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

onsemi KSD794AYSTU

Name: KSD794AYSTU
Brand: onsemi
SKU: KSD794AYSTU
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: KSD794AYSTU

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: KSD794AYSTU.pdf

Description:: TRANS NPN 60V 3A TO-126-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

KSD794AYSTU from ON Semiconductor is an NPN epitaxial silicon power transistor in TO-126 package, rated for 60 V V_CEO, 3 A DC collector current, and 10 W collector dissipation at T_C = 25°C, designed for audio frequency power amplification stages in consumer audio systems and linear power supply regulators.

For engineers reviewing the KSD794AYSTU datasheet, pinout, applications, or equivalent options, key selection criteria include V_CEO rating, h_FE classification (Y-grade: 160–320), saturation voltage at 1.5 A, safe operating area limits, and thermal derating behavior above 25°C case temperature.

Technical Context

The KSD794AYSTU operates as a linear-mode NPN bipolar junction transistor with complementary pairing to KSB744A. Its design supports Class AB audio output stages and series pass regulation where low V_CE(sat) (≤0.3 V typ. at I_C = 1.5 A, I_B = 0.15 A) and high h_FE (160–320 at I_C = 0.5 A) enable efficient current sourcing with minimal base drive overhead.

It features f_T = 60 MHz at V_CE = 5 V, I_E = 0.1 A, supporting stable operation up to mid-audio frequencies without unintended oscillation; Cob = 40 pF at V_CB = 10 V ensures predictable Miller effect in amplifier feedback networks.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	60 V - Maximum collector-emitter voltage before breakdown under open-base conditions; defines safe headroom in 48 V rail applications.
I_C (DC)	3 A - Continuous collector current capability at 25°C ambient; sets upper bound for steady-state load handling.
P_C (T_C=25°C)	10 W - Thermal power limit at case temperature of 25°C; requires heatsinking for sustained >1 W operation.
h_FE2	160–320 - DC current gain at V_CE = 5 V, I_C = 0.5 A; enables low-base-current biasing in driver stages.
V_CE(sat)	0.3 V (typ.) - Collector-emitter voltage drop at I_C = 1.5 A, I_B = 0.15 A; minimizes conduction loss in linear regulators.
f_T	60 MHz - Current gain bandwidth product; ensures adequate gain margin for stable audio-frequency amplification.
C_ob	40 pF - Output capacitance at V_CB = 10 V; influences high-frequency stability and slew rate in feedback loops.

Pinout & Package

Package: TO-126, through-hole, 3-pin, epoxy-molded plastic with metal tab (collector-connected). Dimensions per Fairchild Rev. A1: 16.10 × 13.06 × 4.2 mm (L × W × H), mounting hole Ø3.20 mm.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Emitter terminal	Low-impedance current return path; connected to ground or negative rail in common-emitter configurations.
2 (Collector)	Collector terminal	Main current output node; electrically tied to metal tab for thermal conduction and electrical connection in PCB layout.
3 (Base)	Base control terminal	Current-controlled input; requires external resistor network to set I_B for desired I_C and operating point stability.

Key Features

Feature	Design Value
Complementary pair to KSB744A	Enables matched push-pull output stages in audio amplifiers without gain or thermal mismatch concerns.
Y-class h_FE2 binning	Guarantees h_FE ≥160 at I_C = 0.5 A, reducing variation in bias current across production batches.
10 W power dissipation at T_C = 25°C	Supports medium-power linear applications without forced-air cooling when mounted on ≥25 cm² copper area.
Low V_CE(sat) (0.3 V typ.)	Reduces conduction loss by >40% vs. standard general-purpose transistors at 1.5 A, improving thermal efficiency.
TO-126 mechanical robustness	Withstands >5 kgf mounting torque and meets JEDEC JESD22-A108 reliability standards for solder joint integrity.

