Digital DC-DC converter for RF power amplifier applications

Flex Power Modules has launched the BMR685, the first digital DC-DC converter for RF power amplifiers in the half-brick form factor that can offer continuous output power of up to 1300W.

With telecoms infrastructure shifting to 5G, the RFPA is becoming more power-hungry, and RF power amplifier designers move from LDMOS to GaN transistors. Overall, there’s a demand for highly efficient DC-DC converters to provide the power needed in a compact package. The device’s power-handling abilities make it ideal for these high-power RF power amplifier applications, for both LDMOS and GAN requiring a 50V rail.

The new converter produces high efficiency of up to 97.2% at half load. It provides an output voltage range of 25V to 55V and can deliver up to 26A output current. Its input voltage range is 36V to 75V, and isolation between input and output is 2250V.

The device includes digital functionality, accessed over a PMBus interface, which facilitates easy monitoring of temperature, voltage and current, and simple adjustment of output voltage. It is supported by the Flex Power Designer software tool.

The converter provides an operating temperature range of -40C to +125C, with 100% available power at 100C baseplate temperature. It comprises comprehensive over-voltage, over-temperature and short-circuit protection mechanisms, which indicates it delivers a long operational lifespan, with an MTBF of over 4.97 million hours.

David Xie, director R & D and product management, Flex Power Modules, said: "RF Power Amplifier applications are demanding more and more power, without compromising on efficiency and features. The BMR685 meets all these requirements and more, in a compact package that is easy to integrate into Power Amplifier designs.”

Provided in the industry-standard half-brick format, the device measures 61mm x 57.9mm x 12.7mm (2.4" x 2.28" x 0.5"). It meets safety requirements according to IEC/EN/UL 62368-1.

Electronica China, Shanghai between 14-16 April 2021.