BLF879P,112

Overview

The BLF879P,112 is a 500 W LDMOS RF power transistor designed for broadcast and industrial applications. It operates in the UHF band from 470 MHz to 860 MHz with an internal input matching network. The device features excellent ruggedness, capable of withstanding a VSWR of 40:1 at 860 MHz under rated power conditions. Key electrical parameters include a drain-source voltage rating of 104 V, a quiescent drain current of 1.3 A, and a thermal resistance (junction-to-case) of 0.15 K/W. In narrowband tests at 860 MHz, it delivers 200 W average output power with 21 dB gain and 47% drain efficiency.

Feature Summary

• Internal input matching network for high gain and broadband operation
• High ruggedness suitable for digital and analog transmitter environments
• Optimized thermal behavior with low junction-to-case thermal resistance

Applications

• UHF band communication transmitter applications
• Industrial applications in the UHF band
• Broadcast transmitter systems

Procurement Notes

Verify the specific package variant required for the design, as the BLF879P corresponds to the SOT539A flanged balanced ceramic package with mounting holes, while the BLF879PS uses the SOT539B earless version. Confirm that the ordering suffix matches the intended physical footprint before finalizing procurement orders to ensure mechanical compatibility with the heat sink assembly.

Selection Notes

Select this component for designs requiring high power density in the 470 MHz to 860 MHz range. Ensure the application circuit can maintain the recommended case temperature of 80 °C or lower to achieve the specified thermal performance. Verify that the load impedance remains within the safe operating area, particularly considering the device's capability to handle significant load mismatches during fault conditions.

Part Context

This part belongs to Ampleon's UHF power LDMOS transistor family, specifically engineered for robust performance in demanding RF environments. It serves as a core active element in power amplifier stages where high linearity and efficiency are critical. The product data sheet defines its absolute maximum ratings and typical RF characteristics to guide integration into standard common source amplifier topologies.

Replacement Considerations

The BLF879PS is the direct pin-compatible alternative featuring an earless flanged balanced ceramic package (SOT539B). Designers must verify mechanical clearance and mounting hole alignment when substituting between the SOT539A and SOT539B variants.