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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

onsemi KSC3503CS

Name: KSC3503CS
Brand: onsemi
SKU: KSC3503CS
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: KSC3503CS

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-225AA, TO-126-3

Datasheet:: KSC3503CS.pdf

Description:: TRANS NPN 300V 0.1A TO-126-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

KSC3503CS from onsemi is an NPN epitaxial silicon transistor designed for high-voltage audio and video amplifier stages, featuring V_CEO = 300 V, f_T = 150 MHz, h_FE = 60–120 (at I_C = 10 mA), C_ob = 1.8–2.6 pF, and TO-126-3LD package. It serves as a voltage/current amplifier in CRT video output and low-THD audio circuits.

For engineers reviewing the KSC3503CS datasheet, pinout, applications, or equivalent options, key selection considerations include its 300 V breakdown rating, 150 MHz gain-bandwidth product, low reverse transfer capacitance, thermal resistance of 17.8 °C/W, and complementarity to KSA1381 in push-pull designs.

Technical Context

This NPN transistor operates with high-voltage blocking capability (BVCBO/BVCEO = 300 V) and supports RF-capable amplification up to 150 MHz. Its low C_ob (1.8–2.6 pF) and excellent h_FE linearity reduce distortion in analog signal paths.

Designed for linear operation in Class-A or AB amplifier stages, it delivers stable DC current gain across I_C = 10 mA (h_FE = 60–120) and maintains low V_CE(sat) = 0.6 V at I_C = 20 mA / I_B = 2 mA, enabling efficient biasing in discrete gain blocks.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	300 V - Enables use in high-voltage CRT deflection and audio supply rails without breakdown.
f_T	150 MHz - Supports wideband video amplification and RF-coupled preamp stages.
h_FE	60–120 @ I_C = 10 mA - Provides predictable, linear gain control in fixed-bias amplifier designs.
C_ob	1.8–2.6 pF @ V_CB = 30 V - Minimizes Miller effect and improves high-frequency stability.
R_JC	17.8 °C/W - Allows 7 W dissipation at T_C = 25°C, supporting thermally demanding analog output stages.
V_BE(sat)	1.0 V @ I_C = 20 mA - Ensures reliable turn-on with standard TTL/CMOS driver levels.

Pinout & Package

Package: TO-126-3LD (Case 340AS), surface-mount compatible with tab-connected collector, through-hole mounting, and heatsink interface via metal tab.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Connected to ground or negative rail in common-emitter configurations; defines reference for V_BE and I_C control.
2 (Collector)	Current source terminal	Tab-connected; electrically tied to metal case for direct heatsinking and high-current output path.
3 (Base)	Control input	Receives bias current to regulate I_C; requires external resistor network for stable DC operating point.

Key Features

Feature	Design Value
High-voltage blocking	300 V BVCBO/BVCEO enables safe operation in CRT flyback and HV audio supply interfaces.
Low reverse transfer capacitance	Cre = 1.8 pF minimizes feedback-induced oscillation in high-gain video amplifiers.
Gain linearity	Stable h_FE vs. I_C reduces harmonic distortion in audio voltage amplifiers.
Thermal performance	R_JC = 17.8 °C/W supports continuous 7 W dissipation with minimal heatsink mass.

Applications

Audio Voltage Amplifier	CRT Video Output Stage
Use Scenario: Low-distortion preamplifier for hi-fi receivers and active speaker crossovers. IC Role / Device Role / Timing Role: NPN voltage amplifier in common-emitter configuration with emitter degeneration. Use Value: h_FE linearity and low C_ob preserve THD < 0.1% at 20 kHz under 10 V_PP swing.	Use Scenario: Horizontal deflection driver and video output buffer in analog CRT monitors. IC Role / Device Role / Timing Role: High-slew-rate current source driving Yoke/Video load impedance. Use Value: 300 V rating withstands flyback spikes; 150 MHz f_T ensures full 10 MHz video bandwidth.
General-Purpose Linear Amplifier	Complementary Pair Driver
Use Scenario: DC-coupled instrumentation gain stage requiring stable bias and low noise. IC Role / Device Role / Timing Role: Single-ended Class-A amplifier with fixed base bias and emitter resistor. Use Value: V_CE(sat) = 0.6 V and h_FE = 60–120 allow precise I_C setting and predictable gain calibration.	Use Scenario: Upper NPN device in complementary emitter-follower output stage with KSA1381. IC Role / Device Role / Timing Role: High-voltage NPN partner matched to PNP KSA1381 for symmetrical swing. Use Value: Identical V_CEO, f_T, and package enable balanced thermal tracking and crossover distortion reduction.

Audio Voltage Amplifier

CRT Video Output Stage

Use Scenario: Low-distortion preamplifier for hi-fi receivers and active speaker crossovers.

IC Role / Device Role / Timing Role: NPN voltage amplifier in common-emitter configuration with emitter degeneration.

Use Value: h_FE linearity and low C_ob preserve THD < 0.1% at 20 kHz under 10 V_PP swing.

Use Scenario: Horizontal deflection driver and video output buffer in analog CRT monitors.

IC Role / Device Role / Timing Role: High-slew-rate current source driving Yoke/Video load impedance.

Use Value: 300 V rating withstands flyback spikes; 150 MHz f_T ensures full 10 MHz video bandwidth.

General-Purpose Linear Amplifier

Complementary Pair Driver

Use Scenario: DC-coupled instrumentation gain stage requiring stable bias and low noise.

IC Role / Device Role / Timing Role: Single-ended Class-A amplifier with fixed base bias and emitter resistor.

