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BQ25601: Undershoot

Shunsuke Nagata
Genius 13060 points
Part Number: BQ25601
Other Parts Discussed in Thread: TPS562201,

HI,

My customer concerns Undershoot at Switching node output and PWN high side driver positive supply.

 Figure 1. Undershoot for BTST pin

Figure 2. Undershoot for SW1 and SW2 pin

The undershoots for SW and BTST over minimum Absolute Max.  I guess this undershoot flow the internal low side body diode and it is forward direction, so , it may not take a damage for silicon. But could you please give me your comment for this undershoot if it take damage to silicon? If it take damage to silicon, could you please give countermeasure? 

Regards,
Nagata.

  • 0
    TI__Genius 11850 points

    Hi Nagata,

    Based on the waveforms you sent, it doesn't look like your customer is exceeding the absolute maximum ratings for SW and BTST. Please correct me if I'm misreading your waveforms, but from what I can tell, SW is from -1.6 V to 7.12 V, and BTST is from 4.64 V to 13 V. These are within the absolute maximum rating ranges of -2 V to 16 V for SW and -0.3 V to 22 V for BTST.

    For reference, here is a waveform I captured on an EVM. SW is shown in yellow, and BTST is shown in red. The maximum and minimum voltages are also within the datasheet's specified ranges.

    Best regards,

    Angelo

  • 0 in reply to Angelo Zhang87
    TI__Genius 13060 points

    Hi, Angelo -san,

    Thank you for your message.  Do you have specific absolute infomation for transient? e.g. below is TPS562201 datasheet. It has 10ns transient spec.

    If you doesn't transient spec infomation, do you have performance infomation? ( If you doesn't share it at Public E2E, could you please send message to s-nagata@ti.com?

    Regards,
    Nagata.

  • 0 in reply to Shunsuke Nagata
    TI__Genius 11850 points
    Hi Nagata-san,

    Sorry, we don't have this information for the BQ25601. Future parts will probably include these transient specs in the datasheet.
    On the BQ25601, SW and BTST should always be kept within the ranges given in the Absolute Maximum Ratings table.

    Best regards,
    Angelo