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

onsemi KSC2518O

Name: KSC2518O
Brand: onsemi
SKU: KSC2518O
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: KSC2518O

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-220-3

Datasheet:: KSC2518O.pdf

Description:: TRANS NPN 400V 4A TO-220-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

KSC2518O from Fairchild Semiconductor is an NPN epitaxial silicon power transistor designed for high-voltage, high-speed switching in inductive load applications such as horizontal deflection circuits in CRT displays and SMPS snubber stages. It supports 400 V V_CEO, 4 A DC collector current, 40 W power dissipation at T_C = 25°C, and achieves 1 µs turn-on time with 0.7 µs fall time under specified pulsed conditions.

For engineers reviewing the KSC2518O datasheet, pinout, applications, or equivalent options, key selection criteria include reverse-biased SOA validation under clamped inductive switching, V_CE(sat) ≤ 1 V at I_C = 1.5 A / I_B = 0.3 A, and TO-220 package thermal performance up to 150°C junction temperature.

Technical Context

The KSC2518O operates as a single NPN bipolar junction transistor optimized for fast switching in high-voltage linearity-critical circuits. Its design incorporates epitaxial base construction and process tuning to sustain 400 V in both forward- and reverse-biased SOA modes, with validated clamped inductive turn-off at 125°C case temperature using 180 µH loads.

It delivers low saturation voltages (V_CE(sat) = 1 V, V_BE(sat) = 1.5 V) at I_C/I_B = 5, enabling efficient drive in self-oscillating or pulse-width modulated topologies. The device's 1 µs t_ON, 2.5 µs t_STG, and 0.7 µs t_F are measured under standardized pulsed conditions (V_CC = 150 V, R_L = 75 Ω, I_B1 = –I_B2 = 0.4 A).

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	400 V - Maximum continuous collector-emitter voltage before breakdown under open-base condition
I_C (DC)	4 A - Sustained collector current capability with heatsink at T_C = 25°C
P_C	40 W - Maximum steady-state power dissipation at case temperature of 25°C
V_CE(sat)	1 V - Low on-state voltage drop at I_C = 1.5 A, I_B = 0.3 A, minimizing conduction loss
t_F	0.7 µs - Fast fall time enabling high-frequency switching up to ~500 kHz in hard-switched topologies
hFE1	30–60 - DC current gain range at V_CE = 5 V, I_C = 0.3 A, supporting stable base drive design
T_J	150 °C - Maximum allowable junction temperature, defining thermal derating envelope

Pinout & Package

Package: TO-220 (3-lead, straight lead, insulated tab). Standard through-hole mounting with metal tab electrically connected to collector.

Pin/Terminal	Circuit Role	Design Meaning
1 (Base)	Control electrode	Receives forward bias current to initiate conduction; requires ≥0.3 A for full saturation at 1.5 A collector load
2 (Collector)	High-voltage output node	Connected to metal tab; rated for 400 V blocking and 4 A DC; primary heat path to heatsink
3 (Emitter)	Current return path	Low-impedance emitter connection; referenced to ground or negative rail in common-emitter configuration

Key Features

Feature	Design Value
Reverse-biased SOA rating	Validated at 450 V (V_CEX(sus)1) with clamped 180 µH inductive load at 125°C case temperature
Low V_CE(sat)	1 V maximum at I_C = 1.5 A / I_B = 0.3 A, reducing conduction losses in high-duty-cycle operation
Fast switching	1 µs t_ON, 2.5 µs t_STG, 0.7 µs t_F under standardized pulsed test conditions
High-voltage ruggedness	Rated for 500 V V_CBO and 400 V V_CEO, supporting CRT flyback and industrial HV supply designs

