onsemi FJD3305H1TM

Overview

FJD3305H1TM from Fairchild Semiconductor is a high-voltage NPN silicon power transistor in D-PAK package, rated for 400 V V_CEO, 4 A I_C (DC), and 50 W P_C at T_C = 25°C, optimized for electronic ballast and switch-mode power supply applications requiring fast switching and wide safe operating area.

For engineers reviewing the FJD3305H1TM datasheet, pinout, applications, or equivalent options, key selection criteria include breakdown voltage margin, saturation voltage at 4 A, thermal resistance (R_θJC = 2.0°C/W), switching speed (t_ON = 0.8 μs), and RBSOA compliance in high-voltage inductive switching.

Technical Context

The FJD3305H1TM employs epitaxial planar construction with rugged base-emitter junction design to sustain high reverse-biased safe operating area (RBSOA) under inductive turn-off stress. Its f_T = 4 MHz and low Cob = 65 pF support stable high-frequency switching up to several hundred kHz.

It operates with DC current gain h_FE = 19–28 at I_C = 1 A and V_CE = 5 V, and achieves V_CE(sat) = 1.0 V at I_C = 4 A / I_B = 1 A - enabling efficient conduction in medium-power hard-switched topologies where thermal management via case mounting is critical.

Key Specifications

Pinout & Package

Package: D-PAK (TO-252AA), surface-mount, single-ended heat transfer via exposed drain pad (pin 2). Mounting requires minimum copper pad per datasheet for thermal and mechanical reliability.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN power transistor applications.

Compared with STGD3HF60H and MJD3053T4G, the FJD3305H1TM uniquely balances 400 V blocking, 4 A current, and RBSOA integrity for electronic ballast - offering superior safe operating area at mid-range voltage/current versus higher-voltage or higher-speed alternatives.

Availability

FJD3305H1TM is available at Aetrix Electronics and suitable for electronic ballast, switch-mode power supply, and induction heating applications requiring stable component supply, long-lifecycle availability, and consistent parametric performance across production batches.

Supply support for FJD3305H1TM 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 discrete and analog ICs, acquired by ON Semiconductor in 2016; its legacy products maintain broad industrial design-in and qualification history.

The FJD3305H1TM belongs to Fairchild's high-voltage NPN transistor family designed specifically for energy-efficient lighting and medium-power switch-mode conversion - emphasizing ruggedness, thermal performance, and manufacturability in wave-soldered consumer and industrial equipment.

FAQ

What is the maximum continuous collector current rating for the FJD3305H1TM?

The FJD3305H1TM is rated for 4 A DC collector current (I_C) at T_C = 25°C. Derating is required above 25°C case temperature per the 1.0 W/°C slope shown in Figure 10 of the datasheet. At T_C = 100°C, the usable I_C drops to approximately 2.5 A. This rating assumes proper PCB copper area and thermal interface to maintain junction temperature ≤150°C. The FJD3305H1TM must not be operated beyond its specified safe operating area limits.

Does the FJD3305H1TM support lead-free wave soldering?

Yes, the FJD3305H1TM is qualified for lead-free wave soldering per J-STD-020, as explicitly stated in the "Features" section of the datasheet. Its D-PAK package and internal construction tolerate peak temperatures up to 260°C for 10 seconds. Proper preheat and dwell profiles must be followed to avoid thermal shock to the die or bond wires. The FJD3305H1TM marking "J3305H1" remains legible post-soldering when process parameters are within specification.

What is the typical V_CE(sat) of the FJD3305H1TM at full-rated current?

The FJD3305H1TM exhibits V_CE(sat) = 1.0 V typical at I_C = 4 A and I_B = 1 A, per the Electrical Characteristics table on page 2 of the datasheet. This value is measured under pulsed conditions (≤300 μs, ≤2% duty cycle) to limit self-heating. In continuous conduction, thermal effects may raise V_CE(sat) by up to 0.15 V depending on case temperature. The FJD3305H1TM maintains this saturation voltage across its full operating junction temperature range (−65°C to +150°C).

Can the FJD3305H1TM replace the older FJD3305 in existing designs?

Yes, the FJD3305H1TM is a direct replacement for the FJD3305, sharing identical D-PAK package, pinout (base-collector-emitter), and core electrical specifications including V_CEO, I_C, and R_θJC. The "H1" suffix denotes an updated process with improved RBSOA and tighter h_FE distribution. No PCB or schematic changes are needed when upgrading from FJD3305 to FJD3305H1TM, and the FJD3305H1TM meets all original FJD3305 application requirements including electronic ballast and SMPS.

What thermal interface requirements apply to the FJD3305H1TM's exposed collector pad?

Per the Thermal Characteristics table, the FJD3305H1TM's R_θJC = 2.0°C/W assumes mounting on a minimum copper pad (as defined in JEDEC standards for TO-252). To achieve this, use ≥1 in² (6.5 cm²) of 2-oz copper with thermal vias to inner ground planes. Thermal paste or phase-change material is recommended between the D-PAK's exposed collector pad and heatsink. Poor thermal interface increases effective R_θJC, risking premature thermal shutdown or second breakdown in the FJD3305H1TM.