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

onsemi KSD227YBU

Name: KSD227YBU
Brand: onsemi
SKU: KSD227YBU
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: KSD227YBU

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: KSD227YBU.pdf

Description:: TRANS NPN 25V 0.3A TO-92-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

KSD227YBU from Fairchild Semiconductor is an NPN epitaxial silicon transistor designed for low-frequency power amplifier applications, with V_CEO = 25 V, I_C = 300 mA, P_C = 400 mW, h_FE = 120–240 (Y-class), and TO-92 package - used in audio preamplifier stages and relay driver circuits.

For engineers reviewing the KSD227YBU datasheet, pinout, applications, or equivalent options, key selection criteria include DC current gain classification, saturation voltage at rated current, breakdown voltage margins, thermal derating behavior, and complementary pairing with KSA642 for push-pull configurations.

Technical Context

This device operates as a general-purpose bipolar junction transistor with fixed-emitter biasing capability and linear amplification characteristics optimized below 10 MHz. Its h_FE range (120–240) and V_CE(sat) ≤ 0.4 V at I_C = 300 mA support stable Class-A amplifier operation and switching duty up to 50% duty cycle.

The KSD227YBU exhibits low leakage (I_CBO ≤ 0.1 µA at V_CB = 25 V) and high junction temperature tolerance (T_J = 150 °C), enabling reliable use in ambient temperatures up to 85 °C without forced cooling in PCB-mounted applications.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	25 V - maximum safe collector-emitter voltage before avalanche breakdown under open-base condition
I_C	300 mA - continuous DC collector current rating defining linear output drive capability
P_C	400 mW - thermal power limit at T_A = 25 °C; requires derating above 25 °C per 4.0 mW/°C
h_FE	120–240 - Y-class DC current gain range measured at V_CE = 1 V, I_C = 50 mA
V_CE(sat)	≤ 0.4 V - maximum saturation voltage at I_C = 300 mA, I_B = 30 mA, ensuring low conduction loss in switch mode
T_J	150 °C - absolute maximum junction temperature, supporting operation in enclosed industrial enclosures

Pinout & Package

Package: TO-92 - molded plastic case with 3.60 mm body width, 4.58 mm height, and 2.29 mm lead spacing; leads tinned for solderability and RoHS-compliant plating.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Reference node for base biasing; connects to ground or low-impedance return path in common-emitter configuration
2 (Base)	Control input terminal	Accepts forward-biased current to modulate collector current; requires series resistor for current limiting in digital drive
3 (Collector)	Output current source terminal	Delivers amplified or switched load current; routed to V_CC via load resistor or transformer primary in amplifier designs

Key Features

Feature	Design Value
Y-class h_FE binning	Guaranteed 120–240 gain range enables consistent bias point setting across production batches
Low V_CE(sat)	≤ 0.4 V at full-rated current reduces power dissipation in saturated switching applications
Complementary pairing	Designed as NPN counterpart to KSA642 PNP transistor for matched push-pull amplifier stages
High V_CEO/V_CB0 ratio	25 V / 30 V rating supports margin against transient overvoltage in inductive load switching

Applications

Audio Preamp Stage	Relay Driver Circuit
Use Scenario: Low-noise voltage amplification of line-level analog signals prior to power stage in consumer audio equipment. IC Role / Device Role / Timing Role: NPN transistor configured in common-emitter topology with emitter degeneration resistor for stable gain and bandwidth control. Use Value: h_FE = 120–240 ensures predictable bias current and minimal distortion at 1 kHz; V_CE(sat) ≤ 0.4 V avoids clipping near rail limits.	Use Scenario: Driving 12 V, 100 mA coil relays from microcontroller GPIO pins in industrial PLC I/O modules. IC Role / Device Role / Timing Role: Switch-mode BJT operating in saturation region, controlled by TTL-compatible base drive. Use Value: I_C = 300 mA rating exceeds relay hold current; TO-92 package allows direct through-hole mounting on dense control boards.
DC Motor Speed Control	LED Constant-Current Source
Use Scenario: Linear current regulation for small brushed DC motors in battery-powered tools requiring smooth low-speed torque. IC Role / Device Role / Timing Role: Emitter-follower configured transistor delivering adjustable load current via potentiometer-controlled base voltage. Use Value: P_C = 400 mW supports 200 mA motor current at 2 V drop; T_J = 150 °C permits operation inside sealed tool housings.	Use Scenario: Precision constant-current sink for high-brightness white LEDs in signage backlighting with thermal stability requirements. IC Role / Device Role / Timing Role: Fixed-base biased transistor regulating LED current through emitter resistor feedback. Use Value: I_CBO ≤ 0.1 µA minimizes temperature-induced current drift; h_FE consistency ensures repeatable current setting across units.

Audio Preamp Stage

Relay Driver Circuit

Use Scenario: Low-noise voltage amplification of line-level analog signals prior to power stage in consumer audio equipment.

IC Role / Device Role / Timing Role: NPN transistor configured in common-emitter topology with emitter degeneration resistor for stable gain and bandwidth control.

Use Value: h_FE = 120–240 ensures predictable bias current and minimal distortion at 1 kHz; V_CE(sat) ≤ 0.4 V avoids clipping near rail limits.

Use Scenario: Driving 12 V, 100 mA coil relays from microcontroller GPIO pins in industrial PLC I/O modules.

IC Role / Device Role / Timing Role: Switch-mode BJT operating in saturation region, controlled by TTL-compatible base drive.

Use Value: I_C = 300 mA rating exceeds relay hold current; TO-92 package allows direct through-hole mounting on dense control boards.

DC Motor Speed Control

LED Constant-Current Source

Use Scenario: Linear current regulation for small brushed DC motors in battery-powered tools requiring smooth low-speed torque.

