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TPS1HB16-Q1: How to distinguish short to gnd and short to battery at ON state

Zirui Su
Expert 5340 points
Part Number: TPS1HB16-Q1

Hi team

My customer needs some diagnose function like short to GND/open load/short to battery detection. Currently at OFF state customer used external output pull-up resistor to distinguish the  open load fault.

 The customer requires that in the ON state, it is also necessary to distinguish between the open load fault and the short to the battery fault, but I think the chip seems to be indistinguishable. The two faults are judged by the current of the SNS pin less than a certain value, but they cannot be distinguished specifically whether it is open load or short to battery fault.

Therefore, in the ON state mode of the chip, what is the recommended design to distinguish between these two types of faults (short to battery or open load)? Thank you.

  • 0
    TI__Mastermind 25055 points

    Zirui,

    So in the title/body of this text we have a few different faults mentioned:

    • Short to ground
    • Short to battery
    • Open load

    Between short to ground and both short to battery/open load the way to distinguish between these faults in the ON state is to use an ADC to measure the sense pin as you mentioned. If the measured current is below a certain threshold then it can be assumed it is an open load or short to battery.

    I believe what the main question was here though was how to differentiate between on state short to battery and on state open load detection. To do there there has to be specific provisions in the schematic to test for this... it is not something the high side switch can do on its own. The common way of doing this is by hooking the output of the high side switch to an analog input channel of the microcontroller through a resistor divider and then toggling the EN pin low when a fault is detected via the low SNS signal. If there is voltage on the output then it can be assumed there is a short to battery. If there is no voltage on the output it can be assumed there is an open load. 

  • 0 in reply to Timothy Logan
    TI__Expert 5340 points

    Hi Logan

    Yes the main question I would like to know is how to differentiate between on state short to battery and on state open load detection. Are there any chip recommendations that can distinguish specifically between short to battery and open load and customer need at that time EN is high, thank you

  • 0 in reply to Zirui Su
    TI__Mastermind 25055 points

    Zirui,

    Currently, none of our devices have a mechanism to differentiate between open load versus short-to-battery. In practice, the general strategy here is that the high side switch will report a fault to the microcontrroller. After this fault is reported to the microcontroller (via FAULT/SNS), the microcontroller's software will take action to determine what the exact fault is (via EN/SNS) and mitigate/report the issue.