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DRV8803: What is the Quiescent current of DRV8803 if nENBL pin is pulled to high?

Tor Sovel
Prodigy 160 points
Part Number: DRV8803


We are using 2 of this chip in our CAN module and we would like to put the module on sleep with the least possible standby current. Our target is <1mA, we pulled the nENBL pin to high to disable the outputs but we are still seeing 3.75mA. I looked at the DRV8803 datasheet and it only mentioned Supply current of 1.6mA typical and no mention about quiescent current during nENBL pulled high.

What is the Quiescent current of DRV8803 if nENBL pin is pulled to high (outputs disabled)?

  • 0
    TI__Guru** 114905 points

    Hi Tor,

    The quiescent current should be approximately the same as the operating current with IN1 through IN4 low.

    The operating current was measured without loads attached.

    Can you disconnect the loads, re-measure the currents, and report the results 

    -- with IN1 through IN4, nENBL, and RESET low

    -- with IN1 through IN4, and RESET low; and nENBL high

  • 0 in reply to Rick Duncan
    Prodigy 160 points

    Hi Rick,

    I am testing with no loads connected. I am getting the same results (3.75mA,@12-18V Vin) whether IN1-4,RESET are low or high @ nENBL high.

    Below is my schematic, showing 1 of 2 DRV8803 but similar connection.

    Tor

  • 0 in reply to Tor Sovel
    TI__Guru** 114905 points

    Hi Tor,

    Thank you for the information. We will investigate further, but may not have the information until Wednesday.

    One note about the schematic, the VCLAMP connection is different than recommended by the datasheet.

    The datasheet recommends connecting VCLAMP to VM, or to a zener to VM.

    Please consider connecting per the datasheet recommendation.

  • 0 in reply to Rick Duncan
    Prodigy 160 points

    The VCLAMP doesn't really matter in our application. The TVS is just there to protect the output from getting over the maximum voltage rating from inductive loads. Our product is only rated 9-32V.

    I am pretty sure the 3.75mA are mostly going to the 2x DRV8803 even with nENBL pins high.

  • 0 in reply to Tor Sovel
    TI__Guru** 114905 points

    Hi Tor,

    I tried to duplicate your finding on a DRV8803EVM and was not able to.

    The DRV8803EVM was reconfigured to eliminate any additional current paths such as regulators, mcu, etc.

    In all cases (nENBL high/low, nRESET high/low, INx high/low) with no load from 12V to 18V, the most supply current observed was 1.64mA.

    Is it possible there is something else on your board consuming the additional current?

  • 0 in reply to Rick Duncan
    Prodigy 160 points

    Hi Rick,

    Is the 1.64mA you have observed is for 1 DRV8803? We have 2 DRV8803 in our module so 1.64mA x 2 is 3.28mA (close to what I am measuring ~3.75mA, which the other 0.47mA is the quiescent of all other circuits in our module).

    Thanks,

    Tor

  • 0 in reply to Tor Sovel
    TI__Guru** 114905 points

    Hi Tor,

    Yes, 1.64mA was observed on 1 DRV8803.

    Thank you for confirming that you measured 2.

    Depending on the average use time of the DRV8803, one option to reduce current is to place a load switch in line with the VM. A small P-channel should be sufficient since the VM current is only a few mA.

  • 0 in reply to Rick Duncan
    Prodigy 160 points

    Hi Rick,

    Thank you for confirming. 

    Tor