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

onsemi KSB744AYSTU

Name: KSB744AYSTU
Brand: onsemi
SKU: KSB744AYSTU
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: KSB744AYSTU

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: KSB744AYSTU.pdf

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

Quantity:: RFQ Add To RFQ list

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Product details

Overview

KSB744AYSTU from ON Semiconductor (formerly Fairchild) is a PNP epitaxial silicon power transistor designed for audio frequency amplification and switching in medium-power linear and saturated applications. It features V_CEO = −60 V, I_C = −3 A DC, P_C = 10 W at T_C = 25°C, h_FE = 100–200 (Class O), and f_T = 45 MHz - used in complementary push-pull output stages of audio amplifiers.

For engineers reviewing the KSB744AYSTU datasheet, pinout, applications, or equivalent options, key selection criteria include its −60 V V_CEO, TO-126 package thermal performance, Class O h_FE binning, saturation voltage behavior at high current, and complementary pairing with KSD794A NPN transistors.

Technical Context

This device operates as a medium-power PNP bipolar junction transistor optimized for linear amplification and hard-switching. Its design emphasizes low V_CE(sat) (−0.5 V @ I_C = −1.5 A, I_B = −0.15 A) and stable h_FE across collector currents from 20 mA to 0.5 A, supporting consistent gain in Class AB audio output stages.

The KSB744AYSTU is specified for operation up to T_J = 150°C with safe operating area (SOA) defined for both DC and pulsed conditions (10 ms, 50% duty cycle). Its Cob = 60 pF at V_CB = −10 V enables predictable high-frequency roll-off in audio band-limited designs.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−60 V - Maximum sustainable collector-emitter voltage before breakdown in common-emitter configuration; defines rail voltage headroom in amplifier output stages.
I_C (DC)	−3 A - Continuous collector current rating; sets maximum linear output capability without thermal runaway under heatsinked conditions.
P_C (T_C=25°C)	10 W - Power dissipation limit at case temperature 25°C; requires thermal interface design for real-world PCB mounting.
h_FE (Class O)	100–200 - DC current gain binning range at V_CE = −5 V, I_C = −0.5 A; ensures matched gain with complementary KSD794A in push-pull pairs.
f_T	45 MHz - Current gain bandwidth product at V_CE = −5 V, I_C = −0.1 A; supports stable audio band amplification with margin into RF interference region.
V_CE(sat)	−0.5 V @ I_C = −1.5 A, I_B = −0.15 A - Low saturation voltage minimizes conduction loss and heat generation in switching or saturated-mode operation.
C_ob	60 pF @ V_CB = −10 V, f = 1 MHz - Output capacitance affecting high-frequency stability and Miller effect in amplifier feedback networks.

Pinout & Package

Package: TO-126 - Three-lead, through-hole plastic power package with integral metal tab for heatsinking; lead spacing 2.28 mm, body height 14.20 mm max, tab diameter ø3.20 mm.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal in PNP configuration	Connected to positive supply rail in common-emitter amplifier; polarity reversal critical for correct biasing.
2 (Collector)	Main current output terminal	Electrically connected to heatsink tab; must be isolated from chassis unless circuit ground reference permits.
3 (Base)	Control input for minority-carrier injection	Requires negative base drive relative to emitter; base resistor sizing determined by h_FE bin and target I_C.

Key Features

Feature	Design Value
Complementary pair designation	Explicitly engineered as PNP counterpart to KSD794A NPN; matched V_CEO, I_C, and h_FE ranges enable symmetrical push-pull stage design.
Class O h_FE binning	Guaranteed 100–200 h_FE at I_C = −0.5 A; reduces gain mismatch in dual-transistor output stages and simplifies bias network calibration.
High SOA at pulse conditions	Rated for I_C(Pulse) = −5 A (PW ≤ 10 ms, duty ≤ 50%); supports transient overload handling in audio clipping or motor drive surge events.
Low V_CE(sat) at high current	−0.5 V at −1.5 A collector current; directly lowers power loss and thermal stress compared to general-purpose PNP transistors with >−1.0 V saturation.

