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TPS25942A: When the current drops, a spike voltage will occur before and after the e-fuse.

Yasuhara
Prodigy 190 points
Part Number: TPS25942A

Tool/software:

Hi,

In a circuit using e-fuse (TPS25942ARVCR), a spike voltage occurs on the power line during the PMIC power OFF sequence.

+5V_IN is supplied with 5V from a stabilized power supply.

D5.0V is connected to the PMIC.

The color of the oscilloscope waveform corresponds to the signal name as follows.
Blue line: +5V_IN (actually 4V)
Light blue line: D5.0V (actually 4V)
Red line: D3.3V (PMIC output)
Green line: D1.8V (PMIC output)

Do you know the cause of the spike voltage occurring before and after the e-fuse when the current flowing through it decreases?
Is there any way to solve this?

TPS25942ARVCR_SpikeVoltage.pdf

  • 0
    TI__Mastermind 21750 points

    Hi Yasuhara San,

    You are seeing this undershoot transient at input of eFuse, can you confirm this? 

    If yes, can you also probe current (input and output current).

    This is not expected. If current decreases very rapidly due to PMIC, we should have seen this undershoot at output side of eFuse. 

    This looks more like input side got short to gnd.

    By adding a Schottky diode to clamp this undershoot, this should be resolved but we should also find the reason first which is causing this.

    Best Regards,
    Arush