Applications

Audio Power Amplifier Output Stage	Linear Voltage Regulator Pass Element
Use Scenario: Final output stage in 10–20 W Class AB home audio amplifiers driving 4–8 Ω speakers. IC Role / Device Role / Timing Role: NPN power switch providing current gain and voltage swing; biased in active region for analog signal reproduction. Use Value: High h_FE (160–320) reduces driver-stage loading; low V_CE(sat) preserves output voltage headroom and minimizes heat generation.	Use Scenario: Series pass transistor in adjustable 3–24 V, 1–2 A linear regulators for test equipment power supplies. IC Role / Device Role / Timing Role: Continuously variable resistive element controlled by error amplifier feedback loop. Use Value: 60 V V_CEO allows 48 V input-to-24 V output designs; 10 W P_C supports full-load operation with modest heatsinking.
DC Motor Speed Controller	High-Current Switching Interface
Use Scenario: Unidirectional PWM-driven 12 V/2 A brushed DC motor in industrial actuators. IC Role / Device Role / Timing Role: Low-frequency switching transistor operating in saturation/cutoff, not linear mode. Use Value: 5 A pulsed I_CP handles motor inrush; TO-126 tab enables direct heatsink attachment for intermittent 2 A duty cycles.	Use Scenario: Level-shifting interface between 3.3 V microcontroller GPIO and 12 V solenoid load. IC Role / Device Role / Timing Role: Digital switch turning on/off inverter coils or relay drivers with <10 µs response. Use Value: f_T = 60 MHz ensures fast turn-on/turn-off; Cob = 40 pF avoids excessive capacitive loading on MCU pins.

Audio Power Amplifier Output Stage

Linear Voltage Regulator Pass Element

Use Scenario: Final output stage in 10–20 W Class AB home audio amplifiers driving 4–8 Ω speakers.

IC Role / Device Role / Timing Role: NPN power switch providing current gain and voltage swing; biased in active region for analog signal reproduction.

Use Value: High h_FE (160–320) reduces driver-stage loading; low V_CE(sat) preserves output voltage headroom and minimizes heat generation.

Use Scenario: Series pass transistor in adjustable 3–24 V, 1–2 A linear regulators for test equipment power supplies.

IC Role / Device Role / Timing Role: Continuously variable resistive element controlled by error amplifier feedback loop.

Use Value: 60 V V_CEO allows 48 V input-to-24 V output designs; 10 W P_C supports full-load operation with modest heatsinking.

DC Motor Speed Controller

High-Current Switching Interface

Use Scenario: Unidirectional PWM-driven 12 V/2 A brushed DC motor in industrial actuators.

IC Role / Device Role / Timing Role: Low-frequency switching transistor operating in saturation/cutoff, not linear mode.

Use Value: 5 A pulsed I_CP handles motor inrush; TO-126 tab enables direct heatsink attachment for intermittent 2 A duty cycles.

Use Scenario: Level-shifting interface between 3.3 V microcontroller GPIO and 12 V solenoid load.

IC Role / Device Role / Timing Role: Digital switch turning on/off inverter coils or relay drivers with <10 µs response.

Use Value: f_T = 60 MHz ensures fast turn-on/turn-off; Cob = 40 pF avoids excessive capacitive loading on MCU pins.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD794A	Different package (TO-252/DPAK); lower P_C (1.5 W @ T_A); same V_CEO/I_C/h_FE specs.	Suitable for surface-mount designs with limited board space; not interchangeable without layout change.	Select MJD794A only if SMT assembly and thermal management via PCB copper are preferred over through-hole heatsinking.
KSC2690A	Higher V_CEO (80 V); lower h_FE (60–120); same TO-126 package and pinout.	Better for 60–72 V input rails but requires higher base drive; less suitable for low-distortion audio due to lower gain linearity.	Choose KSC2690A when extended voltage margin is critical and gain consistency is secondary to breakdown safety.

Compared with KSD794AYSTU, MJD794A trades mechanical robustness and thermal capacity for SMT compatibility, while KSC2690A prioritizes voltage headroom over gain uniformity-making KSD794AYSTU optimal for cost-sensitive, thermally demanding audio and regulator applications requiring tight h_FE control.

Availability

KSD794AYSTU is available at Aetrix Electronics and suitable for audio power amplifiers, linear voltage regulators, and DC motor controllers requiring stable component supply, consistent h_FE binning, and proven TO-126 thermal performance.

