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DRV8313: Switching sequence of control signals?

Andreas Arnold
Prodigy 100 points
Part Number: DRV8313

Hi,

we are using the above mentioned driver DRV8313 for driving three inductive loads. This works fine so far, but we have discovered an issue with the control signals.

Sometimes, the switching of the half-bridge does not start, when ENx is asserted before the PWM on INx starts. I searched in the datasheet for any advice of the sequence, in which the control signals shall be asserted. Can you please specify, in which order and with which timings the signals ENx, INx, nRESET and nSLEEP must be set. 

We are using this driver in a safety relevant application, so we need to be sure that the driver is working correctly.

Thanks,

Andreas Arnold

  • +1
    TI__Intellectual 1350 points

    Hello Andreas,

    This device ignores all inputs if the nSLEEP pin or the nRESET pin is at logic low. Make sure that these pins are tied high. Both of these pins function via internal pulldown resistor. nSLEEP must be high for at least 1 ms before you can assert nRESET, ENx, and INx. Using ENx or INx to switch OUTx results in different propagation delays according to Page 7 (section 6.6) of the Data Sheet.

    best,

    Johnny

  • 0 in reply to Johnny Vallespir
    Prodigy 100 points

    Hi Johnny,

    We will respect the 1ms-Timing for nSLEEP. In all tests before, we had tied nSLEEP and nRESET directly to VCC.

    Driving sequence now is: all signals to low on startup --> nSLEEP = HI --> (wait 2ms) --> nRESET = HI (wait 2ms) --> ENx = HI and Start of the PWM on INx.

    This configuration seems to work properly.

    But the question remains: where can I find the sequence in the datasheet?

    Thanks,

    Andreas

  • 0 in reply to Andreas Arnold
    TI__Intellectual 1350 points

    Andreas,


    The DRV8313 is one of our older devices (RTM from December 2012). The only pertinent powerup information required is nSLEEP being at least 1 ms, so you may not need to wait 2 ms after nRESET goes HI. This is because the nRESET is only needed for resetting fault conditions. There is an internal power-up-reset circuit so that driving nRESET at power up is not required. So therefore, you may get away with beginning to drive ENx/INx inputs shortly after setting nRESET = HI.

    best,

    Johnny