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

onsemi BC548BG

Name: BC548BG
Brand: onsemi
SKU: BC548BG
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC548BG

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 Long Body

Datasheet:: BC548BG.pdf

Description:: TRANS NPN 30V 0.1A TO92

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BC548BG from onsemi is an NPN silicon general-purpose amplifier transistor in TO-92 package, rated for 30 V_CEO, 100 mA continuous collector current, and 625 mW power dissipation at 25°C ambient. It delivers DC current gain (h_FE) of 220–450 at I_C = 2 mA, V_CE = 5 V, and exhibits f_T = 300 MHz for RF and audio amplification stages.

For engineers reviewing the BC548BG datasheet, pinout, applications, or equivalent options, key selection criteria include its V_CEO/V_CBO ratings, h_FE binning (B grade), thermal resistance (R_JA = 200°C/W), Pb-free TO-92 packaging, and suitability for low-voltage linear amplification and switching in consumer and industrial electronics.

Technical Context

The BC548BG operates as a discrete bipolar junction transistor with fixed NPN polarity, optimized for small-signal amplification and medium-speed switching. Its base-emitter forward voltage (V_BE(on)) is 0.55–0.77 V at I_C = 2–10 mA, and saturation voltage (V_CE(sat)) remains ≤0.25 V at I_C = 10 mA / I_B = 0.5 mA.

Thermal design is constrained by R_JA = 200°C/W and R_JC = 83.3°C/W, requiring heatsinking or derating above 25°C ambient. Electrical behavior is characterized across −55°C to +150°C junction temperature range, with noise figure of 2.0 dB at I_C = 0.2 mA, V_CE = 5 V, and 1 kHz.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	30 V - Maximum safe collector-emitter voltage before breakdown; defines upper rail limit in amplifier or switch designs.
I_C (continuous)	100 mA - Absolute maximum DC collector current; sets load-driving capability without thermal runaway.
h_FE (I_C = 2 mA)	220–450 - Confirmed DC current gain range for BC548B grade; enables predictable biasing in common-emitter stages.
f_T	300 MHz - Unity-gain bandwidth; supports audio preamps and low-frequency RF amplification up to ~100 MHz.
P_D @ T_A = 25°C	625 mW - Maximum ambient-rated power dissipation; requires ≥200°C/W thermal path or active cooling above 25°C.
V_BE(on)	0.55–0.77 V - Base-emitter turn-on voltage range; determines base resistor sizing for stable DC bias networks.
R_JA	200°C/W - Junction-to-ambient thermal resistance; dictates PCB copper area and airflow requirements for thermal management.

Pinout & Package

BC548BG uses the industry-standard TO-92 (Case 29, Style 17) plastic package with bent leads and Pb-free finish. Dimensions: 4.45–5.20 mm (L) × 4.32–5.33 mm (W) × 3.18–4.19 mm (H). Leads are arranged in linear order with emitter, base, and collector terminals.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Reference node for bias network; connects to ground or negative rail in common-emitter configuration.
2 (Base)	Control input	Receives current-limited drive signal; requires series resistor to limit I_B and prevent saturation overshoot.
3 (Collector)	Output current source	Delivers amplified I_C = h_FE × I_B; connects to load and positive supply via collector resistor or direct coupling.

Key Features

Feature	Design Value
Pb-free TO-92 package	Complies with RoHS Directive 2011/65/EU; eliminates lead contamination risk during reflow and end-of-life recycling.
V_CEO = 30 V	Enables operation in 24 V industrial control circuits and 5–12 V consumer power rails without overvoltage stress.
h_FE binning (B grade)	Guarantees minimum h_FE = 220 at I_C = 2 mA; reduces variation in gain-critical amplifier stages.
f_T = 300 MHz	Supports high-fidelity audio amplification (20 Hz–20 kHz) with ample gain margin and low phase distortion.
Low V_CE(sat) ≤ 0.25 V	Minimizes conduction loss in switching applications; improves efficiency in LED drivers and relay interfaces.

