JAJSKM1C october 2019 – september 2021 UCC5870-Q1
PRODUCTION DATA
The VGTH Monitor function is used to measure the gate threshold voltage of the power transistor during power up. When enabled using the CONTROL2[VGTH_MEAS] bit (CONTROL2), the switch between DESAT and OUTH is turned on. A constant current source charges the gate capacitance of the power transistor and the gate voltage ramps up gradually. Once the channel starts to conduct, the gate voltage is naturally held at the threshold voltage level as the power transistor in a diode configuration. After the blanking time, tdVGTHM, the integrated ADC samples the gate voltage, and reports the measurement in register ADCDATA8. The measurement is actually a divided down version (divided by 8) of the gate voltage. The actual threshold voltage is calculated as:
This measurement is then used by the MCU to judge the health of the power transistor.