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

onsemi KSD261CGTA

Name: KSD261CGTA
Brand: onsemi
SKU: KSD261CGTA
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: KSD261CGTA

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: KSD261CGTA.pdf

Description:: TRANS NPN 20V 0.5A TO-92-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

KSD261CGTA from ON Semiconductor is an NPN epitaxial silicon transistor designed for low-frequency power amplification, with V_CEO = 20 V, I_C = 500 mA, P_C = 500 mW, and h_FE ranging 120–400 (Y/G classification). It features center-collector TO-92 packaging and serves in audio preamplifier stages, relay drivers, and DC power control circuits.

For engineers reviewing the KSD261CGTA datasheet, pinout, applications, or equivalent options, key selection criteria include its 20 V collector-emitter breakdown voltage, 500 mA continuous collector current rating, center-collector lead configuration, thermal resistance of 250 °C/W, and suitability for linear amplification below 100 kHz.

Technical Context

The KSD261CGTA operates as a general-purpose bipolar junction transistor optimized for low-frequency analog and switching applications. Its structure uses epitaxial base technology to achieve stable h_FE across temperature and bias conditions, with guaranteed minimum h_FE of 120 at I_C = 100 mA and V_CE = 1 V.

It exhibits low saturation voltage (V_CE(sat) ≤ 0.40 V at I_C = 500 mA, I_B = 50 mA) and minimal leakage (I_CBO ≤ 0.1 μA at V_CB = 25 V), supporting reliable operation in Class-A amplifier stages and saturated-switching configurations where gain linearity and turn-on efficiency are critical.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	20 V - Maximum safe collector-emitter voltage before avalanche breakdown; defines usable supply headroom in low-voltage amplifier designs.
I_C	500 mA - Continuous collector current rating; supports medium-power drive capability for relays, small solenoids, and audio output stages.
P_C	500 mW - Total package power dissipation limit at T_A = 25 °C; requires thermal derating above ambient or heatsinking for sustained loads.
h_FE	120–400 - DC current gain range across Y/G classifications; enables predictable biasing in fixed-gain amplifier topologies without feedback trimming.
V_CE(sat)	0.18–0.40 V - Low saturation voltage at full rated current; minimizes conduction loss and self-heating in switching applications.
R_θJA	250 °C/W - Junction-to-ambient thermal resistance on standard FR-4 PCB; informs thermal design margin for continuous operation near P_C limit.

Pinout & Package

Package: TO-92 3L molded plastic case with center-collector configuration (Pin 1: Emitter, Pin 2: Collector, Pin 3: Base), supplied in ammo packing.

Pin/Terminal	Circuit Role	Design Meaning
1	Emitter	Current exit terminal; connects to ground or low-impedance return path in common-emitter configurations.
2	Collector	Current entry terminal; ties to load or positive supply rail; center position enables symmetric PCB layout in TO-92 footprint.
3	Base	Control input; accepts current-limited drive (e.g., via resistor from microcontroller GPIO) to modulate collector current.

Key Features

Feature	Design Value
Low-frequency power amplification	Optimized for <100 kHz operation with stable h_FE and low distortion in Class-A audio preamp stages.
Center-collector TO-92 pinout	Pin 1 = Emitter, Pin 2 = Collector, Pin 3 = Base - simplifies PCB routing symmetry and reduces trace inductance in high-gain stages.
Complementary pairing	Designed as NPN counterpart to KSA643 PNP transistor, enabling push-pull output stages with matched gain and thermal behavior.
Low saturation voltage	V_CE(sat) ≤ 0.40 V at I_C = 500 mA - ensures efficient switching in relay driver and LED current-source applications.