Applications

Horizontal Deflection Output Stage	SMPS Snubber Switch
Use Scenario: Horizontal output stage in CRT television and monitor deflection systems requiring repetitive 15.734 kHz switching into highly inductive yoke loads. IC Role / Device Role / Timing Role: Main switching transistor handling peak currents up to 8 A (pulsed), clamping energy during retrace via external diode/resistor network. Use Value: Reverse-biased SOA rating (450 V @ 125°C) ensures reliable operation under worst-case inductive kickback without secondary breakdown.	Use Scenario: Active snubber switch in offline flyback or forward converters operating above 200 V input, dissipating stored inductor energy during MOSFET dead time. IC Role / Device Role / Timing Role: Bipolar switch triggered synchronously with main FET gate signal to clamp voltage spikes and recover energy. Use Value: 1 µs t_ON and 0.7 µs t_F enable precise timing alignment with primary switch transitions, minimizing overlap loss.
Industrial HV Power Supply	Ultrasonic Generator Driver
Use Scenario: Series-pass or switching element in regulated 300–400 V DC industrial power supplies powering motor drives or plasma generators. IC Role / Device Role / Timing Role: High-voltage series regulator or hard-switched chopper controlling output voltage via base current modulation. Use Value: 400 V V_CEO and 4 A I_C support direct operation across full rectified AC line peaks without cascading devices.	Use Scenario: Half-bridge driver stage in ultrasonic cleaning or welding generators operating at 20–40 kHz with reactive piezoelectric loads. IC Role / Device Role / Timing Role: Complementary NPN switch in totem-pole output stage delivering high peak current pulses to resonant tank. Use Value: Low V_CE(sat) (1 V) and high hFE (30–60) reduce base drive requirements and improve efficiency at 2–5 A peak load currents.

Horizontal Deflection Output Stage

SMPS Snubber Switch

Use Scenario: Horizontal output stage in CRT television and monitor deflection systems requiring repetitive 15.734 kHz switching into highly inductive yoke loads.

IC Role / Device Role / Timing Role: Main switching transistor handling peak currents up to 8 A (pulsed), clamping energy during retrace via external diode/resistor network.

Use Value: Reverse-biased SOA rating (450 V @ 125°C) ensures reliable operation under worst-case inductive kickback without secondary breakdown.

Use Scenario: Active snubber switch in offline flyback or forward converters operating above 200 V input, dissipating stored inductor energy during MOSFET dead time.

IC Role / Device Role / Timing Role: Bipolar switch triggered synchronously with main FET gate signal to clamp voltage spikes and recover energy.

Use Value: 1 µs t_ON and 0.7 µs t_F enable precise timing alignment with primary switch transitions, minimizing overlap loss.

Industrial HV Power Supply

Ultrasonic Generator Driver

Use Scenario: Series-pass or switching element in regulated 300–400 V DC industrial power supplies powering motor drives or plasma generators.

IC Role / Device Role / Timing Role: High-voltage series regulator or hard-switched chopper controlling output voltage via base current modulation.

Use Value: 400 V V_CEO and 4 A I_C support direct operation across full rectified AC line peaks without cascading devices.

Use Scenario: Half-bridge driver stage in ultrasonic cleaning or welding generators operating at 20–40 kHz with reactive piezoelectric loads.

IC Role / Device Role / Timing Role: Complementary NPN switch in totem-pole output stage delivering high peak current pulses to resonant tank.

Use Value: Low V_CE(sat) (1 V) and high hFE (30–60) reduce base drive requirements and improve efficiency at 2–5 A peak load currents.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD253	V_CEO = 300 V, P_C = 30 W, TO-252 package, lower SOA robustness under clamped inductive stress	Not rated for 400 V sustained operation; unsuitable for CRT horizontal output or 400 V bus SMPS snubbers	Select only for <300 V DC-link applications where thermal constraints allow surface-mount layout
2SC5200	V_CEO = 230 V, I_C = 15 A, higher current but lower voltage rating; different hFE distribution and SOA profile	Designed for audio amplifier output stages, not optimized for fast HV switching or reverse SOA	Use only in linear or low-frequency (<100 kHz) high-current applications; avoid in clamped inductive switching

Compared with MJD253 and 2SC5200, the KSC2518O uniquely combines 400 V V_CEO, validated reverse-biased SOA at elevated temperature, and sub-microsecond switching-making it irreplaceable in CRT deflection and high-voltage snubber roles where voltage margin and inductive ruggedness are non-negotiable.

