BLF989U

Overview

The BLF989U is a 900 W LDMOS RF power transistor designed for broadcast Doherty, class-AB transmitter, and industrial applications. It operates in the frequency range from 400 MHz to 860 MHz with excellent ruggedness suitable for digital and analog signals. The device features a drain-source voltage of 108 V and a junction temperature rating up to 225 °C. In class-AB broadband operation at 700 MHz, it delivers an average output power of 135 W with a typical power gain of 22.5 dB and drain efficiency of 35%. The component utilizes a flanged balanced ceramic package (SOT539A) with two mounting holes.

Feature Summary

• Designed for broadband and Doherty operation
• Integrated dual-sided ESD protection
• Excellent ruggedness against load mismatch
• High power gain and efficiency

Applications

• Broadcast transmitter applications in the UHF band
• Digital and analog broadcasting systems
• Industrial, scientific and medical (ISM) applications

Procurement Notes

Verify the specific ordering suffix to confirm the package variant, as the BLF989 uses SOT539A while the BLF989S uses SOT539B. Confirm RoHS compliance status via official Ampleon product details before procurement. Ensure design accounts for the absolute maximum ratings to prevent permanent damage during operation.

Selection Notes

Select this component for high-power UHF applications requiring robust performance in Doherty architectures. Verify thermal management capabilities given the junction-to-case thermal resistance. Ensure the operating frequency falls within the specified 400 MHz to 860 MHz range for optimal gain and efficiency characteristics.

Part Context

The BLF989U belongs to the Ampleon BLF989 series of UHF power LDMOS transistors. It is specifically engineered for high-efficiency broadband applications. The series includes variants like the BLF989S, which differs in package configuration but shares similar electrical characteristics for broadcast and industrial use cases.

Replacement Considerations

The BLF989S is a related variant using the SOT539B earless flanged balanced ceramic package. Verify mechanical compatibility and pinout similarities if substituting between these specific package types within the same product family.

FAQ

What is the maximum load mismatch the BLF989 can withstand?

The device is capable of withstanding a load mismatch corresponding to VSWR ≥ 40:1 through all phases under specific test conditions.

What is the thermal resistance from junction to case?

The typical thermal resistance from junction to case (Rth(j-c)) is 0.13 K/W when measured at Tcase = 90°C, VDS = 50V, PL = 135W, and PAR = 8 dB.

Is the BLF989U automotive qualified?

No, unless expressly stated otherwise, Ampleon products are not designed or authorized for automotive use and are not suitable for life support or safety-critical systems.