IC Role / Device Role / Timing Role: Emitter-follower configured transistor delivering adjustable load current via potentiometer-controlled base voltage.

Use Value: P_C = 400 mW supports 200 mA motor current at 2 V drop; T_J = 150 °C permits operation inside sealed tool housings.

Use Scenario: Precision constant-current sink for high-brightness white LEDs in signage backlighting with thermal stability requirements.

IC Role / Device Role / Timing Role: Fixed-base biased transistor regulating LED current through emitter resistor feedback.

Use Value: I_CBO ≤ 0.1 µA minimizes temperature-induced current drift; h_FE consistency ensures repeatable current setting across units.

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
BC547C	Lower I_C (100 mA), lower P_C (500 mW but derated to 300 mW at T_A > 50 °C), h_FE = 420–800 (C-grade)	Not suitable for 300 mA continuous loads; better for signal amplification than power switching	Select only when gain consistency matters more than current capacity and thermal headroom is ample
MPSA13	Higher h_FE (50–250, typical 150), same TO-92, but V_CEO = 30 V and P_C = 625 mW	Broader gain spread may require individual bias tuning; higher power rating supports heavier loads	Prefer when designing for variable supply rails up to 30 V or needing extra thermal margin beyond 400 mW

Compared with BC547C and MPSA13, the KSD227YBU offers tighter h_FE binning (120–240), guaranteed 300 mA current handling, and optimized saturation performance for relay/motor drive - making it preferable where batch-to-batch gain matching and robust switching are design priorities.

Availability

KSD227YBU is available at Aetrix Electronics and suitable for audio preamplifier stages, relay driver circuits, and DC motor speed control applications requiring stable component supply, consistent h_FE binning, and proven thermal reliability in TO-92 form factor.

Supply support for KSD227YBU 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 KSD227YBU belongs to Fairchild's legacy general-purpose bipolar transistor product line, engineered for cost-sensitive, medium-power linear and switching applications in industrial controls and consumer electronics.

FAQ

What is the h_FE range specified for KSD227YBU?

The KSD227YBU is Y-class binned with a guaranteed DC current gain (h_FE) range of 120 to 240, measured at V_CE = 1 V and I_C = 50 mA. This tighter binning improves predictability in bias network design compared to broader-spread alternatives like the standard KSD227O (70–140) or KSD227G (200–400). The KSD227YBU thus delivers repeatable performance across manufacturing lots.

Is KSD227YBU pin-compatible with other TO-92 NPN transistors?

Yes, the KSD227YBU uses standard TO-92 pinout (Emitter-Base-Collector = Pin 1-2-3), matching industry convention for through-hole NPN transistors including BC547, 2N3904, and MPSA13. However, electrical parameters - especially h_FE, V_CE(sat), and P_C - differ significantly; direct substitution requires verification of gain, saturation voltage, and thermal margin in the target circuit. The KSD227YBU must be evaluated individually for each application.

What is the maximum allowable collector current for continuous operation of KSD227YBU?

The KSD227YBU is rated for a continuous collector current (I_C) of 300 mA at T_A = 25 °C. Above this ambient temperature, derating applies: the device must be operated at reduced current per the thermal resistance curve - approximately 4.0 mW/°C reduction in P_C above 25 °C. At 75 °C ambient, the usable I_C drops to ~240 mA to maintain safe junction temperature. The KSD227YBU's thermal design must account for PCB copper area and airflow.

Does KSD227YBU have a complementary PNP part?

Yes, the KSD227YBU is explicitly designed as the NPN complement to the KSA642 PNP transistor. Both share matching voltage ratings (V_CEO = 25 V, V_ECO = 25 V), power dissipation (P_C = 400 mW), and TO-92 packaging. Their h_FE ranges are aligned to enable balanced push-pull amplifier stages and H-bridge drivers. When using the KSD227YBU with KSA642, ensure identical layout symmetry and thermal coupling for optimal crossover distortion suppression.

What is the typical V_CE(sat) value for KSD227YBU under rated conditions?

The KSD227YBU has a maximum V_CE(sat) of 0.4 V when tested at I_C = 300 mA and I_B = 30 mA, with typical value around 0.14 V under the same conditions. This low saturation voltage minimizes power loss during switching and supports efficient operation in relay drivers and motor control circuits. Designers should verify base drive strength to ensure full saturation; insufficient I_B will raise V_CE(sat) and increase heating. The KSD227YBU performs best with ≥10× overdrive (I_B/I_C ≥ 0.1).

KSD227YBU 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:: NPN

Current - Collector (Ic) (Max):: 300 mA

Voltage - Collector Emitter Breakdown (Max):: 25 V

Vce Saturation (Max) @ Ib, Ic:: 400mV @ 30mA, 300mA

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 120 @ 50mA, 1V

Power - Max:: 400 mW

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

KSD227YBU FAQ

1.How can I place an order for KSD227YBU through Aetrix?

Please submit a Request for Quotation (RFQ) for KSD227YBU 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 KSD227YBU reliable?

The price and inventory of KSD227YBU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KSD227YBU is usually 5 days.

3.What payment methods are accepted for KSD227YBU?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KSD227YBU transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for KSD227YBU?

KSD227YBU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your KSD227YBU 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 KSD227YBU?

For technical support, including KSD227YBU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KSD227YBU requirements.

6.How does Aetrix verify that KSD227YBU is sourced from the original manufacturer or authorized distributors?

All KSD227YBU 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 KSD227YBU meets industry standards.

7.What is the process for return or replacement of KSD227YBU?

All KSD227YBU units undergo pre-shipment inspection (PSI). If there is an issue with KSD227YBU, 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 KSD227YBU part is unused and in its original packaging.

Return procedure for KSD227YBU:

1.Submit a request within 90 days.

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

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