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

onsemi BC548ABU

Name: BC548ABU
Brand: onsemi
SKU: BC548ABU
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC548ABU

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: BC548ABU.pdf

Description:: TRANS NPN 30V 0.1A TO-92-3

Quantity:: RFQ Add To RFQ list

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Inventory:4,564

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Product details

Overview

BC548ABU from ON Semiconductor is an NPN epitaxial silicon transistor designed for general-purpose switching and amplification in low-power analog and digital circuits, with V_CEO = 30 V, I_C = 100 mA, h_FE = 110–220 (Class A), and TO-92 package. It operates reliably in consumer audio preamps, LED drivers, and logic-level interface stages.

For engineers reviewing the BC548ABU datasheet, pinout, applications, or equivalent options, key selection criteria include DC current gain classification, saturation voltage at defined drive conditions, junction temperature limit, and TO-92 mechanical compatibility in space-constrained PCB layouts.

Technical Context

This device belongs to the BC546–BC550 family of through-hole NPN transistors fabricated using epitaxial silicon process technology. Its base-emitter on voltage is specified at 580–700 mV (V_CE = 5 V, I_C = 2 mA), and collector-emitter saturation voltage reaches 250 mV max at I_C = 100 mA / I_B = 5 mA.

It exhibits f_T = 300 MHz under V_CE = 5 V, I_C = 10 mA, and has Cob = 3.5–6.0 pF at V_CB = 10 V - confirming suitability for audio-frequency amplification and medium-speed switching up to ~10 MHz.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	30 V - maximum safe collector-emitter voltage before breakdown; defines usable supply rail headroom in switch/amplifier designs
I_C (DC)	100 mA - continuous collector current limit; sets upper bound for load-driving capability in relay drivers or LED sinks
h_FE Class	A (110–220) - guaranteed DC current gain range at V_CE = 5 V, I_C = 2 mA; enables predictable biasing in linear amplifier stages
V_CE(sat)	250 mV max at I_C = 100 mA / I_B = 5 mA - low saturation voltage minimizes power loss and heating in saturated-switch applications
P_C	500 mW - total package power dissipation limit at T_A = 25°C; requires derating above 25°C ambient per thermal resistance spec
f_T	300 MHz - current-gain bandwidth product; supports stable small-signal amplification up to mid-VHF range

Pinout & Package

BC548ABU is housed in a standard JEDEC TO-92 3-lead molded plastic package with straight leads (bulk packing). Pin 1 is Collector, Pin 2 is Base, Pin 3 is Emitter - verified per Fairchild/ON Semiconductor physical dimensions documentation (Rev. 1.1.1, Figure 7).

Pin/Terminal	Circuit Role	Design Meaning
1 (Left, when flat side faces viewer)	Collector	Main current output terminal; connects to load or supply rail in common-emitter configurations
2 (Center)	Base	Control input; requires current-limited drive to achieve target h_FE-dependent collector current
3 (Right)	Emitter	Current return path; typically grounded in common-emitter switches or biased via resistor in amplifiers

Key Features

Feature	Design Value
Switching & Amplifier Dual Use	Validated by h_FE stability across I_C = 0.1–100 mA and low V_CE(sat), enabling reuse across signal conditioning and digital logic interfacing
Low-Noise Capability	Typical noise figure = 2.0–10.0 dB (V_CE = 5 V, I_C = 200 μA, f = 1 kHz, R_G = 2 kΩ); suitable for microphone preamp and sensor signal chain front-ends
Complementary Pair Support	Explicitly designed as NPN counterpart to BC556–BC560 PNP series; enables matched push-pull stage implementation
TO-92 Mechanical Standardization	JEDEC-compliant footprint ensures compatibility with legacy hand-soldering workflows, wave solder pallets, and automated insertion tooling

Applications

Audio Pre-amplifier Stage	LED Current Sink Driver
Use Scenario: Low-voltage, battery-powered portable audio equipment requiring clean gain before ADC sampling. IC Role / Device Role / Timing Role: NPN small-signal amplifier in common-emitter configuration with emitter degeneration resistor. Use Value: h_FE = 110–220 and NF ≤ 10 dB ensure stable voltage gain and minimal added noise at 1–10 kHz signal band.	Use Scenario: Driving indicator or status LEDs from microcontroller GPIO pins with current limiting. IC Role / Device Role / Timing Role: Saturated switch controlling LED anode/cathode current path. Use Value: V_CE(sat) ≤ 250 mV at I_C = 20 mA reduces power loss and heat rise in compact enclosures.
Logic Level Translator	Relay Coil Driver
Use Scenario: Interfacing 3.3 V MCU outputs to 5 V or 12 V peripheral logic inputs. IC Role / Device Role / Timing Role: Common-emitter inverter with pull-up resistor on collector. Use Value: Guaranteed h_FE ≥ 110 ensures full saturation with ≤ 200 μA base drive, supporting fast edge transitions.	Use Scenario: Driving electromagnetic relay coils (e.g., 12 V, 40 mA) from low-current control signals. IC Role / Device Role / Timing Role: High-side or low-side switch managing coil energization/de-energization. Use Value: I_C = 100 mA rating and P_C = 500 mW allow safe 12 V/40 mA operation with margin for back-EMF transient handling.

Audio Pre-amplifier Stage

LED Current Sink Driver

Use Scenario: Low-voltage, battery-powered portable audio equipment requiring clean gain before ADC sampling.

IC Role / Device Role / Timing Role: NPN small-signal amplifier in common-emitter configuration with emitter degeneration resistor.

Use Value: h_FE = 110–220 and NF ≤ 10 dB ensure stable voltage gain and minimal added noise at 1–10 kHz signal band.

