DRV8871 Current regulation accuracy

masahiko shimizu

Other Parts Discussed in Thread: DRV8871

Hi,

Could you please tell me how DRV8871 sense motor current for current regulation?
I think that it is as overcurrent protection.
In other words, It shows DRV8871 senses FET ds voltage.

Customer wants to know current regulation accuracy of DRV8871.
Above question is for this request.
If you tell me current regulation accuracy, could you please let me know?

Best regards,
Shimizu

over 9 years ago

0 Wilson Zuo over 9 years ago

TI__Mastermind 26065 points

Hi Shimizu

It is a little different as Vds sense. It is sensed from a mirror structure of the internal MOSFETs, which is producing a small portion of the real current directly. The regulation accuracy is similar to our device using external Rsense.

Best regards,

0 masahiko shimizu over 9 years ago in reply to Wilson Zuo

Guru 11235 points

Hi Wilson,

Thank you for your support.
I add questions about this.

Do we need to take care the following item for the regulation accuracy?
- VILIM error
- External resistor

I am concerned whether Ron affects current sense accuracy even if current sense is by mirror.

Best regards,
Shimizu

0 RE over 9 years ago in reply to masahiko shimizu

TI__Mastermind 20985 points

Shimizu-san, current regulation accuracy is described at the top of datasheet Page 9.

System designers should always understand the min and max I_TRIP, based on the R_ILIM resistor component tolerance and the DRV8871 specified V_ILIM range.

Best regards,
RE

0 masahiko shimizu over 9 years ago in reply to RE

Guru 11235 points

Hi RE,

Thank you for your support.
I understand that Ron does not matter.
I tell customer what you and Wilson said.

Best regards,
Shimizu

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DRV8871 Current regulation accuracy