onsemi KSC5402DTTU

Overview

KSC5402DTTU from ON Semiconductor (formerly Fairchild) is an NPN silicon planar power transistor with built-in freewheeling diode, designed for high-voltage, high-speed switching in electronic ballasts and inductive load circuits. It delivers 450 V V_CEO, 2 A DC collector current, 50 W power dissipation in TO-220 package, and features a wide safe operating area for robust operation under transient stress.

For engineers reviewing the KSC5402DTTU datasheet, pinout, applications, or equivalent options, key selection criteria include its 450 V blocking capability, integrated diode forward voltage (0.86 V @ 1 A), dynamic saturation voltage under inductive switching (1.5 V @ 3 μs), storage time < 1.25 μs at 125°C, and thermal resistance of 2.5°C/W (junction-to-case, TO-220).

Technical Context

This device employs a planar epitaxial structure optimized for high-voltage switching with low dynamic saturation voltage and controlled storage time. Its integrated freewheeling diode enables self-contained inductive energy recirculation without external components.

The transistor supports both resistive and inductive load switching with validated timing parameters: t_ON ≤ 150 ns, t_OFF ≤ 1.25 μs (25°C), and t_STG ≤ 1.2 μs (25°C, IC = 1 A). Thermal design is enabled by R_θJC = 2.5°C/W in TO-220 mounting, supporting stable operation up to T_J = 150°C.

Key Specifications

Pinout & Package

Package: TO-220 (3-lead, straight lead, insulated tab). Mounting requires electrically isolated heatsink due to collector-connected tab.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ST13007D and MJD127G, the KSC5402DTTU uniquely combines 450 V blocking, 2 A current, TO-220 thermal performance, and monolithic diode integration-making it irreplaceable in compact, high-voltage, inductive-switching designs without layout or thermal compromises.

Availability

KSC5402DTTU is available at Aetrix Electronics and suitable for electronic ballast control, inductive load switching, and high-voltage flyback converter applications requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for KSC5402DTTU 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

ON Semiconductor (formerly Fairchild Semiconductor) is a global leader in intelligent power and sensing solutions, serving automotive, industrial, cloud, and consumer markets with energy-efficient semiconductor technologies.

The KSC5402DTTU belongs to Fairchild's legacy high-voltage planar bipolar transistor family, engineered specifically for reliability-critical lighting and power conversion applications demanding ruggedness, consistent timing, and integrated protection.

FAQ

What is the maximum junction temperature rating for the KSC5402DTTU?

The KSC5402DTTU has a maximum junction temperature (T_J) rating of 150°C, verified per Absolute Maximum Ratings table. This allows continuous operation in high-ambient environments such as enclosed lighting fixtures or industrial enclosures, provided thermal design maintains T_J ≤ 150°C using the specified R_θJC = 2.5°C/W and appropriate heatsinking. Derating curves in Figure 24 confirm linear power reduction above 25°C case temperature.

Does the KSC5402DTTU have a built-in freewheeling diode, and what is its forward voltage?

Yes, the KSC5402DTTU integrates a freewheeling diode monolithically. Its forward voltage (V_F) is 0.86 V typical at 1 A and 25°C, with a maximum of 1.5 V under the same conditions. At 125°C, V_F drops to 0.6 V minimum, improving efficiency during high-temperature operation. This diode eliminates the need for an external catch diode in inductive switching circuits.

What is the storage time (t_STG) of the KSC5402DTTU at 125°C and 1 A collector current?

At 125°C and I_C = 1 A, the KSC5402DTTU exhibits a storage time (t_STG) of 1.35 μs maximum, as specified in the Electrical Characteristics table under "INDUCTIVE LOAD SWITCHING" conditions (V_Z = 300 V, L_C = 200 μH). This value is critical for high-frequency ballast timing stability and ensures predictable turn-off behavior across temperature extremes.

Is the KSC5402DTTU pin-compatible with the KSC5402D variant?

Yes, the KSC5402DTTU and KSC5402D share identical pinout, package outline (TO-220), and electrical specifications. The "TTU" suffix denotes tape-and-reel packaging for automated assembly, while "D" indicates tube packaging. Both variants use the same die, thermal characteristics, and absolute maximum ratings-enabling direct substitution in manufacturing without PCB or schematic changes.

What is the safe operating area (SOA) limitation for the KSC5402DTTU at 100 μs pulse width?

Per Figure 23 ("Forward Bias Safe Operating Area"), the KSC5402DTTU supports up to 2 A at 450 V for DC operation, and significantly higher current at shorter pulses. At 100 μs pulse width, the SOA extends to approximately 4 A at 300 V and 1.5 A at 450 V-validating its suitability for pulsed inductive loads like solenoids and flyback transformers with controlled duty cycles and adequate thermal management.