onsemi KSP55TA

Overview

KSP55TA from ON Semiconductor is a PNP epitaxial silicon transistor in TO-92 package, rated for -60 V collector-emitter voltage, -500 mA continuous collector current, and 625 mW power dissipation. It delivers DC current gain (h_FE) ≥50 at -10 mA and -100 mA, with -0.25 V saturation voltage at -100 mA/-10 mA drive-commonly used in low-voltage switching and signal amplification circuits in consumer power supplies and LED drivers.

For engineers reviewing the KSP55TA datasheet, pinout, applications, or equivalent options, key selection criteria include its PNP polarity, TO-92 mechanical compatibility, -60 V V_CEO rating, -0.25 V V_CE(sat) at rated current, and 105 MHz f_T bandwidth-critical for discrete amplifier stages and logic-level interface switching.

Technical Context

The KSP55TA operates as a general-purpose PNP bipolar junction transistor optimized for linear amplification and saturated switching. Its epitaxial base structure supports stable h_FE across -10 mA to -100 mA, with V_BE(on) = -1.2 V at -100 mA and V_CE(sat) = -0.25 V under same conditions-enabling predictable turn-on behavior in emitter-follower and common-emitter configurations.

Designed for ambient operation up to 150°C junction temperature, it features low leakage (ICBO ≤ -0.1 μA at -60 V), high breakdown margin (V_CBO = -60 V), and complementarity to KSP05/KSP06 NPN devices-facilitating push-pull output stage design in analog and digital interface circuits.

Key Specifications

Pinout & Package

Package: TO-92, 3-lead plastic through-hole package with straight or bent leads (JEDEC TO-92 compliant); lead spacing 0.2 inch; suitable for wave soldering and manual assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPSA56 and BC557B, the KSP55TA offers balanced trade-offs: -60 V rating fits most 48 V industrial rails, 625 mW dissipation exceeds standard 500 mW alternatives, and its -0.25 V V_CE(sat) delivers lower conduction loss than BC557B in switching roles-making it optimal for cost-sensitive, medium-voltage discrete designs.

Availability

KSP55TA is available at Aetrix Electronics and suitable for DC power supply regulation, LED constant-current driver, logic-level interface translation, and audio pre-amplifier stage applications requiring stable component supply, long-term manufacturability, and JEDEC-standard TO-92 compatibility.

Supply support for KSP55TA 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 KSP55TA belongs to ON Semiconductor's general-purpose bipolar transistor product line, designed for cost-effective, robust discrete switching and amplification in non-safety-critical commercial and industrial electronics.

FAQ

What is the maximum junction temperature rating for the KSP55TA?

The KSP55TA has a maximum junction temperature (T_J) of 150°C, as specified in its Absolute Maximum Ratings table. This rating allows operation in high-ambient environments such as enclosed power supplies or automotive under-hood modules-provided thermal design maintains junction temperature below this limit during peak power dissipation. Derating curves in the datasheet confirm safe operation down to 25°C ambient at full 625 mW.

Is the KSP55TA pin-compatible with the KSP56TA?

No, the KSP55TA and KSP56TA share identical TO-92 packaging and pinout (Emitter-Base-Collector, pins 1–2–3), but they differ in absolute maximum ratings: KSP55TA is rated for -60 V V_CEO, while KSP56TA supports -80 V. Substituting KSP55TA for KSP56TA in >60 V applications risks premature breakdown; however, both may be interchanged in circuits operating ≤60 V with verified thermal and gain margins.

Does the KSP55TA require a heatsink in typical applications?

The KSP55TA typically does not require an external heatsink when dissipating ≤300 mW at 25°C ambient, as its TO-92 package has a thermal resistance (R_θJA) of ~200°C/W. At full 625 mW, junction temperature would exceed 150°C without derating-so heatsinking or ambient reduction is necessary only in sustained high-power switching or elevated ambient (>50°C) scenarios. PCB copper area acts as effective passive heatsinking.

What is the typical base-emitter on voltage (V_BE(on)) for the KSP55TA?

The KSP55TA exhibits a typical V_BE(on) of -1.2 V at V_CE = -1 V and I_C = -100 mA, per its Electrical Characteristics table. This value remains stable across production lots and supports predictable base resistor calculation for saturation-e.g., a 1 kΩ base resistor delivers ~1.2 mA I_B, sufficient to drive -100 mA I_C given h_FE ≥50.

Can the KSP55TA be used in linear amplifier configurations?

Yes, the KSP55TA is suitable for linear amplifier use, particularly in common-emitter and emitter-follower topologies. Its f_T of 105 MHz and h_FE ≥50 across -10 mA to -100 mA ensure stable mid-band gain and low distortion up to 20 kHz. For best linearity, operate within V_CE = -1 V to -5 V and avoid deep saturation or cutoff regions-verified in the Typical Performance Characteristics section of the datasheet.