onsemi KSA928AOBU

Overview

KSA928AOBU from onsemi is a PNP epitaxial silicon transistor designed for audio power amplifier stages, with −30 V collector-emitter breakdown voltage, −2 A continuous collector current capability, 1000 mW power dissipation, DC current gain (hFE) of 100–320 at −500 mA, and 120 MHz transition frequency. It serves as a complement to the NPN KSC2328A in push-pull output configurations for low-to-mid-power audio systems.

For engineers reviewing the KSA928AOBU datasheet, pinout, applications, or equivalent options, key selection criteria include its TO-92 3 LF package, PNP polarity, safe operating area up to −1.4 A/−14 V in DC operation, thermal resistance of 125°C/W, and suitability for Class AB audio output stages requiring complementary bipolar switching.

Technical Context

This device operates as a medium-power PNP bipolar junction transistor optimized for linear amplification rather than switching. Its −30 V VCEO rating and 120 MHz fT support stable gain in audio-frequency ranges up to ~20 kHz with minimal phase shift, while its 100–320 hFE range enables predictable biasing in emitter-follower or common-emitter configurations.

The KSA928AOBU exhibits low saturation voltage (VCE(sat) ≤ −2.0 V at IC = −1.5 A, IB = −30 mA) and moderate output capacitance (Cob = 48 pF at VCB = −10 V), making it suitable for driver-stage amplification where linearity and thermal stability are prioritized over ultra-high-speed switching.

Key Specifications

Pinout & Package

Package: TO-92 3 LF (Case 135AM), lead-formed, Pb-free, through-hole mounting. Dimensions: 8.0 mm × 4.9 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPSA92 and KSA733, the KSA928AOBU delivers superior audio-specific performance via its 120 MHz fT, tightly specified Cob, and hFE binning (O/Y) - enabling predictable biasing and low harmonic distortion in linear amplifier roles where signal integrity matters.

Availability

KSA928AOBU is available at Aetrix Electronics and suitable for portable audio devices, industrial annunciator systems, intercom transmitters, and Hi-Fi preamp drivers requiring stable component supply and long-term manufacturability.

Supply support for KSA928AOBU 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 management, analog, sensors, and discrete components for automotive, industrial, and consumer markets.

The KSA928AOBU belongs to onsemi's legacy bipolar transistor product line, engineered specifically for audio-frequency linear amplification and complementary pair operation in cost-sensitive, thermally constrained applications.

FAQ

What is the maximum continuous collector current rating for KSA928AOBU?

The KSA928AOBU has a maximum continuous collector current (IC) rating of −2 A at TA = 25°C. This rating assumes proper PCB thermal relief per the datasheet's FR-4 land pattern specification. Derating is required above 25°C ambient, at 8.0 mW/°C, and actual sustained current must remain within the Safe Operating Area curve shown in Figure 5 of the KSA928AOBU datasheet.

Is KSA928AOBU pin-compatible with KSC2328A?

No, KSA928AOBU is not pin-compatible with KSC2328A. While they are complementary PNP/NPN devices intended for use together in push-pull circuits, their pinouts differ: KSA928AOBU uses E-C-B (Emitter–Collector–Base) in TO-92, whereas KSC2328A uses C-B-E (Collector–Base–Emitter) in the same package. Layout must account for this inversion to avoid wiring errors.

What does the "O" suffix in KSA928AOBU indicate?

Within the KSA928A family, the "O" suffix denotes the hFE classification bin: KSA928AOBU has a DC current gain (hFE) range of 100–200 at VCE = −2 V and IC = −500 mA. This bin provides tighter gain control than the "Y" variant (160–320), simplifying bias network design in production audio amplifiers where predictable quiescent current is critical.

Can KSA928AOBU be used in switching applications?

Yes, KSA928AOBU can operate in switching mode, with VCE(sat) ≤ −2.0 V at IC = −1.5 A and IB = −30 mA. However, its 120 MHz fT and lack of specified switching time parameters mean it is optimized for linear audio amplification-not high-speed digital switching. For >10 kHz switching, consider dedicated switching transistors with faster turn-on/turn-off times.

What is the thermal resistance junction-to-ambient (RθJA) for KSA928AOBU?

The thermal resistance junction-to-ambient (RθJA) for KSA928AOBU is 125°C/W, measured on an FR-4 PCB sized 76 mm × 114 mm × 1.57 mm with minimum land pattern per the datasheet. This value assumes natural convection only; adding copper pour or airflow reduces effective RθJA and improves power handling beyond the nominal 1000 mW rating.