DRV8912-Q1: PWM Frequency

Hi, Stephen,

Welcome to e2e, and thanks for your interest in our products.

Let us discuss options and get back to you by the end of tomorrow.

Hi Stephen,

Producing a custom variant is a complex business decision and one we probably cannot settle over the forum.  Do you have an FAE that visits you regularly?

For your application, are you using PWM to control the opening, or to reduce current during hold?  If its the latter, is it possible to try reducing duty cycle after the valve is opened?  By default the slew-rate is already the lower setting, but that was another thought, if by chance SR is set to the higher setting, try going back to the slower SR.

Another thought - are you evaluating the EVM, or is the device already designed on your board?  If there is still room to change the design, we have other devices offer PWM inputs, allowing frequency control from your micro.  My assumption is the DRV8912 was chosen in part because it has PWM built-in, but thought I'd mention just in case.

Regards,
Mike

Hi Don,

Many thanks for getting back to me. We look forward to your response.

Steve.

Hi Mike,

Thank you for the swift response. We do not have an FAE that visits unfortunately.

For our application we are using PWM to control the current flow during the holding period. It is working well with the exception of the audible noise. We have tried several duty cycle values but the issue remains - I will take a look at the SR setting to see if it has an effect, thanks.

Yes, that is correct, the DRV8912 was chosen because of the internal PWM and current drive capabilities. We are evaluating using the EVM at the moment but work is underway in parallel to layout a board, hence why this is fairly urgent. If you could recommend another part that offers similar performance and fault detection coverage then we would be interested to review the datasheet. Many thanks.

Steve.

Hi Steve,

In terms of devices with high channel count, and integrated PWM, the DRV89xx family is what we have available today.  Other devices like the DRV8718 has the fault detection features you'd want, but the PWM is supplied externally, and the FETs are also external, so BOM and size go up.

Is there any possibility of using a lower PWM frequency?  I realize some loads will need the higher frequency and dropping lower is not an option.

Regards,
Mike

Hi Mike, 

Thank you very much for the feedback. I will take a look at the DRV8718 and see if we could adapt our design. In terms of lowering the frequency, unfortunately that is not an option for us at the moment. 

Best regards,

Steve.