MCT8316A: Motor Brake current

Hi Sunny,

I will get back to you in few hours.

Thanks and Best regards

Venkatadri S

Hi Sunny,

Please see my reply below for each point

1、When using BRAKE pin brakes, is the current controllable, and if so, through which register?

NO, Brake current depends on the motor speed, bemf. The brake enabled all low side FET which causes BEMF to regenerate current , the magnitude depends on motor energy.

2、What current does the Brake Current Threshold control? What is the relationship between voltage and current? In which case does it work?

If current based brake is selected through Brake Mode, brake routine exits when the recirculation current on the phase drops below the configured threshold. Brake routine works when start command issued or brake is commanded through pin

3、Does the Brake Time register still work when using the Brake pin brake? Or does the Brake Time register work in that case?

Brake pin applies brake always as long as pin is high.

Please refer to the startup sequence as when brake routing follows time.

Thanks and Best regards

Venkatadri S

If I want to control the current of the motor less than 5A when braking with BRAKE, what should I do?

Hi Sunny,

You can use BRAKE_DUTY_THRESHOLD value, this decelerates motor to safe speed before applying brake.

At reduced speed brake current will be limited.

Since device can handle up to 8A, what is the concern?

Thanks and Best Regards 

Venkatadri S 

BRAKE_DUTY_THRESHOLD is to implement deceleration after reaching this, what I want to do now is to decelerate immediately for BRAKE High while controlling the current of the motor less than 5A, what should I do?

Hi Sunny,

One method you can leverage is configure HW_LOCK_LIMIT or SW_LOCK_LIMIT, set the threshold you want to limit and then set reasonable retry time.

Suppose brake causes higher current to recirculate and when this current exceeds threshold HW fault triggers, exits brake and FETS will be tristate.

After retry interval (interval configurable from 10ms to 14s), device again applies brake.

Disadvantage is that, when brake state is exited due to HW LOCK fault, tristate can cause inductive current to flow back to supply causing Voltage spikes.

You to do tests and set the threshold, interval time. If acceptable, you can use the way I explained.

Thanks and Best Regards 

Venkatadri S 

Thanks for your reply, I will try this way

Hi Sunny,

Thank you, I will wait for your reply.

Thanks and Best Regards 

Venkatadri S