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

onsemi KSD1408YTU

Name: KSD1408YTU
Brand: onsemi
SKU: KSD1408YTU
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: KSD1408YTU

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-220-3 Full Pack

Datasheet:: KSD1408YTU.pdf

Description:: TRANS NPN 80V 4A TO-220F-3

Quantity:: RFQ Add To RFQ list

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Inventory:6,476

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Product details

Overview

KSD1408YTU from ON Semiconductor is an NPN epitaxial silicon power transistor in TO-220F package, rated for 80 V V_CEO, 4 A I_C, and 25 W P_C at T_C = 25°C, designed for linear and switching power amplifier applications where high current gain and low saturation voltage are required.

For engineers reviewing the KSD1408YTU datasheet, pinout, applications, or equivalent options, key selection criteria include verified DC current gain (h_FE1 = 40–80 at I_C = 0.5 A), V_CE(sat) ≤ 1.5 V at I_C = 3 A / I_B = 0.3 A, safe operating area robustness, complementary pairing with KSB1017, and TO-220F thermal performance under continuous conduction.

Technical Context

The KSD1408YTU operates as a medium-power NPN bipolar junction transistor optimized for audio and power amplifier output stages. Its design emphasizes high collector current capability (I_C = 4 A), low V_CE(sat) (≤1.5 V), and stable h_FE across 0.5–3 A collector current range - critical for Class AB amplifier biasing and thermal stability.

It features a TO-220F insulated package with electrically isolated collector tab, enabling direct heatsink mounting without insulating hardware. The device's f_T = 8 MHz and C_ob = 90 pF support mid-frequency power amplification up to several megahertz while maintaining switching integrity in PWM-driven applications.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	80 V - Maximum allowable collector-emitter voltage before breakdown; defines safe DC rail limit in amplifier or switch designs.
I_C	4 A - Continuous collector current rating; supports high-output audio stages and motor drive half-bridges.
P_C @ T_C=25°C	25 W - Thermal dissipation capacity at case temperature 25°C; requires heatsinking for sustained operation above ~10 W.
h_FE1	40–80 - DC current gain at V_CE = 5 V, I_C = 0.5 A; enables stable base drive design for linear amplifiers.
V_CE(sat)	≤1.5 V @ I_C = 3 A, I_B = 0.3 A - Low saturation voltage reduces conduction loss and improves efficiency in switching applications.
f_T	8 MHz - Current gain bandwidth product; confirms usable frequency response for audio and low-MHz switching.
C_ob	90 pF @ V_CB = 10 V - Output capacitance impacts switching speed and RF stability; relevant for snubber design and layout parasitics.

Pinout & Package

Package: TO-220F (insulated flange), with electrically isolated collector tab. Dimensions comply with JEDEC TO-220F standard; flange mounting requires no insulator when heatsink is grounded.

Pin/Terminal	Circuit Role	Design Meaning
1 (Base)	Control input	Receives base current to modulate collector current; requires current-limiting resistor in most driver circuits.
2 (Collector)	High-current output node	Electrically isolated via TO-220F flange; connects directly to heatsink and load return path without insulation.
3 (Emitter)	Reference terminal	Serves as common emitter node; typically tied to ground or low-side shunt in amplifier/switch configurations.

Key Features

Feature	Design Value
Complementary pairing	Explicitly designated complement to KSB1017 PNP transistor - enables matched push-pull amplifier stage design.
High current gain consistency	h_FE1 = 40–80 and h_FE2 = 15–240 across I_C = 0.5–3 A ensures predictable base drive requirements over operating range.
Low saturation voltage	V_CE(sat) ≤ 1.5 V at full-rated 3 A collector current minimizes power loss and thermal stress in switching mode.
Thermal robustness	Junction temperature rating of 150°C and derating curve allow reliable operation up to 125°C case temperature with proper heatsinking.

