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Original question:

TPS612592: question about TPS612592

TPS612592: Question about TPS612592

Jimmy Huang
Expert 2465 points
Part Number: TPS612592
Other Parts Discussed in Thread: TPS61023, TPS61022

Hello：

Please confirm if the maximum pulling current of 1.4ATPS612592YFFR meets the requirements?Thanks！！！

Turn on the reverse wireless switch (just turn on the switch, do not perform reverse wireless charging), use an electronic load meter to load at the output end of the circuit, step by 100mA to increase the current on the electronic load. When it reaches a certain critical value, the output voltage on the oscilloscope drops to 0 or the output current drops to 0. At this time, the upper limit of the inductor current is the overcurrent protection point current value.

Actual measurement result: The electronic load meter draws BOOST-OUT to 1.4A, and at this time, the inductance (PL4001) current is 3.05A, triggering OCP.

  • 0
    TI__Expert 4075 points

    Hi Jimmy,

    TPS612592 does not shutdown at current limit. It'll limit the inductor current at 3.6A when the current limit is met. Vout will drop but not to zero. So most likely the device triggers over temperature protection before current limit is met. Please add Vout in the same screen, single trigger Vout falling edge and adjust the time scale to 200us/div.

    Best Regards,

    Travis

  • 0 in reply to Travis Wang
    Expert 2465 points

    hello Travis：

    When testing VOUT, when the pulling current is 1.4A, the voltage of VOUT will drop to 0V, and the maximum current at the inductor end will reach 3.2A. What is the protection mechanism here that causes the chip to not work?

  • 0 in reply to Jimmy Huang
    TI__Expert 4075 points

    Hi Jimmy,

    Looks like the device triggers overtemperature before the current limit. TPS6125x uses BGA package without thermal pad so the thermal performance does not support full load for a long time. You can try reducing the time for each current step (100ms) to test its current limit. If you need the 3.6A IL capability, you can switch to TPS61023 or TPS61022.

    Best Regards,

    Travis

  • 0 in reply to Travis Wang
    Expert 2465 points

    Hi Travis：

    The customer is using a fan to blow the IC, but the VOUT will still be pulled down. The maximum current at the VOUT end is 1.4A, and the maximum current at the inductor end is 3.2A

    Also, I would like to ask, if the maximum current at the inductor end is 3.6A, what is the maximum current at the VOUT end? Thank you!!!

  • 0 in reply to Jimmy Huang
    TI__Expert 4075 points

    Hi Jimmy,

    I've tested on bench. TPS6125x series triggers thermal shutdown in 1-2 seconds under your condition. Fan may not be so useful because the thermal resistance mainly exists inside the package.

    The output current can be calculated by: 

    But because of the limitation in thermal performance, this part can only work in 3.6A inductor current for less than 1 second. If you cannot accept the thermal performance, please try TPS61023.

    Best Regards,

    Travis

  • 0 in reply to Travis Wang
    Expert 2465 points

    Hi Travis：

    Thank you for your feedback.

    The customer has some understanding of the range of inductance current.
    Can you help confirm the current range of Iout or the maximum current of Iout? Thanks!!!
  • 0 in reply to Jimmy Huang
    TI__Expert 4075 points

    Hi Jimmy,

    Like the equation given before, the Iout depends on Vin.

    Best Regards,

    Travis