DRV8705-Q1: Configure DRV8705S control register parameters

jy Liu

Prodigy 10 points

Part Number: DRV8705-Q1

CSA_BLK,CSA_DIV,CSA_GAIN，How do I set these three parameters?

over 2 years ago

0 Ryan Kehr over 2 years ago

TI__Guru 54645 points

Hello!

All depends on what the customer is trying to do. What is the max (peak) current in the system and what is the size of the sense resistor? This will help determine the gain. I would set AREF/2 as the option that will center the voltage at the midpoint of the ADC reference to allow for directional sensing.

For CSA_BLK, also start with the default. This can be increased if noise is an issue on the CSA output.

Regards,

Ryan

0 jy Liu over 2 years ago

Prodigy 10 points

Hi!

Thank you very much for your answer!

The peak current of the driving motor is 30A, and the size of the sense resistor is 2512.

0 Ryan Kehr over 2 years ago in reply to jy Liu

TI__Guru 54645 points

Hello again,

Sorry, I should have been more clear. What is the value of the sense resistor? This is used to calculate the voltage on the sense amp.

Regards,

Ryan

0 jy Liu over 2 years ago in reply to Ryan Kehr

Prodigy 10 points

Hi,

Sorry, My understanding is wrong, the value of this sense resistor is 7.5mΩ.

0 Ryan Kehr over 2 years ago in reply to jy Liu

TI__Guru 54645 points

Thank you!

So, V (voltage across sense) = I * R. 225mV at peak. I would use the lowest gain setting. 10. This is assuming they have a 5V MCU.

Regards,

Ryan

Motor drivers

Motor drivers forum

DRV8705-Q1: Configure DRV8705S control register parameters