Applications

Audio Pre-amplifier Stage	LED Driver Circuit
Use Scenario: Amplifying weak microphone or line-level signals prior to ADC sampling or further processing. IC Role / Device Role / Timing Role: Small-signal NPN amplifier in common-emitter topology with resistive bias network and emitter degeneration. Use Value: Delivers stable 300 MHz f_T headroom and 220–450 h_FE for consistent voltage gain across production units.	Use Scenario: Switching 20–100 mA LED strings in indicator panels, status displays, or backlighting modules. IC Role / Device Role / Timing Role: Medium-current saturated switch with base-driven control and collector-connected LED anode. Use Value: Achieves V_CE(sat) ≤ 0.25 V at I_C = 10 mA, minimizing power loss and thermal rise in compact enclosures.
Industrial Sensor Interface	Relay Driver Stage
Use Scenario: Conditioning analog output from temperature, pressure, or proximity sensors before transmission to microcontroller inputs. IC Role / Device Role / Timing Role: DC-coupled buffer or level-shifter with low-noise (2.0 dB NF) and wide operating temperature range. Use Value: Maintains signal integrity from −55°C to +150°C junction temperature, supporting harsh-environment sensor nodes.	Use Scenario: Driving 5–24 VDC electromagnetic relays with coil currents up to 80 mA in PLC I/O modules and automation controllers. IC Role / Device Role / Timing Role: High-gain saturated switch with flyback diode protection and fast turn-off via base discharge path. Use Value: Provides guaranteed h_FE ≥ 220 to ensure full saturation with minimal base drive, reducing MCU GPIO loading.

Audio Pre-amplifier Stage

LED Driver Circuit

Use Scenario: Amplifying weak microphone or line-level signals prior to ADC sampling or further processing.

IC Role / Device Role / Timing Role: Small-signal NPN amplifier in common-emitter topology with resistive bias network and emitter degeneration.

Use Value: Delivers stable 300 MHz f_T headroom and 220–450 h_FE for consistent voltage gain across production units.

Use Scenario: Switching 20–100 mA LED strings in indicator panels, status displays, or backlighting modules.

IC Role / Device Role / Timing Role: Medium-current saturated switch with base-driven control and collector-connected LED anode.

Use Value: Achieves V_CE(sat) ≤ 0.25 V at I_C = 10 mA, minimizing power loss and thermal rise in compact enclosures.

Industrial Sensor Interface

Relay Driver Stage

Use Scenario: Conditioning analog output from temperature, pressure, or proximity sensors before transmission to microcontroller inputs.

IC Role / Device Role / Timing Role: DC-coupled buffer or level-shifter with low-noise (2.0 dB NF) and wide operating temperature range.

Use Value: Maintains signal integrity from −55°C to +150°C junction temperature, supporting harsh-environment sensor nodes.

Use Scenario: Driving 5–24 VDC electromagnetic relays with coil currents up to 80 mA in PLC I/O modules and automation controllers.

IC Role / Device Role / Timing Role: High-gain saturated switch with flyback diode protection and fast turn-off via base discharge path.

Use Value: Provides guaranteed h_FE ≥ 220 to ensure full saturation with minimal base drive, reducing MCU GPIO loading.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN small-signal amplifier applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC547BG	V_CEO = 45 V, V_CBO = 50 V; h_FE = 110–450 at I_C = 2 mA	Higher voltage rating supports 36 V industrial rails; same TO-92 Pb-free package and pinout	Select when higher collector-emitter standoff is required without changing layout or bias design.
BC548CG	h_FE = 420–800 at I_C = 2 mA; otherwise identical max ratings and package	Higher gain bin enables lower base drive current and improved noise performance in ultra-low-power sensor amps	Choose for gain-critical, low-I_B designs where tighter h_FE spread improves repeatability.

