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DRV8244-Q1: Enable Pin vs. register

Part Number: DRV8244-Q1

Hello Team, 

in SPI version DRV8244 can be switched off by register writing (DRV_off).

Is it still necessary to use the HW pin or can it be left open?

Means floating pin or recommended to connect to GND or VCC?

Many Thanks

Josef

  • Josef,

    Good question!

    The DRVOFF pin is internally pulled up to VDD.  So, if left floating...part will always be in OFF state per table below as it is logically OR'ed with the internal register.

    So, if the customer ONLY wants SPI control of this feature, the DRVOFF pin should be externally connected to GND.

    Regards,

    Ryan

  • Hello Mr. Kehr,

    thank you for your support, but I stil have some questions.

    You wrote, that the SPI bit and the DRVOFF Pin can be OR'ed internally. So why shall it be always in OFF state, when the DRVOFF Pin is floating? If I get it correct, it shall not matter, in which state the external PIN is. On the other hand if we set this external PIN on GND, we always has to choose the AND condition, hasn't we? If it is in OR condition it would be always active, wouldn't it?

    Another question: Is it possible, that the quiescent current in sleep mode is higher because of the pull up to VDD and a short to GND on the DRVOFF Pin?

    Thank you for strong support. 

    BR, 

    Martin Blinzler

  • Mr. Blinzler,

    I think there is an error in the datasheet that is causing me some confusion.  I am confirming.  Please give me another 24 hours.

    Regards,

    Ryan

  • Mr. Blinzler,

    So, no error in the datasheet, just confusion on my part. 

    If the DRVOFF_SEL bit is set to "1", then a logical AND exists between the external DRVOFF pin and the internal S_DRVOFF bits.  Therefore, if you float the external DRVOFF pin (which has an internal pull-up), then you can control the DRVOFF state with the S_DRVOFF bits.  A "1" would disable the outputs and a "0" would enable the outputs.

    I hope that is more clear and I apologize for the confusion.

    Regards,

    Ryan

  • Hi Mr. Kehr,

    so is my understanding correct, that it is possible to have a floating DRV_OFF Pin, if we select the AND condition for DRVOFF_SEL  and control the activation with the S_DRVOFF Bit in SPI?

    Thank you for clarification.

    BR,

    Martin Blinzler

  • Mr. Blinzler,

    Your understanding is correct.  I apologize for my earlier confusion.  I was only considering the "OR" case.  

    Regards,

    Ryan