• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 64 subscribers
  • Views 144 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPSM8D6C24: Start-up conditions

Masashi Mineda
Intellectual 655 points
Part Number: TPSM8D6C24
Other Parts Discussed in Thread: TPS3842

Tool/software:

Dear Sirs and Madams,

We are considering the TPSM8D6C24 and have a question regarding its behavior on startup.

The current startup waveform is as follows:

-- Red : VIN

-- Green : EN

-- Yellow : VOUT

The soft start period is set to 1ms, so it works as expected at 944us.

However, there is a delay of approximately 7.94ms before it starts up.

I checked the datasheet and TON_DELAY is still at its initial value of 0.

Is it correct to understand that this is due to the "This time delay, tdelay(uvlo_PMBus) (6-ms typical)" mentioned in the NOTE?

As stated in Figure 7-14. Start-Up from EN/UVLO in the datasheet, does this mean that if I want to start up at the EN timing, I need to wait a sufficient amount of time (6ms　typ) after VIN is supplied?

Regards,

MM

  • +1
    TI__Guru 53525 points
    Masashi Mineda said:

    Is it correct to understand that this is due to the "This time delay, tdelay(uvlo_PMBus) (6-ms typical)" mentioned in the NOTE?

    As stated in Figure 7-14. Start-Up from EN/UVLO in the datasheet, does this mean that if I want to start up at the EN timing, I need to wait a sufficient amount of time (6ms　typ) after VIN is supplied?

    Yes.

    The time starts with AVIN rising above it's UVLO_ON level of about 2.9V, which starts the power-on process for the TPSM8D6C24 logic.  This power-on process includes loading NVM trim, configuration and user programmable settings, as well as pin detection.

    I would recommend allowing 12ms to ensure the power-on sequence has completed.

  • 0 in reply to Peter James Miller
    Intellectual 655 points

    Hi Peter,

    Thank you for your answer.

    The voltage supply destination of the TPSM8D6C24 requires a sequence, and we were having trouble with it not starting up at the expected timing.

    We will use a supervisor IC such as the TPS3842 that can set a delay to monitor the input voltage of the TPSM8D6C24 and set it so that the sequence starts after 12 ms or more have elapsed.

    Regards,

    MM

  • 0 in reply to Masashi Mineda
    TI__Guru 53525 points

     

    Glad to be able to help.