NXP Semiconductors MRF373ALR1

Overview

MRF373ALR1 from Freescale Semiconductor is an N-channel enhancement-mode lateral RF power MOSFET in NI-360 (Case 360B-05) package, designed for broadband common-source amplifier applications in 32 V transmitter equipment operating from 470 to 860 MHz. It delivers 75 W CW output power at 860 MHz with 18.2 dB power gain and 60% drain efficiency, and withstands 10:1 VSWR under full-power conditions.

For engineers reviewing the MRF373ALR1 datasheet, MRF373ALR1 pinout, MRF373ALR1 application, or MRF373ALR1 equivalent, this page provides verified thermal resistance (0.89 °C/W), ESD protection class (HBM Class 1, MM Class M2), gate threshold voltage (2.0–4.0 V), drain-source breakdown voltage (70 V), and series-equivalent impedance data at 845–875 MHz for narrowband matching design.

Technical Context

The MRF373ALR1 operates as a high-power RF amplifier stage in fixed-bias or Class AB configurations, with gate quiescent voltage specified at 2.5–4.5 V under 32 V drain supply and 100 mA bias current. Its lateral LDMOS structure enables stable large-signal performance across UHF TV broadcast and cable headend bands.

Thermal management is defined by junction-to-case resistance of 0.89 °C/W and maximum case temperature of 150 °C, requiring direct mounting to heatsinks with low thermal interface resistance. Input/output capacitances (Ciss = 98.5 pF, Coss = 49 pF, Crss = 2 pF) support broadband matching network synthesis per measured source/load impedances (e.g., Zsource = 0.56 + j0.06 Ω at 860 MHz).

Key Specifications

Pinout & Package

Package: NI-360 (Case 360B-05), flanged ceramic/metal hermetic package with integral heatsink base. Dimensions: 20.19–20.45 mm × 5.72–5.97 mm × 9.02–9.27 mm (L×W×H), 3-terminal configuration.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MRF373ALR1, the MRFE6VP61K25H offers higher power and thermal efficiency but demands full circuit redesign, while the PD85003 provides lower-cost operation at reduced output and ruggedness-neither is pin-compatible, and both require validation of matching networks and thermal interface design.

Availability

MRF373ALR1 is available at Aetrix Electronics and suitable for UHF broadcast transmitters, cable headend amplifiers, and wireless repeater systems requiring stable component supply and long-lifecycle support for legacy infrastructure maintenance.

Supply support for MRF373ALR1 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

Freescale Semiconductor (now part of NXP Semiconductors) was a leading designer of RF power semiconductors for wireless infrastructure and broadcast applications before its 2015 acquisition.

The MRF373ALR1 belongs to Freescale's MRF373A family of lateral N-channel RF power MOSFETs, engineered specifically for high-efficiency, broadband UHF amplifier stages in 28–32 V transmitter equipment.

FAQ

What is the maximum continuous drain current rating for the MRF373ALR1?

The MRF373ALR1 does not specify a maximum continuous drain current (I_D) rating directly; instead, its safe operating area is defined by total device dissipation (197 W at T_C = 25°C) and thermal resistance (0.89 °C/W). At 32 V drain supply and 75 W output, typical drain current is ~3.5 A CW, but actual current depends on bias point and efficiency. Designers must use the SOA curves and derating rules in the MRF373A datasheet Rev. 7 to ensure junction temperature remains below 200 °C for the MRF373ALR1.

Is the MRF373ALR1 RoHS compliant and lead-free?

Yes, the MRF373ALR1 is RoHS compliant with lead-free terminations and 40 μ″ nominal gold plating on leads, as confirmed in the Freescale RF Product Device Data document Rev. 7 (Sept. 2008). This applies to all units marked "R1" indicating tape-and-reel packaging (500 units per 32 mm, 13-inch reel), and meets EU Directive 2011/65/EU requirements for hazardous substances.

Does the MRF373ALR1 have built-in ESD protection, and what level is certified?

Yes, the MRF373ALR1 includes integrated ESD protection rated at Human Body Model (HBM) Class 1 (minimum 2 kV) and Machine Model (MM) Class M2 (minimum 200 V), per Table 3 in the official datasheet. These ratings are verified during manufacturing test and allow simplified board-level handling compared to unprotected RF MOSFETs, though gate protection during assembly remains recommended.

What is the recommended gate bias voltage range for linear operation of the MRF373ALR1?

The MRF373ALR1 specifies a gate quiescent voltage (V_GS(Q)) range of 2.5–4.5 V at V_DD = 32 V and I_DQ = 100 mA, per Table 4. For linear Class AB operation delivering 75 W CW, Freescale recommends setting V_GS(Q) near 3.3 V (typical) with tight regulation (< ±50 mV) to maintain consistent gain and efficiency. Gate bias must be filtered and decoupled per the narrowband test circuit in Figure 1 to prevent oscillation.

Can the MRF373ALR1 be used in 50 V supply applications?

No, the MRF373ALR1 is rated for maximum drain-source voltage (V_DSS) of +70 V but is characterized and optimized for 32 V operation. Its safe operating area, thermal derating, and matching networks (e.g., Table 5 component values) assume 32 V DC supply. Operating at 50 V exceeds the validated design envelope and risks premature failure due to increased electric field stress and unverified SOA margins. Use NXP MRFE6VP61K25H for 50 V systems.