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  • TI Thinks Resolved

DRV8305-Q1: SPI Communication Ready after Power-Up

Genius 4275 points

Replies: 5

Views: 137

Part Number: DRV8305-Q1

Dear, Sir.

My customer would like to monitor nFAULT=Low to High changing status during power-up

and then, start SPI communication for resister setting.

So I would like to make sure several as below. Please give your advice.

1. nFAULT Delay, across PVDD_UVLO2 to nFAULT=>High.

   The situation is diffrent, but tPD, E-SD is defined as max. 1us.

 I guess max. 1us would be enough as this kind of delay.

   How do you think?

2. tSPI_READY is defined as max. 10ms. It is after PVDD>VPVDD_UVLO1.

   The customer will monitor the change state nFAULT Low to High.

   I guess max. 10ms delay would be safer starting SPI communication.

   How do you think?

Best Regards,

H. Sakai

  • Hi Sakai-San,
    Please follow the timing guideline for tSPI_READY in this case (10ms). This timing ensures that the 5V VREG has sufficient time to power up and stabilize before SPI operation starts.

    tpf,E-SD is only applicable for error conditions.
  • In reply to Anuj Narain:

    Dear, Anuj-san. 

    Thank you so much for your advice. 

    I will follow tSPI_READY (10ms). 

    How much time would be reasonable as nFAULT Delay,

    across PVDD_UVLO2 to nFAULT => High?

    Of course, You don't need to assure that. 

    Best Regards, 

    H. Sakai

  • In reply to hideyuki sakai:

    Hi Sakai-San, the time is actually not that long and you may observe your samples being ready even within 2-3ms. We recommend some margin however to allow the regulator to stabilize.
  • In reply to Anuj Narain:

    Dear, Anuj-san.

    Thank you for your advice.

    I would like to know the time from PVDD across PVDD_UVLO2 to
    nFAULT Low=>High. I thought it was quite short time.
    Is it sure that it is 2~3ms? I would like double-confirm.

    Best Regards,
    H. Sakai
  • In reply to hideyuki sakai:

    Hi Sakai-San,
    The time may actually be shorter. Since power up sequence is a state machine the time may be shorter or longer depending on how fast each condition is met.

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