ZHCSKF2C February 2019 – January 2023 UCC21750
PRODUCTION DATA
In the applications of traction inverter or motor drive, the power semiconductors are in hard switching mode. With the strong drive strength of the UCC21750, the dV/dt can be high, especially for SiC MOSFET. Noise cannot only be coupled to the gate voltage due to the parasitic inductance, but also to the input side as the non-ideal PCB layout and coupled capacitance.
The UCC21750 features a 40-ns internal deglitch filter to IN+, IN– and RST/EN pin. Any signal less than 40 ns can be filtered out from the input pins. For noisy systems, external low-pass filter can be added externally to the input pins. Adding low-pass filters to IN+, IN– and RST/EN pins can effectively increase the noise immunity and increase the signal integrity. When not in use, the IN+, IN– and RST/EN pins must not be floating. IN– must be tied to GND if only IN+ is used for non-inverting input to output configuration. The purpose of the low-pass filter is to filter out the high frequency noise generated by the layout parasitics. While choosing the low-pass filter resistors and capacitors, both the noise immunity effect and delay time must be considered according to the system requirements.