NXP Semiconductors MRF085HR5

Overview

MRF085HR5 from NXP Semiconductors is a high-ruggedness, 85 W CW, 50 V RF power LDMOS transistor designed for broadband operation from 1.8 to 1215 MHz. It delivers 25.6 dB power gain and 73.3% drain efficiency at 520 MHz under CW conditions, with >65:1 load mismatch tolerance and integrated ESD protection-used in industrial plasma etching, VHF broadcast transmitters, and aerospace weather radar amplifiers.

For engineers reviewing the MRF085HR5 datasheet, MRF085HR5 pinout, MRF085HR5 application, or MRF085HR5 equivalent, key selection criteria include its 520 MHz narrowband test validation, dual-gate/dual-drain topology, ruggedness under extreme VSWR, thermal resistance of 0.85 °C/W, and NI-650H-4L package compatibility with high-power RF PCB layouts.

Technical Context

This device is a laterally diffused MOSFET with enhancement-mode, N-channel architecture and isolated source (backside metal). Its unmatched input/output design enables broadband use without external matching networks across 30–520 MHz and narrowband optimization at 520 MHz.

Characterized at VDD = 50 Vdc and TC = 85 °C, it supports single-ended or push-pull configurations, operates over –40 to +150 °C case temperature, and features gate threshold voltage of 1.5–3.0 Vdc with 2.0–3.3 Vdc quiescent gate voltage at 100 mA IDQ(A+B).

Key Specifications

Pinout & Package

The MRF085HR5 is housed in the NI-650H-4L air-cavity ceramic package with backside source connection. The package features four terminals: two drains (A/B), two gates (A/B), and electrically common source via the metallized case bottom.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RF power amplifier applications.

Compared with MRF085HR5, MRF085HR3 offers identical RF performance in higher-reel quantity, while MRFE6VP61K25H provides greater power headroom and frequency extension at the cost of increased board space and thermal management complexity.

Availability

MRF085HR5 is available at Aetrix Electronics and suitable for industrial plasma etching, VHF broadcast transmitters, and aerospace weather radar systems requiring stable component supply, long-lifecycle availability, and traceable sourcing.

Supply support for MRF085HR5 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

NXP Semiconductors is a global semiconductor leader specializing in secure connectivity solutions for automotive, industrial, and communication markets, with deep expertise in RF power technologies.

The MRF085HR5 belongs to NXP's high-ruggedness LDMOS transistor product line, engineered specifically for mission-critical RF power amplification in industrial heating, broadcast, and defense radar where reliability under extreme VSWR is non-negotiable.

FAQ

What is the maximum continuous drain-source voltage rating for the MRF085HR5?

The MRF085HR5 has a maximum drain-source voltage (VDSS) rating of +133 Vdc, with a minimum of –0.5 Vdc. This rating is specified in Table 1 of the official NXP datasheet (Rev. 1, Oct. 2017) and defines the absolute limit for safe DC biasing. Exceeding +133 Vdc risks permanent breakdown, while operation near –0.5 Vdc must avoid forward conduction through parasitic structures. The MRF085HR5 is typically operated at 50 Vdc for optimal 85 W CW performance.

Does the MRF085HR5 require external gate resistors for stability in broadband operation?

Yes-the MRF085HR5 benefits from external gate stopper resistors (typically 1–5 Ω in series with each gate) to suppress VHF/UHF parasitic oscillations, especially in broadband 30–520 MHz applications. While the device is characterized in NXP's reference circuit without explicit gate resistors, application note AN1908 and layout guidelines for NI-650H-4L packages recommend localized damping. The MRF085HR5's low Crss (0.17 pF) helps but does not eliminate the need for careful RF layout and gate stabilization.

Can the MRF085HR5 be operated in Class C mode, and what gate voltage range supports it?

Yes-the MRF085HR5 supports Class C operation due to its extended negative gate-source voltage rating (–6.0 Vdc) and integrated ESD protection, which improves gate robustness during hard switching. For Class C, gate bias is typically set below VGS(th) (1.5–3.0 Vdc), often between –1.0 and –2.5 Vdc, with RF drive peaking above threshold. The MRF085HR5's specified VGS(Q) range of 2.0–3.3 Vdc at 100 mA IDQ confirms stable Class AB operation, while the –6.0 Vdc VGS limit enables controlled cutoff in Class C.

What is the thermal resistance junction-to-case for the MRF085HR5, and how is it measured?

The MRF085HR5 has a thermal resistance (RθJC) of 0.85 °C/W, measured under CW conditions at TC = 85 °C, 85 W output, 50 Vdc drain supply, and IDQ(A+B) = 100 mA at 520 MHz (Table 2, NXP datasheet Rev. 1). This value reflects steady-state conduction through the NI-650H-4L package's ceramic base and backside source metallization. It assumes proper solder reflow per AN1908 and direct thermal interface to a heatsink-critical for maintaining TJ ≤ +225 °C in continuous operation.

Is the MRF085HR5 pin-compatible with earlier revisions like MRF085H or MRF085HR3?

Yes-the MRF085HR5 shares identical pinout, package (NI-650H-4L), and electrical specifications with MRF085H and MRF085HR3. The "R5" suffix denotes only tape-and-reel packaging (50 units, 44 mm tape width, 13-inch reel), while "R3" indicates 250-unit reels. All variants use the same top-view pin numbering: Drain A (pin 1), Drain B (pin 2), Gate A (pin 3), Gate B (pin 4), with source connected to the backside metal. No PCB layout change is needed when substituting MRF085HR5 for MRF085H or MRF085HR3.