STSPIN9P12 Vref connection if not using current comparator

[drwho]

Hi, I'm designing a driver using 3x STSPIN9P12 to drive a Permanent Magnet Synchronous motor (PMSM).  I have a ADC connected to the SNSO outputs to measure current and I am controlling the current in the MCU's control loop.  I am not using the COUT and VREF pins.

1. Can / should VREF be tied to GND?
2. I think the TOFF pin does not exist on this version.  Do I leave TOFF floating?  or should TOFF be tied to GND?

Jon

[Peter BENSCH · Accepted solution]

Welcome @drwho, to the community!

1. you should connect VREF to GND to prevent interference pulses from being captured and the internal comparator from switching unintentionally
2. you should connect TOFF to GND, possibly via a 0 ohm resistor, which you can change later if necessary

Hope that helps?

Regards
/Peter

[drwho]

Yes it does thank you.  Another question...pins 1-4 are no connect.  Would it be ok to connect these to Vm?  It allows for a wider trace connection to EPAD2.

[Peter BENSCH]

Yes, you can of course connect the nc pins 1...4 freely, as can be seen, for example, in the GERBER of the evaluation boards.

Regards
/Peter