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DRV8251A: sleep mode delay

Dan Zuzuly
Prodigy 10 points
Part Number: DRV8251A

In one mode, I am using this as a single output high side driver by just driving IN1.  If the input a frequency below ~460Hz, the driver will start adding the 50uS sleep delay, which affects the accuracy of the duty cycle.  I can add a dummy inverted signal to IN2, and the delay goes away - BUT it is no longer just a high side driver (Output 1 now push pull, not just high side drive).  Is there a way to disable the sleep mode delay without driving the other input?    Or is there a similar part that does not have this issue?  (input frequency could go down to 80Hz).     I am looking for <10uS rise/fall time, 100mA high side drive, output short circuit protected in case of shorted load.  

  • 0
    TI__Mastermind 22200 points

    Hey Dan,

    For this application you would be better served by a part that has Independent 1/2-Bridge Control as an option.  These devices are designed to function as high/low side drivers as needed.  The DRV8220 is a 20V/1.76A option, or the DRV8243 is a recently released 40V/20A half-bridge driver.

    Here are all our devices with this feature:  https://www.ti.com/motor-drivers/brushed-dc-bdc-drivers/products.html#1077=Independent%201%2F2-Bridge&

    Any of these half-bridge drivers should have a datasheet section about recommended connections for a high/low side load:

    As for trying to get this working on the DRV8251A, I would try disabling current regulation:

    Regards,

    Jacob

  • 0 in reply to Jacob Thompson
    Prodigy 10 points

    Jacob, 

      OK, Let me take a look at the data sheets.  Thanks

       Dan

  • 0 in reply to Jacob Thompson
    Prodigy 10 points

    Jacob,    I did have the DRV8251A current sense pin grounded when I did my original test, and it was still getting the sleep delay < 460Hz.  

      I do need the 40V capability, but the DRV8243 is 20A (I need 100mA) - seems a little overkill.   Also, it would be hard to test the DRV8243 without laying out a pcb because of its VQFN-HR package.     Any other suggestions in a SO type package?    The DRV8251A seemed good except for the delay at slower frequencies.  

  • 0 in reply to Dan Zuzuly
    TI__Mastermind 22200 points

    Hey Dan,

    As a software solution for using DRV8251A, could you try inputting a very short pulse of at least 1us (or as short as you can make it, as long as it is >1 us)  in between consecutive input pulses?  This should have minimal effect on the output but I think would keep the device awake.  You might have to experiment with the length of the pulse if the device still goes to sleep, I think 1us would be enough since that is tPD (Input to output propagation delay), though it might need to be 5us (time of 200kHz input signal, device maximum frequency).  

    Ahh fair, how about the DRV8876? 40V, 3.5A,  the PWP package is 16-Pin HTSSOP.  Has a separate nSLEEP pin so no automatic sleep mode after 1-1.5ms.  Or the N-version if you don't need current sensing, DRV8876N

    Best,

    Jacob