onsemi KSA940TU

Overview

KSA940TU from onsemi is a PNP epitaxial silicon power transistor designed for vertical deflection output amplification in CRT display systems, with −150 V V_CEO, −1.5 A I_C, 25 W P_C (T_C=25°C), and f_T = 4 MHz - deployed in TV and monitor horizontal/vertical scan circuits.

For engineers reviewing the KSA940TU datasheet, pinout, applications, or equivalent options, key selection criteria include safe operating area (SOA) compliance at high-voltage switching, DC current gain (h_FE = 40–140 @ −500 mA), and TO-220-3LD thermal performance in deflection stage designs.

Technical Context

This PNP power transistor operates in linear amplification and switching modes within CRT deflection yoke drivers, where high V_CEO/V_CBO (−150 V) supports flyback voltage tolerance and low V_CE(sat) (≤ −1.5 V @ −500 mA/−50 mA) minimizes conduction loss during active scan periods.

Its f_T of 4 MHz enables stable operation across vertical sweep frequencies up to 15.734 kHz (NTSC) and 15.625 kHz (PAL), while Cob = 55 pF at −10 V ensures predictable Miller capacitance behavior in high-dV/dt deflection node environments.

Key Specifications

Pinout & Package

Package: TO-220-3LD (Case 340AT), leaded, through-hole, thermally optimized for vertical mounting with heatsink contact via collector tab.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP vertical deflection amplifier applications.

Compared with KSA940TU, KSA940 lacks RoHS compliance and MJE15034 offers higher voltage rating but demands board redesign - KSA940TU remains optimal for drop-in CRT deflection replacements requiring Pb-free assurance and unchanged layout.

Availability

KSA940TU is available at Aetrix Electronics and suitable for CRT television repair, legacy monitor refurbishment, and industrial instrumentation requiring stable component supply with full traceability and long-lifecycle support.

Supply support for KSA940TU 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 specializing in energy-efficient power, analog, sensor, and logic solutions for automotive, industrial, and consumer markets.

The KSA940TU belongs to onsemi's legacy high-voltage bipolar power transistor product line, engineered specifically for CRT deflection, horizontal/vertical output, and high-reliability analog switching applications.

FAQ

What is the maximum safe collector-emitter voltage for KSA940TU?

The KSA940TU has a rated V_CEO of −150 V at T_C = 25°C. This rating ensures reliable operation under CRT flyback voltage stress. Exceeding this value risks avalanche breakdown or permanent junction damage, especially during transient conditions without proper snubbing. Always verify SOA curves in the official onsemi KSA940/D datasheet before final design validation.

Is KSA940TU pin-compatible with KSC2073?

No - KSA940TU is a PNP transistor while KSC2073 is an NPN device; they form a complementary pair but have opposite polarity and cannot be interchanged. Their pinouts (both TO-220-3LD) match mechanically (B-C-E), but circuit placement must respect polarity: KSA940TU emitter connects to negative rail, KSC2073 emitter to ground. Using them incorrectly will cause immediate failure.

Does KSA940TU require a heatsink in vertical deflection applications?

Yes - KSA940TU dissipates up to 25 W at T_C = 25°C, and typical vertical output stages operate near thermal limits. A properly mounted aluminum heatsink (≥1.5°C/W thermal resistance) is mandatory to maintain T_J ≤ 150°C. Without heatsinking, junction temperature exceeds safe limits within seconds under load, triggering thermal runaway.

What is the base-emitter forward voltage of KSA940TU at rated current?

The KSA940TU exhibits V_BE(on) between −0.65 V and −0.85 V at V_CE = −10 V and I_C = −500 mA. This relatively low turn-on voltage reduces base drive power and eases interfacing with TTL or CMOS-compatible pre-driver ICs, supporting efficient current sourcing from common vertical sync generators.

Can KSA940TU be used in audio amplifier output stages?

No - KSA940TU is optimized for high-voltage, moderate-bandwidth deflection applications (f_T = 4 MHz), not audio fidelity. Its Cob = 55 pF and limited h_FE linearity at low currents make it unsuitable for Hi-Fi output stages. Audio designs require devices with tighter gain matching, lower noise, and broader bandwidth - use dedicated audio power transistors like MJ15003 instead of KSA940TU.