onsemi KSA733CLBU

Overview

KSA733CLBU from ON Semiconductor is a PNP epitaxial silicon transistor designed for low-frequency amplifier and switching applications, with VCBO = −60 V, VCEO = −50 V, IC = −150 mA, hFE = 350–700 (L-class), and TO-92 package. It serves as a complement to the NPN KSC945 in push-pull or differential pair configurations.

For engineers reviewing the KSA733CLBU datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed hFE classification (L-grade), low VCE(sat) of −0.18 V min at IC = −100 mA/IB = −10 mA, fT up to 180 MHz, noise figure ≤20 dB at 1 MHz, and TO-92 mechanical compatibility for through-hole audio and signal conditioning circuits.

Technical Context

This PNP bipolar junction transistor operates in linear amplification and saturated switching modes. Its DC current gain (hFE) is binned to 350–700 (L-class), ensuring predictable biasing in analog stages; VCE(sat) ≤ −0.3 V at rated drive confirms efficient on-state conduction.

The device features low output capacitance (Cob = 2.8 pF at VCB = −10 V), supporting stable gain in low-frequency (<10 MHz) small-signal amplifiers, and a noise figure of 6.0–20 dB at 1 MHz with Rs = 10 kΩ - suitable for preamplifier input stages where SNR matters.

Key Specifications

Pinout & Package

Package: TO-92 (3-lead, plastic, through-hole). Lead configuration: Emitter (Lead 1), Base (Lead 2), Collector (Lead 3) - confirmed by "Suffix '-C' means Center Collector" note and standard KSA733 pinout documentation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPSA92 and KSA992, the KSA733CLBU delivers tighter hFE control (350–700), lower noise, and optimal fit for low-power, low-frequency analog circuits where TO-92 compatibility and gain predictability are essential - not merely voltage or power scalability.

Availability

KSA733CLBU is available at Aetrix Electronics and suitable for audio pre-amplifier stages, DC power sequencing switches, differential pair input stages, and legacy equipment signal conditioning requiring stable component supply and long-term obsolescence mitigation.

Supply support for KSA733CLBU 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 management, analog, sensors, and logic devices for automotive, industrial, and communications markets.

The KSA733CLBU belongs to ON Semiconductor's legacy bipolar transistor portfolio, originally developed by Fairchild and optimized for cost-sensitive, high-reliability low-frequency analog and switching functions in consumer and industrial electronics.

FAQ

What is the pin configuration of the KSA733CLBU?

The KSA733CLBU uses a TO-92 package with lead order: Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector. This "center collector" arrangement (denoted by suffix "-C") matches complementary NPN devices like KSC945 for symmetrical PCB layout in push-pull circuits. Mechanical drawings confirm this orientation per Fairchild Rev. A2 datasheet.

What does the "L" in KSA733CLBU signify?

"L" denotes the hFE classification bin: 350–700 at VCE = −6 V and IC = −1 mA. This tight gain range improves repeatability in bias-critical analog designs such as emitter followers or Class-A amplifiers. The full part number KSA733CLBU reflects Fairchild's original nomenclature retained post-ON Semiconductor integration.

Is KSA733CLBU suitable for audio amplifier applications?

Yes - the KSA733CLBU is explicitly specified as a low-frequency amplifier transistor with noise figure 6.0–20 dB at 1 MHz and Rs = 10 kΩ, making it appropriate for microphone preamps, tone control buffers, and line-driver stages. Its hFE consistency and low VCE(sat) help maintain linearity and efficiency in single-ended or push-pull topologies.

How does KSA733CLBU compare to KSC945?

KSA733CLBU is the PNP complement to the NPN KSC945: both share TO-92 packaging, matched breakdown voltages (VCBO/VCEO), similar fT (50–180 MHz vs. 250 MHz), and compatible hFE bins. Their paired use enables balanced differential amplifiers, push-pull outputs, and level-shifting circuits without gain or timing asymmetry - a key design advantage confirmed in Fairchild application notes.

What is the maximum power dissipation of KSA733CLBU?

The KSA733CLBU has a maximum collector power dissipation (PC) of 250 mW at Ta = 25°C. Derating is required above 25°C - approximately 2.0 mW/°C - down to zero at 150°C junction temperature. This rating supports continuous operation in compact enclosures when combined with moderate current (≤150 mA) and low VCE(sat) operation.