Other Parts Discussed in Thread: DRV8305, DRV8328, DRV8329
I need to implement a hardware disable feature on a 3 phase motor driver using the DRV8300. I am wondering if it's possible to implement this by using a discrete MOSFET to switch the power to the GVDD pin of the DRV chip, and if so, how quickly the enable and disable functionality will work. I assume this "power switch" transistor would be located between the bypass capacitor and the power supply rail.
- Approx. how long will it take the DRV8300 to discharge its bypass capacitor from 12V to 4.2V (where the undervoltage lockout kicks in)? Would it require several transitions of the input PWM signal to dissipate the stored energy?
- What is the time delay between when GVDD < GVDDUV (power supply voltage < undervoltage lockout threshold) and when the gate drive outputs go to the hi-z state?
- Assuming one of the PWM logic level inputs is high, what is the time delay between when GVDD > GVDDUV (power supply voltage > undervoltage lockout threshold) and when the corresponding gate drive output will be driven to the on state?
- Are there any concerns with disconnecting the power to the GVDD pin without disconnecting the bootstrap pins?
Thanks for any feedback! I was hoping to use the DRV8305 (with a dedicated enable input) for this application, but now that part is not available.