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TPS25990: Hot short circuit problem

TeHe
Prodigy 50 points
Part Number: TPS25990
Other Parts Discussed in Thread: , TPS25985

Hi, 

I have circuit below.  Efuses are parallel. When i am doing hot short circuit when base current is ~30A, it seems that fast current detection is not working correctly and turning off efuses. It seems that UVLO is tripping efuses, which is not good ( we have changed uvlo setting in register to 5.xV ). If we look IMON below we can see combined monitor is measuring correct current but in some reason it doesnt trip after IMON is 2V...

  • 0
    TI__Mastermind 30915 points

    We will get back to you by today. 

  • 0
    Prodigy 50 points

    Hmmm, it seems working days are very long in TI! Is it still today there? :) ( Just kidding ) 

  • 0 in reply to TeHe
    TI__Mastermind 30915 points

    Extremely sorry for the delay in getting back to you. I went through your waveforms and did not have any clue to the issue. Because, I have never seen this kind of short-circuit response. How are you applying short-circuit, through an electronic load? Is this repeatable in all your boards? 

  • 0 in reply to Avishek Pal
    Prodigy 50 points

    No worries, i was only kidding, sorry :) If i have no loading and i will do hot short, parallel combination will work correctly. If i have before short some loading like in this picture ~30A, behaviour is like that. It is somehow related to parallel combination of efuses. If i do same test with only master efuse ( no paralleling , everyhthing is ok. 

  • 0 in reply to TeHe
    TI__Mastermind 30915 points

    Please see the below waveforms. The UVLO protection was completely disabled in the TPS25990 by two ways:

    1. EN/UVLO pin is connected to VIN through a 1 MΩ resistance. A 1 μF ceramic capacitor is connected across the EN/UVLO pin and GND. This helps in making the EN/UVLO pin stable during output hot short event.
    2. VIN_UV_FLT (59h) is set to 0x0000 (0 V) through firmware.

    Initial:

    16:47:40.879: SAA #1: ReadByte (Address 70d, Cmd 0x78): ACK 0x00

    16:47:40.941: Pause 50 ms

    16:47:40.945: SAA #1: ReadWord (Address 70d, Cmd 0x79): ACK 0x0000

    16:47:41.005: Pause 50 ms

    16:47:41.011: SAA #1: ReadByte (Address 70d, Cmd 0x7A): ACK 0x00

    16:47:41.067: Pause 50 ms

    16:47:41.069: SAA #1: ReadByte (Address 70d, Cmd 0x7B): ACK 0x00

    16:47:41.129: Pause 50 ms

    16:47:41.136: SAA #1: ReadByte (Address 70d, Cmd 0x7C): ACK 0x00

    16:47:41.193: Pause 50 ms

    16:47:41.202: SAA #1: ReadByte (Address 70d, Cmd 0x7D): ACK 0x00

    16:47:41.256: Pause 50 ms

    16:47:41.258: SAA #1: ReadByte (Address 70d, Cmd 0x7E): ACK 0x00

    16:47:41.320: Pause 50 ms

    16:47:41.329: SAA #1: ReadByte (Address 70d, Cmd 0x80): ACK 0x00

    16:47:41.382: Pause 50 ms

    16:47:41.386: SAA #1: ReadWord (Address 70d, Cmd 0xF3): ACK 0x0021

    16:47:41.446: Pause 50 ms

    16:47:41.455: SAA #1: BlockRead (Address 70d, Cmd 0xFD): ACK 0x00000000000000

    16:47:41.510: Pause 50 ms

    16:47:41.512: SAA #1: ReadByte (Address 70d, Cmd 0xFA): ACK 0x1D

     

    After output hot-short:

    16:56:10.764: SAA #1: ReadByte (Address 70d, Cmd 0x78): ACK 0x41

    16:56:10.828: Pause 50 ms

    16:56:10.831: SAA #1: ReadWord (Address 70d, Cmd 0x79): ACK 0x8941

    16:56:10.891: Pause 50 ms

    16:56:10.898: SAA #1: ReadByte (Address 70d, Cmd 0x7A): ACK 0x20

    16:56:10.953: Pause 50 ms

    16:56:10.958: SAA #1: ReadByte (Address 70d, Cmd 0x7B): ACK 0x00

    16:56:11.016: Pause 50 ms

    16:56:11.018: SAA #1: ReadByte (Address 70d, Cmd 0x7C): ACK 0x00

    16:56:11.080: Pause 50 ms

    16:56:11.091: SAA #1: ReadByte (Address 70d, Cmd 0x7D): ACK 0x00

    16:56:11.142: Pause 50 ms

    16:56:11.144: SAA #1: ReadByte (Address 70d, Cmd 0x7E): ACK 0x00

    16:56:11.205: Pause 50 ms

    16:56:11.214: SAA #1: ReadByte (Address 70d, Cmd 0x80): ACK 0x00

    16:56:11.267: Pause 50 ms

    16:56:11.271: SAA #1: ReadWord (Address 70d, Cmd 0xF3): ACK 0x0281

    16:56:11.329: Pause 50 ms

    16:56:11.342: SAA #1: BlockRead (Address 70d, Cmd 0xFD): ACK 0x5C720000000000

    16:56:11.393: Pause 50 ms

    16:56:11.405: SAA #1: ReadByte (Address 70d, Cmd 0xFA): ACK 0x5E

    Reading status registers confirms that the devices turned off due to short-circuit event only.

    This experiment was performed on the TPS25990EVM. TPS25990 and TPS25985 devices are in parallel on the EVM. 

  • 0 in reply to Avishek Pal
    Prodigy 50 points

    Hmmm, looks as it should be. Thanks for the test! I have to think little and maybe repeat some of tests...

  • 0 in reply to TeHe
    TI__Mastermind 30915 points

    I am closing the thread till then.