Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

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

onsemi KSC2258STU

Name: KSC2258STU
Brand: onsemi
SKU: KSC2258STU
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: KSC2258STU

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: KSC2258STU.pdf

Description:: TRANS NPN 250V 0.1A TO-126-3

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:4,013

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

KSC2258STU from Fairchild Semiconductor is an NPN epitaxial silicon transistor designed for high-voltage general amplification and TV video output stages, with V_CEO = 250 V, I_C = 100 mA DC, P_C = 4 W at T_C = 25°C, f_T = 100 MHz, and TO-126 package. It operates reliably up to 150°C junction temperature.

For engineers reviewing the KSC2258STU datasheet, pinout, applications, or equivalent options, key selection factors include its high breakdown voltage (250 V), low saturation voltage (V_CE(sat) = 1.2 V @ I_C = 50 mA), wide bandwidth (100 MHz f_T), and thermal robustness in TO-126 power packaging.

Technical Context

This device is a medium-power, high-voltage NPN bipolar junction transistor optimized for linear amplification in video signal paths and switching applications requiring stable gain above 40 at 40 mA collector current. Its 100 MHz f_T and low Cob (3–4.5 pF) support high-frequency video output drive without excessive phase shift or loading.

The KSC2258STU features a rugged epitaxial base structure enabling reliable operation under high V_CE stress (250 V) and pulsed current (I_CP = 150 mA). Its V_BE(on) of 1.2 V at I_C = 40 mA ensures predictable turn-on behavior in emitter-follower or common-emitter configurations.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	250 V - supports operation in high-voltage video output stages without breakdown
I_C (DC)	100 mA - enables medium-power analog amplification with thermal margin in TO-126
f_T	100 MHz - provides sufficient bandwidth for NTSC/PAL video signal amplification
V_CE(sat)	1.2 V @ I_C = 50 mA, I_B = 5 mA - minimizes conduction loss in switching or saturated amplifier modes
C_ob	3–4.5 pF @ V_CB = 50 V - limits high-frequency feedback and maintains stability in video gain stages
P_C	4 W @ T_C = 25°C - delivers usable power handling with heatsink-compatible TO-126 thermal path
h_FE	40 min @ V_CE = 20 V, I_C = 40 mA - ensures predictable current gain in linear video driver designs

Pinout & Package

Package: TO-126 - thermally enhanced plastic power package with metal tab for heatsinking; pin 1 = Emitter, pin 2 = Collector (tab-connected), pin 3 = Base.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current exit terminal	Common reference node in emitter-follower or grounded-emitter configurations
2 (Collector)	Current entry terminal	Internally connected to metal tab - must be electrically isolated from heatsink unless referenced to same potential
3 (Base)	Control input	Drives transistor into active/saturation via ~5 mA base current for 50 mA collector output

Key Features

Feature	Design Value
High V_CEO rating	250 V enables use in CRT deflection, video output, and HV bias supply switching without derating
Low V_CE(sat)	1.2 V reduces power dissipation and improves efficiency in saturated video driver stages
100 MHz f_T	Supports full-bandwidth amplification of composite video signals up to ~5 MHz with gain margin
TO-126 thermal design	4 W power dissipation at 25°C case temperature allows direct mounting to aluminum heatsinks
Low output capacitance	3–4.5 pF Cob minimizes high-frequency roll-off and stabilizes feedback networks in video amps

Applications

TV Video Output Amplifier	High-Voltage Line Driver
Use Scenario: Amplifying composite video signals before driving coaxial cable or CRT grid inputs in analog television receivers. IC Role / Device Role / Timing Role: NPN transistor operating in common-emitter configuration to deliver 1–2 Vpp output swing at 5 MHz bandwidth. Use Value: High f_T (100 MHz) and low Cob (3–4.5 pF) preserve video rise time and minimize group delay distortion.	Use Scenario: Driving horizontal deflection yoke or flyback transformer primary windings in CRT-based displays. IC Role / Device Role / Timing Role: Switching transistor in self-oscillating or synchronized line-output stage with 250 V V_CEO headroom. Use Value: 250 V V_CEO and 4 W power handling allow safe operation under inductive kickback and pulse stress.
Video Signal Buffer	Medium-Power Analog Gain Stage
Use Scenario: Isolating and impedance-matching video DAC outputs to downstream filters or transmission lines. IC Role / Device Role / Timing Role: Emitter-follower configured as unity-gain buffer with low output impedance (~50 Ω). Use Value: Low V_CE(sat) (1.2 V) and high h_FE (≥40) ensure minimal DC offset and stable bias across temperature.	Use Scenario: Providing fixed-gain amplification in analog test equipment, oscilloscope vertical amplifiers, or signal generators. IC Role / Device Role / Timing Role: Linear amplifier biased in Class-A with V_CE ≈ 12–24 V and I_C ≈ 20–60 mA. Use Value: Stable h_FE and low Cob enable predictable midband gain and flat frequency response up to 10 MHz.

TV Video Output Amplifier

High-Voltage Line Driver

Use Scenario: Amplifying composite video signals before driving coaxial cable or CRT grid inputs in analog television receivers.

IC Role / Device Role / Timing Role: NPN transistor operating in common-emitter configuration to deliver 1–2 Vpp output swing at 5 MHz bandwidth.

Use Value: High f_T (100 MHz) and low Cob (3–4.5 pF) preserve video rise time and minimize group delay distortion.

Use Scenario: Driving horizontal deflection yoke or flyback transformer primary windings in CRT-based displays.

IC Role / Device Role / Timing Role: Switching transistor in self-oscillating or synchronized line-output stage with 250 V V_CEO headroom.

Use Value: 250 V V_CEO and 4 W power handling allow safe operation under inductive kickback and pulse stress.

