Low loss 3-phase ideal diode bridge rectifier reference design

May 12, 2016 // By Graham Prophet
Linear Technology's evaluation board DC2465 demonstrates a low loss 3-phase ideal diode bridge rectifier reference design. Conventional 3-phase rectifiers employ six diodes, but the diodes drop voltage and dissipate significant power at just a few amperes of load current, leading to heat sinking and active cooling that complicate thermal design and increase solution size.

The DC2465 design replaces the six diodes with three LT4320 ideal diode bridge controllers, driving six low loss N-channel MOSFETs, reducing power and voltage losses. This enables an overall system to be specified to operate with a smaller, more cost-effective power supply due to the enhanced power efficiency. Low voltage applications benefit from the extra margin afforded by saving the two diode drops inherent in diode bridges. Compared to traditional approaches, the MOSFET bridge enables a rectifier design that is highly space- and power-efficient.

The DC2465 board rectifies line-to-line AC voltages from 9V[RMS] to 48V[RMS] with frequencies up to 400 Hz while sourcing a load of up to 25A without forced airflow. Efficiency at 9V input is raised from 84% for a diode bridge to 97% for the active bridge.

The DC2465 evaluation board is priced at $125.00. The LT4320 ideal diode bridge controller IC is offered in 8-pin MSOP, PDIP, and 3 x 3mm DFN packages.

Linear Technology; www.linear.com/demo/DC2465