yuan, 

    Let me repeat back what I interpreted to be your problem/s and you can correct me if I misunderstood you. 

    1. Your prototype has to always have PB_IN asserted low in order to work at all. You can never release the PB_IN and have the board still be running, even if you assert POWER_ON high while PD_IN is asserted low.
      1. If you assert POWER_ON high while PB_IN is held low then the power rails will remain on. Please see figure 33 on page 34 in the datasheet.
    2. PGOOD goes low after 15 seconds of PB_IN asserted low on your prototype. The our EVM in your possession does not do the same thing but, PGOOD remains high even if PB_IN is asserted low for 15 second. 
      1. If you hold PB_IN low for greater than 15 seconds, the PGOOD is supposed to toggle low then high again. It should be low for 0.5 ms. Please see PB_IN section on page 34 in the datasheet.
  • 0 in reply to Michael Green
    Prodigy 80 points

    Thanks your reply!I will try other way to solve this problem.Thanks!