Compared with BC547BG and BC548CG, the BC548BG offers balanced voltage rating (30 V), verified B-grade h_FE (220–450), and optimal trade-off between saturation loss and thermal margin for cost-sensitive 5–24 V embedded systems.

Availability

BC548BG is available at Aetrix Electronics and suitable for audio pre-amplifiers, LED driver circuits, industrial sensor interfaces, and relay driver stages requiring stable component supply, long-term manufacturability, and RoHS-compliant sourcing.

Supply support for BC548BG 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and IoT applications.

The BC548BG belongs to onsemi's legacy BC546–BC548 family of general-purpose NPN transistors, designed for reliable, low-cost amplification and switching in consumer electronics, industrial controls, and instrumentation.

FAQ

What is the maximum collector-emitter voltage rating for BC548BG?

The BC548BG has a maximum collector-emitter voltage (V_CEO) rating of 30 V DC. This value is confirmed in the Absolute Maximum Ratings table of the official onsemi datasheet (Rev. 8, August 2021) and defines the upper limit for safe operation without avalanche breakdown. Exceeding this voltage risks permanent device failure, especially under transient conditions or elevated temperatures.

Does BC548BG have a Pb-free package?

Yes, BC548BG is explicitly designated as a Pb-free variant in onsemi's ordering information, using a RoHS-compliant TO-92 package. The "G" suffix in BC548BG indicates compliance with lead-free soldering standards, and the datasheet confirms it meets JEDEC J-STD-020 moisture sensitivity level (MSL) requirements for surface-mount assembly processes.

What is the h_FE range for BC548BG at I_C = 2 mA?

The BC548BG has a DC current gain (h_FE) range of 220 to 450 when tested at I_C = 2.0 mA and V_CE = 5.0 V, per the Electrical Characteristics table in the onsemi BC546B/BC547A,B,C/BC548B,C datasheet. This B-grade binning ensures predictable bias point stability across production lots for amplifier and switching applications.

What is the thermal resistance (R_JA) of BC548BG?

The BC548BG has a junction-to-ambient thermal resistance (R_JA) of 200°C/W, as specified in the Thermal Characteristics section of the onsemi datasheet. This value assumes standard mounting on FR-4 PCB with no added heatsink; actual thermal performance depends on copper area, airflow, and board stack-up, and derating is required above 25°C ambient temperature.

How is the pinout configured for BC548BG in TO-92 package?

The BC548BG uses TO-92 Style 17 pinout: Pin 1 is Collector, Pin 2 is Base, and Pin 3 is Emitter - confirmed in the Mechanical Case Outline diagram (Page 2) of the onsemi datasheet. This orientation is standardized across BC546–BC548 variants and must be verified visually during PCB layout and assembly to avoid reverse-bias or open-circuit failures.

BC548BG Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 Long Body

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:: 250mV @ 500µA, 10mA

Current - Collector Cutoff (Max):: 15nA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 200 @ 2mA, 5V

Power - Max:: 625 mW

Frequency - Transition:: 300MHz

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92 (TO-226)

BC548BG FAQ

1.How can I place an order for BC548BG through Aetrix?

Please submit a Request for Quotation (RFQ) for BC548BG 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 BC548BG reliable?

The price and inventory of BC548BG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC548BG is usually 5 days.

3.What payment methods are accepted for BC548BG?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC548BG transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC548BG?

BC548BG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC548BG 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 BC548BG?

For technical support, including BC548BG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC548BG requirements.

6.How does Aetrix verify that BC548BG is sourced from the original manufacturer or authorized distributors?

All BC548BG 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 BC548BG meets industry standards.

7.What is the process for return or replacement of BC548BG?

All BC548BG units undergo pre-shipment inspection (PSI). If there is an issue with BC548BG, 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 BC548BG part is unused and in its original packaging.

Return procedure for BC548BG:

1.Submit a request within 90 days.

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

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