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

onsemi KSP76BU

Name: KSP76BU
Brand: onsemi
SKU: KSP76BU
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: KSP76BU

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 (TO-226AA)

Datasheet:: KSP76BU.pdf

Description:: TRANS PNP DARL 50V 0.5A TO-92-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

KSP76BU from Fairchild Semiconductor is a PNP epitaxial silicon Darlington transistor optimized for medium-power switching and amplification in industrial control and power management circuits, featuring V_CEO = −50 V, I_C = −500 mA, P_C = 625 mW, h_FE ≥ 10,000 at I_C = −10 mA, and V_CE(sat) = −1.5 V at I_C = −100 mA. It operates reliably up to T_J = 150 °C and is housed in a TO-92 package.

For engineers reviewing the KSP76BU datasheet, pinout, applications, or equivalent options, this page delivers verified electrical parameters, terminal roles, thermal limits, safe operating area context, and validated alternative transistors for high-gain PNP Darlington switching in relay drivers, lamp controls, and low-frequency power stages.

Technical Context

The KSP76BU integrates two cascaded PNP bipolar junction transistors in a monolithic Darlington configuration, delivering ultra-high DC current gain (h_FE ≥ 10,000) with single-base control. Its V_CEO rating of −50 V supports operation in 48 V DC systems and industrial logic-level interfacing.

Designed for linear and saturated switching, it exhibits V_BE(on) = 2.0 V at I_C = −100 mA and maintains low leakage: I_CBO ≤ −100 nA at V_CE = −40 V, enabling stable biasing in temperature-varying environments up to 150 °C junction temperature.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−50 V: Maximum collector-emitter voltage before breakdown under open-base condition; enables use in 48 V supply rails.
I_C	−500 mA: Continuous collector current rating; supports driving relays, solenoids, and indicator lamps.
P_C	625 mW: Maximum power dissipation at T_A = 25 °C; requires heatsinking above ~200 mW in enclosed enclosures.
h_FE	≥10,000 at I_C = −10 mA: High current gain reduces required base drive current-e.g., <1 µA base current suffices for 10 mA collector load.
V_CE(sat)	−1.5 V at I_C = −100 mA, I_B = −0.1 mA: Low saturation voltage minimizes conduction loss in switching applications.
T_J(max)	150 °C: Maximum junction temperature; allows operation in industrial ambient environments up to 85 °C with appropriate derating.

Pinout & Package

Package: TO-92 - 3-lead through-hole plastic package with standard lead spacing (1.27 mm pitch), 4.58 mm height, and 3.60 mm body width; suitable for wave soldering and manual assembly.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current source terminal for PNP Darlington pair	Connected to positive rail in high-side switch configurations; must be referenced to system ground via load.
2 (Base)	Control input for both internal transistors	Receives low-current logic-level signal; requires current-limiting resistor to prevent overdrive and thermal runaway.
3 (Collector)	Current sink terminal	Connected to load (e.g., relay coil or lamp anode); pulled low when device is on, sourcing current from emitter.

Key Features

Feature	Design Value
Ultra-high DC current gain	h_FE ≥ 10,000 at I_C = −10 mA enables microampere-level base drive for milliampere loads.
Low V_CE(sat)	−1.5 V at I_C = −100 mA ensures <150 mW conduction loss, reducing thermal stress in sustained ON states.
High V_CEO rating	−50 V withstand capability supports direct interface with 48 V industrial buses without external clamping.
Robust thermal performance	150 °C max junction temperature and −55 °C to +150 °C storage range suit wide-temperature industrial deployments.

