DRV10970EVM: Issues controlling a motor with this EVM

Timothy Marriott

Part Number: DRV10970EVM
Other Parts Discussed in Thread: DRV10970,

Hi Everyone,

Initially, I was able to get the DRV10970 EVM to spin a brushless motor. Unfortunately, it no longer drives the motor and no longer illuminates the locked rotor LED.

I'm using a small brushless motor with 3 Hall IC's. I soldered 2.2kohm resistors on R17-R19 as pull-up resistors and placed jumpers on J5, J7, and J8.

I can see that the PWM is working from the potentiometer/555 timer, but the UVW phase outputs are measuring ~70mV regardless of the potentiometer position. Other voltages such as VINT and HPWR are correct. I've tried a few different motors and I've also tried every combination of hall/phase wiring to rule that out.

Is the PCB broken? Any info or tips are greatly appreciated.

Thanks,

Tim

over 4 years ago

0 Vishnu Balaraj over 4 years ago

TI__Mastermind 24405 points

Hi Timothy,

Thanks for posting your question in MD forum. Looks like the device is not commutating.

Here are a few debug tips:

1. Manually spin the motor to make sure hall signals are generated by the IC.

2. I'm sure you would have read the datasheet. Just wanted to make sure your Hall IC connection and your Hall IC outputs and BEMF waveform match the waveform shown in figure 28 and 29.

Regards,

Vishnu.

0 Timothy Marriott over 4 years ago in reply to Vishnu Balaraj

Prodigy 30 points

Thanks Vishnu. I can see that the hall sensors are working when I spin the motor.

I read the datasheet and the user guide for the EVM. What confuses me is that there are no commutation signals coming from the DRV10970. When I first started using the DRV10970EVM, it would try to commutate the motor and illuminate the red LED signalling a locked rotor. It would repeat this process every couple seconds. Now, it doesn't even try to commutate.

I've tried a few different motors, some with hall sensors and some without sensors. I can't see commutation signals for any motor.

DRV10970

0 Vishnu Balaraj over 4 years ago in reply to Timothy Marriott

TI__Mastermind 24405 points

Hi Timothy,

Can you please check the voltage at Vcp pin? This pin should read Vm+5V. If not then the Charge pump is blown.

Is the FR bit set correctly based on the phase driving sequence? Also just make sure you followed the tips in the datasheet (page 26) to find the correct U, V, and W phases and the respective Hall sensors.

Regards,

Vishnu

0 Timothy Marriott over 4 years ago in reply to Vishnu Balaraj

Prodigy 30 points

I measured a voltage of 13mV at the Vcp pin (pin 8) on the DRV10970. I think this might be my issue. Do the charge pumps become blown easily?

0 Vishnu Balaraj over 4 years ago in reply to Timothy Marriott

TI__Mastermind 24405 points

Hi Timothy,

In general, Charge pumps get blown when there is Electrical over stress (EOS). EOS condition occurs when the motor regenerates power back to the driver or when there is spike in Vcc. Please consider replacing the part.

Regards,

Vishnu.

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DRV10970EVM: Issues controlling a motor with this EVM

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