Applications

Audio Power Amplifier Output Stage	DC Motor Driver (Half-Bridge)
Use Scenario: Complementary push-pull output stage in 10–20 W discrete audio amplifiers. IC Role / Device Role / Timing Role: PNP power switch providing current sourcing during positive half-cycle of audio signal. Use Value: Matched h_FE and V_CEO with KSD794A minimizes crossover distortion; low V_CE(sat) improves efficiency and thermal margin.	Use Scenario: High-side switch in brushed DC motor control with PWM frequencies < 20 kHz. IC Role / Device Role / Timing Role: PNP-based high-side driver enabling bidirectional motor control when paired with NPN low-side switch. Use Value: −60 V V_CEO accommodates 48 V motor rails with safety margin; TO-126 tab allows direct heatsinking to chassis.
Linear Voltage Regulator Pass Element	Relay/LED Driver Interface
Use Scenario: Series pass transistor in adjustable linear regulators delivering up to 2 A load current. IC Role / Device Role / Timing Role: Current-controlled series element regulating output voltage via base-emitter bias network. Use Value: 10 W P_C at T_C = 25°C supports continuous operation at 2 A × 5 V dropout without forced cooling.	Use Scenario: High-current interface between microcontroller GPIO and 12 V relay coil or LED string. IC Role / Device Role / Timing Role: Saturated PNP switch sinking up to −3 A to activate inductive or resistive loads. Use Value: −0.5 V V_CE(sat) limits power dissipation to < 1.5 W at 3 A, reducing need for external flyback protection in relay drive.

Audio Power Amplifier Output Stage

DC Motor Driver (Half-Bridge)

Use Scenario: Complementary push-pull output stage in 10–20 W discrete audio amplifiers.

IC Role / Device Role / Timing Role: PNP power switch providing current sourcing during positive half-cycle of audio signal.

Use Value: Matched h_FE and V_CEO with KSD794A minimizes crossover distortion; low V_CE(sat) improves efficiency and thermal margin.

Use Scenario: High-side switch in brushed DC motor control with PWM frequencies < 20 kHz.

IC Role / Device Role / Timing Role: PNP-based high-side driver enabling bidirectional motor control when paired with NPN low-side switch.

Use Value: −60 V V_CEO accommodates 48 V motor rails with safety margin; TO-126 tab allows direct heatsinking to chassis.

Linear Voltage Regulator Pass Element

Relay/LED Driver Interface

Use Scenario: Series pass transistor in adjustable linear regulators delivering up to 2 A load current.

IC Role / Device Role / Timing Role: Current-controlled series element regulating output voltage via base-emitter bias network.

Use Value: 10 W P_C at T_C = 25°C supports continuous operation at 2 A × 5 V dropout without forced cooling.

Use Scenario: High-current interface between microcontroller GPIO and 12 V relay coil or LED string.

IC Role / Device Role / Timing Role: Saturated PNP switch sinking up to −3 A to activate inductive or resistive loads.

Use Value: −0.5 V V_CE(sat) limits power dissipation to < 1.5 W at 3 A, reducing need for external flyback protection in relay drive.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD700RL	TO-252 (DPAK) surface-mount package; V_CEO = −60 V, I_C = −2 A, h_FE = 25–250 (unbinned).	Not pin-compatible; requires PCB redesign; lower I_C rating limits peak power handling.	Select when automated SMT assembly is required and thermal design accommodates lower P_C (1.5 W @ T_A).
KSB884YTU	Same TO-126 package; V_CEO = −120 V, I_C = −3 A, h_FE = 100–200 (Class O), but f_T = 30 MHz.	Higher voltage rating increases cost and may degrade switching speed; suitable where bus overvoltage margin > 60 V is mandated.	Select only if system-level fault tolerance requires > −60 V V_CEO; otherwise KSB744AYSTU offers better f_T/cost balance for audio use.

Compared with MJD700RL and KSB884YTU, the KSB744AYSTU delivers optimal combination of through-hole manufacturability, −60 V/−3 A rating, Class O h_FE consistency, and 45 MHz f_T - making it the preferred choice for cost-sensitive, thermally managed audio and industrial linear amplifier designs.

