onsemi KSA931OTA

Overview

KSA931OTA from ON Semiconductor is a PNP epitaxial silicon transistor designed for low-frequency amplification and medium-speed switching applications, with VCBO = −80 V, VCEO = −60 V, IC = −700 mA, PC = 1 W, and hFE = 40–240 (depending on classification). It serves as a complement to the NPN KSC2331 in push-pull or differential amplifier stages.

For engineers reviewing the KSA931OTA datasheet, pinout, applications, or equivalent options, key selection criteria include its TO-92L package, guaranteed hFE grouping (R/O/Y), −0.7 V VCE(sat) at −500 mA, and suitability for linear audio preamplifiers, relay drivers, and power supply error amplifiers.

Technical Context

The KSA931OTA operates as a general-purpose PNP bipolar junction transistor with fixed-emitter biasing capability and DC current gain controlled by base current injection. Its safe operating area supports pulsed operation up to 350 µs with ≤2% duty cycle, and thermal derating begins above 25°C ambient.

It features low output capacitance (Cob = 13 pF at VCB = −10 V), high fT = 100 MHz under VCE = −10 V/IC = −50 mA conditions, and robust breakdown ratings including BVEBO = −8 V, ensuring stable operation in feedback and level-shifting circuits.

Key Specifications

Pinout & Package

Package: TO-92L - Molded plastic through-hole package with 2.54 mm lead pitch, 4.90 mm body length, and 3.90 mm width; optimized for manual assembly and wave soldering.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPSA92 and BC557, the KSA931OTA uniquely balances −60 V VCEO, −700 mA IC, and 1 W PC in TO-92L-making it optimal for industrial relay drivers and audio preamps where both voltage headroom and current capability matter.

Availability

KSA931OTA is available at Aetrix Electronics and suitable for industrial control systems, audio equipment manufacturing, and power supply design requiring stable component supply and long-term obsolescence management.

Supply support for KSA931OTA 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 logic solutions for automotive, industrial, cloud, and consumer markets.

The KSA931OTA belongs to ON Semiconductor's legacy general-purpose bipolar transistor portfolio, originally developed by Fairchild Semiconductor to serve linear amplification and medium-power switching needs in cost-sensitive, high-reliability applications.

FAQ

What is the maximum continuous collector current rating for the KSA931OTA?

The KSA931OTA has a maximum continuous collector current (IC) rating of −700 mA at Ta = 25°C. Derating is required above this temperature per the power derating curve: PC decreases linearly to zero at 150°C junction temperature. Operation at −700 mA must ensure junction temperature remains ≤150°C with appropriate PCB copper area or heatsinking.

Does the KSA931OTA have a specified hFE bin, and how does it affect circuit design?

Yes-the KSA931OTA is classified into R (hFE = 40–80), O (70–140), and Y (120–240) gain bins. This binning enables predictable DC biasing in amplifier stages and facilitates matched pairing with KSC2331 for differential circuits. Selecting Y-grade KSA931OTA ensures higher transconductance and lower base drive requirements in switching applications.

Can the KSA931OTA be used as a direct replacement for the KSA931 in existing designs?

Yes-the KSA931OTA is a direct form-fit-function replacement for KSA931, sharing identical TO-92L package dimensions, pinout (E-C-B), and electrical specifications. The "OTA" suffix denotes tape-and-reel packaging per ON Semiconductor's post-Fairchild nomenclature update; all performance parameters remain unchanged from the original KSA931.

What is the safe operating area (SOA) limitation for pulsed operation of the KSA931OTA?

The KSA931OTA supports pulsed operation with PW ≤ 350 µs and duty cycle ≤ 2%, as defined in its absolute maximum ratings. Under these conditions, peak IC may exceed −700 mA provided average power stays within 1 W and junction temperature remains ≤150°C. SOA curves in the datasheet confirm safe operation up to −1 A at VCE = −20 V for single pulses.

How does the KSA931OTA's Cob of 13 pF impact high-frequency circuit performance?

With Cob = 13 pF at VCB = −10 V, the KSA931OTA maintains usable gain up to ~100 MHz (fT), making it suitable for audio and low-MHz signal paths. In RF or fast-switching applications, this capacitance may introduce phase lag or reduce bandwidth; designers should limit use to ≤10 MHz small-signal amplification or employ neutralization techniques if higher frequency stability is required.