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TPS1641: About ILIM Operation

Ryu Yamashita
Genius 3935 points
Part Number: TPS1641


Tool/software:

Hi team,

The operation of ILIM is described as follows within the range “ILIM ≤ IOUT < IOCP”:

The device provides current up to IOCP for a duration of IDLY and then limits current to ILIM for a maximum duration of tILIM-DUR.

I understand that it continues to supply current during IDLY and then limits it to ILIM after IDLY. What happens after tILIM-DUR?

Also, is it possible to set ILIM to a value greater than IOCP?
If so, what would the behavior be in that case?

Best Regards,
Ryu.

  • 0
    TI__Mastermind 35371 points

    Hi Ryu,

    Ryu Yamashita said:
    What happens after tILIM-DUR?

    tLIM_DUR is the maximum time device stays in current limiting before shutting down. Find below explanation from datahseet

    "During the current limiting, the device dissipates a power of (VIN – VOUT) × IOUT and the device gets heated up. If the junction temperature of device reaches thermal shutdown temperature (TTSD), the device turns off the internal FET. If the device does not go into thermal shutdown, the internal FET is turned off after a duration of tILIM-DUR. After the internal FET is turned off, the TPS16412 and TPS16416 auto-retry while the TPS16413 and TPS16417 latch off. If ILIM pin is connected to GND or left open, the device turns-off the internal FET. If the IDLY pin is left open or connected to GND, device provides tILIM-DUR = 155 ms unless the device enters thermal shutdown. Table 8-1 summarizes the device behavior for different output currents."

    If you set ILIM > IOCP, device will never go into current limiting.

    Device will shut off as soon as current goes above IOCP value. 

    Thanks 

    Amrit 

  • 0 in reply to Amrit Jit
    Genius 3935 points

    Hi Amrit,

    Thank you for your reply.
    Could you please clarify one more thing?
    You mentioned that during the OPEN state, tILIM-DUR is 155ms. How is this value calculated?
    For example, if a 27nF capacitor is connected to CDLY, I believe IDLY would be 13.5ms. Therefore, I assume tILIM-DUR would be 2×IDLY, or 27ms.
    Is this correct?

    Best Regards,
    Ryu.

  • 0 in reply to Ryu Yamashita
    Genius 3935 points

    Hi Amrit,

    Could you please reply here?

    Best Regards,
    Ryu.

  • 0 in reply to Ryu Yamashita
    TI__Mastermind 35371 points

    Hi Ryu,

    Sorry for the delay.

    tLIM-DUR is internally fixed value. It's the max time device stays in current limit. Find the table below which summarizes.

    Refer to datasheet for more details

    Thanks

    Amrit 

  • 0 in reply to Amrit Jit
    Genius 3935 points

    Hi Amrit,

    Thank you for your reply.
    I believe I understand the state transition table.
    Does “fixed value” mean tILIM-DUR is always 155ms?
    What does tILIM-DUR represent in the following table section?

    Best Regards,
    Ryu.

  • 0 in reply to Ryu Yamashita
    Genius 3935 points

    Hi Amrit,

    Could you please reply here?

    Best Regards,
    Ryu.

  • 0 in reply to Ryu Yamashita
    Genius 3935 points

    Hi Amrit,

    I'm in a hurry, so I'd appreciate a reply.
    If replying is difficult, could you let me know when you'll be able to get back to me?

    Best Regards,
    Ryu.

  • 0 in reply to Ryu Yamashita
    TI__Mastermind 35371 points

    Hello Ryu,

    Sorry for the delay.I was on leave for some time.

    I made a mistake in my statement previously. You are correct tLIM-DUR is 2xtPDLY. If DLY pin is gnd then it's 155msec.

    I got confused with other eFuse. Sorry for the confusion.

    Thanks

    Amrit 

  • 0 in reply to Amrit Jit
    Genius 3935 points

    Hi Amrit,

    Thank you for your reply.
    So does this mean that if 2xtPDLY is 155ms or less, everything becomes 155ms?
    If it exceeds that, will 2xtPDLY be applied?

    Best Regards,
    Ryu

  • 0 in reply to Ryu Yamashita
    Genius 3935 points

    Hi Amrit,

    Could you please reply?

    Best Regards,
    Ryu.

  • 0 in reply to Ryu Yamashita
    TI__Mastermind 35371 points

    Hello Ryu,

    Ryu Yamashita said:
    So does this mean that if 2xtPDLY is 155ms or less, everything becomes 155ms?

    No, If only IDLY pin is left open or GND, then tLIM-DUR is 155mS.

    If cap connected at IDLY pin then tLIM-DUR is max 2xtPDLY.

    Thanks 
    Amrit