Is there a voltage range specified for linear operation of the current sensing outputs on the MP6543C?
I noticed when sampling two phase currents on my BLDC, that if the resistor values are too large on the SOx outputs, there is a gentle clipping of the waveforms. If I either warmed up that same motor, or decreased the SOx resistor values (both options reducing the SOx output amplitude), the waveforms no longer clipped. Attached below are the raw 12bit ADC plots of these samples, the first is a cold motor, the second a warm motor.
The datasheet does not specify this linear range. Can MPS please provide a spec for this?
Hi Ezra,
Welcome to the MPS Forums.
Could you share the corresponding voltage levels for the ADC plots you shared?
I looked into the datasheet and there is a range of 0-3.6V for the current sensing output voltage swing. Please see image below.
This may be the cause of the clipping seen on your current sense output waveform.
Best regards,
Zachary
Thanks for your reply Zachary!
Yeah I wasn’t sure of what to make of that spec. Since the values were measured using the internal 3.3V LDO of the MP6543C as the positive reference for the 12 bit ADC and the plots didn’t hit the rails (instead capped out at roughly 3.7k and 370) I gathered that there was a linear range limitation.
