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

onsemi KSE701STU

Name: KSE701STU
Brand: onsemi
SKU: KSE701STU
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: KSE701STU

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: KSE701STU.pdf

Description:: TRANS PNP DARL 60V 4A TO-126-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

KSE701STU from Fairchild Semiconductor is a PNP epitaxial silicon Darlington transistor in TO-126 package, rated for -60 V V_CEO, -4 A I_C, 40 W P_C at T_C=25°C, with h_FE ≥750 at I_C = -1.5 A and V_CE = -3 V, used in high-current linear amplification and relay driver stages.

For engineers reviewing the KSE701STU datasheet, pinout, applications, or equivalent options, key selection criteria include verified DC current gain at high collector current, built-in base-emitter resistors (R1 ≈10 kΩ, R2 ≈0.6 kΩ), saturation voltage under specified drive conditions, thermal derating behavior, and complementary pairing with KSE801 series.

Technical Context

The KSE701STU integrates monolithic Darlington structure with on-chip base-emitter resistors to simplify biasing and improve turn-off speed. Its architecture delivers high h_FE (≥750) at I_C = -1.5 A while maintaining V_CE(sat) ≤ -2.5 V under I_C = -1.5 A / I_B = -30 mA drive.

It operates as a single-ended PNP power switch with fixed internal resistor network enabling direct TTL/CMOS-compatible drive. Junction temperature rating of 150°C and SOA-defined safe operating limits support continuous conduction in industrial control loads.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	-60 V - Maximum allowable collector-emitter voltage before breakdown in open-base configuration
I_C	-4 A - Continuous DC collector current capability at case temperature ≤25°C
P_C	40 W - Maximum power dissipation at T_C = 25°C; derates linearly above 25°C per published curve
h_FE	≥750 - Minimum DC current gain at V_CE = -3 V, I_C = -1.5 A, ensuring low base drive requirement
V_CE(sat)	≤ -2.5 V - Collector-emitter saturation voltage at I_C = -1.5 A, I_B = -30 mA, defining conduction loss in switching mode
R1 / R2	≈10 kΩ / ≈0.6 kΩ - Integrated base-emitter resistors enabling self-biasing and reducing external component count

Pinout & Package

Package: TO-126 (3-lead, through-hole, thermally enhanced plastic). Case outline matches JEDEC TO-126 standard with emitter (pin 1), collector (pin 2), base (pin 3) arrangement.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Emitter terminal of PNP Darlington pair	Common reference node for current sourcing; connected to positive rail in high-side switch configurations
2 (Collector)	Collector terminal of PNP Darlington pair	Output node carrying load current; requires heatsinking when dissipating >5 W
3 (Base)	Input control terminal with integrated resistive network	Accepts logic-level drive; internal R1/R2 enable direct connection to microcontroller GPIO without external bias resistors

Key Features

Feature	Design Value
Monolithic Darlington construction	Integrates two PNP transistors and base-emitter resistors on one die, eliminating discrete assembly and improving matching/reliability
High h_FE at medium current	Guarantees ≥750 gain at I_C = -1.5 A, reducing required base drive current by >90% vs. single-stage PNP
Built-in base-emitter resistors	R1 ≈10 kΩ and R2 ≈0.6 kΩ provide stable turn-on/turn-off biasing, eliminating need for external base resistors in most applications
Complementary to KSE801 series	Enables matched push-pull or H-bridge output stages with NPN counterpart KSE801STU for symmetrical drive capability

Applications

Motor Drive Stage	Relay Driver Circuit
Use Scenario: Driving 24 V DC solenoid valves or small DC motors in programmable logic controller (PLC) output modules. IC Role / Device Role / Timing Role: High-current PNP switch providing load current sourcing from positive rail to grounded load. Use Value: Built-in R1/R2 allows direct interface with 3.3 V/5 V microcontroller outputs; V_CE(sat) ≤ -2.5 V ensures <1.5 W conduction loss at 1.5 A load.	Use Scenario: Controlling industrial electromechanical relays requiring ≥100 mA coil current in building automation panels. IC Role / Device Role / Timing Role: Single-transistor relay driver replacing discrete BJT + base resistor combinations. Use Value: h_FE ≥750 enables full relay activation with ≤200 µA MCU GPIO current, reducing firmware overhead and PCB area.
Linear Amplifier Stage	High-Side Power Switch
Use Scenario: Low-frequency audio or sensor signal amplification in analog front-end circuits where low noise and high gain are critical. IC Role / Device Role / Timing Role: Class-A linear amplifier core delivering stable DC-coupled gain with minimal thermal drift. Use Value: Junction temperature limit of 150°C supports sustained operation at elevated ambient; V_CEO = -60 V accommodates supply rails up to ±24 V.	Use Scenario: Enabling/disabling 12–24 V power rails in test equipment power supplies with reverse-polarity protection. IC Role / Device Role / Timing Role: High-side switch controlling power delivery to downstream circuitry via emitter-follower configuration. Use Value: TO-126 package provides mechanical stability and thermal path to heatsink; ICEO ≤ -100 µA ensures low leakage during standby.

Motor Drive Stage

Relay Driver Circuit

Use Scenario: Driving 24 V DC solenoid valves or small DC motors in programmable logic controller (PLC) output modules.

IC Role / Device Role / Timing Role: High-current PNP switch providing load current sourcing from positive rail to grounded load.

Use Value: Built-in R1/R2 allows direct interface with 3.3 V/5 V microcontroller outputs; V_CE(sat) ≤ -2.5 V ensures <1.5 W conduction loss at 1.5 A load.

Use Scenario: Controlling industrial electromechanical relays requiring ≥100 mA coil current in building automation panels.

