DRV8323: best practices for unused current sense amplifiers

Lenio Cacula

Part Number: DRV8323

If a BLDC application is using a single shunt, (a) what is the best procedure for connecting the unused current sense amplifiers? (b) If the customer wants to use one of the current sense amplifiers for a function other than motor current sensing, would that be okay?

Thank you!

over 4 years ago

0 Adam Sidelsky over 4 years ago

TI__Guru 62550 points

Lenio,

For an unused CSA we recommend the following:

All CSA inputs (SPC/SNC) to GND

SOx - Output of CSA floating

The CSA should not be used for a different purpose because the SPx pin is also used for the source connection and discharge path for the Low Side FET gate. The unused CSA SPx and SNx should be connected to GND as well as the source pin of the low side FET.

Regards,

-Adam

0 Lenio Cacula over 4 years ago in reply to Adam Sidelsky

TI__Genius 16110 points

I thought the sources of all three low side MOSFET's could be connected to the shunt and that connected to one of the CSA's. Based on what you are saying, the shunt is connected to only one of the bridges. Can you please confirm?

0 Adam Sidelsky over 4 years ago in reply to Lenio Cacula

TI__Guru 62550 points

Lenio,

Assuming you are using the B channel CSA, I would connect SPA/SNA/SNB/SPC/SNC to the GND side of the sense resistor. Only SPB will be connected to the top side of the sense resistor.

The source connection of all three low side FETs will be common and connected to SPB and the top of the sense resistor.

Regards,

-Adam

Motor drivers

Motor drivers forum

DRV8323: best practices for unused current sense amplifiers