Availability

KSC2518O is available at Aetrix Electronics and suitable for horizontal deflection circuits, SMPS snubber stages, industrial HV power supplies, and ultrasonic generator drivers requiring stable component supply and long-term obsolescence management.

Supply support for KSC2518O 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 discrete devices, analog ICs, and interface solutions before its acquisition by ON Semiconductor in 2016.

The KSC2518O belongs to Fairchild's high-voltage bipolar transistor family engineered specifically for CRT horizontal deflection and high-reliability inductive switching applications demanding rugged SOA and fast transient response.

FAQ

What is the maximum collector-emitter voltage rating for the KSC2518O?

The KSC2518O has a maximum collector-emitter voltage rating (V_CEO) of 400 V under open-base conditions at T_C = 25°C. This rating is confirmed in the Absolute Maximum Ratings table and supported by sustaining voltage tests (V_CEO(sus) = 400 V at I_C = 2 A, I_B1 = 0.4 A). Operation beyond this voltage risks avalanche breakdown or secondary breakdown, especially under inductive loads.

Does the KSC2518O have a documented reverse-biased safe operating area?

Yes, the KSC2518O includes a fully characterized reverse-biased SOA in its datasheet, with V_CEX(sus)1 = 450 V specified at T_a = 125°C, I_C = 2 A, I_B1 = –I_B2 = 0.4 A, and L = 180 µH clamped. This makes the KSC2518O suitable for applications involving inductive turn-off stress, such as CRT horizontal deflection and active snubbers.

What is the pin configuration of the KSC2518O in its TO-220 package?

The KSC2518O uses a standard TO-220 package with three leads: Pin 1 is Base, Pin 2 is Collector (connected to the metal tab), and Pin 3 is Emitter. This configuration is explicitly shown in the "1.Base 2.Collector 3.Emitter" note and verified in the mechanical drawing. The collector-tab connection mandates electrical isolation when mounting to heatsinks.

What is the typical DC current gain (hFE) range for the KSC2518O?

The KSC2518O is classified as "O" grade, with hFE1 (measured at V_CE = 5 V, I_C = 0.3 A) ranging from 30 to 60. This gain band is confirmed in the hFE Classification table and enables predictable base drive design for saturation in high-voltage switching applications without excessive overdrive.

Can the KSC2518O be used in place of the KSC2518 without modification?

Yes-the KSC2518O is the "O"-grade variant of the KSC2518 family, differing only in hFE binning (30–60 vs. "R": 20–40, "Y": 40–80). All absolute maximum ratings, SOA curves, switching times, and package dimensions are identical between KSC2518 and KSC2518O. No PCB or circuit changes are required when substituting KSC2518O for KSC2518.

KSC2518O Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-220-3

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 4 A

Voltage - Collector Emitter Breakdown (Max):: 400 V

Vce Saturation (Max) @ Ib, Ic:: 1V @ 300mA, 1.5A

Current - Collector Cutoff (Max):: 10µA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 30 @ 300mA, 5V

Power - Max:: 40 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220-3

KSC2518O FAQ

1.How can I place an order for KSC2518O through Aetrix?

Please submit a Request for Quotation (RFQ) for KSC2518O 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 KSC2518O reliable?

The price and inventory of KSC2518O are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSC2518O is usually 5 days.

3.What payment methods are accepted for KSC2518O?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSC2518O transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for KSC2518O?

KSC2518O orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your KSC2518O 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 KSC2518O?

For technical support, including KSC2518O datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSC2518O requirements.

6.How does Aetrix verify that KSC2518O is sourced from the original manufacturer or authorized distributors?

All KSC2518O 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 KSC2518O meets industry standards.

7.What is the process for return or replacement of KSC2518O?

All KSC2518O units undergo pre-shipment inspection (PSI). If there is an issue with KSC2518O, 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 KSC2518O part is unused and in its original packaging.

Return procedure for KSC2518O:

1.Submit a request within 90 days.

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

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