Applications

Audio Power Amplifier	DC Motor Driver Stage
Use Scenario: Output stage in Class AB audio amplifiers delivering 10–30 W into 4–8 Ω loads. IC Role / Device Role / Timing Role: NPN output transistor in complementary pair with KSB1017, handling positive half-cycle current delivery. Use Value: Low V_CE(sat) and stable h_FE reduce crossover distortion and improve thermal tracking with its PNP complement.	Use Scenario: High-side or low-side switch in brushed DC motor H-bridge driver modules. IC Role / Device Role / Timing Role: Medium-power switching transistor controlling motor current direction and magnitude in discrete driver IC alternatives. Use Value: 4 A I_C rating and 80 V V_CEO support 24 V industrial motors with surge margin; TO-220F isolation simplifies heatsink integration.
Linear Regulator Pass Element	Power Supply Switching Transistor
Use Scenario: Series pass transistor in adjustable linear regulators supplying up to 3 A load current. IC Role / Device Role / Timing Role: Voltage-controlled current source regulating output by dissipating excess input-output differential voltage. Use Value: 25 W P_C and 150°C T_J enable stable operation under worst-case dropout conditions with active heatsinking.	Use Scenario: Discrete switch in offline flyback or forward converter primary side where integrated controllers lack sufficient current drive. IC Role / Device Role / Timing Role: Fast-switching NPN transistor gated by optocoupler-isolated driver for isolated feedback control. Use Value: f_T = 8 MHz and low C_ob support clean turn-off behavior at ≤100 kHz switching frequencies with minimal snubber demand.

Audio Power Amplifier

DC Motor Driver Stage

Use Scenario: Output stage in Class AB audio amplifiers delivering 10–30 W into 4–8 Ω loads.

IC Role / Device Role / Timing Role: NPN output transistor in complementary pair with KSB1017, handling positive half-cycle current delivery.

Use Value: Low V_CE(sat) and stable h_FE reduce crossover distortion and improve thermal tracking with its PNP complement.

Use Scenario: High-side or low-side switch in brushed DC motor H-bridge driver modules.

IC Role / Device Role / Timing Role: Medium-power switching transistor controlling motor current direction and magnitude in discrete driver IC alternatives.

Use Value: 4 A I_C rating and 80 V V_CEO support 24 V industrial motors with surge margin; TO-220F isolation simplifies heatsink integration.

Linear Regulator Pass Element

Power Supply Switching Transistor

Use Scenario: Series pass transistor in adjustable linear regulators supplying up to 3 A load current.

IC Role / Device Role / Timing Role: Voltage-controlled current source regulating output by dissipating excess input-output differential voltage.

Use Value: 25 W P_C and 150°C T_J enable stable operation under worst-case dropout conditions with active heatsinking.

Use Scenario: Discrete switch in offline flyback or forward converter primary side where integrated controllers lack sufficient current drive.

IC Role / Device Role / Timing Role: Fast-switching NPN transistor gated by optocoupler-isolated driver for isolated feedback control.

Use Value: f_T = 8 MHz and low C_ob support clean turn-off behavior at ≤100 kHz switching frequencies with minimal snubber demand.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD127G	V_CEO = 100 V, I_C = 2 A, h_FE = 30–120, TO-263 package	Lower current rating but higher voltage margin; surface-mount instead of through-hole	Preferred for space-constrained PCBs requiring ≥100 V breakdown; not drop-in due to package and pinout mismatch.
2SC5200	V_CEO = 230 V, I_C = 15 A, h_FE = 80–240, TO-3P package	Higher voltage/current ratings; larger thermal mass and different pinout	Used in high-fidelity amplifiers needing >100 W output; requires mechanical redesign and increased heatsink capacity.

Compared with MJD127G and 2SC5200, the KSD1408YTU offers balanced 80 V/4 A capability in a cost-effective TO-220F through-hole package with proven thermal interface and complementary pairing - making it optimal for mid-power discrete amplifier and motor control designs where layout simplicity and thermal reliability are prioritized over extreme voltage or current scaling.

