TIDT255 January 2022
This isolated open-loop LLC transformer driver converter provides 4 rails outputs, each output has dual +18-V and –5-V outputs up to 0.5 W for traction inverter applications. The UCC25800-Q1 device is used here as the controller. The LLC topology allows the transformer to have significant leakage inductance, but a much smaller primary-secondary capacitance, which significantly reduces common-mode current injection through the bias transformer. This reference design offers a high level of integration and high efficiency in a compact form factor, it has passed CISPR 25 class 3 conducted EMI standard.