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Original question:

TPS25981: Selecting E-Fuse to protect the batteries

TPS25948: Selecting E-Fuse to protect the batteries

JIAN JIN
Prodigy 30 points
Part Number: TPS25948

Tool/software:

Hi,

I have asked the questions some days ago.https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1531669/tps25981-selecting-e-fuse-to-protect-the-batteries

But I have to update the requirement in below. So the fuse have to be open after 15s when the current is 8A. Sorry for that!

  • Almost immediate open when there is a dead-short on this wire (current up to 100 A),
  • Open after 15s when current is ~8A.

*************************************************************

I just repeat the application and block diagram here:

The two batteries (12V 18AH lead acid batteries) are in parallel to increase the battery capacity.

- There is a power source from the panel which has higher voltage (i.e. 13VDC) could charge the batteries in the normal application.

- If there is power loss in the power source, the batteries could survive the power, so that's say, The batteries will reverse power.

 And there should be a efuse or circuit break which is close to each battery to protect each battery.

 And if two terminals are connected in reverse poles, like below, the huge current would be go through the two batteries. Then the efuse or circuit break could work to protect each battery.

So, still the question, could you pls kindly advice the suitable MPN for eFuses or Circuit Break which could be the solution to this case? Thanks.

 

  • 0
    TI__Mastermind 39045 points

    Hi Jian,

    The TPS25948 device have a pin called ITIMER pin. This pin can be used for blanking timer to introduce some time delay when OCP event is detected. Do keep in mind that proper evaluation will be required as usually customers don't use this functionality for very long-time delays like 15s. Also check #4 below.

    Best Regards,
    Arush

  • 0 in reply to Arush Gupta
    TI__Mastermind 39045 points

    Another thing I would like to add is this blanking timer functionality is skipped during the short circuit protection.

  • 0 in reply to Arush Gupta
    Prodigy 30 points

    Hi Gupta,

    Thanks a lot for your feedback. I missed your reply some days ago since there is no reminding from my e-mail.

    Anyhow, I'm still searching for the more proper chip for my application, could you pls help to introduce the one which is more suitable to my application/requirement?

    Here is the requirement,

    • Almost immediate open when there is a dead-short on this wire (current up to 100 A),
    • Open after 15s when current is ~8A.
    • Two 12V 18AH lead acid batteries could be reverse connected and this is the protection device.
    • We would like the voltage drop to be very small or negligible under normal working conditions above.

    Thanks a lot!

  • 0 in reply to JIAN JIN
    TI__Mastermind 39045 points

    Hi Jian,

    I believe you can use TPS25948.

    JIAN JIN said:
    Almost immediate open when there is a dead-short on this wire (current up to 100 A),

    Short circuit protection should cause fast trip. Covered in TPS25948.

    JIAN JIN said:
    Open after 15s when current is ~8A.

    This can be done using itimer pin but will need some evaluation. Do note that startup will also become slow.

    JIAN JIN said:
    Two 12V 18AH lead acid batteries could be reverse connected and this is the protection device

    I think we discussed this in our previous thread.

    JIAN JIN said:
    We would like the voltage drop to be very small or negligible under normal working conditions above.

    The ron is 12mOhms so drop will be very less.

    Let me know if you have any specific issue/question.

    Best regards,
    Arush