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Original question:

DRV8704: How to increase starting speed and torque

DRV8704: Can I improve the Source/Sink Current by Parallel drive way?

Eggsy Pang
Expert 4985 points
Part Number: DRV8704
Other Parts Discussed in Thread: DRV8701

Hi Team,

        My customer would like to improve the Source/Sink Current to driver their MOSFET. They want to driver a 50V /10A (RSM) motor.

So they let the A1HS short to B1HS ; A2HS short to B2HS ; AOUT1 short to BOUT1 ; AOUT2 short to BOUT2;   A1LS short to B1LS ; A2LS short to B2LS ; AISENP short to BISENP;  AISENN short to BISENN, which call "Parallel drive way".

May I know above "Parallel drive way" is ok?

Do you have any suggestions?

Thanks!

  • 0
    TI__Guru** 114905 points
    Hi Eggsy,

    The DRV8704 was not designed to connect the outputs in parallel. The timing in the two paths may be slightly different, leading to undesired results.

    Is your customer experiencing a problem with rise and fall times?
    What FETs are being used?
    What register settings are being used?
    Are TDRIVEN and TDRIVEP both set to 2'b11?
  • 0 in reply to Rick Duncan
    TI__Expert 4985 points
    Hi Rick,

    Customer would like to choose a device support BDC to runing in 50V/10A. They think it need 1A to driver FET but DRV8074 driver current is 400ma. So they want to know if DRV8074 can designed to connect the outputs in parallel , in order to increase the driver current.
    I can find the suitable socket to deal with it.
    Do you have any chioce?
    Thanks!
  • 0 in reply to Eggsy Pang
    TI__Guru** 114905 points
    Hi Eggsy,

    No, the DRV8704 should not be used with the outputs connected in parallel.

    Please provide the FETs used and the desired rise/fall time. We should be able to provide a solution.
  • 0 in reply to Rick Duncan
    TI__Expert 4985 points
    Hi Rick,

    They plan use two parallel FETs, the FETs is HGN036N08S, which means they need 8 FETs to driver one BDC motor. So they hope the driver current is bigger than 1.5A.

    Do you have suggestions?
    Thanks!
  • 0 in reply to Eggsy Pang
    TI__Guru** 114905 points
    Hi Eggsy,

    Please point the customer to www.ti.com/.../slva714c.pdf

    The document explains the benefits of the IDRIVE and TDRIVE implemented in the DRV8701. The DRV8704 has a similar implementation.

    The DRV8701 has up to 150mA IDRIVEsource and 300mA IDRIVEsink, while the DRV8704 has up to 200mA IDRIVEsource and 400mA IDRIVEsink.