Applications

Relay Driver Circuit	Lamp/LED Power Switch
Use Scenario: Driving 24–48 V DC electromagnetic relays in PLC output modules and motor starter panels. IC Role / Device Role / Timing Role: High-gain PNP Darlington switch providing galvanically isolated, low-drive-current interface between microcontroller GPIO and relay coil. Use Value: Eliminates need for external driver transistors or optocouplers; single KSP76BU replaces discrete BJT pairs while maintaining <1 µA base current requirement.	Use Scenario: Controlling incandescent lamps, LED arrays, or halogen lighting in building automation and signage systems. IC Role / Device Role / Timing Role: Medium-power current sink switch placed between lamp cathode and ground, activated by logic-level signals. Use Value: V_CE(sat) = −1.5 V limits power loss to <150 mW at 100 mA, preventing thermal shutdown during continuous illumination cycles.
DC Motor Speed Control	Industrial Sensor Interface
Use Scenario: Low-frequency PWM-based speed regulation of small brushed DC motors in HVAC actuators and valve positioners. IC Role / Device Role / Timing Role: Saturated-switching element in the low-side path of H-bridge or single-direction motor driver stage. Use Value: High h_FE allows direct MCU GPIO drive without buffer ICs; −50 V V_CEO accommodates back-EMF spikes up to 40 V.	Use Scenario: Level-shifting and current amplification for analog sensor outputs (e.g., thermistor bridges, pressure transducers) feeding ADC inputs. IC Role / Device Role / Timing Role: Linear-mode amplifier configured as emitter follower to provide low-impedance buffered output. Use Value: Stable h_FE and low I_CBO (<100 nA) ensure minimal offset drift across −40 °C to +85 °C operating range.

Relay Driver Circuit

Lamp/LED Power Switch

Use Scenario: Driving 24–48 V DC electromagnetic relays in PLC output modules and motor starter panels.

IC Role / Device Role / Timing Role: High-gain PNP Darlington switch providing galvanically isolated, low-drive-current interface between microcontroller GPIO and relay coil.

Use Value: Eliminates need for external driver transistors or optocouplers; single KSP76BU replaces discrete BJT pairs while maintaining <1 µA base current requirement.

Use Scenario: Controlling incandescent lamps, LED arrays, or halogen lighting in building automation and signage systems.

IC Role / Device Role / Timing Role: Medium-power current sink switch placed between lamp cathode and ground, activated by logic-level signals.

Use Value: V_CE(sat) = −1.5 V limits power loss to <150 mW at 100 mA, preventing thermal shutdown during continuous illumination cycles.

DC Motor Speed Control

Industrial Sensor Interface

Use Scenario: Low-frequency PWM-based speed regulation of small brushed DC motors in HVAC actuators and valve positioners.

IC Role / Device Role / Timing Role: Saturated-switching element in the low-side path of H-bridge or single-direction motor driver stage.

Use Value: High h_FE allows direct MCU GPIO drive without buffer ICs; −50 V V_CEO accommodates back-EMF spikes up to 40 V.

Use Scenario: Level-shifting and current amplification for analog sensor outputs (e.g., thermistor bridges, pressure transducers) feeding ADC inputs.

IC Role / Device Role / Timing Role: Linear-mode amplifier configured as emitter follower to provide low-impedance buffered output.

Use Value: Stable h_FE and low I_CBO (<100 nA) ensure minimal offset drift across −40 °C to +85 °C operating range.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MPSA56	V_CEO = −80 V, h_FE = 100–300 (standard BJT, not Darlington), P_C = 625 mW	Lower gain requires higher base drive; better for fast-switching where Darlington delay is unacceptable	Select when switching speed >10 kHz is needed and gain >100 suffices
PN2907A	V_CEO = −60 V, h_FE = 100–300, P_C = 625 mW, TO-92	Non-Darlington architecture yields faster turn-off but demands ~10× more base current than KSP76BU	Prefer for cost-sensitive designs where base drive capability is ample and propagation delay matters

Compared with MPSA56 and PN2907A, the KSP76BU provides 30–100× higher DC gain and lower base drive burden, making it optimal for microcontroller-driven low-speed switching where thermal margin and simplicity outweigh speed requirements.

Availability

KSP76BU is available at Aetrix Electronics and suitable for industrial control, relay interfacing, and lamp switching applications requiring stable component supply, long-lifecycle support, and consistent parametric performance across production batches.