IC Role / Device Role / Timing Role: Single-transistor relay driver replacing discrete BJT + base resistor combinations.

Use Value: h_FE ≥750 enables full relay activation with ≤200 µA MCU GPIO current, reducing firmware overhead and PCB area.

Linear Amplifier Stage

High-Side Power Switch

Use Scenario: Low-frequency audio or sensor signal amplification in analog front-end circuits where low noise and high gain are critical.

IC Role / Device Role / Timing Role: Class-A linear amplifier core delivering stable DC-coupled gain with minimal thermal drift.

Use Value: Junction temperature limit of 150°C supports sustained operation at elevated ambient; V_CEO = -60 V accommodates supply rails up to ±24 V.

Use Scenario: Enabling/disabling 12–24 V power rails in test equipment power supplies with reverse-polarity protection.

IC Role / Device Role / Timing Role: High-side switch controlling power delivery to downstream circuitry via emitter-follower configuration.

Use Value: TO-126 package provides mechanical stability and thermal path to heatsink; ICEO ≤ -100 µA ensures low leakage during standby.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD701T4	TO-252 (DPAK) surface-mount package; identical V_CEO/I_C/h_FE specs but no integrated base resistors	Requires external base bias network; suited for automated SMT assembly rather than through-hole prototyping	Select when board space is constrained and reflow compatibility is required; verify external R_B values for target I_B
KSE801STU	NPN complement with same package, voltage/current ratings, and integrated resistors; not electrically interchangeable	Used in push-pull or complementary symmetry circuits only; cannot replace KSE701STU in single-ended PNP roles	Choose only for dual-rail output stages where matched NPN/PNP pairs are needed

Compared with MJD701T4 and KSE801STU, the KSE701STU uniquely combines through-hole TO-126 mounting, integrated bias resistors, and guaranteed high h_FE at 1.5 A-making it optimal for manual assembly, low-component-count relay drivers, and legacy industrial designs requiring proven reliability.

Availability

KSE701STU is available at Aetrix Electronics and suitable for motor drive stages, relay driver circuits, linear amplifier stages, and high-side power switches requiring stable component supply across long-lifecycle industrial programs.

Supply support for KSE701STU 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 components before its acquisition by ON Semiconductor in 2016.

The KSE701STU belongs to Fairchild's legacy high-voltage PNP Darlington transistor family, designed specifically for robust, low-complexity switching and amplification in industrial control, power supply, and automation equipment.

FAQ

What is the maximum junction temperature rating for the KSE701STU?

The KSE701STU has a maximum junction temperature (T_J) rating of 150°C, as specified in the Absolute Maximum Ratings table. This defines the upper thermal limit for reliable operation. Exceeding this temperature risks permanent degradation of the Darlington structure. Thermal design must ensure that actual T_J remains below 150°C under worst-case ambient and power dissipation conditions, using the published power derating curve.

Does the KSE701STU require external base resistors for operation?

No, the KSE701STU does not require external base resistors because it integrates R1 ≈10 kΩ and R2 ≈0.6 kΩ internally. These resistors provide automatic biasing for turn-on and assist in turn-off by shunting stored base charge. This feature allows direct connection to logic-level sources such as microcontroller GPIO pins, simplifying circuit design and reducing component count compared to discrete BJT solutions.

Is the KSE701STU pin-compatible with other devices in the KSE700 series?

Yes, the KSE701STU shares identical TO-126 pinout (Emitter–Collector–Base) and mechanical footprint with KSE700STU, KSE702STU, and KSE703STU. However, electrical differences exist: KSE700/701 have V_CEO = -60 V, while KSE702/703 are rated for -80 V. Substituting across this group requires verification of voltage margin in the target application.

What is the typical V_CE(sat) of the KSE701STU under standard test conditions?

The KSE701STU has a maximum V_CE(sat) of -2.5 V when tested at I_C = -1.5 A and I_B = -30 mA, per the Electrical Characteristics table. This value reflects conduction loss in saturated switching mode. At higher currents (e.g., I_C = -4 A), V_CE(sat) increases to -3.0 V, so thermal management must account for increased power dissipation in high-current operation.

Can the KSE701STU be used as a direct replacement for the KSE700STU?

Yes, the KSE701STU can serve as a functional replacement for the KSE700STU in most applications, as both share identical package, pinout, V_CEO, V_CBO, I_C, and h_FE specifications. The primary distinction lies in their position within the family matrix: KSE700/701 are rated for -60 V, while KSE702/703 are -80 V variants. No layout or schematic changes are needed when substituting KSE701STU for KSE700STU.

KSE701STU Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: PNP - Darlington

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

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

Vce Saturation (Max) @ Ib, Ic:: 2.8V @ 40mA, 2A

Current - Collector Cutoff (Max):: 100µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 750 @ 2A, 3V

Power - Max:: 40 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-126-3

KSE701STU FAQ

1.How can I place an order for KSE701STU through Aetrix?

Please submit a Request for Quotation (RFQ) for KSE701STU 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 KSE701STU reliable?

The price and inventory of KSE701STU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSE701STU is usually 5 days.

3.What payment methods are accepted for KSE701STU?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSE701STU transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for KSE701STU?

KSE701STU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your KSE701STU 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 KSE701STU?

For technical support, including KSE701STU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSE701STU requirements.

6.How does Aetrix verify that KSE701STU is sourced from the original manufacturer or authorized distributors?

All KSE701STU 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 KSE701STU meets industry standards.

7.What is the process for return or replacement of KSE701STU?

All KSE701STU units undergo pre-shipment inspection (PSI). If there is an issue with KSE701STU, 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 KSE701STU part is unused and in its original packaging.

Return procedure for KSE701STU:

1.Submit a request within 90 days.

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

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