STMicroelectronics STW34NB20

Overview

STW34NB20 from STMicroelectronics is an N-channel enhancement-mode power MOSFET designed for high-current, high-voltage switching in industrial power converters. It delivers 200 V V_DSS, 34 A continuous drain current at T_C = 25 °C, 0.062 Ω typical R_DS(on), 60–80 nC total gate charge, and 150 °C maximum junction temperature - enabling robust operation in welding inverters and UPS systems.

For engineers reviewing the STW34NB20 datasheet, STW34NB20 pinout, STW34NB20 application, or STW34NB20 equivalent, key selection considerations include its TO-247 package thermal resistance (0.69 °C/W), avalanche-rated 34 A repetitive I_AR, 650 mJ single-pulse E_AS, and low C_iss/C_oss for fast switching with reduced EMI in hard-switched topologies.

Technical Context

This MOSFET employs ST's PowerMESH™ process with a patented strip layout and edge termination, delivering industry-leading R_DS(on) per die area and exceptional dv/dt immunity (>50 V/ns). Its gate threshold voltage (3–5 V) ensures compatibility with standard 10 V gate drivers, while minimized intrinsic capacitances (C_iss = 2400–3300 pF, C_oss = 650–900 pF) support high-frequency operation up to 100 kHz in SMPS designs.

The device integrates a fast, low-loss body diode with 290 ns reverse recovery time and 2.7 µC Q_rr at 150 °C, enabling efficient synchronous rectification and unclamped inductive switching. Its 100% avalanche-tested construction guarantees ruggedness under transient overvoltage conditions without external snubbers.

Key Specifications

Pinout & Package

STW34NB20 uses the TO-247 package - a through-hole, thermally optimized 3-pin power package with isolated tab (drain-connected), offering low thermal resistance (R_th(j-case) = 0.69 °C/W) and mechanical robustness for high-power mounting.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IXTH30N20P and IRFP460, STW34NB20 offers the best balance of low R_DS(on), moderate Q_g, and proven avalanche ruggedness - making it optimal for 200 V industrial converters demanding reliability at 30–100 kHz switching.

Availability

STW34NB20 is available at Aetrix Electronics and suitable for welding inverters, UPS DC-AC stages, industrial motor drives, and high-power SMPS requiring stable component supply across multi-year production cycles.

Supply support for STW34NB20 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, specializing in power management, microcontrollers, sensors, and automotive ICs.

The STW34NB20 belongs to ST's PowerMESH™ MOSFET product line, engineered specifically for high-efficiency, high-reliability industrial power conversion where thermal performance, avalanche tolerance, and switching speed are critical.

FAQ

What is the maximum safe operating temperature for STW34NB20?

The STW34NB20 has a maximum junction temperature (T_j(max)) of 150 °C, verified by absolute maximum ratings and thermal characterization data. Operation above this limit risks permanent degradation of the silicon die and bond wires. Derating is required above T_C = 25 °C per the 1.44 W/°C derating factor, and heatsink design must ensure case temperature remains within safe limits under worst-case load and ambient conditions.

Does STW34NB20 require a gate resistor for reliable switching?

Yes - a gate resistor (typically 4.7 Ω, as used in datasheet switching tests) is required to control dV/dt, suppress ringing, and limit peak gate current. Without it, parasitic inductance in the gate loop can cause oscillation, overshoot, or false turn-on. The recommended value balances switching speed (lower R_G) against EMI and gate driver stress (higher R_G), and must be selected based on actual PCB layout and driver capability.

Can STW34NB20 replace IRFP460 in existing designs?

Direct replacement is not recommended without circuit revalidation. While both use TO-247 packages and serve high-voltage switching roles, STW34NB20 has significantly lower R_DS(on) (0.062 Ω vs. 0.27 Ω) and gate charge (70 nC vs. 140 nC), altering gate drive requirements and thermal behavior. Layout, gate driver sizing, and snubber networks must be reassessed to avoid overvoltage or oscillation due to faster switching edges.

Is the body diode in STW34NB20 suitable for synchronous rectification?

No - the integrated body diode is optimized for freewheeling and clamping, not synchronous rectification. Its 290 ns reverse recovery time and 2.7 µC Q_rr generate significant switching loss and voltage overshoot when used as a controlled rectifier. For synchronous operation, an external Schottky or MOSFET-based synchronous rectifier with dedicated control logic is required to achieve high efficiency.