Use Value: V_CE(sat) = 0.6 V and h_FE = 60–120 allow precise I_C setting and predictable gain calibration.

Use Scenario: Upper NPN device in complementary emitter-follower output stage with KSA1381.

IC Role / Device Role / Timing Role: High-voltage NPN partner matched to PNP KSA1381 for symmetrical swing.

Use Value: Identical V_CEO, f_T, and package enable balanced thermal tracking and crossover distortion reduction.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN high-voltage amplifier applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD350	V_CEO = 300 V, f_T = 100 MHz, TO-220 package, R_JC = 3.5 °C/W	Higher power (30 W), lower f_T, larger footprint	Preferred for higher-power audio outputs where thermal margin > 7 W is required.
KSC2383	V_CEO = 160 V, f_T = 100 MHz, same TO-126-3LD package	Lower voltage rating limits use in CRT or HV supply rails	Suitable only for ≤160 V applications; not interchangeable in 300 V designs.

Compared with MJD350 and KSC2383, the KSC3503CS offers optimal balance of 300 V rating, 150 MHz bandwidth, and TO-126 thermal-mechanical fit-making it uniquely suited for space-constrained, high-fidelity video/audio amplifiers requiring both voltage headroom and frequency response.

Availability

KSC3503CS is available at Aetrix Electronics and suitable for CRT display systems, high-fidelity audio amplifiers, and general-purpose linear amplifier designs requiring stable component supply and long-lifecycle support.

Supply support for KSC3503CS 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 is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The KSC3503CS belongs to onsemi's high-voltage bipolar transistor family, engineered specifically for analog video, audio, and CRT deflection circuits demanding ruggedness, linearity, and thermal reliability.

FAQ

What is the maximum collector-emitter voltage rating for the KSC3503CS?

The KSC3503CS has a guaranteed BV_CEO = 300 V at I_C = 1 mA and I_B = 0. This rating allows safe operation in high-voltage analog circuits such as CRT horizontal deflection and HV audio supply stages. Exceeding this voltage risks irreversible junction breakdown. The KSC3503CS must be operated within absolute maximum ratings defined in the onsemi datasheet to ensure reliability and longevity.

Is the KSC3503CS pin-compatible with the KSA1381?

No-the KSC3503CS is an NPN transistor while the KSA1381 is a PNP device; they are complementary but not pin-compatible. Their pinouts differ: KSC3503CS uses E-C-B (pin 1–2–3), whereas KSA1381 uses E-C-B in reversed polarity. Both share the TO-126-3LD package outline, enabling mechanical symmetry in push-pull layouts, but external circuitry must account for polarity inversion. The KSC3503CS datasheet explicitly states "complement to KSA1381" for functional pairing-not pin-for-pin replacement.

What is the typical current gain (h_FE) of the KSC3503CS and under what conditions is it specified?

The KSC3503CS exhibits h_FE = 60–120 when measured at V_CE = 10 V and I_C = 10 mA. This range reflects process variation across production lots and ensures predictable DC biasing in linear amplifier designs. Gain remains stable over I_C = 1–50 mA per typical curves, supporting consistent performance in audio preamps and video drivers. The KSC3503CS does not specify minimum h_FE at higher currents, so design margins should be verified per application.

Does the KSC3503CS have built-in protection features like thermal shutdown or ESD clamping?

No-the KSC3503CS is a discrete NPN bipolar junction transistor with no integrated protection circuitry. It relies entirely on external design safeguards: series base resistors, emitter degeneration, heatsinking, and voltage clamping networks. Its RoHS-compliant Pb-free construction meets environmental standards but does not imply functional protection. System-level robustness for the KSC3503CS must be achieved through proper PCB layout, derating, and companion components-not internal features.

Can the KSC3503CS be used in switching applications?

While the KSC3503CS can operate in saturation/switching mode, it is optimized for linear amplification-not fast digital switching. Its V_CE(sat) = 0.6 V and f_T = 150 MHz support moderate-speed switching (≤1 MHz), but lack of specified t_on/t_off or storage time limits high-frequency PWM use. For dedicated switching, onsemi recommends devices like MMBT4401 or NSS12201. The KSC3503CS datasheet emphasizes audio/video linearity, not switching efficiency-so its use in switching must be validated per circuit requirements.

KSC3503CS Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-225AA, TO-126-3

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 100 mA

Voltage - Collector Emitter Breakdown (Max):: 300 V

Vce Saturation (Max) @ Ib, Ic:: 600mV @ 2mA, 20mA

Current - Collector Cutoff (Max):: 100nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 40 @ 10mA, 10V

Power - Max:: 7 W

Frequency - Transition:: 150MHz

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-126-3

KSC3503CS FAQ

1.How can I place an order for KSC3503CS through Aetrix?

Please submit a Request for Quotation (RFQ) for KSC3503CS on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for KSC3503CS reliable?

The price and inventory of KSC3503CS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSC3503CS is usually 5 days.

3.What payment methods are accepted for KSC3503CS?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSC3503CS transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for KSC3503CS?

KSC3503CS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your KSC3503CS order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for KSC3503CS?

For technical support, including KSC3503CS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSC3503CS requirements.

6.How does Aetrix verify that KSC3503CS is sourced from the original manufacturer or authorized distributors?

All KSC3503CS products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that KSC3503CS meets industry standards.

7.What is the process for return or replacement of KSC3503CS?

All KSC3503CS units undergo pre-shipment inspection (PSI). If there is an issue with KSC3503CS, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The KSC3503CS part is unused and in its original packaging.

Return procedure for KSC3503CS:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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