onsemi KSH31CTF

Overview

KSH31CTF from ON Semiconductor is an NPN epitaxial silicon transistor designed for low-speed switching and general-purpose amplification, with 100 V collector-emitter sustaining voltage (V_CEO(sus)), 3 A DC collector current (I_C), 15 W collector dissipation at T_C = 25°C, and D-PAK surface-mount package - commonly used in power supply control circuits, relay drivers, and DC motor interfaces.

For engineers reviewing the KSH31CTF datasheet, pinout, applications, or equivalent options, key selection criteria include its V_CEO(sus) = 100 V rating, I_C = 3 A capability, V_CE(sat) ≤ 1.2 V at I_C = 3 A / I_B = 375 mA, h_FE ≥ 10 at I_C = 3 A, and thermal performance in D-PAK with 15 W P_C @ T_C.

Technical Context

The KSH31CTF operates as a medium-power bipolar junction transistor optimized for linear amplification and saturated-switching roles where robust voltage blocking and moderate current handling are required. Its design supports DC bias stability via h_FE = 10–50 (measured at V_CE = 4 V), low V_BE(on) = 1.8 V at I_C = 3 A, and f_T = 3 MHz for bandwidth-limited signal conditioning.

Thermal derating is defined down to zero power at T_C = 175°C, with maximum junction temperature of 150°C and storage range from –65°C to +150°C. The device exhibits I_CEO ≤ 50 µA at V_CE = 60 V and I_CES ≤ 20 µA at V_CE = 100 V, confirming high off-state leakage immunity under rated blocking conditions.

Key Specifications

Pinout & Package

D-PAK (TO-252) surface-mount package with exposed drain pad for thermal enhancement; standardized 3-pin configuration optimized for automated assembly and board-level heat transfer.

Key Features

Applications

Equivalent & Alternatives

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

Compared with KSH31CTF, MJD31C offers reduced thermal capability but tighter gain spec at lower current, while STP31C delivers identical electrical envelope with enhanced h_FE consistency - making it preferable for volume production where gain variation impacts calibration stability.

Availability

KSH31CTF is available at Aetrix Electronics and suitable for power supply control, DC motor driver, relay driver, and LED array switching applications requiring stable component supply across industrial OEM and embedded control programs.

Supply support for KSH31CTF 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 is a global semiconductor manufacturer specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The KSH31CTF belongs to ON Semiconductor's legacy high-voltage bipolar transistor product line, originally developed by Fairchild and optimized for cost-sensitive, medium-power linear and switching applications in industrial controls and power conversion.

FAQ

What is the maximum collector-emitter sustaining voltage for KSH31CTF?

The KSH31CTF has a collector-emitter sustaining voltage (V_CEO(sus)) of 100 V when I_C = 30 mA and I_B = 0. This rating defines the highest voltage the device can block in active switching mode before entering avalanche breakdown, making it suitable for 48 V system interfaces and auxiliary power supplies. The KSH31CTF maintains this rating across its specified temperature range.

Does KSH31CTF require a heatsink in typical applications?

KSH31CTF can operate without an external heatsink at ambient temperatures ≤50°C and power dissipation ≤2 W, thanks to its D-PAK package's thermal resistance (R_θJC ≈ 1.7°C/W). For continuous 3 A operation at elevated ambient or higher duty cycles, a copper pour or small heatsink is recommended. The KSH31CTF datasheet specifies 15 W maximum dissipation only at T_C = 25°C - actual board-level thermal design must validate junction temperature.

Is KSH31CTF pin-compatible with TIP31C?

KSH31CTF uses the D-PAK (TO-252) package with pinout Base–Collector–Emitter, whereas TIP31C uses TO-220 with pinout Emitter–Base–Collector. They are electrically similar per datasheet but not pin-compatible. To replace TIP31C with KSH31CTF, a footprint redesign or adapter board is required. The KSH31CTF retains functional equivalence in circuit behavior but demands layout adaptation.

What is the DC current gain (h_FE) range for KSH31CTF at full load?

At V_CE = 4 V and I_C = 3 A, the KSH31CTF guarantees h_FE ≥ 10, with typical values reaching 50. This wide spread reflects process variation inherent to bipolar transistors; designers must verify bias networks across h_FE extremes. The KSH31CTF's gain specification ensures reliable saturation under worst-case conditions while allowing headroom for linear amplification at lower currents.

Can KSH31CTF be used in PWM motor control applications?

Yes, KSH31CTF supports PWM motor control at frequencies ≤10 kHz due to its t_F (turn-off time) < 1 µs and t_R (turn-on time) < 0.5 µs under typical test conditions. However, its f_T = 3 MHz and relatively high stored charge limit efficiency above 20 kHz. For optimal PWM performance, ensure base drive provides ≥375 mA peak current and fast edge rates. The KSH31CTF remains effective for low-frequency, high-torque motor commutation.