Use Scenario: Driving indicator or status LEDs from microcontroller GPIO pins with current limiting.

IC Role / Device Role / Timing Role: Saturated switch controlling LED anode/cathode current path.

Use Value: V_CE(sat) ≤ 250 mV at I_C = 20 mA reduces power loss and heat rise in compact enclosures.

Logic Level Translator

Relay Coil Driver

Use Scenario: Interfacing 3.3 V MCU outputs to 5 V or 12 V peripheral logic inputs.

IC Role / Device Role / Timing Role: Common-emitter inverter with pull-up resistor on collector.

Use Value: Guaranteed h_FE ≥ 110 ensures full saturation with ≤ 200 μA base drive, supporting fast edge transitions.

Use Scenario: Driving electromagnetic relay coils (e.g., 12 V, 40 mA) from low-current control signals.

IC Role / Device Role / Timing Role: High-side or low-side switch managing coil energization/de-energization.

Use Value: I_C = 100 mA rating and P_C = 500 mW allow safe 12 V/40 mA operation with margin for back-EMF transient handling.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN general-purpose transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC547BTA	Same TO-92 package; h_FE = 200–450 (Class B); V_CEO = 45 V	Higher gain and breakdown voltage enable improved noise immunity and wider supply range	Select when higher h_FE tolerance or >30 V rail operation is required; not drop-in due to gain shift
2N3904TA	TO-92; h_FE = 100–300; V_CEO = 40 V; f_T = 300 MHz; lower Cob (4 pF typical)	Better high-frequency response and tighter h_FE distribution support precision analog design	Prefer for new designs needing consistent gain or >10 MHz signal integrity; requires layout verification for bias point shift

Compared with BC548ABU, BC547BTA offers higher gain and voltage margin but shifts operating point in fixed-bias circuits, while 2N3904TA delivers superior RF performance and tighter h_FE spread at the cost of reduced legacy compatibility in repair contexts.

Availability

BC548ABU is available at Aetrix Electronics and suitable for audio pre-amplifiers, LED driver circuits, logic level translators, and relay coil drivers requiring stable component supply across prototyping, industrial control, and consumer electronics production.

Supply support for BC548ABU 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, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and IoT applications.

The BC548ABU belongs to ON Semiconductor's legacy general-purpose bipolar transistor product line, originally developed by Fairchild and maintained for backward-compatible repairs, educational kits, and cost-sensitive linear/switching applications.

FAQ

What is the maximum collector-emitter voltage rating for BC548ABU?

The BC548ABU has a maximum collector-emitter voltage (V_CEO) rating of 30 V at T_A = 25°C. This value is absolute - exceeding it risks avalanche breakdown. Designers must ensure worst-case supply transients and inductive kickback remain below this threshold, especially in relay or motor driver circuits where BC548ABU may be used.

Does BC548ABU have a specified noise figure, and under what conditions?

Yes, BC548ABU has a noise figure (NF) of 2.0–10.0 dB, measured at V_CE = 5 V, I_C = 200 μA, f = 1 kHz, and R_G = 2 kΩ. This specification confirms its suitability for low-noise small-signal amplification, such as electret microphone preamplifiers or sensor front-ends where BC548ABU provides predictable SNR performance.

What h_FE classification does BC548ABU belong to, and how is it marked?

BC548ABU is classified as Class A, with DC current gain (h_FE) ranging from 110 to 220 at V_CE = 5 V and I_C = 2 mA. The "A" suffix in the part number denotes this gain bin, and the device is marked "BC548A" on the TO-92 package body per Fairchild/ON Semiconductor ordering information.

Can BC548ABU be used as a direct replacement for BC547B in existing designs?

No - BC548ABU is not a direct replacement for BC547B. While both share TO-92 packaging and pinout, BC547B has h_FE = 200–450 and V_CEO = 45 V versus BC548ABU's h_FE = 110–220 and V_CEO = 30 V. Substituting BC548ABU may cause insufficient gain or premature breakdown; redesign validation is required before interchange.

What is the thermal resistance junction-to-ambient (R_θJA) for BC548ABU in TO-92 package?

The BC548ABU datasheet does not explicitly list R_θJA, but its TO-92 package has a typical R_θJA of 200°C/W under still-air conditions. Given its 500 mW power dissipation rating, this implies a maximum junction temperature rise of 100°C above ambient at full power - requiring careful thermal design if BC548ABU operates near P_C limits.

BC548ABU 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):: 100 mA

Voltage - Collector Emitter Breakdown (Max):: 30 V

Vce Saturation (Max) @ Ib, Ic:: 600mV @ 5mA, 100mA

Current - Collector Cutoff (Max):: 15nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 110 @ 2mA, 5V

Power - Max:: 500 mW

Frequency - Transition:: 300MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

BC548ABU FAQ

1.How can I place an order for BC548ABU through Aetrix?

Please submit a Request for Quotation (RFQ) for BC548ABU 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 BC548ABU reliable?

The price and inventory of BC548ABU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC548ABU is usually 5 days.

3.What payment methods are accepted for BC548ABU?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC548ABU transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC548ABU?

BC548ABU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC548ABU 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 BC548ABU?

For technical support, including BC548ABU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC548ABU requirements.

6.How does Aetrix verify that BC548ABU is sourced from the original manufacturer or authorized distributors?

All BC548ABU 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 BC548ABU meets industry standards.

7.What is the process for return or replacement of BC548ABU?

All BC548ABU units undergo pre-shipment inspection (PSI). If there is an issue with BC548ABU, 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 BC548ABU part is unused and in its original packaging.

Return procedure for BC548ABU:

1.Submit a request within 90 days.

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

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