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TPS92630-Q1 single LED short with Fault pin's active

Jacky Chen29
Genius 4735 points
Other Parts Discussed in Thread: TPS92630-Q1, TL4242-Q1

Hola,

We used TPS92630-Q1 in our new project design and have found one issue about that we cannot get the fault signal from the FAULT pin.

After analysis, we found the reason that why we cannot get the open load signal.

The problem is from DC20 and DC19 TVS diode.

If we put the TVS diode at the Iout path then we cannot get the fault signal active even we remove the LED module.

This may have the ESD protection issue, does TI have any suggestion for this？How do we detect LED works normally？

By the way, if we changed Vin to 12V then will it get the Iout voltage over 12V or it will be lower than 12V in maximum output current？

In addition, the TVS voltage of DC20 and DC19 and LED number and forward voltage were listed as below：

VISHAY (VESD05A1B-HD1-GS08) 6.8V TVS & LED is 3V forward voltage the number is one.

  • 0
    TI__Mastermind 27920 points
    The appropriate Applications Engineer has been assigned to respond accordingly. Thank you for your patience.
  • 0 in reply to Akeem Whitehead
    Genius 4735 points
    Thank you Akeem. I hope it will be soon, it's urgent.
  • 0
    TI__Expert 5380 points

    Hi Jacky,

    Thanks for moving the TPS92630-Q1 question to automotive forum where I can track and answer the question in time. 

    When you do the test what input voltage do you put? 12V or 5V? 

    May I know the reason why putting a TVS in parallel with LED module? For ESD protection of the LED purpose? Do you mean remove the TVS, the fault can be reported normally? If so, can you try a higher clamp voltage of the TVS to see if there is still a problem?

    Usually few applications need a TVS to protect the LED? May I know the detailed application of this circuit? 

    Also what is the FB1 and FB2, the resistor R134, R135 value? Another thing is when the input voltage is lower than 8V, the single LED short function will be disabled, so recommend connect VSNSX directly to the Ioutx.

    For the detailed fault detection principle, please refer to the fault table (table 1 ) in the TPS92630-Q1 datasheet.

  • 0 in reply to Anda Zhang
    Genius 4735 points

    Hola Anda,

    When you do the test what input voltage do you put? 12V or 5V?

    =>The test is  performed by 12V

    May I know the reason why putting a TVS in parallel with LED module? For ESD protection of the LED purpose?

    =>The LED module is our of the sensor which is used for BSD radar sensor warning . Due the IO of LED output, so we add TVS there.

    Do you mean remove the TVS, the fault can be reported normally? If so, can you try a higher clamp voltage of the TVS to see if there is still a problem?

    =>Yes, the function become normally after remove TVS. We will use other type ESD protection component.

    Usually few applications need a TVS to protect the LED? May I know the detailed application of this circuit?

    =>As 2nd item description.

    Also what is the FB1 and FB2, the resistor R134, R135 value? Another thing is when the input voltage is lower than 8V, the single LED short function will be disabled,

    =>FB1 &FB2 is bead (only reserve component) R134&135 is 0ohm

    so recommend connect VSNSX directly to the Ioutx.

    =>We will use the same circuit , because the power will be changed to 12V

  • 0 in reply to Jacky Chen29
    Genius 4735 points

    Hola Anda,

    Please see my answer as below in red ink.

    When you do the test what input voltage do you put? 12V or 5V?

    =>The test is  performed by 12V.

    May I know the reason why putting a TVS in parallel with LED module? For ESD protection of the LED purpose?

    =>The LED module is our of the sensor which is used for BSD radar sensor warning . Due the IO of LED output, so we add TVS there.

    Do you mean remove the TVS, the fault can be reported normally? If so, can you try a higher clamp voltage of the TVS to see if there is still a problem?

    =>Yes, the function become normally after remove TVS. We will use other type ESD protection component.

    Usually few applications need a TVS to protect the LED? May I know the detailed application of this circuit?

    =>As 2nd item description.

    Also what is the FB1 and FB2, the resistor R134, R135 value? Another thing is when the input voltage is lower than 8V, the single LED short function will be disabled,

    =>FB1 &FB2 is bead (only reserve component) R134&135 is 0ohm.

    so recommend connect VSNSX directly to the Ioutx.

    =>We will use the same circuit , because the power will be changed to 12V.

  • 0 in reply to Jacky Chen29
    TI__Expert 5380 points
    Hi Jacky,

    Thanks for the information. Obviously when removing the LED module, the TPS92630-Q1 can still work normally because the the TVS will act as a LED load. Does customer can accept the solution of removing the TVS diodes or using a TVS larger than input voltage?
  • 0 in reply to Anda Zhang
    Genius 4735 points

    Hola Anda,

    Thank you for your prompt reply.

    Regarding to current open issue of TVS that we will solve it by ourself.

    But the original LED that we want is :

    The open load or short function can be determined by each channel and that means we may have 2 digital output at least.

    I am not sure if you have similar product that we can replace. Thank you very much.

  • 0 in reply to Anda Zhang
    Genius 4735 points
    Hola Anda,
    Do you have any update of this？Thank you.
  • 0 in reply to Jacky Chen29
    TI__Expert 5380 points
    Hi Jacky,

    Sorry for the late reply. If you don't mind we can send mail to me to discuss it in detail as it will be faster. For TPS92630-Q1, it can't report each channel fault separately unless customer uses one TPS92630-Q1 for one LED. But this will increase the cost a lot. We also have TL4242-Q1 which is one channel LED driver. But it can only report the open fault instead of short fault.
  • 0 in reply to Anda Zhang
    Genius 4735 points
    Hola Anda,
    Thank you very so much.
  • 0 in reply to Anda Zhang
    Genius 4735 points

    Hola Anda,

    Thanks for your information and I have another question about improve efficiency.

    Last week our engineer help to check the efficiency, but it is not well.

    We find it is similar as LDO.

    If we want 100mA output (totally), then the input current also need 100mA.

    But our voltage of output point is limited by our LED module.

    Is there any solution that we can improve this？ Thank you ～

    Brs