STMicroelectronics STF40N20

Overview

STF40N20 from STMicroelectronics is an N-channel 200V, 40A, 0.038Ω R_DS(on) Power MOSFET in TO-220FP package, optimized for high-efficiency isolated DC-DC converters as a primary switch. It features low gate charge (75 nC), minimized input capacitance (2500 pF C_iss), and 100% avalanche tested ruggedness.

For engineers reviewing the STF40N20 datasheet, STF40N20 pinout, STF40N20 application, or STF40N20 equivalent, key selection criteria include R_DS(on) at 10 V drive, gate charge trade-offs for switching loss, thermal resistance (R_thj-case = 3.1 °C/W), and diode recovery performance (t_rr = 192 ns) in hard-switched topologies.

Technical Context

This STripFET™ II device uses a planar vertical structure with optimized cell pitch and reduced gate-to-drain overlap to achieve low Q_g and high figure-of-merit (R_DS(on) × Q_g). Its gate threshold voltage (2–4 V) ensures robust noise immunity while enabling standard 10 V gate drive compatibility.

The integrated body diode exhibits fast reverse recovery (t_rr = 192 ns, Q_rr = 922 nC at 25°C) and low forward voltage (V_SD = 1.5 V at 20 A), supporting synchronous rectification and ZVS-assisted operation in resonant converters.

Key Specifications

Pinout & Package

STF40N20 is housed in a TO-220FP (Full-Pak) package with insulated tab, eliminating need for mounting insulator in heatsink-integrated designs. The package provides enhanced creepage/clearance and improved thermal coupling vs standard TO-220.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar N-channel 200V power MOSFET applications.

Compared with STP40N20, STF40N20 trades 2.3× higher R_thj-case for simplified assembly and safety compliance; versus IRFP460, it delivers 4.7× lower R_DS(on) × Q_g, enabling 30% reduction in total switching + conduction loss at 200 kHz.

Availability

STF40N20 is available at Aetrix Electronics and suitable for server power supplies, industrial AC-DC adapters, and solar microinverters requiring stable component supply and long-term industrial lifecycle support.

Supply support for STF40N20 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, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

STF40N20 belongs to the STripFET™ II family, engineered specifically for high-efficiency, high-frequency power conversion in isolated DC-DC and AC-DC topologies where low gate charge and avalanche ruggedness are critical.

FAQ

What is the maximum continuous drain current for STF40N20 at 100°C case temperature?

The maximum continuous drain current is 25 A at T_C = 100°C, as specified in Table 1 of the datasheet. This derating reflects thermal limitations of the TO-220FP package, where junction-to-case resistance (3.1 °C/W) and ambient conditions constrain safe operating area at elevated temperatures.

Does STF40N20 require a gate resistor for reliable operation?

Yes - a gate resistor (typically 4.7–22 Ω) is required to dampen gate ringing, control dV/dt during turn-on/off, and limit peak gate current from the driver. The datasheet's switching time test circuit (Figure 16) specifies R_G = 4.7 Ω, confirming its necessity for reproducible timing and EMI control.

Can STF40N20 be used in synchronous rectification configurations?

No - STF40N20 is a unidirectional N-channel MOSFET with an intrinsic body diode optimized for fast recovery, but it lacks the bidirectional conduction capability and gate control logic required for active synchronous rectification. It functions only as a controlled switch, not as a rectifier replacement.

Is STF40N20 compliant with lead-free soldering standards?

Yes - STF40N20 is ECOPACK® certified with lead-free second-level interconnect, rated for peak soldering temperature of 300°C for 10 seconds at 1.6 mm from case (Table 2). Its packaging meets JEDEC JESD97 and RoHS Directive 2011/65/EU requirements.