Availability

KSB744AYSTU is available at Aetrix Electronics and suitable for audio power amplifiers, DC motor drivers, linear voltage regulators, and relay interface circuits requiring stable component supply and long-term industrial availability.

Supply support for KSB744AYSTU 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 supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The KSB744AYSTU belongs to Fairchild's legacy audio power transistor family, engineered specifically for high-fidelity linear amplification and robust switching in consumer and industrial analog systems.

FAQ

What is the guaranteed h_FE range for KSB744AYSTU?

The KSB744AYSTU is binned to Class O, guaranteeing h_FE = 100–200 when measured at V_CE = −5 V and I_C = −0.5 A. This binning ensures predictable gain matching with complementary KSD794A transistors in push-pull amplifier configurations. The KSB744AYSTU datasheet confirms this range under standard test conditions and does not extend it to other current or voltage points.

Is KSB744AYSTU pin-compatible with KSB744Y or KSB744A?

Yes - KSB744AYSTU uses the same TO-126 package and identical pinout (1: Emitter, 2: Collector, 3: Base) as all KSB744 and KSB744A variants. The "Y" suffix denotes Class O h_FE binning, and "A" indicates −60 V V_CEO rating; "YSTU" adds tape-and-reel packaging. Electrically and mechanically, the KSB744AYSTU is fully interchangeable with KSB744AY and KSB744A in existing designs.

What is the maximum allowable case temperature for continuous operation of KSB744AYSTU?

The KSB744AYSTU has a maximum junction temperature of 150°C and is rated for 10 W collector dissipation at T_C = 25°C. Its derating curve shows linear reduction to zero dissipation at T_C ≈ 175°C. For reliable continuous operation, keep T_C ≤ 125°C - achievable with appropriate heatsinking. The KSB744AYSTU datasheet Figure 8 provides exact derating values per degree above 25°C.

Can KSB744AYSTU replace KSB744 in an existing design?

Yes - KSB744AYSTU supersedes KSB744 with improved V_CEO (−60 V vs. −45 V) and tighter h_FE binning (Class O). All absolute maximum ratings, electrical characteristics, and package dimensions remain compatible. No layout or bias changes are needed; the KSB744AYSTU delivers enhanced voltage margin and more consistent gain, making it a drop-in upgrade for any design originally specifying KSB744 or KSB744A.

Does KSB744AYSTU require a heatsink in typical audio amplifier applications?

Yes - although KSB744AYSTU is rated for 10 W at T_C = 25°C, real-world audio amplifier output stages operate with dynamic power dissipation and ambient temperatures >25°C. Without a heatsink, the TO-126 case temperature will exceed safe limits under sustained 1–2 A load. A minimum 2°C/W heatsink is recommended for continuous 1.5 A operation. The KSB744AYSTU thermal resistance data confirms this requirement in its Safe Operating Area curves.

KSB744AYSTU Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: PNP

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:: 45MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-126-3

KSB744AYSTU FAQ

1.How can I place an order for KSB744AYSTU through Aetrix?

Please submit a Request for Quotation (RFQ) for KSB744AYSTU 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 KSB744AYSTU reliable?

The price and inventory of KSB744AYSTU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSB744AYSTU is usually 5 days.

3.What payment methods are accepted for KSB744AYSTU?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSB744AYSTU transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for KSB744AYSTU?

KSB744AYSTU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your KSB744AYSTU 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 KSB744AYSTU?

For technical support, including KSB744AYSTU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSB744AYSTU requirements.

6.How does Aetrix verify that KSB744AYSTU is sourced from the original manufacturer or authorized distributors?

All KSB744AYSTU 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 KSB744AYSTU meets industry standards.

7.What is the process for return or replacement of KSB744AYSTU?

All KSB744AYSTU units undergo pre-shipment inspection (PSI). If there is an issue with KSB744AYSTU, 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 KSB744AYSTU part is unused and in its original packaging.

Return procedure for KSB744AYSTU:

1.Submit a request within 90 days.

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

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