STMicroelectronics ST2408HI

Overview

ST2408HI from STMicroelectronics is a high-voltage fast-switching NPN power transistor in an ISOWATT218 package, rated for V_CEO = 600 V, I_C = 12 A, and P_tot = 55 W at T_C = 25 °C. It features tight h_FE control (6–9 at I_C = 8 A), V_CE(sat) = 3 V, and optimized switching times (t_s = 2.5 µs, t_f = 260 ns) for horizontal deflection circuits in 17-inch+ monitors and high-end TVs.

For engineers reviewing the ST2408HI datasheet, ST2408HI pinout, ST2408HI application, or ST2408HI equivalent, key selection criteria include safe operating area under inductive load, insulation withstand voltage (2500 V_RMS), thermal resistance (R_thj-case = 2.3 °C/W), and ruggedness against base drive variation in CRT deflection stages.

Technical Context

This transistor uses diffused collector technology to stabilize operation across base drive variations, minimizing worst-case power dissipation in high-energy flyback switching. Its SOA is characterized with inductive load (L = 25 mH), and pulsed test conditions (300 µs, 1.5% duty cycle) define V_CEO(sus), V_CE(sat), and switching parameters.

The device integrates full electrical insulation between all three leads and external heatsink per UL compliance, enabling direct mounting without insulating washers. Thermal design relies on case-to-heatsink interface control (flatness ≤ 80 µm) and torque-limited mounting (0.8–1.0 Nm).

Key Specifications

Pinout & Package

Package: ISOWATT218 (narrow leads), insulated metal tab, weight 4.9 g, mechanical dimensions per STMicroelectronics drawing P025C/B. Mounting torque: 0.8–1.0 Nm; heatsink surface flatness ≤ 80 µm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BU2520DX and 2SC5200, ST2408HI uniquely combines 600 V capability, UL-certified insulation, and tight h_FE control-making it the only drop-in solution for space-constrained, safety-compliant CRT horizontal output designs without redesigning mounting or drive circuitry.

Availability

ST2408HI is available at Aetrix Electronics and suitable for CRT monitor manufacturing, broadcast equipment repair, and industrial display refurbishment requiring stable component supply and long-term BOM continuity.

Supply support for ST2408HI 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, designing and manufacturing analog, power, MCU, and sensor solutions for industrial, automotive, and consumer markets.

The ST2408HI belongs to ST's high-voltage power transistor family engineered specifically for CRT horizontal deflection and flyback power conversion, emphasizing ruggedness, thermal reliability, and safety-compliant packaging.

FAQ

What is the maximum safe operating voltage for ST2408HI in continuous DC mode?

The ST2408HI is rated for V_CEO = 600 V with I_B = 0, meaning it safely blocks up to 600 V between collector and emitter under open-base conditions. For sustained DC operation, derating is required above 25 °C case temperature per the thermal curve; actual usable voltage depends on simultaneous current, heatsink performance, and SOA constraints.

Can ST2408HI replace BU2520DX without circuit modification?

No-while both are high-voltage NPN transistors, BU2520DX has V_CEO = 1500 V but lacks UL-rated insulation and has different h_FE and SOA characteristics. Direct replacement would require verifying base drive compatibility, adding external insulation, and revalidating flyback energy handling under inductive load.

Is ST2408HI still in active production or obsolete?

Per STMicroelectronics' official documentation, ST2408HI is marked "Obsolete Product(s)" in its datasheet revision (December 2002). However, Aetrix Electronics maintains legacy inventory and supports continued supply through authorized channels and controlled-life distribution for repair and maintenance programs.

What is the recommended heatsink interface for ST2408HI mounting?

STMicroelectronics specifies a flatness tolerance of ≤ 80 µm on the heatsink mounting surface and recommends torque of 0.8 Nm (maximum 1.0 Nm) on the mounting screw. No additional insulating washer is needed due to the UL-rated 2500 V_RMS isolation, but thermal compound is advised to optimize R_thj-case performance.