Applications

Audio Preamp Stage	Relay Driver Circuit
Use Scenario: Amplifying weak microphone or line-level signals before ADC sampling or further processing in consumer audio equipment. IC Role / Device Role / Timing Role: NPN transistor configured in common-emitter topology providing 20–30 dB voltage gain with minimal harmonic distortion. Use Value: Stable h_FE and low V_CE(sat) ensure consistent gain across production units and low DC offset at output node.	Use Scenario: Driving electromagnetic relays (e.g., 12 V/500 mA coil) from microcontroller GPIO pins in industrial control panels. IC Role / Device Role / Timing Role: Saturated switch controlling relay coil current; base driven through current-limiting resistor. Use Value: 500 mA I_C rating and 0.40 V max V_CE(sat) minimize power loss and heat generation during extended on-time.
DC Power Control	LED Current Source
Use Scenario: Regulating 5–12 V DC power delivery to peripheral modules using emitter-follower configuration with feedback. IC Role / Device Role / Timing Role: Linear pass element in adjustable LDO-like topology; base voltage set by resistive divider or DAC output. Use Value: 20 V V_CEO allows headroom for input transients; 500 mW P_C supports up to ~400 mA at 1.2 V dropout without heatsink.	Use Scenario: Providing constant-current drive for indicator or status LEDs in automotive dashboards or appliance interfaces. IC Role / Device Role / Timing Role: Current-regulating transistor in two-resistor emitter-bias configuration with fixed base voltage reference. Use Value: Tight h_FE binning (Y/G) ensures repeatable LED brightness across batches without individual calibration.

Audio Preamp Stage

Relay Driver Circuit

Use Scenario: Amplifying weak microphone or line-level signals before ADC sampling or further processing in consumer audio equipment.

IC Role / Device Role / Timing Role: NPN transistor configured in common-emitter topology providing 20–30 dB voltage gain with minimal harmonic distortion.

Use Value: Stable h_FE and low V_CE(sat) ensure consistent gain across production units and low DC offset at output node.

Use Scenario: Driving electromagnetic relays (e.g., 12 V/500 mA coil) from microcontroller GPIO pins in industrial control panels.

IC Role / Device Role / Timing Role: Saturated switch controlling relay coil current; base driven through current-limiting resistor.

Use Value: 500 mA I_C rating and 0.40 V max V_CE(sat) minimize power loss and heat generation during extended on-time.

DC Power Control

LED Current Source

Use Scenario: Regulating 5–12 V DC power delivery to peripheral modules using emitter-follower configuration with feedback.

IC Role / Device Role / Timing Role: Linear pass element in adjustable LDO-like topology; base voltage set by resistive divider or DAC output.

Use Value: 20 V V_CEO allows headroom for input transients; 500 mW P_C supports up to ~400 mA at 1.2 V dropout without heatsink.

Use Scenario: Providing constant-current drive for indicator or status LEDs in automotive dashboards or appliance interfaces.

IC Role / Device Role / Timing Role: Current-regulating transistor in two-resistor emitter-bias configuration with fixed base voltage reference.

Use Value: Tight h_FE binning (Y/G) ensures repeatable LED brightness across batches without individual calibration.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MPSA13	Higher h_FE (50–250 typical), same TO-92 package but side-collector pinout (1-E, 2-B, 3-C); V_CEO = 30 V, P_C = 625 mW.	Not pin-compatible due to different pin assignment; requires PCB layout revision if replacing KSD261CGTA.	Select when higher gain and voltage margin are needed, and board redesign is acceptable.
KSC1845FTA	Same center-collector TO-92 pinout (1-E, 2-C, 3-B); V_CEO = 20 V, I_C = 500 mA, but h_FE = 70–240 and P_C = 625 mW.	Direct pinout match enables drop-in replacement; lower h_FE min may require base drive adjustment.	Preferred for mechanical compatibility and improved power margin; verify gain stability under target bias conditions.

Compared with MPSA13 and KSC1845FTA, the KSD261CGTA offers guaranteed h_FE ≥120 in Y-grade and center-collector layout optimized for symmetrical PCB routing, while KSC1845FTA provides higher power margin and pinout compatibility, and MPSA13 delivers greater voltage headroom at the cost of layout change.

Availability

KSD261CGTA is available at Aetrix Electronics and suitable for audio preamplifiers, relay drivers, and DC power control circuits requiring stable component supply, consistent h_FE binning, and TO-92 mechanical compatibility.

