DRV8870: Question for DRV8870

Hi Annie,

Is the motor spinning as they intended it to, except it whistles at a high frequency?

What PWM frequency are they utilizing?

Can customer provide scope capture of the inputs are well?

Is there a fault? If there is, please place trigger on nFAULT and capture the outputs right before the fault trips.

What is the issue the customer is seeing? The voltage dip on the OUTx pins?

The chip uses the circuit recommended by the manual. It is no nFAULT pin. The input is 10KHz. It is PWM square wave. The duty cycle is 70%.

Hi Annie,

Thank you. Can the customer share a less blurry scope capture of the outputs along with the inputs?

Hi ,Hector Hernandez

The case is a problem I applied DRV8870 in use

input   frequency  10K   PWM 50 - 70  regulated   load  :150mA

waveform

input  10K    70%     3.3Vp   at IN2

The  IN1 is 0V.

Output    IN2

Output  IN1

VREF

VM

This is no load with IN2 pin.

I don't konw , why is not the 0 - 6V range

I hope you have a good idea，thank you.

Hi user,

Can you please share motor part number? Thank you.

Hi user,

If schematic can be shared, please do so. If it needs to be be shared privately, please do so via private message. I will send you a friend request so we can start a private conversation if it is needed.

Hi Hector Hernandez

pump, G04EB

https://www.gardnerdenver.com/en-cn/thomas/rotary-vane-pumps-compressors/g04-series

Hi user,

if the duty cycle is increased enough to avoid the fast slewing change on the outputs, does the high pitch noise decrease?

Hi user,

Any update from your end? Feel free to share.

Hi,

It's ok during duty cycle 100%,  DC +6V   GND，  During 90% as before, 80% as before...

Hi user,

Has a different motor of same part number been utilized? How old is this motor?

One more point: the motor is commutated at a period of 10kHz. At that period, audible noise can be heard from a motor while it is commutating.

It can be expected noise. Can you PWM above 20kHz to see if the noise is reduced.

Hi Hector Hernandez

I've tried to replace the motor， The motor is the latest，This is the case below 10kHz unless DC，I haven't tried 20KHz，but we don't want frequency for 20khz.  because No torque.

Hi Hector Hernandez

Is it the cause of reverse electromotive force，I use reverse diode in the output, but the effect is not good

Hi user,

Have you tried experimenting above 10kHz to test if the noise is reduced?

Hi user,

Any update here? Thank you.

Hi user,

I will close this e2e for now. Please, reply to this thread or open a new one with your inputs. Thank you.