DRV8452: Regarding block diagram of Auto-torque

Higa-san,

Please give me 24 hours to check with system engineer.

Regards,

Ryan

Daisuke Higa said:

I think that ATQ_CALC and ATQ_CNT are reversed in the auto torque block diagram.

No, the block diagram is correct. The PID loop working to keep ATQ_CNT within ATQ_LL and ATQ_UL. When ATQ_CNT is too high due to motor load increased (higher than the programmed ATQ_UL), then the PID loop increases the motor current (full-scale current) to avoid motor missing step, and this causes lower ATQ_CNT. The chip generate ATQ_CNT based on motor BEMF vs. step input. 

Regards,

Brian

Hi Brian-san

Thank you for confirming.

My understanding is that the value of ATQ_CNT is TQ_CALC added to ATQ_LRN in the block diagram below.

If I'm misunderstanding, does the block diagram below mean that the ATQ_CNT value is calculated as the difference between ATQ_LRN and ATQ_CALC?

The datasheet provides the following graph and equation.
I thought that the above block diagram and the following equation do not match.
I'm confused on how to understand it.

Regards,

Higa

Hi,

There is no conflicting of the block and equation and graph.

ATQ_CALC = ATQ_LRN + ATQ_CNT; and so 

ATQ_CNT = ATQ_CALC - ATQ_LRN; which is shown on the block diagram. 

Daisuke Higa said:

If I'm misunderstanding, does the block diagram below mean that the ATQ_CNT value is calculated as the difference between ATQ_LRN and ATQ_CALC?

Yes, it is CALC - LRN.

Brian

Higa-san,

I agree with what Brian mentioned - there is nothing wrong with the block diagram. ATQ_CNT is ATQ_CALC minus ATQ_LRN.

Regards,

Dipankar