onsemi FJPF5555TU

Overview

FJPF5555TU from Fairchild Semiconductor is a high-voltage NPN bipolar junction transistor designed for fast-switching power applications, featuring V_CEO = 400 V, I_C = 5 A (DC), P_C = 40 W, and t_F = 0.3 µs. It serves as a primary switching element in electronic ballasts and SMPS circuits where wide SOA and robust avalanche capability are required.

For engineers reviewing the FJPF5555TU datasheet, pinout, applications, or equivalent options, key selection criteria include safe operating area under inductive loads, saturation voltage at high current (V_CE(sat) = 1.5 V @ I_C = 3.5 A), thermal derating behavior, and TO-220F package mounting compatibility with heatsink interfaces.

Technical Context

This device operates as a single NPN silicon power transistor optimized for high-voltage switching with fast turn-on (t_ON = 2.0 µs @ V_CC = 250 V) and minimal fall time (t_F = 0.3 µs). Its wide forward-biased safe operating area supports repetitive inductive switching up to I_CP = 10 A (pulse) without secondary breakdown.

The FJPF5555TU uses a planar epitaxial base structure enabling stable h_FE = 20–40 at I_C = 0.8–3.5 A and low output capacitance (C_ob = 45 pF @ V_CB = 10 V), critical for minimizing switching losses in resonant and hard-switched topologies.

Key Specifications

Pinout & Package

Package: TO-220F (full-pack, insulated back, vertical mounting with metal tab isolated from collector). Dimensions conform to JEDEC TO-220F standard; tab is electrically isolated and thermally conductive for heatsink attachment.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STF5555 and MJD5555G, the FJPF5555TU offers superior thermal performance via TO-220F isolation and tighter h_FE consistency, making it preferred for thermally demanding ballast and industrial SMPS designs where mechanical heatsinking is feasible.

Availability

FJPF5555TU is available at Aetrix Electronics and suitable for compact fluorescent lamp ballasts, industrial SMPS, induction heating inverters, and LED driver power stages requiring stable component supply and long-lifecycle support.

Supply support for FJPF5555TU 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete devices before its acquisition by ON Semiconductor in 2016.

The FJPF5555TU belongs to Fairchild's FASTr™ high-voltage bipolar transistor family, engineered specifically for reliability-critical switching applications in lighting, industrial power, and resonant converters.

FAQ

What is the maximum junction temperature rating for the FJPF5555TU?

The FJPF5555TU has a maximum junction temperature (T_J) rating of 150°C, as specified in its Absolute Maximum Ratings table. This limit must not be exceeded during operation, and thermal design must ensure that actual junction temperature remains within this bound under worst-case ambient and power dissipation conditions. Derating curves in Figure 8 define allowable collector dissipation versus case temperature, supporting thermal modeling for heatsink sizing in real-world FJPF5555TU deployments.

Is the FJPF5555TU pin-compatible with other TO-220F NPN transistors like the FJP5555?

The FJPF5555TU uses the standard TO-220F pinout (Base–Collector–Emitter, left-to-right with tab facing away), matching industry-standard orientation. However, while mechanical pinout is identical, electrical characteristics-including h_FE, V_CE(sat), and switching times-differ significantly from non-F-series variants such as FJP5555. Therefore, direct substitution requires verification of gain, saturation, and SOA requirements in the target circuit before replacing with FJPF5555TU.

Does the FJPF5555TU have avalanche ruggedness rated in the datasheet?

The FJPF5555TU datasheet does not specify an explicit avalanche energy rating (E_AS), but its wide reverse-biased safe operating area (RBSOA) in Figure 7 and high V_CBO = 1050 V indicate inherent avalanche capability. The device is characterized for inductive switching with resistive load waveforms (Figures 5–6) and demonstrates stable operation under transient overvoltage conditions typical in ballast and SMPS applications-supporting robustness in real-world FJPF5555TU implementations without external clamping in many cases.

What is the recommended base drive current for full saturation of the FJPF5555TU at 3.5 A collector current?

Per the datasheet's V_CE(sat) specification, the FJPF5555TU achieves V_CE(sat) = 1.5 V at I_C = 3.5 A with I_B = 1.0 A. This corresponds to a forced beta (I_C/I_B) of 3.5, well below the device's h_FE minimum of 20, ensuring deep saturation and minimizing thermal stress. For reliable operation, base drive circuits should deliver ≥1.0 A peak current with adequate slew rate to meet t_ON/t_STG timing constraints in the FJPF5555TU application.

Can the FJPF5555TU be used in surface-mount designs?

No-the FJPF5555TU is packaged exclusively in the through-hole TO-220F outline, which requires hole mounting and mechanical heatsink attachment. It is not compatible with surface-mount assembly processes. For SMT alternatives, consider the MJD5555G (TO-263) or NSS5555F (SOT-223), though both differ in voltage, current, and thermal ratings. Any migration from FJPF5555TU to SMT must account for revised layout, thermal path, and drive requirements in the final design.