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TI gate driver DRV8312 & DRV8332 solution

Patrick Pan
Prodigy 355 points
Other Parts Discussed in Thread: DRV8332, DRV8312

Dears

 Some question about DRV8312 & DRV8332.

1. In the datasheet, it is written that the deadtime is typ 5.5ns, which is really too short for us, and is it fixed, or could be changed? and how to?

2. We see that DRV8312 also offer the option with conventional 6 PWM input as shown in the figure below, so if we use this 6 pwm input instead like we did before, the deadtime then could be changed by our real application? (Normally from the drive board EEPROM)

3. we see that there are two OC protection method offered by DRV8312: cycle-by-cycle (CBC) current limiting mode and OC latching (OCL) shut down mode. Our concern is that could we have both OC protection together? They both seems to be useful to our application.

4. The last concerning is the thermal relief if using DRV8332, which may need to use with heatsink together. Anyway, our motor rated current is only 3.8A, and in this condition, does the 8332 chip could afford this power consuing without the heatsink? If no, how big size of the heatsink shall we use? Since our application is a very compact design, thus we are very concerning about the component size.

Thanks

  • 0
    TI__Prodigy 380 points

    Hi Patrick,

    1. and 2.

    The internal dead time is fixed by design for the DRV8312 and DRV8332. I am curious as to why you think the dead time would be too short for your application. The dead time simply prevents shoot through from occurring by ensuring that the high and low side FETs are not both on when the PWM transitions from high to low or low to high. This device has a very robust design that allows for such a short dead time while still preventing shoot through from occurring and there have never been any failures with this device in a motor drive application, including medical applications.

    3. The device can only be in either CBC or OCL, not both. Which mode is used is controlled by setting the M1 mode selection pin to either logic 0 for CBC or logic 1 for OCL.

    Could you explain more how having both options would be useful to your application?

    What current limit value are you planning to use?

    4. A heat sink must be used with the DRV8332. Information for choosing a proper heat sink is given on page 23 of the datasheet.  

     

    Best Regards,

    John

  • 0 in reply to John Burton1
    TI__Mastermind 26065 points

    Hi Patrick

    There is some more comments of your question 3.

    Even in CBC mode, we still have a second level protection with latched off outputs. Please refer to the following decription of datasheet. So acctully you got both CBC and latch protection in CBC mode. The second level is pure analog gate protection with fast response and about 6A more of the setting limit. The device is fully protected from short condition.

    Thanks.

    Wilson Zuo

    Motor Application Team