This reference design describes a 3.5kW, 800V to 14V DC-DC converter with 650V Gallium nitride (GaN) high-electron mobility transistors (HEMT). Using stacked half-bridge (SHB) topology makes the converter work at 800V with 650V GaN HEMT. Using LMG3522R030 as primary switches makes the converter work at a high switching frequency. In this design, the converter uses a smaller transformer size. To ease the thermal performance of active clamping metal-oxide semiconductor field effect transistors (MOSFETs), the converter uses two channel active clamping circuits.

• 650V GaN based stacked half-bridge (SHB) using LMG3522 in 800V battery system
• 200kHz switching frequency, magnetic size is 35% less than 100kHz
• 95.48% at 200kHz, 800V V_in, 13.5V V_out, about 1kW
• Dual active clamping circuits for high-frequency scenario and low synchronous rectifier (SR) MOSFET voltage stress
• Light load efficiency optimization promotes maximum 5% efficiency

• Hybrid, electric, and powertrain systems
• DC/DC converter system

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Block Diagram

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