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TPS65917-Q1: FST First power supply Detect event is not happening

SANTHA KUMAR A
Prodigy 100 points
Part Number: TPS65917-Q1


Hi,

We designed a custom board based on TDA2Ex SOC with PMIC   O917A130TRGZRQ1 part on our design,

Design is validated successfully but below issue is what we are facing.

SOC is booting if you press the power on Button of PMIC manually.

But as per Datasheet First power supply detect event should happen when you apply power to the system and should start.

Now system not starting when you apply the power to the PMIC, It starts if momentary button press on PWRON Pin.

Please suggest is there any other dependency to start system once power is applied to the PMIC,

Please respond ASAP.

Thanks,

Santhakumar.

  • 0
    TI__Genius 16410 points

    Hello Santhakumar,

    First supply detection is enabled when FSD and FSD_MASK bits are set to 0 (unmasked).  when they are masked, then first supply detection is not enabled within the device.  For O917A130TRGZRQ1, both of these are set to 1, so first supply detection is not enabled.

    You can get similar functionality by pulling POWERHOLD/GPIO_5 pin up to LDOVRTC, or by connecting POWERHOLD/GPIO_5 to a POWERGOOD signal from a preregulator.  LDOVRTC is an always-on LDO, so this will cause the PMIC to be enable once its supply power is present.

    Connecting POWERHOLD signal to the pre-regulator's PGOOD signal can achieve the same thing, and also allow the power-down sequence to execute when input supply is removed.  FIgures 1 and 2 of the blog post How to meet power sequencing requirements shows 2 ways to do this.

    Regards,
    Karl

  • 0 in reply to Karl Wallinger
    Prodigy 100 points

    Hi Karl,

    Thanks for your response.

    We tried by putting a pullup for POWERHOLD/GPIO_5 pin up to LDOVRTC and it started working from the first power up, thanks a lot.

    Now the thing is it needs a jumper wire in all our PCBs. This would have been better if this is told in the datasheet. we have referred TDA2Ex EVM schematic and so designed.

    Now could you help me to know any other versions of PMIC chip which would come with the feature of by default  FSD Enabled since our used Chip version doesn't support this feature by default (O917A130TRGZRQ1) as you said. so that we can directly replace the chip with out any Jumper wire on the PCB.

    Regards,

    Santhakumar

  • 0 in reply to SANTHA KUMAR A
    TI__Genius 16410 points
    Hi Santhakumar,

    We do have a PMIC version which is used on the TDA2Ex EVM which uses first supply detection. It's not available online, so please contact your local TI support and we can help you get samples.

    Regards,
    Karl
  • 0 in reply to Karl Wallinger
    Prodigy 100 points

    Hi Karl,

    Could you let me know Exact ordering Part number for the PMIC used in  EVK.

    We couldn't recognize exact part number from Both EVK and Datasheet with respect FSD enable feature.

    Regards,

    Santhakumar

  • 0 in reply to SANTHA KUMAR A
    TI__Genius 16410 points
    Hi Santhakumar,

    O917A139TRGZRQ1 is the PMIC on the TDA2Ex EVM. It supports FSD, and has same power mapping as OTP 0x30, with some differences in the default GPIO selections.

    Regards,
    Karl