onsemi KSH29CITU

Overview

KSH29CITU from ON Semiconductor is an NPN epitaxial silicon transistor designed for low-speed switching and general-purpose amplification, featuring 100 V collector-emitter sustaining voltage (V_CEO(sus)), 1 A DC collector current (I_C), 15 W collector dissipation at T_C = 25°C, and a 3 MHz current gain bandwidth product (f_T). It is commonly used in relay drivers, power supply control circuits, and linear amplifier stages where robust thermal handling and moderate frequency response are required.

For engineers reviewing the KSH29CITU datasheet, pinout, applications, or equivalent options, key selection considerations include its 100 V V_CEO(sus), 15 W T_C-rated power dissipation, D-PAK package thermal performance, I_C/I_B drive capability (1 A / 125 mA), and compatibility with legacy TIP29C-based designs requiring surface-mount upgrade paths.

Technical Context

The KSH29CITU operates as a medium-power NPN bipolar junction transistor optimized for linear amplification and saturated switching. Its 100 V V_CEO(sus) rating enables use in 48 V and 72 V industrial power rails, while its 15 W T_C power dissipation supports heatsink-mounted operation without derating below 100°C case temperature.

With h_FE = 15–75 (measured at V_CE = 4 V, I_C = 1 A and 0.2 A respectively) and V_CE(sat) = 0.7 V at I_C = 1 A / I_B = 125 mA, it delivers predictable saturation behavior and sufficient DC gain for base-driven switching applications without active feedback compensation.

Key Specifications

Pinout & Package

The KSH29CITU is housed in a D-PAK (TO-252) surface-mount package with standard lead formation for PCB thermal relief and mechanical stability. The package features a large exposed drain pad (pin 2) for direct thermal coupling to copper pour or heatsink.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BUW12A and MJD2955T4G, the KSH29CITU offers optimal balance of 100 V ruggedness, D-PAK surface-mount compatibility, and 1 A/15 W power handling-making it preferred for space-constrained industrial switching where TIP29C replacement and thermal efficiency are primary requirements.

Availability

KSH29CITU is available at Aetrix Electronics and suitable for relay driver circuits, linear regulator pass elements, and low-frequency PWM motor control requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for KSH29CITU 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 supplier of energy-efficient semiconductor components, specializing in power management, analog, sensor, and discrete devices for automotive, industrial, and cloud infrastructure markets.

The KSH29CITU belongs to ON Semiconductor's legacy power transistor family derived from Fairchild's TIP-series lineage, engineered specifically for industrial control upgrades requiring surface-mount compatibility, high-voltage transient tolerance, and proven reliability in 24–72 V systems.

FAQ

What is the maximum continuous collector current rating for KSH29CITU?

The KSH29CITU has a DC collector current rating of 1 A at T_C = 25°C. This value decreases with rising case temperature per the power derating curve in the datasheet; at T_C = 100°C, the usable I_C drops to approximately 0.5 A. For sustained 1 A operation, a heatsink maintaining T_C ≤ 60°C is recommended. The KSH29CITU datasheet specifies absolute maximum I_C = 1 A, not peak or pulsed current.

Is KSH29CITU pin-compatible with the through-hole TIP29C transistor?

Yes, the KSH29CITU uses the same 1–2–3 pinout order (Base–Collector–Emitter) as the TIP29C, and its electrical characteristics-including V_CEO(sus) = 100 V, h_FE range, and V_CE(sat)-are intentionally aligned for functional replacement. However, the KSH29CITU is a D-PAK surface-mount device, so PCB layout must accommodate its SMT footprint and thermal pad, unlike the TIP29C's TO-220 through-hole mounting.

What is the typical turn-off time (t_F) of KSH29CITU under standard test conditions?

The KSH29CITU exhibits a typical turn-off time (t_F) of less than 1 µs when tested at V_CC = 10 V and I_C = 10 × I_B. This value is confirmed in the "Typical Characteristics" section of the datasheet (Figure 2). Faster switching is achievable with optimized base drive waveforms, but t_F remains limited by minority carrier lifetime inherent to its epitaxial NPN structure.

Does KSH29CITU require a heatsink for 1 A continuous operation?

Yes, the KSH29CITU requires a heatsink for reliable 1 A continuous operation. Its 15 W power dissipation rating applies only at T_C = 25°C; at ambient temperatures above 40°C or with PCB copper area insufficient for thermal conduction, junction temperature will exceed 150°C without external thermal management. A minimum 25 cm² 2-oz copper pour with thermal vias is recommended even for intermittent 1 A loads.

What is the emitter-base breakdown voltage (V_EBO) specification for KSH29CITU?

The KSH29CITU has a guaranteed minimum emitter-base breakdown voltage (V_EBO) of 5 V, tested with I_E = 1 mA. This parameter defines the maximum reverse voltage allowable between emitter and base terminals before avalanche conduction begins. Exceeding 5 V in reverse-biased E-B configuration risks permanent degradation of h_FE and leakage characteristics.