STMicroelectronics STW21NM50N

Overview

STW21NM50N from STMicroelectronics is an N-channel 500 V, 0.15 Ω (typ), 18 A TO-247 packaged Power MOSFET based on second-generation MDmesh™ technology. It delivers low gate charge (65 nC), high avalanche ruggedness (480 mJ), and fast switching (tr = 18 ns, tf = 30 ns), making it suitable for high-efficiency 500 V flyback, LLC resonant, and PFC stages in industrial SMPS.

For engineers reviewing the STW21NM50N datasheet, STW21NM50N pinout, STW21NM50N application, or STW21NM50N equivalent, key selection criteria include R_DS(on) at 10 V drive, unclamped inductive switching capability, thermal resistance (R_thj-case = 0.89 °C/W), and source-drain diode recovery performance (t_rr = 360 ns @ T_j = 25°C).

Technical Context

This MOSFET employs ST's second-generation MDmesh™ vertical superjunction architecture with strip layout, enabling ultra-low R_DS(on) × Q_g figure-of-merit (0.15 Ω × 65 nC). Its 500 V V_DSS rating supports operation across universal AC input ranges with margin, while 100% avalanche testing ensures robustness under transient overvoltage conditions.

The device features a low C_iss (1950 pF) and C_oss (420 pF) with minimal C_rss (60 pF), supporting high-frequency ZVS/ZCS topologies. Its integrated body diode exhibits soft reverse recovery (Q_rr = 5 µC, I_RRM = 27 A) and low forward voltage (V_SD = 1.5 V @ 18 A), reducing switching losses in synchronous rectification and half-bridge configurations.

Key Specifications

Pinout & Package

STW21NM50N uses the TO-247 package - a through-hole, isolated-tab power package with 3 leads optimized for high-current, high-voltage switching and direct heatsink mounting. Thermal resistance junction-to-case is 0.89 °C/W, and maximum lead temperature is 300 °C for soldering.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage power switching applications.

Compared with IPP50R190CFD7 and IXFH32N50P, STW21NM50N offers optimal balance of R_DS(on), Q_g, and avalanche energy for 500–1000 W industrial SMPS - delivering lower system-level thermal stress than the IXFH32N50P and better conduction efficiency than the IPP50R190CFD7 at full load.

Availability

STW21NM50N is available at Aetrix Electronics and suitable for industrial switch-mode power supplies, telecom rectifiers, induction heating inverters, and UPS output stages requiring stable component supply and long-term manufacturability.

Supply support for STW21NM50N 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, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

STW21NM50N belongs to the MDmesh™ high-voltage Power MOSFET product line, engineered specifically for high-efficiency, high-power-density offline power conversion - emphasizing low R_DS(on) × Q_g, rugged avalanche behavior, and fast body diode recovery.

FAQ

What is the maximum continuous drain current for STW21NM50N at 100°C case temperature?

The maximum continuous drain current (I_D) is 11 A at T_C = 100°C, as specified in Table 1 of the datasheet. This reflects thermal derating from the 18 A rating at 25°C, governed by the device's R_thj-case = 0.89 °C/W and T_j(max) = 150°C limit. Operation above this current requires forced cooling or pulse-width limitation.

Does STW21NM50N have a fully rated avalanche capability, and how is it tested?

Yes - STW21NM50N is 100% individually avalanche tested per datasheet Table 3. It guarantees a minimum single-pulse avalanche energy (E_AS) of 480 mJ at T_j = 25°C with V_DD = 50 V and I_AR = 9 A. Testing follows the unclamped inductive load (UIL) method defined in Figure 18, ensuring ruggedness in hard-switched topologies without external protection.

Can STW21NM50N be used in place of STP21NM50N in an existing TO-220 design?

No - STW21NM50N uses TO-247 packaging (larger footprint, isolated tab), while STP21NM50N uses TO-220 (smaller, non-isolated tab). Mechanical fit, thermal interface, and PCB layout are incompatible. Electrical parameters are closely matched (same V_DSS, R_DS(on), I_D), but substitution requires board redesign and thermal validation due to differing R_thj-case (0.89 vs 1.12 °C/W) and mounting constraints.

What is the typical gate threshold voltage (V_GS(th)) and why does it matter for gate drive design?

The typical gate threshold voltage is 3 V (min 2 V, max 4 V), measured at I_D = 250 µA. This relatively high V_GS(th) improves noise immunity in high-dV/dt environments but requires gate drive voltages ≥10 V to ensure full enhancement and minimal R_DS(on). Driving below 8 V risks partial turn-on, increasing conduction loss and thermal stress during switching transitions.