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TPS25926: TPS259261: Input transition rate at EN/UVLO pin

Bhargav Jyoti Saikia
Intellectual 420 points
Part Number: TPS25926
Other Parts Discussed in Thread: TPS2595

Hello,

I am using TPS259261 E-Fuse to protect my 12V power line. Is it possible to give extremely slow input transitioning signal (like 1 to 3 seconds rising rate) at EN/UVLO pin? In the datasheet I was unable to find anything that specifies the input transition rate. Also, in the block diagram given in the datasheet, it showed that the input comparator at  EN/UVLO pin has hysteresis inbuilt. So, I was thinking whether the EN/UVLO pin will be able to withstand such slow transition rates? Please help.

Thanks.

  • 0
    TI__Guru** 105361 points
    Hi Bhargav,

    Though we have not tried very slow turn-on but it should not be a problem as the pin has hysteresis inbuilt. I suggest to evaluate and check. May I know the use case and the reason for extremely slow signal at EN pin.

    Best Regards,
    Rakesh
  • 0 in reply to Rakesh
    Intellectual 420 points

    Hi Rakesh,

    Thank you for your suggestion. I am trying to implement a 10 sec power-reset circuit using a cheap RC circuit and replace the monostable multivibrator circuit.

    I think there should not be any oscillations in the output. My worry is that will there be any high current inrush during the slow transition, when the input voltage reaches mid-level?

    Thanks.

  • 0 in reply to Bhargav Jyoti Saikia
    TI__Guru** 105361 points
    Hi Bhargav,

    Is it possible to share your schematic for review?
    Inrush current issue can be mitigated by sizing high enough capacitor on the dV/dT pin. Please have a look at new device TPS2595 as alternative. You may like as it offers better current limit accuracy, lower size etc.

    Best Regards,
    Rakesh
  • 0 in reply to Rakesh
    Intellectual 420 points

    Hi Rakesh,

    Thanks for the alternative part. I will check it.

    Sorry if I was not clear. I didn't mean the output current. Actually the input voltage at the EN/UVLO pin transitions very slowly from 0 V to above 1.4 V in 10s( through a resistor divider and saturates at 1.6 V for 12V input). So when the internal enable-logic transitions from 0 to 1, is there any high switching current? Which might stay there for about 10s and may damage the device?

    I have not implemented the schematic yet. I will share it as soon as I implement it.

  • 0 in reply to Bhargav Jyoti Saikia
    TI__Guru** 105361 points
    Hi Bhargav,

    Got it. There will not be significant current change during transition. You can expect maximum change from IQoff (0.13 mA) to IQon (0.42 mA).

    Best Regards,
    Rakesh
  • 0 in reply to Rakesh
    Intellectual 420 points

    Hi Rakesh,

    That comes as a lot of help. Thank you for your support.