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DRV8300: Slew rate on SHx pins on DRV8300D

Ray Vincent Aranzaso
Mastermind 18180 points
Part Number: DRV8300
Other Parts Discussed in Thread: TPS563240,

Hi,

Good Day. I have a customer who is working with TPS563240. Please see below his query for your reference. Thank you very much.

We are interested by the DRV8300 (qty=30k/year) but a we need a technical explanation.

On the page 6 of the datasheet (www.ti.com/.../drv8300.pdf), the Slew rate on SHx pin is only 2v/ns for the integrated Bootstrap Diodes versions (DRV8300D) while the external diodes versions (DRV8300N) are limited with a more standard 50V/ns.

2V/ns is a very small value and practically unusable.
- could you confirm this point of the spec?
- if confirmed, could you explain us the reason?

I already discuss to the customer the "Gate Resistance Selection on page 20 of the DRV8300 Datasheet but he has another query. Please see below.

I had carefully read the datasheet before sending this case. I know that the slew-rate of the output of a half bridge (connected to a motor phase) can be mitigated by the choice of the gate resistors. However a 2V/ns valeur is really tough to obtain. This strong limitation seems to be linked with the spec of the internal boostheat diode and we do not understand why...

Best Regards,

Ray Vincent

  • 0
    TI__Mastermind 21805 points

    Hello Ray,

    This device is designed for motor drive applications up to 200kHz, whereas the TPS563240 is a buck regulator with 1.4MHz switching frequency. When you are switching a motor at 200kHz and below, 2V/ns and far below is common.

    When using the integrated boostrap diode we are limited in the slew rate, but the external bootstrap allows for significantly higher due to internal paths being bypassed.

    Thanks,

    Matt