A high reliability isolated IGBT gate driver with channel multiplexing

Based on SIMC 0.18 um BCD process,a single channel isolated IGBT gate driver is designed, which has 2 A output current, 5 kV isolation voltage and CMTI 100 kV/us. It has high reliability by integrating desaturation protection and bilateral under-voltage lockout protection. In order to save chip area and cost, channel multiplexing technology is proposed. FLTH and RDH are desaturation status monitoring signal and under-voltage lockout status monitoring signal at high-voltage side respectively. FLTH and RDH are transmitted simultaneously using a same digital isolation channel. That greatly simplifies the circuit structure and saves about 10% of chip area. When under-voltage lockout occurs, isolated IGBT gate driver does not work. When under-voltage lockout does not occur, pulse width of the encode signal can be used to distinguish desaturation status. Simulation and test results show that channel multiplexing technology can accurately transmit desaturation state monitoring signal and under-voltage lockout state monitoring signal from high voltage side to low voltage side.