DRV11873EVM PWM

Jacob Sacks

Other Parts Discussed in Thread: DRV11873

Hello,

As according to the user guide for the evaluation module, I removed the 0.0 ohm R5 resistor to allow the use of an external PWM. To test the functionality, I connected the PWM test pin from another board to the modified one. However, my motor, which ran fine before, will not spin properly with the external signal. Is there anything else that is necessary to enable the use of an external PWM signal?

Thanks,

Jake

over 10 years ago

0 Nicholas Oborny over 10 years ago

TI__Mastermind 21305 points

Hi Jake,

The board should not require any additional circuitry. Are you saying you have another DRV11873 EVM that you ran the signal from to the board without R5? Just looking to clarify.

0 Jacob Sacks over 10 years ago in reply to Nicholas Oborny

Prodigy 125 points

Hi Nick,

Yes that's exactly what I did. And I checked the signal with a logic analyzer and it looked correct. However, the board does not seem to drive the motor according to the PWM signal, even though I did before I removed R5.

Jake

0 Nicholas Oborny over 10 years ago in reply to Jacob Sacks

TI__Mastermind 21305 points

Jake,

Can you try with a function generator? It is possible that the 555 Timer cannot source enough current to drive two devices, though this seems unlikely. How long is the connection from board to board? This could be adding alot of inductance.

0 Jacob Sacks over 10 years ago in reply to Nicholas Oborny

Prodigy 125 points

Hi Nick,

It turns out one of my chip resistors on the back of the board connecting the motor outputs to COM had come loose. Reinforcing this connection solved the problem. So it wasn't due to a limit on current from the PWM test pin on the other board or a fault in removing R5. Thank you for your assistance.

Regards,

Jake

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DRV11873EVM PWM