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TPS65311-Q1 / VINPROT Sequence

Kuramochi Tadahiko
Guru 28715 points


Hi,

I received the following question from my customer.

Is the device broken if VINPROT signal is inputted before tstart finishing(3ms)?

Please refer the red line of the following picture.

Best Regards,

Kuramochi

  • 0
    TI__Mastermind 20590 points
    Hi Karamochi, the appropriate applications engineer has been assigned and will respond. Scott
  • 0
    TI__Expert 8730 points

    Hi Kuramochi-san,

    They can short VIN and VINPROT pins together and it is valid. So, Vin and VINPROT signals can come together. Tstart time is specified as max 3ms to guarantee GPFET functionality.

    Please ask them to use minimum 100nF capacitor close to VINPROT pin. Also If they don't use LED driver, HSSENSE must be connected to VINPROT pin.

    Regards,

    Murthy

  • 0 in reply to Krishnamurthy Hegde
    Guru 28715 points

    Murthy-san,

    Thank you for your help.

    Can't  they short VIN and VINPROT when they don't use the GPFET?

    They're not going to use the GPFET

    They don't place capacitor close to VINPROT.
    Is it problem?

    >Also If they don't use LED driver, HSSENSE must be connected to VINPROT pin.
    They don't use LED driver and connect VINPROT and HSSNSE.

    Best Regards,
    Kuramochi

  • 0 in reply to Kuramochi Tadahiko
    TI__Expert 8730 points
    Hello Kuramochi-san,

    In my previous reply, I through I already confirmed that they can short VIN and VINPROT when they don't use GPFET. May be I was not very clear about it.

    "They can short VIN and VINPROT pins together and it is valid"

    100nF filter capacitor is recommended for VINPROT pin and they should use it. It is just like any other supply input pin where we use decoupling capacitor close to its pin.

    Regards,

    Murthy
  • 0 in reply to Krishnamurthy Hegde
    Guru 28715 points
    Murthy-san,

    Thank you for your quick response.

    I'm sorry for my misreading.
    I understood that there is no problem.

    Best Regards,
    Kuramochi
  • 0 in reply to Kuramochi Tadahiko
    Guru 28715 points

    Hi Murth-san,

    I have an additional question.

    >So, Vin and VINPROT signals can come together.


    Can the WAKE signal rise at the same time?

    Best Regards,
    Kuramochi

  • 0 in reply to Kuramochi Tadahiko
    TI__Expert 8730 points

    Hello Kuramochi-san,

    When VIN supply is initially low and device starts up with Low to High on VIN, rising edge of the VIN terminal initiates the start-up sequence. In this condition, WAKE signal does not matter. This is the typical use case when VIN supply is given through ignition switch.

    When VIN supply is already present and device is shutdown using LPM0 command, WAKE signal rise initiates the start up. This is the typical use case when VIN supply is directly connected to the car battery.

    Regards,

    Murthy