Hi All,
I have a question about the DRV8813.
How much does the accuracy of the output current change depending on the set voltage of VREF?
The DRV8881 data sheet had the following graph. Does the DRV8813 also have a graph showing accuracy like this?
From the DRV8881 datasheet
Best Regards,
Ishiwata
Ishiwata-san,
I am a little confused as that figure doesn't show accuracy. It just shows current scaling factor under different TRQ settings.
For accuracy, you can find information in the electrical characteristics table for 3.3V. This accuracy is valid until VREF < 1V....you can just divide VREF by 5V and that is the typical. Percentage variation will be the same in xISENSE trip voltage.
When VREF < 1V, it will degrade. I don't have the actual degradation details. We just don't recommend operating with VREF < 1V.
Regards,
Ryan
Hi Ishiwata san,
VTRIP accuracy SPEC is bellow as Ryan shows. This is same in DRV8881. Accuracy will be same with VREF=1.1V,2.2V,3.3V.
regards
Shinya Morita
Hi Morita san,
Thank you for your reply.
Does these characteristics indicate followings?
xVREF = 3.3 V, 100% current setting → 3.3 V, 71%～100% current setting
xVREF = 3.3 V, 71% current setting → 3.3 V, 38％～71% current setting
xVREF = 3.3 V, 38% current setting → 3.3 V, 20％ or 33%？～38% current setting
As the background of this question, we would like to know whether these characteristics indicate an approximate value at each current settings or range of current setting.
In other words, on the DRV8426’s datasheet, it shows current trip accuracy with range of current setting like as follow;
Also, is it OK with the following understanding?
For example,
xVREF=3.3V 71% Current setting and xVREF=2.343V 100% Current setting are the same VTRIP. (3.3V x 71% = 2.343V)
Both VTRIP is 469mV (TYP).
Best Regards,
Ishiwata