Availability

KSD1408YTU is available at Aetrix Electronics and suitable for audio power amplifiers, DC motor drivers, and linear regulator pass elements requiring stable component supply, consistent parametric binning, and long-term industrial availability.

Supply support for KSD1408YTU 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

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power management, analog, sensor, and logic solutions for automotive, industrial, and consumer markets.

The KSD1408YTU belongs to ON Semiconductor's legacy Fairchild power transistor portfolio, engineered for discrete audio and power conversion applications demanding ruggedness, thermal stability, and complementary device matching.

FAQ

What is the pin configuration of the KSD1408YTU?

The KSD1408YTU uses a standard TO-220F three-terminal configuration: Pin 1 is Base, Pin 2 is Collector (electrically isolated via insulated flange), and Pin 3 is Emitter. This arrangement is confirmed in the official ON Semiconductor datasheet revision A and matches JEDEC TO-220F mechanical drawings. Layout must respect the isolated collector tab to avoid shorting when mounted to grounded heatsinks.

Is the KSD1408YTU RoHS compliant?

Yes, the KSD1408YTU is RoHS compliant per ON Semiconductor's product compliance documentation. It meets Directive 2011/65/EU requirements for restricted hazardous substances, including lead-free terminations and halogen-free molding compound. Compliance status is verified under ON Semiconductor's standardized material declaration process and applies to all currently shipped lots.

What is the maximum safe operating temperature for the KSD1408YTU?

The KSD1408YTU has a maximum junction temperature (T_J) of 150°C and a storage temperature range of –55°C to +150°C. For reliable long-term operation, case temperature should be limited to ≤125°C with appropriate heatsinking, as shown in the published power derating curve. Exceeding 150°C T_J risks permanent degradation of h_FE and increased leakage currents.

Does the KSD1408YTU have a specified avalanche rating?

No, the KSD1408YTU datasheet does not specify an avalanche energy rating (E_AS) or repetitive avalanche capability. It is not characterized or guaranteed for unclamped inductive switching. Designers must implement external clamping (e.g., snubbers or TVS diodes) when used in inductive load switching to prevent secondary breakdown beyond the SOA limits defined in the datasheet.

How does the KSD1408YTU compare to the KSD1408 (without 'YTU' suffix)?

The KSD1408YTU is the updated ON Semiconductor part number replacing the original Fairchild KSD1408 following the Fairchild integration. The 'YTU' suffix denotes tape-and-reel packaging and updated manufacturing traceability; electrically and mechanically, KSD1408YTU is identical to KSD1408 - same die, TO-220F package, absolute maximum ratings, and electrical characteristics per Rev. A datasheet.

KSD1408YTU Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-220-3 Full Pack

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: NPN

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

Voltage - Collector Emitter Breakdown (Max):: 80 V

Vce Saturation (Max) @ Ib, Ic:: 1.5V @ 300mA, 3A

Current - Collector Cutoff (Max):: 30µA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 120 @ 500mA, 5V

Power - Max:: 25 W

Frequency - Transition:: 8MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220F-3

KSD1408YTU FAQ

1.How can I place an order for KSD1408YTU through Aetrix?

Please submit a Request for Quotation (RFQ) for KSD1408YTU 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 KSD1408YTU reliable?

The price and inventory of KSD1408YTU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSD1408YTU is usually 5 days.

3.What payment methods are accepted for KSD1408YTU?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSD1408YTU transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for KSD1408YTU?

KSD1408YTU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your KSD1408YTU 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 KSD1408YTU?

For technical support, including KSD1408YTU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSD1408YTU requirements.

6.How does Aetrix verify that KSD1408YTU is sourced from the original manufacturer or authorized distributors?

All KSD1408YTU 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 KSD1408YTU meets industry standards.

7.What is the process for return or replacement of KSD1408YTU?

All KSD1408YTU units undergo pre-shipment inspection (PSI). If there is an issue with KSD1408YTU, 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 KSD1408YTU part is unused and in its original packaging.

Return procedure for KSD1408YTU:

1.Submit a request within 90 days.

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

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