Low Loss 3-Phase Ideal Diode Bridge Rectifier Reduces Heat, Easing Thermal Design

Linear Technology DC2465 LT4320

Linear Technology Corporation announces the availability of a low loss 3-phase ideal diode bridge rectifier reference design, demonstrated on evaluation board DC2465. Conventional 3-phase rectifiers employ six diodes, but the diodes drop voltage and dissipate significant power at just a few amperes of load current. This requires costly heat sinking and active cooling solutions 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, dramatically reducing power and voltage losses. This enables the 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 Evaluation Board 
The DC2465 Evaluation Board.

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

The Typical LT4320 Application Circuit 
The Typical LT4320 Application Circuit.

The DC2465 evaluation board is available, priced at $125.00 each. The LT4320 ideal diode bridge controller IC is offered in 8-pin MSOP, PDIP, and 3 mm × 3 mm DFN packages. Evaluation circuit boards are available online or from your local Linear Technology sales office.

Thermograph of Passive Diode Bridge.    hermograph of LT4320 Driving Four MOSFETs
Thermograph of Passive Diode Bridge.   Thermograph of LT4320 Driving Four MOSFETs.

Summary of Features: DC2465

  • High Efficiency Rectification of 3-Phase AC Input
  • Replaces Diodes with Low Loss N-Channel MOSFETs
  • Minimizes Heat Dissipation, Easing Thermal Design
  • Maximizes Power Efficiency & Available Voltage
  • Input Rating
    • 9 VAC to 48 VAC RMS Line-to-Line Operation
    • Up to 400 Hz Line Frequency
  • Output Rating
    • 70 VDC Maximum Output Voltage
    • 25 A Maximum Load without Forced Airflow

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