DRV10987: not providing Power to Motor phases

Hi Rabee, 

Monday the 6th is a U.S holiday and we are out of the office, a team member will get back to you in a few days. 

Regards,

Michael

Thank you for the Feedback

Hi Rabee,

I will get back to you tomorrow.

Regards,

Vishnu 

Hi Vinshu,

Can the reason be that the FET's are shoted through, therefore no power exists at the output ?

is there is a way to check that the FET's are not shoted through?

Hi Rabee,

Thanks for your patience!

The motor that you are using has 39Ω phase-phase resistance which is pretty high for DRV10987. What is the rated motor current? I couldn't find this data in the datasheet. I'm assuming it should be very low. I checked the EEPROM configurations and noticed that the Kt is programmed to 20.24 mV/Hz. Actual Kt from the motor datasheet is 17.8 mV/Hz. Can you change this to 18.4 mV/Hz (closest to 17.8 mV/Hz). Also, can you enable all the faults (check register address 0x94) and check what fault is getting triggered after applying voltage to Speed pin? 

Regards,

Vishnu

Thanks, I will check that an come back to you

Hi Rabee,

Sounds good, we will keep this thread open for you.

Thanks,

Matt

Dear Vishnu, 

I meusered the motor current with

• Trapezoidal Commutation
• 10 Ohm Resistor
• 7V2 Voltage
• 219 rpm

Result: Phasecurrent = 122 mA; Motorcurrent = 158 mA

Please refer to the following regarding the Kt value:

Also I enabled the all the faults (0x94 --> 0x3F0F) I got the following fault values (mostly it was returning the value 0 and 63 at startup)

VCC = 20V and SPEED = 2.6V DIR = low

please refer to the following screenshots for the schematic: 

Is the driver so sensitive to Phase-Phase resistance that the motor would not spin? and there is no output at all?

Thank you for your support.

Best,
Rabee

Rabee,

Rabee Mostafa said:

I meusered the motor current with

• Trapezoidal Commutation

This device does not support trapezoidal commutation. Did you use a different device to spin this motor? 

I noticed in your schematic that you are using DRV10987D which is a sleep device. What is the current drawn from the power supply when the motor is stationary? If it is in µA then the device is in sleep mode/power saver mode. In this mode, device will not spin the motor. Depending on the speed input mode, user should bring the device out of sleep mode to spin the motor. Below table shows the details to exit sleep mode.

Once the device is out of sleep mode, device should start drawing around few mA. 

I also noticed that the capacitor C21 is 100 nF and C26 is 0.001 uF. Recommended value for C21 is 10 nF and C26 is 10 uF. 

Regards,

Vishnu.

Thank you, the error was in the two capacitors. now I can spin the motor. 

Regards,

Rabee

Hi Rabee,

Glad to hear that the issue was resolved.

Thanks,

Matt