Supply support for KSD261CGTA 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, cloud, and consumer markets.

The KSD261CGTA belongs to ON Semiconductor's legacy general-purpose bipolar transistor product line, originally developed by Fairchild Semiconductor to serve cost-sensitive, low-frequency linear and switching applications in mass-market electronics.

FAQ

What is the pin configuration of the KSD261CGTA?

The KSD261CGTA uses a center-collector TO-92 package with pinout: Pin 1 = Emitter, Pin 2 = Collector, Pin 3 = Base. This configuration is explicitly indicated by the "-C" suffix in the part number and confirmed in the official datasheet's physical dimensions diagram and ordering information table. The KSD261CGTA differs from non-C variants that use side-collector orientation.

What does the "G" in KSD261CGTA signify?

Within the KSD261CGTA designation, the "G" denotes the h_FE classification grade, specifying a DC current gain range of 200–400 at V_CE = 1 V and I_C = 100 mA. This grading is defined in the Electrical Characteristics table of the KSD261 datasheet and distinguishes it from the "Y" grade (120–240). The "G" grade ensures higher and more consistent gain for precision biasing in the KSD261CGTA.

Can the KSD261CGTA replace the KSD261GTA?

No, the KSD261CGTA cannot directly replace the KSD261GTA because they differ in pinout configuration: KSD261CGTA has center-collector (1-E, 2-C, 3-B), whereas KSD261GTA uses side-collector (1-E, 2-B, 3-C). Swapping them without PCB modification would reverse collector and base connections, causing circuit failure. The KSD261CGTA requires matching layout support to function correctly.

What is the maximum operating junction temperature for the KSD261CGTA?

The KSD261CGTA has a maximum junction temperature (T_J) rating of 150 °C, as specified in the Absolute Maximum Ratings table. This value defines the upper thermal limit for reliable semiconductor operation; sustained operation near this temperature requires careful PCB thermal design, including adequate copper area and airflow, especially given its R_θJA of 250 °C/W. Exceeding 150 °C risks permanent degradation of the KSD261CGTA.

Is the KSD261CGTA suitable for switching applications?

Yes, the KSD261CGTA is suitable for low-frequency switching applications such as relay driving and LED current control, supported by its 500 mA I_C rating, low V_CE(sat) (≤0.40 V), and fast turn-on/turn-off characteristics evident in typical performance curves. However, it is not optimized for high-speed or RF switching; its f_T is unspecified and device characterization focuses on <100 kHz operation, making the KSD261CGTA appropriate for power control-not signal switching-tasks.

KSD261CGTA Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: NPN

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

Voltage - Collector Emitter Breakdown (Max):: 20 V

Vce Saturation (Max) @ Ib, Ic:: 400mV @ 50mA, 500mA

Current - Collector Cutoff (Max):: 100nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 200 @ 100mA, 1V

Power - Max:: 500 mW

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

KSD261CGTA FAQ

1.How can I place an order for KSD261CGTA through Aetrix?

Please submit a Request for Quotation (RFQ) for KSD261CGTA 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 KSD261CGTA reliable?

The price and inventory of KSD261CGTA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSD261CGTA is usually 5 days.

3.What payment methods are accepted for KSD261CGTA?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSD261CGTA transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for KSD261CGTA?

KSD261CGTA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your KSD261CGTA 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 KSD261CGTA?

For technical support, including KSD261CGTA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSD261CGTA requirements.

6.How does Aetrix verify that KSD261CGTA is sourced from the original manufacturer or authorized distributors?

All KSD261CGTA 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 KSD261CGTA meets industry standards.

7.What is the process for return or replacement of KSD261CGTA?

All KSD261CGTA units undergo pre-shipment inspection (PSI). If there is an issue with KSD261CGTA, 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 KSD261CGTA part is unused and in its original packaging.

Return procedure for KSD261CGTA:

1.Submit a request within 90 days.

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

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