Video Signal Buffer

Medium-Power Analog Gain Stage

Use Scenario: Isolating and impedance-matching video DAC outputs to downstream filters or transmission lines.

IC Role / Device Role / Timing Role: Emitter-follower configured as unity-gain buffer with low output impedance (~50 Ω).

Use Value: Low V_CE(sat) (1.2 V) and high h_FE (≥40) ensure minimal DC offset and stable bias across temperature.

Use Scenario: Providing fixed-gain amplification in analog test equipment, oscilloscope vertical amplifiers, or signal generators.

IC Role / Device Role / Timing Role: Linear amplifier biased in Class-A with V_CE ≈ 12–24 V and I_C ≈ 20–60 mA.

Use Value: Stable h_FE and low Cob enable predictable midband gain and flat frequency response up to 10 MHz.

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
MJE13005	V_CEO = 400 V, I_C = 1.5 A, P_C = 75 W, TO-220 - higher power but lower f_T (~4 MHz)	Used in SMPS power switches and high-current ballast drivers, not video bandwidth-critical roles	Select when higher voltage margin and power handling outweigh bandwidth needs
2SC3838	V_CEO = 250 V, I_C = 150 mA, f_T = 120 MHz, TO-126 - slightly higher current and bandwidth	Targeted for UHF/VHF RF amplifiers and fast-switching video sync circuits	Prefer when >100 mA continuous current or extended HF response beyond 100 MHz is required

Compared with MJE13005 and 2SC3838, the KSC2258STU offers optimal balance of 250 V breakdown, 100 MHz bandwidth, and TO-126 thermal performance for analog video output stages where fidelity and thermal manageability are prioritized over raw power or extreme RF capability.

Availability

KSC2258STU is available at Aetrix Electronics and suitable for TV video output amplifiers, high-voltage line drivers, video signal buffers, and medium-power analog gain stages requiring stable component supply and long-term industrial availability.

Supply support for KSC2258STU 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete devices before its acquisition by ON Semiconductor in 2016.

The KSC2258STU belongs to Fairchild's legacy high-voltage NPN transistor family, engineered specifically for analog video signal conditioning and CRT display subsystems in consumer and industrial equipment.

FAQ

What is the maximum collector-emitter voltage rating for KSC2258STU?

The KSC2258STU has a maximum collector-emitter voltage (V_CEO) rating of 250 V at T_C = 25°C. This rating is confirmed in the Absolute Maximum Ratings table of the official Fairchild datasheet Rev. A (February 2000). Exceeding this voltage risks avalanche breakdown and permanent device failure. Derating is required above 25°C case temperature per the power derating curve.

Is KSC2258STU suitable for video amplifier applications?

Yes, the KSC2258STU is explicitly designated as a "TV Video Output Amplifier" in its Fairchild datasheet. Its 100 MHz f_T, low output capacitance (3–4.5 pF), and stable h_FE make it well-suited for composite video signal amplification in analog television receivers and related video equipment where bandwidth and linearity are critical.

What package type does KSC2258STU use and how is it mounted?

KSC2258STU uses the TO-126 package, with pin 1 = Emitter, pin 2 = Collector (internally connected to the metal tab), and pin 3 = Base. The collector tab must be electrically isolated from the heatsink using mica or silicone insulator unless the heatsink is referenced to the collector potential. Mounting requires mechanical pressure and thermal compound for effective heat transfer.

What is the DC current gain (h_FE) of KSC2258STU under typical operating conditions?

The KSC2258STU exhibits h_FE ≥ 40 at V_CE = 20 V and I_C = 40 mA, as specified in the Electrical Characteristics table. At lower currents (I_C = 5 mA, V_CE = 50 V), h_FE drops to ≥30. These values are measured at T_C = 25°C and define the minimum guaranteed gain for bias design in linear amplifier or switching applications.

Does KSC2258STU have a documented replacement or second-source part?

No direct second-source or pin-compatible replacement is documented by Fairchild for KSC2258STU. However, the 2SC3838 (Toshiba) is a functionally comparable TO-126 NPN transistor with matching V_CEO (250 V), higher I_C (150 mA), and improved f_T (120 MHz), making it a viable alternative where layout revision is acceptable.

KSC2258STU Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: NPN

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

Voltage - Collector Emitter Breakdown (Max):: 250 V

Vce Saturation (Max) @ Ib, Ic:: 1.2V @ 5mA, 50mA

Current - Collector Cutoff (Max):: -

DC Current Gain (hFE) (Min) @ Ic, Vce:: 40 @ 40mA, 20V

Power - Max:: 4 W

Frequency - Transition:: 100MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-126-3

KSC2258STU FAQ

1.How can I place an order for KSC2258STU through Aetrix?

Please submit a Request for Quotation (RFQ) for KSC2258STU 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 KSC2258STU reliable?

The price and inventory of KSC2258STU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSC2258STU is usually 5 days.

3.What payment methods are accepted for KSC2258STU?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSC2258STU transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for KSC2258STU?

KSC2258STU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your KSC2258STU 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 KSC2258STU?

For technical support, including KSC2258STU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSC2258STU requirements.

6.How does Aetrix verify that KSC2258STU is sourced from the original manufacturer or authorized distributors?

All KSC2258STU 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 KSC2258STU meets industry standards.

7.What is the process for return or replacement of KSC2258STU?

All KSC2258STU units undergo pre-shipment inspection (PSI). If there is an issue with KSC2258STU, 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 KSC2258STU part is unused and in its original packaging.

Return procedure for KSC2258STU:

1.Submit a request within 90 days.

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

Tech Hub

2026-09-09 Counterfeit Electronic Components: How to Detect, Authenticate, and Test Suspect Parts

Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …

2026-09-08 Obsolete Electronic Components: How to Source and Evaluate Replacements

A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…