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BOOSTXL-DRV8323RS: Is running a 36V, 250W-500W Ebike motor too much for the BOOSTXL-DRV8323RS?

Jaden Reding
Prodigy 50 points
Part Number: BOOSTXL-DRV8323RS
Other Parts Discussed in Thread: CSD88599Q5DC, DRV8323, CSD88584Q5DC

Hi there,

I am looking to drive a 36V, 250W - 500W Ebike BLDC Hub motor with the BOOSTXL-DRV8323RS and would like to run the motor at about 240 rpm. I'll be using a battery with 36V nominal voltage and the the input voltage range of the BOOSTXL-DRV8323RS (6V - 54V) so that should be fine.

However, I would like to consistently output 36V from the BOOSTXL-DRV8323RS but I see that driver uses Mosfet's with max voltages of 40V. Will consistently outputting 36V putting too much stress on the BOOSTXL-DRV8323RS? Can it handle it? What is the recommended output voltage range for the BOOSTXL-DRV8323RS?

Thanks

Jaden

  • 0
    TI__Mastermind 18900 points

    Hello Jaden,

    Unfortunately, I'm unable to find the source of the max 40V range specification. The external power MOSFETs are on the EVM are the CSD88599Q5DC which are 60V (54V recommended max) FETs and the DRV8323 which has a absolute max of 60V (54V recommended max). So in this case of this specific EVM, 36V should be fine for "typical" and not "atypical or stress" testing.

    You still bring up a valid question, however. Some users like to do two times their RMS or expected system voltage (which would be 36V*2 = 72V in this case). This would mean that the 60V max voltage of both the DRVx and the MOSFETs introduce risk into the design. But this is all under your system's expectations.

    In your eventual system, you can add protection, such as zener diodes, or add more bulk capacitance that prevent voltage pumping. There are also good layout techniques and motor algorithms that can suppress voltage on the supply. Alternatively, switching to the DRV835x which is 100V compliant, will give you plenty of margin.

    Best,

    -Cole

  • 0 in reply to Cole Macias
    Prodigy 50 points

    Hi Cole, thanks for the response!

    I sourced the max 40V from the BOOSTXL-DRV8323Rx EVM User’s Guide

    On page 4 of the guide, this image shows CSD88584Q5DC 40V Mosfet's. 

    Do you have a source for the CSD88599Q5DC?

    Thanks,

    Jaden

  • 0 in reply to Jaden Reding
    TI__Mastermind 18900 points

    Hello Jaden,

    I'm referencing the design files directly as these are the files that are used to manufacture the EVM, specifically the schematic. Also, just took the EVM out of the box and took this picture (you can see 88599 on the top of the package of the FET):

    Don't get me wrong, we need to fix the picture in that user guide to prevent any other confusion. But I hope this helps.

    Best,

    -Cole

  • 0 in reply to Cole Macias
    Prodigy 50 points

    Definitely does. Thanks for the confirmation.

    Jaden