DRV8243-Q1: How to do the analog signal samping and holding of IPROPI pin for PWM driven with DRV8243 HW version

Hi Shiyu,

Just to clarify, currently the IPROPI signal is going into the ADC on the MCU, or it is not? You are saying they have a hard time sampling the signal on the MCU side?

What kind of load are they currently driving in the example is it resistive? 

What are they trying to do with this current information?

best,

Keerthi

1. "currently the IPROPI signal is going into the ADC on the MCU, or it is not?" -- Yes.

2. "What kind of load are they currently driving in the example is it resistive?" -- The load for DRV8243 is a motor.

3. "What are they trying to do with this current information?" -- We use DRV8243 to drive a motor with PWM type(20KHz). The current of motor is not continuous due to PWM driven. So the IPROPI signal is also not continuous as the above waveform. But the frequency of our MCU analog sampling is once every 1ms, which could not be synchronized with the PWM signal of the driver. Therefore, the IPROPI signal we currently collect is constantly jumping because it could not be synchronized with PWM driving signal. 

Are there any IC or circuits for analog sampling and holding to add to the  IPROPI pin to let MCU could detect the continuous current ADC value even if the PWM (20KHz) driven.

I hope you could understand my meaning.

THS!

Hi Shiyu,

One option would be to use an external ADC with faster sampling; TI has a whole portfolio of high-speed ADC's. Another option could be to implement some kind of moving average to smooth out the variation. An example of this can be found in the EVM firmware.

Best,

Keerthi

Maybe my focus point is sampling and holding function. As you know, as TI pre-driver, there is the similar function for DRV8705. I would like to know how to use discrete devices or integrated ICs to achieve this function?

Hi Shiyu,

Is this automotive application?

We do have such circuits like the following:

LFx98x Monolithic Sample-and-Hold Circuits datasheet (Rev. C) (ti.com)

Is this what you are talking about?

Best,

Keerthi

It is automotive application.

Do you have any AEC-Q200 components such as above?