DC1902B: Ideal Bridge Controller, 12~24VAC,9~60VDC

Demonstration circuit 1902B features the ideal diode bridge controller LT®4320 suitable for applications that require low to medium current AC to DC full-wave rectification or DC polarity correction and a small compact solution.

The LT4320 drives four N-channel MOSFETs to perform full-wave rectification functionally similar to a diode bridge but with much lower power dissipation. This topology eases thermal design, and increases usable output voltage. In addition, an all N-channel topology has benefits over a P-channel topology such as a wider selection of MOSFETs, lower cost, lower RDS(ON), and smaller footprint.

Only a few essential components are required to operate the LT4320 as an ideal diode bridge: four N-channel MOSFETs, a bypass ceramic capacitor, and an AC smoothing capacitor (CLOAD). The DC1902B includes low RDS(ON) N-channel MOSFETs (21mΩ typical) to support low to medium current applications. When an AC voltage source is used, the onboard CLOAD (C2) capacitor allows for up to 1.5A of average output current. Add additional CLOAD capacitance to support higher current AC applications. A unidirectional TVS (D1) is included to protect the application from brief overvoltage events up to the part rating. A footprint for bidirectional TVS (D2) is also included and is recommended for electrically harsh conditions.