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TPS1641: In to Out short detection.

Kengo.Y
Guru 11245 points
Part Number: TPS1641

Tool/software:

Hi team,

I used TPS16412.
In to Out short detection caused start up problems.
Therefore, could you tell me some questions?

1 : In the following equation, when it has Iripple, TPS16412 assert a in to out short detection?


2 : I believe without the In to Out short detection is TPS16416.
     Is this all the same as TPS16412 except for the In to Out short detection?
     I need UL certification.

3 : Could you tell me when this detection would be useful?
      Is DC current the basic use case?

BR,
Kengo.

  • 0
    TI__Mastermind 31541 points

    Hello Kengo,

    Find the FAQ on IN to OUT short working and where to use it.

    [FAQ] TPS1641: TPS1641 IN to OUT Short detection working - Power management - INTERNAL forum - Power management - INTERNAL - TI E2E support forums

    Which variant UL certificate you need? TPS1641 all variants are UL certified.

    Thanks 

    Amrit 

  • 0 in reply to Amrit Jit
    Guru 11245 points

    Hi Amrit,

    Thank you for your comments,

    I can not open your URL. It seems like internal forum.
    Could you share PDF or other documents?

    I understood about UL certificate.

    BR,
    Kengo.

  • +1 in reply to Kengo.Y
    TI__Mastermind 31541 points

    Hello Kengo,

    Thanks for highlighting this. I will make it available for public forum. Below is exaplanation for IN to OUT short 

    TPS16410, TPS16411, TPS16412 and TPS16413 provide IN to OUT short detection and its indication on FLT output. IN to OUT short detection eliminates the need of additional eFuse or power limiting circuit in case of IN to OUT short test for IEC60335, UL60730, and similar standards.

    Working of IN to OUT short detection: 

    • TPS1641 (TPS16410, TPS16411, TPS16412, TPS16413) has IN to OUT detection which takes VIN, VOUT, IOUT as input to calculate the IN to OUT resistance.

               If the device detects a resistance less than Rshort (as mentioned below) across IN and OUT pins, device asserts the FLT pin low and latches off.

    • Device has 200mSec clock cycle where it checks IN to OUT resistance 5 times. If resistance drops Rshort for 3 times out of 5, IN to OUT short protection is asserted.

    • To calculate IN to OUT resistance, device sinks 30 mA current through ISINK block as shown in device block diagram below. Sink turn on time is 800uSec.
    • Average current sink in one cycle = (800uS*30mA*5) /200mSec = 600uA

    When NOT to use IN to OUT short detection:

    During Switching load or current ripple, current through TPS1641 keeps on changing which results in different IN to OUT resistance level and sometimes results in false detection of IN to OUT short detection in some of the events. So, it’s advised to use variants (TPS16414, TPS16415, TPS16416, TPS16417) which doesn’t have IN to OUT short detection feature for switching load and higher current ripples.

    Below table suggests device variants based on switching load frequency fSW (in kHz) and ripple load current IRipple (in mAp-p).

    Thanks and Regards

    Amrit Jit