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TPS4H160-Q1: When OUT1 shorted to battery OUT2-3 lose CS measurment

David Shumate
Expert 7875 points
Part Number: TPS4H160-Q1

Hi Team,

I need your help explaining short to battery behavior for the TPS4H160. When we short OUT1 of the TPS4H160 to battery as shown in the below diagram we see the current sense measurement of other non shorted channels reduce to 0A/0V:

For OUT1 I think it makes sense that the current sense reads as 0 because the IR drop across the FET is opposite polarity vs normal operation.

What I don't understand is why this would affect the current sense output of other channels. I would expect that Vshort would push the Vs voltage up through the shorted channel but I would think the other channels would be able to report current correctly. 

Can you help with any explanation?

Thanks,

David

  • 0
    TI__Mastermind 32650 points

    Hi David,

    Does the customer have waveforms that describe this? Does the current still flow in the other channels to their respective loads? Are the loads being PWM'd or are they DC on? Can the customer share a schematic of their setup?

    I assume the customer is just changing the SEL and SEH settings to check the other channels correct?

    Thanks,

    Shreyas

  • 0
    Prodigy 10 points

    Shreyas,

    Does the customer have waveforms that describe this? What type of waveforms are you hoping to see?

    Does the current still flow in the other channels to their respective loads? Yes, verified with external current measurements.

    Are the loads being PWM'd or are they DC on? Both, all four channels are on 100%. The GND return of one channel’s load is PWM’d.

    I assume the customer is just changing the SEL and SEH settings to check the other channels correct? Yes

    Backfeeding an output is resulting in a 200 count shift down in ADC readings on the I-Sense output of the other channels causing them to appear to be zero current. If load current is higher we see non-zero current being reported, albeit shiftied down by 200 counts. So the value of the reported current is wrong.

    200 ADC counts is roughly 156mV at our micro pin. This is equivalent to negative shift of about 500uA on the current mirror output.

    Thanks,

    Keith