Toshiba Semiconductor and Storage SSM3H137TU,LF

Overview

SSM3H137TU,LF from Toshiba Electronic Devices & Storage Corporation is a silicon N-channel MOSFET designed for low-voltage switching in compact relay driver circuits. It delivers R_DS(ON) = 240 mΩ (max) at V_GS = 10 V / I_D = 1.0 A, supports 34 V drain-source voltage, and operates with ±20 V gate-source rating - enabling robust control in space-constrained industrial interface modules.

For engineers reviewing the SSM3H137TU,LF datasheet, SSM3H137TU,LF pinout, SSM3H137TU,LF application, or SSM3H137TU,LF equivalent, key selection criteria include its UFM package footprint, 4.0 V logic-level gate drive compatibility, low pulse power dissipation (800 mW on FR4), and verified avalanche energy rating of 3.5 mJ - all critical for reliable relay coil switching and load control in embedded control units.

Technical Context

This discrete N-channel enhancement-mode MOSFET uses planar silicon process technology optimized for low-threshold switching at 4.0 V gate drive. Its static characteristics feature V_th = 0.7–1.7 V and R_DS(ON) that decreases predictably with increasing V_GS, supporting stable on-state performance across 4.0–10 V logic levels.

Dynamic behavior is characterized by C_iss = 119 pF (typ), C_oss = 40 pF (typ), and switching times of t_on = 320 ns / t_off = 800 ns under standard test conditions (V_DD = 20 V, I_D = 0.5 A, R_GS = 10 Ω), making it suitable for medium-speed digital load switching where gate charge (Q_g = 3.0 nC typ) must be minimized without sacrificing ruggedness.

Key Specifications

Pinout & Package

SSM3H137TU,LF is housed in the ultra-small UFM (Ultra Fine Pitch Miniature) surface-mount package (2.0 × 2.1 × 0.9 mm, 6.6 mg), optimized for high-density PCB layouts in portable and industrial control modules.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar N-channel MOSFET switching applications.

Compared with DMN2004LK-7 and AO3400, the SSM3H137TU,LF offers balanced trade-offs: moderate R_DS(ON) with guaranteed avalanche ruggedness and ultra-low gate charge, making it uniquely suited for space-constrained, inductively loaded relay drivers where reliability under transient stress is non-negotiable.

Availability

SSM3H137TU,LF is available at Aetrix Electronics and suitable for relay driver modules, industrial I/O expansion cards, and automated test equipment requiring stable component supply and long-term lifecycle support.

Supply support for SSM3H137TU,LF 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

Toshiba Electronic Devices & Storage Corporation designs and manufactures discrete semiconductors, power devices, and logic ICs with emphasis on reliability, efficiency, and industrial-grade robustness.

The SSM3H137TU,LF belongs to Toshiba's SSM series of small-signal MOSFETs engineered specifically for logic-level switching in compact, high-reliability control applications such as relay drivers and programmable I/O interfaces.

FAQ

What is the maximum continuous drain current for SSM3H137TU,LF?

The SSM3H137TU,LF has a maximum continuous drain current (I_D) of 2 A at T_a = 25 °C, derating linearly above 25 °C per the specified thermal resistance. This rating assumes proper PCB copper area (645 mm²) and ambient cooling - actual usable current depends on layout and airflow. The SSM3H137TU,LF maintains safe operation within this limit while delivering R_DS(ON) ≤ 295 mΩ at 4.0 V gate drive.

Does SSM3H137TU,LF require a gate resistor for relay driving?

A gate resistor is recommended for the SSM3H137TU,LF to dampen ringing and control switching speed - especially with inductive loads like relay coils. Typical values range from 10 Ω to 100 Ω depending on MCU drive strength and EMI requirements. The SSM3H137TU,LF's low Q_g (3.0 nC typ) allows fast turn-on even with modest gate resistance, preserving timing integrity in time-critical relay sequencing.

Is SSM3H137TU,LF suitable for automotive applications?

The SSM3H137TU,LF is not qualified to AEC-Q101 and is not intended for automotive safety-critical systems. While it meets industrial temperature range (−55 to +150 °C), its design and qualification focus on industrial control, automation, and consumer-grade smart home interfaces. For automotive use, engineers should select AEC-Q101–qualified alternatives - the SSM3H137TU,LF remains appropriate for non-safety automotive test equipment or aftermarket accessories.

Can SSM3H137TU,LF replace a bipolar transistor in relay driver circuits?

Yes - the SSM3H137TU,LF can directly replace small-signal NPN transistors (e.g., BC817, MMBT2222A) in low-side relay drivers. Its logic-level gate simplifies drive circuitry, eliminates base current calculation, and improves efficiency via lower saturation voltage (equivalent to R_DS(ON)). Unlike BJTs, the SSM3H137TU,LF draws negligible gate current, reducing MCU GPIO loading and enabling higher channel density in multi-relay modules.

What is the thermal resistance junction-to-ambient for SSM3H137TU,LF?

The SSM3H137TU,LF does not specify a fixed R_th(j-a) value because thermal performance depends entirely on PCB layout. Per Toshiba's test condition, it achieves 800 mW power dissipation on a 25.4 mm × 25.4 mm FR4 board with 645 mm² copper pad - implying an effective R_th(j-a) ≈ 200 °C/W under those conditions. Engineers must simulate or measure thermal performance for their specific layout; the SSM3H137TU,LF's UFM package demands careful copper pour design to maintain T_ch ≤ 150 °C.