Supply support for KSP76BU 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 designer and manufacturer of analog and discrete semiconductors, acquired by ON Semiconductor in 2016; its legacy products remain widely deployed in industrial and automotive systems.

The KSP76BU belongs to the KSP75/76/77 family of PNP Darlington transistors engineered for high-current gain, medium-voltage switching, and robust thermal operation in factory automation, power supplies, and electromechanical control systems.

FAQ

What is the maximum collector-emitter voltage rating for the KSP76BU?

The KSP76BU has a guaranteed V_CEO (collector-emitter breakdown voltage) of −50 V at I_C = −100 µA with open base. This rating is confirmed in the Fairchild datasheet Rev. A1 (July 2001) and defines the absolute maximum voltage the device can block in common-emitter configuration without avalanche conduction. Exceeding −50 V risks irreversible breakdown and permanent damage to the KSP76BU.

Does the KSP76BU require a base resistor, and what value is recommended?

Yes, the KSP76BU requires an external base resistor to limit base current and prevent thermal runaway. For reliable saturation at I_C = −100 mA, a 4.7 kΩ resistor is typical when driven from a 5 V logic source (I_B ≈ −0.1 mA). The exact value depends on drive voltage and desired collector current; always verify I_B/I_C ratio ≥ 1/1000 per the KSP76BU's Darlington structure.

Is the KSP76BU pin-compatible with other TO-92 PNP transistors like the 2N3906?

No-the KSP76BU uses E-B-C pinout (Emitter=Pin1, Base=Pin2, Collector=Pin3), whereas the 2N3906 uses E-C-B (Emitter=Pin1, Collector=Pin2, Base=Pin3). Swapping them without board revision causes functional failure. Always confirm pin assignment using the official KSP76BU datasheet diagram-not generic TO-92 assumptions-before PCB layout or replacement.

Can the KSP76BU be used in linear amplifier mode, not just switching?

Yes, the KSP76BU can operate in linear (active) mode as an emitter-follower or common-emitter amplifier, provided V_CE remains within safe operating area limits and power dissipation stays below 625 mW with proper derating. Its high h_FE and low I_CBO support stable biasing, but frequency response is limited by Darlington capacitance-suitable for DC to ~100 kHz applications only.

What is the junction-to-ambient thermal resistance (R_θJA) for the KSP76BU in TO-92 package?

The Fairchild KSP76BU datasheet does not specify R_θJA explicitly, but typical TO-92 packages with similar construction exhibit R_θJA ≈ 200 °C/W under still-air conditions. For the KSP76BU operating at 300 mW, this implies ~60 °C rise above ambient-requiring board-level copper pour or airflow if ambient exceeds 65 °C. Derate power linearly above 25 °C per the datasheet's thermal curve.

KSP76BU Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 (TO-226AA)

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: PNP - Darlington

Current - Collector (Ic) (Max):: 500 mA

Voltage - Collector Emitter Breakdown (Max):: 50 V

Vce Saturation (Max) @ Ib, Ic:: 1.5V @ 100µA, 100mA

Current - Collector Cutoff (Max):: 500nA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 10000 @ 100mA, 5V

Power - Max:: 625 mW

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

KSP76BU FAQ

1.How can I place an order for KSP76BU through Aetrix?

Please submit a Request for Quotation (RFQ) for KSP76BU 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 KSP76BU reliable?

The price and inventory of KSP76BU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSP76BU is usually 5 days.

3.What payment methods are accepted for KSP76BU?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSP76BU transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for KSP76BU?

KSP76BU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your KSP76BU 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 KSP76BU?

For technical support, including KSP76BU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSP76BU requirements.

6.How does Aetrix verify that KSP76BU is sourced from the original manufacturer or authorized distributors?

All KSP76BU 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 KSP76BU meets industry standards.

7.What is the process for return or replacement of KSP76BU?

All KSP76BU units undergo pre-shipment inspection (PSI). If there is an issue with KSP76BU, 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 KSP76BU part is unused and in its original packaging.

Return procedure for KSP76BU:

1.Submit a request within 90 days.

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

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