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DRV8353: Schematic verification

Gokul Karthik Sai Vamshi
Prodigy 90 points
Part Number: DRV8353

I am working on a FOC ESC and using DRV8353HRTAT (40 pin QFN). After going through the data sheet i have made the schematic according to what i have understood. But i still doubt if i have interpreted the information correctly.

My interpretations - 

IDRIVE (Pin 28) - Idrive > Qgd / tr which for the mosfets i have choosen is - 21nC/10ns = 2.1 amps. So this pin should be supplied with 2.1 amps.

VDS (Pin 29) - trip current point - Vds > Imax * Rds(on) which for my case is - 100A * 4.4mOHM = 0.44 volts. So this pin should be given 4.4 volts.

Gain (Pin 30) - gain settings - for my case - as vref is 3.3V, Rsense = 1.6mOHM, Imax is 100 amps, gain should be more than 20/20 v. So im going with a gain of 20/20.

It would be of great help if my assumptions are verified.

DRV schematic image   

Entire schematic picture

  • 0
    TI__Genius 12231 points

    Hi Gokul,

    Thank you for using our forum. 

    Allow some time to review your schematic and parameters and we will aim to give a confirmation/recommendation after analysis.

    Best Regards,

    -Joshua

  • 0 in reply to Gokul Karthik Sai Vamshi
    TI__Genius 12231 points

    Of course. 

    Do you have any additional info on the planned end-application of this design?

    Best Regards,

    -Joshua

  • 0 in reply to Joshua Maize
    TI__Genius 12231 points

    Hi Gokul, 

    Thank you for your patience. 

    For the GAIN, IDRIVE, and VDS pins on this H variant device (Hardware), the associated values are predefined by their external resistor connections. 

    Gokul Karthik Sai Vamshi said:
    IDRIVE (Pin 28) - Idrive > Qgd / tr which for the mosfets i have choosen is - 21nC/10ns = 2.1 amps. So this pin should be supplied with 2.1 amps.

    For iDRIVE on the H/W variant, the IDRIVEp and IDRIVEn current values are selected together by setting one of seven possible resistor connections given on the selection table on page 13/14 of the DRV835x datasheet. 

    Can you provide the datasheet for the MOSFETs used? You should also calculate IDRIVEn (Idrive > Qgd / tf) before selecting the proper current setting.

    Gokul Karthik Sai Vamshi said:
    VDS (Pin 29) - trip current point - Vds > Imax * Rds(on) which for my case is - 100A * 4.4mOHM = 0.44 volts. So this pin should be given 4.4 volts.

    For a VDS_OCP threshold > 0.44 V on the H/W version of this device you can set the value by connecting a 75kohm resistor to DVDD which will give you a typical threshold of 0.63V up to a max of 0.77V, meaning that it will trip a significant amount above the desired peak voltage/current limit (~143A) which may not be desirable for your use as it could never trip before damage occurs depending your components. 

    Gokul Karthik Sai Vamshi said:
    Gain (Pin 30) - gain settings - for my case - as vref is 3.3V, Rsense = 1.6mOHM, Imax is 100 amps, gain should be more than 20/20 v. So im going with a gain of 20/20.

    That gain of 20/20 is correct for your values, and to choose the gain setting of 20/20 you can achieve this by simply connecting the gain pin to Hi-Z (>500k Ohm). 

     

    If you have not already moved forward with design, I might caution the use of these specific MOSFETs for this specific motor driver, or instead use the SPI variant (DRV835xS) of this device to better suite your design needs when it comes to IDRIVE and VDS protection. 

    Please let me know if I can add any additional or clarifying information.

    Best Regards,

    -Joshua