Supply support for KSD794AYSTU 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, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The KSD794AYSTU belongs to ON Semiconductor's legacy Fairchild bipolar power transistor family, engineered for high-fidelity audio amplification and robust linear regulation where gain consistency, saturation voltage, and thermal reliability are primary design constraints.

FAQ

What is the maximum continuous collector current for KSD794AYSTU?

The KSD794AYSTU supports a maximum DC collector current of 3 A at T_A = 25°C. This rating assumes adequate heatsinking and derates linearly above 25°C case temperature per the published derating curve. At T_C = 100°C, the usable I_C drops to approximately 1.5 A. Always verify thermal design using the SOA graph in the KSD794AYSTU datasheet for pulsed or transient loads.

Is KSD794AYSTU pin-compatible with KSD794Y?

Yes, KSD794AYSTU is pin-compatible with KSD794Y and other KSD794-series variants in TO-126 package. All share identical pinout (1: Emitter, 2: Collector, 3: Base) and mechanical footprint. However, KSD794AYSTU specifies V_CEO = 60 V (vs. 45 V for KSD794), so substitution into existing KSD794 designs is safe only if voltage stress remains below 45 V.

What does the 'Y' suffix indicate in KSD794AYSTU?

The 'Y' in KSD794AYSTU denotes the h_FE2 gain bin: 160–320 at V_CE = 5 V and I_C = 0.5 A. This high-gain classification ensures tighter current gain distribution versus 'R' (60–120) or 'O' (100–200) bins, making KSD794AYSTU especially suitable for low-base-drive amplifier stages where bias stability matters.

Can KSD794AYSTU be used in switching applications?

Yes, KSD794AYSTU can operate in switching mode (saturation/cutoff) for low-frequency (<10 kHz) applications like motor control or relay driving. Its 5 A pulsed collector current and 0.3 V typical V_CE(sat) support efficient on-state conduction. However, its f_T = 60 MHz and Cob = 40 pF make it less optimal than dedicated switching transistors for >100 kHz PWM due to slower turn-off and higher switching losses.

Does KSD794AYSTU have a built-in emitter resistor or protection diode?

No, KSD794AYSTU is a bare NPN bipolar transistor with no integrated emitter resistor, base-emitter clamp diode, or thermal shutdown circuitry. External components-including base current limiting resistors, emitter degeneration resistors, and flyback diodes for inductive loads-must be added per application requirements. Refer to the KSD794AYSTU Safe Operating Area chart to avoid second breakdown during transient overloads.

KSD794AYSTU Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Tube

Product Status:: Last Time Buy

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 3 A

Voltage - Collector Emitter Breakdown (Max):: 60 V

Vce Saturation (Max) @ Ib, Ic:: 2V @ 150mA, 1.5A

Current - Collector Cutoff (Max):: 1µA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 160 @ 500mA, 5V

Power - Max:: 1 W

Frequency - Transition:: 60MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-126-3

KSD794AYSTU FAQ

1.How can I place an order for KSD794AYSTU through Aetrix?

Please submit a Request for Quotation (RFQ) for KSD794AYSTU 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 KSD794AYSTU reliable?

The price and inventory of KSD794AYSTU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSD794AYSTU is usually 5 days.

3.What payment methods are accepted for KSD794AYSTU?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSD794AYSTU transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for KSD794AYSTU?

KSD794AYSTU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your KSD794AYSTU 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 KSD794AYSTU?

For technical support, including KSD794AYSTU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSD794AYSTU requirements.

6.How does Aetrix verify that KSD794AYSTU is sourced from the original manufacturer or authorized distributors?

All KSD794AYSTU 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 KSD794AYSTU meets industry standards.

7.What is the process for return or replacement of KSD794AYSTU?

All KSD794AYSTU units undergo pre-shipment inspection (PSI). If there is an issue with KSD794AYSTU, 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 KSD794AYSTU part is unused and in its original packaging.

Return procedure for KSD794AYSTU:

1.Submit a request within 90 days.

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

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