STMicroelectronics STFI9N80K5

Overview

STFI9N80K5 from STMicroelectronics is an N-channel 800 V, 0.73 Ω typ. R_DS(on), 7 A MDmesh™ K5 Power MOSFET in I²PAKFP (TO-281) package, featuring ultra-low gate charge (12 nC), 100% avalanche tested, and integrated Zener-protected gate. It serves as a high-voltage switching device in offline SMPS primary-side power switches.

For engineers reviewing the STFI9N80K5 datasheet, STFI9N80K5 pinout, STFI9N80K5 application, or STFI9N80K5 equivalent, key selection criteria include R_DS(on) × area FoM, dv/dt ruggedness (50 V/ns), unclamped inductive switching capability, and thermal resistance (R_thj-case = 5 °C/W).

Technical Context

This MOSFET employs ST's proprietary MDmesh™ K5 vertical superjunction structure to achieve industry-leading figure of merit (FoM), enabling high power density in compact designs. Its optimized cell layout reduces both conduction loss (0.73 Ω typ. at V_GS = 10 V, I_D = 3.5 A) and switching loss via low C_iss (340 pF), C_oss (37 pF), and Q_gd (6.7 nC).

The device integrates back-to-back gate-source Zener diodes (V_(BR)GSO = 30 V) for ESD robustness and eliminates external clamping components. It supports unclamped inductive switching with single-pulse avalanche energy up to 200 mJ at T_j = 25 °C and meets 2500 V_RMS insulation withstand voltage between leads and heat sink.

Key Specifications

Pinout & Package

The STFI9N80K5 is housed in an I²PAKFP (TO-281) package with isolated mounting base, ECOPACK® compliant, and features three terminals: Drain (D), Gate (G), Source (S). The package provides enhanced creepage/clearance and 2500 V_RMS isolation for safety-critical AC-DC applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STF9N80K5, STFI9N80K5 offers certified reinforced insulation and surface-mount compatibility, while IPP90R1K2P7XKSA1 trades higher on-resistance for improved gate-drive efficiency-making STFI9N80K5 optimal for safety-critical, space-constrained industrial SMPS.

Availability

STFI9N80K5 is available at Aetrix Electronics and suitable for industrial SMPS, LED driver power stages, AC-DC adapters, and UPS inverter stages requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for STFI9N80K5 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 microcontrollers, power devices, sensors, and analog ICs for industrial, automotive, and consumer markets.

The MDmesh™ K5 product line targets high-efficiency, high-power-density offline power conversion, specifically engineered to replace older superjunction MOSFETs in 600–800 V applications with superior FoM and ruggedness.

FAQ

What is the maximum recommended gate drive voltage for STFI9N80K5?

The absolute maximum gate-source voltage is ±30 V, but ST specifies V_GS = 10 V for R_DS(on) characterization and recommends 12–15 V for robust turn-on with margin against Miller-induced false triggering. Driving above 18 V yields diminishing R_DS(on) improvement and increases gate oxide stress risk.

Does STFI9N80K5 require an external gate resistor in typical SMPS designs?

Yes - a gate resistor (typically 4.7–10 Ω) is required to control dV/dt and dI/dt during switching, suppress ringing, and limit peak gate current. The intrinsic gate resistance is only 7 Ω, insufficient for damping; omitting the external resistor risks shoot-through and EMI in hard-switched topologies.

Can STFI9N80K5 be used in synchronous rectification configurations?

No - STFI9N80K5 is an N-channel high-side switch optimized for primary-side switching, not low-side synchronous rectification. Its body diode recovery time (T_rr = 292 ns) and Q_rr (2.66 µC) are not optimized for reverse recovery in secondary-side positions, and its gate threshold (3–5 V) lacks the tight distribution needed for precise synchronous control.

How does the I²PAKFP package improve thermal performance versus standard TO-220FP?

The I²PAKFP (TO-281) package maintains identical R_thj-case = 5 °C/W as TO-220FP but adds electrical isolation between drain and mounting base, enabling direct heatsink attachment without insulating pads. This reduces thermal interface resistance and improves long-term reliability in high-vibration environments.