A 110–250V 2MHz isolated DC-DC converter with integrated high-speed synchronous three-level gate drive

This paper presents techniques for high-voltage isolated converters to achieve high power efficiency at high switching frequencies. To minimize the converter switching loss, an isolated quasi-square-wave zero-voltage switching three-level half-bridge architecture is adopted. An integrated synchronous three-level gate driver is proposed to ensure reliability of all eGaN power FETs and provide fast propagation delays for high-frequency converter operation. Thanks to the auto-reconfigurability of the proposed V_SW-based dead-time controller in the gate driver, ZVS of all power FETs with minimal body diode conduction loss can be achieved in a wide input range (110V-250V) to guarantee the reliability of the proposed converter. Implemented in a 0.7μm 700V CMOS-LDMOS process, the proposed gate driver achieves ≤ 18ns propagation delays and enables a 250V 45W isolated three-level converter to achieve the peak power efficiencies of 94.2% and 89.1% at 1MHz and 2MHz, respectively.