onsemi KSA708YTA

Overview

KSA708YTA from onsemi is a PNP epitaxial silicon transistor designed for low-frequency amplification and medium-speed switching applications, with −80 V collector-base voltage, −60 V collector-emitter voltage, 800 mW power dissipation, and DC current gain (hFE) of 120–240 at −50 mA collector current. It serves as a complement to the KSC1008 NPN transistor in push-pull amplifier stages and relay driver circuits.

For engineers reviewing the KSA708YTA datasheet, pinout, applications, or equivalent options, key selection criteria include its TO-92 3 LF (Pb-free) package, verified −700 mA absolute maximum collector current, saturation voltage performance under high drive conditions, and suitability for discrete audio preamplifier and industrial control signal conditioning designs.

Technical Context

The KSA708YTA operates as a general-purpose PNP bipolar junction transistor with fixed emitter-base and collector-base junction structures optimized for linear amplification and saturated switching. Its fT of 50 MHz supports stable operation up to low-MHz signal frequencies, while Cob of 13 pF ensures minimal Miller effect in common-emitter configurations.

Designed for DC-coupled and capacitively coupled low-frequency analog stages, the device exhibits predictable VBE(sat) (−0.9 to −1.1 V) and VCE(sat) (−0.3 to −0.7 V) under −500 mA/−50 mA drive, enabling reliable biasing in Class-A and Class-AB output stages without thermal runaway risk at TA = 25°C.

Key Specifications

Pinout & Package

Package: TO-92 3 LF (Pb-free), case outline 135AR, lead-formed, dimensions 4.83 mm × 4.76 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPSA92 and KSA992, the KSA708YTA offers tighter hFE consistency and optimized saturation behavior for mid-power linear and switching roles, making it preferable in cost-sensitive, thermally constrained audio and industrial control designs where −80 V breakdown suffices.

Availability

KSA708YTA is available at Aetrix Electronics and suitable for audio preamplifier stages, relay driver circuits, industrial signal conditioning, and discrete push-pull output applications requiring stable component supply and Pb-free compliance.

Supply support for KSA708YTA 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 supplier focused on energy-efficient electronics, delivering power management, analog, sensing, and connectivity solutions.

The KSA708YTA belongs to onsemi's general-purpose bipolar transistor product line, engineered for reliability in industrial control, audio, and discrete switching applications where robust parametric consistency and RoHS compliance are essential.

FAQ

What is the pin configuration of the KSA708YTA?

The KSA708YTA uses a TO-92 3 LF package with pin 1 as Emitter, pin 2 as Base, and pin 3 as Collector - confirmed by onsemi's official marking diagram and mechanical drawings (Case 135AR). This arrangement is standardized across all KSA708 variants and differs from center-collector versions like KSA708C. The KSA708YTA must be mounted with correct orientation to avoid reverse-bias damage in circuit operation.

Is the KSA708YTA still in active production?

No - the KSA708YTA is officially discontinued per onsemi's January 2026 Rev. 4 datasheet, which states "DISCONTINUED" in the Ordering Information table and notes that the device is not available. However, Aetrix Electronics maintains limited legacy inventory with full traceability and supports design continuity through qualified alternatives and cross-reference guidance for the KSA708YTA.

What is the maximum operating temperature for the KSA708YTA?

The KSA708YTA has a maximum junction temperature (TJ) of 150°C and a storage temperature range of −55°C to +150°C. At ambient temperatures up to 85°C, the device sustains full rated performance when mounted on a standard FR-4 PCB with minimum 10 mm² copper pour under the collector tab. Derating begins above 25°C ambient per the datasheet's thermal resistance curve, and the KSA708YTA must not exceed 150°C TJ under any operating condition.

How does the KSA708YTA compare to the KSA708YBU variant?

The KSA708YTA and KSA708YBU share identical electrical specifications and TO-92 3 package geometry but differ in packaging format and compliance: KSA708YTA ships in FNFLD (2000-unit tape-and-reel), is Pb-free (LF), and is discontinued; KSA708YBU ships in bulk (10,000 units), is also Pb-free, and was historically offered as an active alternative. Both use Case 135AN/135AR outlines and have identical pinout, hFE, and voltage ratings - the KSA708YTA remains functionally interchangeable where physically available.

Can the KSA708YTA replace a 2N3906 in existing designs?

The KSA708YTA is not a direct replacement for the 2N3906: it has higher voltage ratings (−80 V vs. −40 V VCBO), higher current capability (−700 mA vs. −200 mA IC), and higher power dissipation (800 mW vs. 625 mW), but its hFE range (120–240) is narrower than the 2N3906's (100–300). While electrically compatible in many low-frequency amplifier roles, the KSA708YTA's higher gain may require base resistor recalculations in bias networks originally designed for the 2N3906 to avoid saturation shift or thermal drift.