DRV8353R: Speed Control with DRV8353R

Hello Tasin,

Short Answer

In general, the DRV835x does not have speed regulation and does not have the opportunity to take in a speed reference directly. It needs a processor or MCU to do that.

Long Answer:

At the most basic level (excluding 1x PWM which I'll talk about later), the DRV8353 is a gate driver. It uses the INx pins (which are digital input pins that usually come from a MCU or processor in the for of a PWM input) to control the GHx and GLx (the outputs the received PWM to the gates of the power MOSFETs that deliver current to the motor). There is no control or motor control algorithm, as it is the job of the MCU or processor to intelligently switch the gates. "Garbage in on INx, garbage out Gx".

With PWM 1x mode, "a single PWM sourced from a simple controller. The PWM is applied on the INHA pin and determines the output frequency and duty cycle of the [Power MOSFET gates]". Specifically, the DRV835x needs inputs and those inputs "uses 6-step block commutation tables that are stored internally" to the DRV. These inputs could be hall sensors or signals generated by digital inputs from the MCU. See section 8.3.1.1.3 1x PWM Mode (PWM_MODE = 10b or MODE Pin = Hi-Z) in the datasheet for more info.

With the introduction of the hall sensors, you might think there is some speed regulation but there is not. This is because the input PWM determines the output frequency and duty cycle. There is no speed feedback. There is no reference to say that "10% PWM duty cycle is generating 100Hz and we need 120Hz so we need to increase the PWM duty cycle". Again, another form of garbage in, garbage out.

We also don't have any other devices that we can recommend (right now) that can do this.

Best,

-Cole