STMicroelectronics SD2931-12MR

Overview

SD2931-12MR from STMicroelectronics is a gold-metallized N-channel DMOS RF power transistor in M174MR epoxy-sealed package, rated for 50 V DC large-signal operation up to 230 MHz. It delivers ≥150 W output power with 14 dB gain at 175 MHz, features 0.45 °C/W junction-to-case thermal resistance, and supports 10:1 load mismatch tolerance - deployed in industrial ISM RF amplifiers requiring ruggedness under high moisture and thermal stress.

For engineers reviewing the SD2931-12MR datasheet, SD2931-12MR pinout, SD2931-12MR application, or SD2931-12MR equivalent, key selection criteria include its 125 V drain-source breakdown voltage, sorted GFS (6.0–7.5 mho) and VGS(Q) (2.65–3.15 V), thermally enhanced M174MR package with exposed thermal base, and verified 55–65% drain efficiency at 150 W output.

Technical Context

This RF power MOSFET employs a common-source push-pull configuration optimized for HF/VHF broadband amplification. Its gold metallization ensures stable gate contact under thermal cycling, while the moisture-resistant epoxy seal enables reliable operation in humid industrial environments - critical for ISM band transmitters operating at 13.56 MHz, 27.12 MHz, and 175 MHz.

The device uses a thermally enhanced M174MR package with dedicated thermal base (Pin 5), achieving 25% lower R_thJC than standard SD2931. Dynamic performance is characterized at 50 V drain supply, 250 mA quiescent current, and includes Crss = 18 pF and CISS = 480 pF - enabling stable matching network design for fixed-tuned and broadband RF stages.

Key Specifications

Pinout & Package

The SD2931-12MR uses the M174MR 5-pin epoxy-sealed package with an exposed copper thermal base (Pin 5) for direct heatsink mounting. The package meets stringent moisture resistance requirements for operation in high-humidity industrial environments.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SD2931-11MR, the -12MR offers identical RF performance but improved lot traceability for GFS/VGS sorting; versus MRF158G, it delivers +50% output power and 31% better thermal resistance - making it the preferred choice for high-reliability, high-power ISM amplifiers.

Availability

SD2931-12MR is available at Aetrix Electronics and suitable for industrial RF heating, ISM plasma generation, and medical diathermy systems requiring stable component supply, long-lifecycle support, and moisture-resistant packaging.

Supply support for SD2931-12MR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, power, and RF components for industrial, automotive, and consumer applications.

The SD2931-12MR belongs to ST's high-power RF DMOS transistor product line, engineered specifically for rugged, high-efficiency amplification in industrial ISM bands where thermal robustness and environmental resilience are non-negotiable.

FAQ

What is the maximum continuous drain current rating for SD2931-12MR?

The absolute maximum continuous drain current is 20 A at T_CASE = 25 °C, per Table 1 of DS9247 Rev 4. However, practical operation at 150 W output limits average ID to ~12 A under typical Class AB conditions with 50 V supply and 250 mA quiescent current.

Does SD2931-12MR require external gate protection?

Yes - the device has ±40 V absolute maximum gate-source voltage rating. A series gate resistor (typically 10–47 Ω) and parallel Zener clamp (e.g., 18 V) are recommended to suppress RF-induced gate ringing and ESD transients observed in HF/VHF amplifier layouts.

How does the M174MR package differ from standard M174?

M174MR adds moisture-resistant epoxy encapsulation and refined thermal base plating, achieving <10% internal humidity after dry-pack storage and 25% lower R_thJC. Mechanical dimensions match M174, ensuring drop-in compatibility with existing heatsinks and fixtures.

Can SD2931-12MR operate at 30 MHz with full 150 W output?

No - at 30 MHz, maximum rated P_OUT is 120 W (per Figure 22), limited by reduced gain and efficiency. The 150 W rating is specified only at 175 MHz; operation at 30 MHz requires derating to maintain safe junction temperature and reliability.