onsemi KSC5502DTTU

Overview

KSC5502DTTU from ON Semiconductor (formerly Fairchild) is a high-voltage NPN triple-diffused planar silicon transistor in TO-220 package, rated for 600 V V_CEO, 2 A DC collector current, and 118.16 W power dissipation at T_C = 25°C. It integrates a built-in free-wheeling diode and targets electronic ballast and switching power supply applications requiring robust avalanche energy handling (2.5 mJ) and wide safe operating area.

For engineers reviewing the KSC5502DTTU datasheet, pinout, applications, or equivalent options, key selection criteria include its 600 V blocking capability, 1.06 °C/W junction-to-case thermal resistance, TO-220 mechanical compatibility, and verified performance under inductive load switching with t_OFF ≤ 5.0 μs at 125°C.

Technical Context

This device employs triple-diffused planar construction to achieve high breakdown voltage (V_CBO = 1200 V) and stable h_FE across temperature (8–18 at 125°C, I_C = 0.2 A). Its integrated anti-parallel diode enables self-contained flyback operation without external components.

Switching behavior is characterized by controlled storage time (t_STG = 1.2–2.0 μs at 25°C, resistive), low dynamic saturation voltage (V_CE(DSAT) = 1.8 V at 3 μs, I_C = 0.4 A), and fast turn-off (t_OFF = 3.7–5.0 μs) under 300 V inductive conditions - critical for high-frequency electronic ballasts and SMPS.

Key Specifications

Pinout & Package

Package: TO-220, 3-lead, molded plastic. Mounting tab is Collector (pin 2); leads are Base (1), Collector (2), Emitter (3) - confirmed per Fairchild TO-220B03 drawing and datasheet Figure 30 equivalent circuit.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ST13007D and BU508A, KSC5502DTTU uniquely combines 600 V blocking, integrated diode, TO-220 form factor, and validated 2.5 mJ avalanche energy - making it optimal for space-constrained electronic ballasts where diode integration and thermal efficiency are critical.

Availability

KSC5502DTTU is available at Aetrix Electronics and suitable for electronic ballast control, AC-DC switching power supplies, and induction heating driver applications requiring stable component supply and long-term industrial availability.

Supply support for KSC5502DTTU 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 high-performance silicon solutions for automotive, industrial, cloud computing, and IoT applications, with core expertise in power management and analog semiconductors.

The KSC5502DTTU belongs to Fairchild's legacy high-voltage bipolar transistor family designed specifically for electronic lighting ballasts and industrial switching power supplies - emphasizing ruggedness, integrated functionality, and thermal reliability.

FAQ

What is the maximum junction temperature rating for the KSC5502DTTU?

The KSC5502DTTU has a maximum junction temperature (T_J) rating of 150°C, as specified in its Absolute Maximum Ratings table. This limit applies under all operating conditions and must be respected in thermal design. Derating curves in Figure 24 confirm power dissipation drops linearly above 25°C case temperature, reaching zero at 150°C. Thermal design must ensure actual T_J remains below this threshold during worst-case operation - especially under high-duty-cycle or high-ambient conditions. The KSC5502DTTU's R_θJC = 1.06 °C/W enables precise junction temperature estimation when mounted on a properly sized heatsink.

Does the KSC5502DTTU have a built-in free-wheeling diode, and how is it connected?

Yes, the KSC5502DTTU integrates a monolithic free-wheeling diode between emitter and collector terminals, with anode at emitter and cathode at collector - confirmed in the Equivalent Circuit diagram (page 1) and VF parameter test conditions. This configuration allows automatic current recirculation during inductive load turn-off, eliminating the need for an external diode in flyback or resonant topologies. The diode's forward voltage ranges from 0.75 V (I_F = 0.2 A, 25°C) to 1.50 V (I_F = 1 A, 25°C), and its recovery time (t_fr) is 650–785 ns, supporting efficient operation up to ~50 kHz in electronic ballasts. The KSC5502DTTU's internal diode shares the same thermal path as the transistor, ensuring matched temperature behavior.

What is the safe operating area (SOA) profile of the KSC5502DTTU, and where is it documented?

The KSC5502DTTU's Forward Bias Safe Operating Area is graphically defined in Figure 23 of its datasheet, covering DC, 5 ms, 1 ms, and 50 μs pulse widths up to 2 A and 600 V. The SOA curve confirms no secondary breakdown limitation up to these boundaries - a direct result of its triple-diffused planar structure. This enables reliable operation under transient overloads such as lamp ignition surges or motor startup currents. Unlike many bipolar transistors, the KSC5502DTTU maintains SOA integrity even at elevated junction temperatures, as validated by testing at 125°C. Designers must reference Figure 23 and apply appropriate derating; the KSC5502DTTU's SOA compliance is a key differentiator versus generic high-voltage NPNs lacking this characterization.

How does the KSC5502DTTU's switching performance compare between 25°C and 125°C junction temperatures?

At 125°C, the KSC5502DTTU exhibits measurable but controlled degradation: t_OFF increases from 3.7–5.0 μs to 4.5 μs, t_STG rises from 1.2–2.0 μs to 1.5–3.75 μs, and V_CE(sat) increases by ~0.5–1.0 V depending on operating point. However, h_FE remains functional (min 3.0 at I_C = 1 A), and avalanche energy (E_AS) is specified only at 25°C - implying reduced ruggedness at high temperature. These shifts are fully characterized in the Electrical Characteristics tables and Figures 10–18. For thermal design, the KSC5502DTTU's R_θJC = 1.06 °C/W and derating curve (Figure 24) allow accurate prediction of junction temperature rise, ensuring the KSC5502DTTU stays within its validated switching envelope across the full industrial temperature range.

Can the KSC5502DTTU be used as a direct replacement for the KSC5502DTM in a DPAK-based design?

No - the KSC5502DTTU (TO-220) and KSC5502DTM (DPAK/TO-252) are mechanically and thermally incompatible replacements. While both share identical electrical specifications (V_CEO, I_C, h_FE, etc.), the KSC5502DTTU uses a TO-220 package with lead spacing, mounting hole, and thermal interface incompatible with DPAK footprints. Its R_θJC = 1.06 °C/W and P_C = 118.16 W differ significantly from the KSC5502DTM's R_θJC = 1.42 °C/W and P_C = 87.83 W. Substituting KSC5502DTTU into a DPAK layout would require PCB redesign, new heatsink, and revalidation of thermal and mechanical stress. The KSC5502DTTU is not a drop-in replacement for KSC5502DTM; it serves distinct mechanical integration requirements.