STMicroelectronics STFW3N170

Overview

STFW3N170 from STMicroelectronics is an N-channel 1700 V, 7 Ω typ. (13 Ω max), 2.6 A PowerMESH™ high-voltage power MOSFET in TO-3PF package, designed for high-speed switching in high-voltage DC-DC converters and industrial snubberless flyback topologies.

For engineers reviewing the STFW3N170 datasheet, STFW3N170 pinout, STFW3N170 application, or STFW3N170 equivalent, key selection criteria include its 1700 V V_DS, 44 nC total gate charge, 1.58 µs reverse recovery time, 3.5 kV insulation withstand voltage, and 100% avalanche-tested ruggedness for unclamped inductive load reliability.

Technical Context

This device employs ST's strip-layout-based MESH OVERLAY process to minimize intrinsic capacitances (C_iss = 1100 pF, C_oss = 50 pF) and gate charge (Q_g = 44 nC), enabling fast switching with low switching losses. Its 2 °C/W R_thJC supports high-power dissipation up to 63 W at T_C = 25 °C.

The integrated source-drain diode exhibits V_SD = 1.5 V at 2.6 A and trr = 1.58 µs (T_J = 25 °C), optimized for hard-switched flyback and resonant converter freewheeling. Avalanche capability is validated at E_AS = 2 mJ (single-pulse, T_J = 25 °C).

Key Specifications

Pinout & Package

TO-3PF metal-can package with isolated tab; thermally and electrically insulated case rated for 3.5 kV RMS. Dimensions conform to ST's TO-3PF Type A mechanical specification (L4 = 43.6–44.0 mm, G = 10.8–11.0 mm).

Key Features

Applications

Equivalent & Alternatives

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

Compared with STW3N170 and IXTH3N170, STFW3N170 uniquely combines certified 3.5 kV isolation, 100% avalanche screening, and TO-3PF thermal performance-making it the sole choice for space-constrained, safety-critical high-voltage switch applications requiring direct heatsink mounting.

Availability

STFW3N170 is available at Aetrix Electronics and suitable for industrial flyback converters, capacitor discharge units, snubberless AC-DC adapters, and high-voltage DC link protection requiring stable component supply and long-term lifecycle support.

Supply support for STFW3N170 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, MEMS, power, and microcontroller solutions for industrial, automotive, and consumer markets.

STFW3N170 belongs to the PowerMESH™ high-voltage MOSFET product line, engineered specifically for rugged, high-efficiency switching in 1–5 kW industrial power supplies and energy discharge systems where reliability under unclamped inductive stress is critical.

FAQ

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

The STFW3N170 supports 1.6 A continuous drain current at T_C = 100 °C, as specified in Table 1 of DS9384 Rev 5. This derating reflects thermal limits imposed by the TO-3PF package's 2 °C/W R_thJC and safe operating area constraints-not silicon capability alone.

Does STFW3N170 require a negative gate voltage for reliable turn-off?

No. The device specifies ±30 V gate-source voltage rating but operates reliably with 0 V to +10 V gate drive. A negative gate bias is not required due to its 4 V typical V_GS(th) and low Miller capacitance (C_rss = 7 pF), minimizing dV/dt-induced turn-on risk in well-layouted circuits.

Can STFW3N170 replace STW3N170 in existing designs?

Yes, with mechanical and thermal caveats: STFW3N170 uses TO-3PF (isolated tab), while STW3N170 uses TO-247 (non-isolated). Direct replacement requires verifying heatsink isolation, mounting torque (TO-3PF uses M3.5 screw), and layout clearance for the larger TO-3PF outline (L4 = 44 mm vs. TO-247's 15.8 mm).

What is the recommended gate resistor value for 100 kHz switching?

A 4.7 Ω gate resistor is validated per Figure 13 in DS9384 Rev 5 for 100 kHz operation, yielding t_d(on) = 25 ns and t_f = 53 ns. Lower values (<2.2 Ω) increase peak gate current beyond 1.5 A and risk ringing; higher values (>10 Ω) degrade switching speed and raise losses disproportionately.