onsemi KSP43BU

Overview

KSP43BU from onsemi is an NPN epitaxial silicon transistor designed for high-voltage switching and amplification in discrete power control circuits, with V_CEO = 200 V, I_C = 500 mA, P_C = 625 mW, h_FE ≥ 40 at I_C = 10 mA, and f_T = 50 MHz - used in relay drivers, power supply feedback stages, and industrial timer circuits.

For engineers reviewing the KSP43BU datasheet, pinout, applications, or equivalent options, key selection criteria include verified 200 V collector-emitter breakdown, TO-92-3 (case 135AN) leaded package compatibility, saturation voltage ≤0.5 V at I_C/I_B = 20 mA/2 mA, and RoHS-compliant Pb-free construction.

Technical Context

This device operates as a general-purpose NPN bipolar junction transistor optimized for medium-power linear and switching applications where high V_CEO and stable DC current gain are required. It features a maximum junction temperature of 150°C and storage range from −55°C to +150°C, supporting operation in industrial ambient environments.

Electrical characterization is defined under pulsed test conditions (pulse width ≤300 µs, duty cycle ≤2%), with guaranteed BVCBO = 200 V, ICBO ≤100 nA at VCB = 160 V, and Cob = 4 pF at VCB = 20 V - confirming suitability for low-capacitance, high-voltage signal routing.

Key Specifications

Pinout & Package

Package: TO-92-3 (Pb-free), case 135AN - standardized through-hole plastic package with 4.825 mm × 4.76 mm footprint, bent leads, and JEDEC-compliant mechanical outline.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPSA43 and KSP44, the KSP43BU delivers optimal balance of 200 V robustness, 40+ h_FE at operating current, and proven thermal stability in TO-92 packages - making it preferred for cost-sensitive industrial controls where exact V_CEO margin is known.

Availability

KSP43BU is available at Aetrix Electronics and suitable for relay driver circuits, SMPS feedback amplifiers, industrial timer output stages, and low-power DC motor control requiring stable component supply and long-term industrial lifecycle support.

Supply support for KSP43BU 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

onsemi (formerly ON Semiconductor) is a global semiconductor manufacturer specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

The KSP43BU belongs to onsemi's legacy discrete transistor portfolio, engineered for reliability in industrial automation, power conversion, and electromechanical control systems where high-voltage tolerance and thermal resilience are critical.

FAQ

What is the maximum collector-emitter voltage rating for KSP43BU?

The KSP43BU has a guaranteed V_CEO rating of 200 V at T_A = 25°C, tested with I_C = 1 mA and I_B = 0. This rating applies to common-emitter configuration and must be derated linearly above 25°C ambient per the datasheet thermal curve. Exceeding 200 V risks irreversible breakdown; design margins should maintain ≤160 V under worst-case transients. The KSP43BU datasheet confirms this value in both Absolute Maximum Ratings and Electrical Characteristics tables.

Is KSP43BU RoHS compliant and lead-free?

Yes, the KSP43BU is explicitly stated as Pb-free, halogen-free/BFR-free, and RoHS compliant per the onsemi datasheet revision 4 (January 2025). It uses lead-free terminations and complies with EU Directive 2011/65/EU. The TO-92-3 package (case 135AN) carries no exemptions; full material declarations are available via onsemi's compliance portal. This makes the KSP43BU suitable for export-controlled and environmentally regulated industrial end equipment.

What is the pin configuration of KSP43BU in TO-92-3 package?

The KSP43BU uses standard TO-92-3 (case 135AN) pinout: Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector - verified in the Marking Diagram and Ordering Information sections of the official datasheet. Leads are bent, and orientation follows JEDEC TO-92 outline with flat side facing viewer and leads downward. This matches industry-standard TO-92 layouts, ensuring drop-in compatibility with existing footprints designed for KSP42/KSP43 family devices.

What is the typical DC current gain (h_FE) of KSP43BU at 10 mA collector current?

The KSP43BU exhibits h_FE ≥40 at V_CE = 10 V and I_C = 10 mA, per the Electrical Characteristics table. This value is guaranteed minimum; typical units measure 60–100 in production. Gain remains stable across I_C = 1–30 mA range, supporting consistent base drive design. The KSP43BU datasheet specifies this parameter under pulse test conditions (≤300 µs, ≤2% duty cycle) to avoid self-heating effects.

Can KSP43BU replace KSP42BU in existing designs?

KSP43BU can replace KSP42BU only if the circuit operates below 200 V collector-emitter stress - since KSP42BU supports 300 V while KSP43BU is rated for 200 V. All other parameters (P_C, I_C, package, pinout) match. However, KSP43BU has lower BVCBO (200 V vs. 300 V) and different ICBO test condition (VCB = 160 V), so voltage-transient immunity must be re-verified. The KSP43BU datasheet explicitly positions it as a lower-voltage variant within the same family.