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L6472 Spurious Over Current

brett2
Associate
Posted on September 26, 2014 at 22:05

I'm having a similar issue as someone else posted last year. We had problems with overheating of the IC, so I increased the slew rate and that helped. But now, we're seeing random over-currents and I am wondering if dropping the fast decay duration alone will be enough. We have several motors in the 3 ohm/ 3mH range, My current parameters are what was recommended for the L6472 Eval board:

POW_SR = 00

ton_min = 4us

toff_min = 21us

toff_fast = 10us

fast_step = 16us

tsw = 48us

The advice given to a previous poster was:

Hello,

 

 

This seems to be an offset effect on the current sensing circuitry.

 

You can try the following solutions:

 

- slightly increase the target current, this way the sensing circuitry should work better

 

- decrease the fast decay duration (the fast decay causes the system to go out of control)

 

- decrease the slew rate

 

I tried dropping fast_step to 10us, and it seems to work ok, but the error is intermittent, and I'd like to have some margin. Any suggestions?

Also, I wonder if you can explain why adjusting the SR or fast decay helps. 

#l6472-current-regulation
1 REPLY 1
Enrico Poli
ST Employee
Posted on October 03, 2014 at 16:00

Hi,

what is the target current you set? What is the OCD threshold value?

Regadrs

Enrico