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DRV8872: OCP function verify

Part Number: DRV8872

Hi All:

My customer is Verifying the OCP trip function of DRV8872. (this is using in the Automotive small motor drive)

Can we use a DC electronic load to test it? ( [DC load + to OUT + ], [DC load - to OUT-]) or have other method?

Andrew

  • Hi Andrew,

    Electronic loads are not recommended for OCP trip testing. Typically DC electronic loads do not react fast enough.

    What part of the OCP trip function is your customer verifying?
  • Hi Rick

    My Customer setting IN1=1 ,IN2=0.Test the DRV8872 with an electronic load at 0.5A intervals. But when test to 3.1A . The nFAULT is driven low. So I think customer's test method may have problem . Could you provide the correct way to test the OCP function? Customer wants to see the nfault signal drive low when the output is 3.7A~6.4A(datasheet page 5 OCP trip level).

    Thanks.

    Andrew
  • Hi Andrew,

    There could be two problems. One could be the electronic load operation is affecting the test. The other is overtemperature could be affecting the load is constantly increasing with no time to reduce the junction temperature.

    We have had good results using a large inductor with a time constant of >1ms and a max current of 10A.
    Enable the outputs and monitor the current and nFAULT.
    When nFAULT asserts, determine the current approximately 1.5us prior to nFAULT asserting.
    This is close to the OCP current.

    Also please note the OCP level is for normal operation. A short circuit could have higher current levels as shown in Figure 13.