Hi everyone,
I’m using the STGIB8CH60TS-E IPM in my motor drive design and trying to configure the smart shutdown (overcurrent protection) function using the CIN pin.
As per the datasheet, the internal comparator reference voltage (Vref) is typically 510 mV (460 mV min, 560 mV max).
I’ve used a 50 mΩ shunt resistor on the DC return path (between the negative DC bus and the IPM’s NU/NV/NW pins). Based on this:
IOC=VrefRshunt=0.510.05=10.2 A (typical)I_{OC} = \frac{V_{ref}}{R_{shunt}} = \frac{0.51}{0.05} = 10.2\text{ A (typical)}IOC=RshuntVref=0.050.51=10.2 A (typical)
So the expected trip current should be around 10 A.
For filtering, I’ve used R = 2 kΩ and C = 1 nF (RC = 2 µs) at the CIN pin to suppress switching noise.
I’d like to confirm a few points:
Is my calculation and setup for the IOC threshold correct for triggering the smart shutdown?
Are my RSF/CSF values (2kΩ, 1nF) reasonable, or should they be closer to the 1 µs time constant recommended in the datasheet?3
- Are there any calculation to find R and C value for filter
Thanks in advance for your time and suggestions!
