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

onsemi BC547BG

Name: BC547BG
Brand: onsemi
SKU: BC547BG
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC547BG

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: BC547BG.pdf

Description:: TRANS NPN 45V 0.1A TO92

Quantity:: RFQ Add To RFQ list

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Inventory:3,369

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Product details

Overview

BC547BG from onsemi is an NPN silicon general-purpose amplifier transistor in TO-92 package, rated for 45 V_CEO, 100 mA continuous collector current, and 625 mW power dissipation at 25°C ambient - widely used in low-power switching and linear amplification stages of consumer audio preamps, sensor signal conditioning circuits, and LED driver bias networks.

For engineers reviewing the BC547BG datasheet, pinout, applications, or equivalent options, key selection criteria include DC current gain (h_FE = 200–450 at I_C = 2 mA), V_CE(sat) ≤ 0.25 V at I_C/I_B = 10, f_T = 300 MHz, and Pb-free TO-92 mechanical compatibility with legacy BC547B designs.

Technical Context

The BC547BG operates as a standard bipolar junction transistor with fixed-emitter biasing capability and moderate frequency response. Its h_FE range (200–450 at I_C = 2 mA) supports stable Class-A small-signal amplification, while V_CE(sat) ≤ 0.25 V enables efficient low-side switching up to 100 mA load current.

Thermal resistance R_JA = 200°C/W and R_JC = 83.3°C/W define its thermal envelope under natural convection; junction temperature range of −55°C to +150°C permits operation in industrial ambient environments without forced cooling.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	45 V - Maximum safe collector-emitter voltage before breakdown; sets upper rail limit for single-supply amplifier stages.
I_C (continuous)	100 mA - Sustained collector current capacity; suitable for driving relays, small solenoids, or LED arrays.
P_D @ T_A = 25°C	625 mW - Power handling at room ambient; derates 5 mW/°C above 25°C for thermal design margin.
h_FE	200–450 @ I_C = 2 mA - DC current gain range defining base drive requirements for predictable saturation or linear biasing.
f_T	300 MHz - Unity-gain bandwidth; supports audio-frequency amplification and low-speed digital switching up to ~30 MHz.
V_CE(sat)	≤ 0.25 V @ I_C/I_B = 10 - Low saturation voltage minimizes power loss and heat generation in switching applications.
C_obo	1.7–4.5 pF - Output capacitance affecting high-frequency stability and bandwidth in amplifier feedback loops.

Pinout & Package

BC547BG uses the industry-standard TO-92 (Case 29, Style 17) plastic package with bent leads, 5.2 mm height, and 1.39 mm lead diameter. Pin 1 is Collector, Pin 2 is Base, Pin 3 is Emitter - verified per onsemi mechanical drawing CASE 29−11.

Pin/Terminal	Circuit Role	Design Meaning
1 - Collector	Output current terminal	Carries amplified load current; connects to positive supply rail in common-emitter switch configurations.
2 - Base	Control input terminal	Receives bias current to regulate collector-emitter conduction; requires current-limiting resistor in most designs.
3 - Emitter	Reference/return terminal	Provides emitter return path; grounded in common-emitter topology or tied to bias network in emitter-follower setups.

Key Features

Feature	Design Value
Pb-free TO-92 package	Fully RoHS-compliant construction with no lead content; compatible with lead-free reflow profiles (J-STD-020).
High h_FE consistency	Guaranteed 200–450 h_FE range at I_C = 2 mA ensures predictable base drive across production lots.
Low V_CE(sat)	≤ 0.25 V at I_C/I_B = 10 reduces conduction losses in battery-powered switching circuits.
Wide operating temperature	−55°C to +150°C junction range supports deployment in automotive engine compartments and industrial control enclosures.
300 MHz f_T	Enables stable audio preamplifier gain up to 20 kHz with >10 dB gain margin and minimal phase shift.

Applications

Audio Preamp Stage	Sensor Signal Amplifier
Use Scenario: Boosting weak microphone or piezoelectric sensor output to line-level voltage for ADC input. IC Role / Device Role / Timing Role: NPN small-signal amplifier in common-emitter configuration with emitter degeneration resistor. Use Value: h_FE ≥ 200 ensures sufficient gain with low base current draw; f_T = 300 MHz avoids roll-off below 20 kHz.	Use Scenario: Amplifying thermistor or photodiode current in analog front-end of environmental monitoring node. IC Role / Device Role / Timing Role: Transimpedance or current-buffer stage with DC-coupled bias network. Use Value: V_CEO = 45 V allows headroom for 24 V supply rails; low C_obo (≤ 4.5 pF) preserves signal integrity at sub-MHz frequencies.
LED Driver Bias Circuit	Low-Power Relay Driver
Use Scenario: Providing constant-current bias to high-efficiency white LEDs in portable lighting modules. IC Role / Device Role / Timing Role: Linear current regulator using emitter-follower topology with sense resistor feedback. Use Value: V_CE(sat) ≤ 0.25 V minimizes dropout voltage and extends battery life; 100 mA I_C rating supports multi-LED strings.	Use Scenario: Switching 12 V/50 mA relay coils in home automation controllers and PLC I/O modules. IC Role / Device Role / Timing Role: Low-side switch with flyback diode protection and base resistor limiting. Use Value: Guaranteed h_FE ≥ 200 ensures full saturation with ≤ 0.5 mA base drive; TO-92 footprint simplifies manual assembly and repair.

Audio Preamp Stage

Sensor Signal Amplifier

Use Scenario: Boosting weak microphone or piezoelectric sensor output to line-level voltage for ADC input.

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

Use Value: h_FE ≥ 200 ensures sufficient gain with low base current draw; f_T = 300 MHz avoids roll-off below 20 kHz.

Use Scenario: Amplifying thermistor or photodiode current in analog front-end of environmental monitoring node.

IC Role / Device Role / Timing Role: Transimpedance or current-buffer stage with DC-coupled bias network.

Use Value: V_CEO = 45 V allows headroom for 24 V supply rails; low C_obo (≤ 4.5 pF) preserves signal integrity at sub-MHz frequencies.

LED Driver Bias Circuit

Low-Power Relay Driver

Use Scenario: Providing constant-current bias to high-efficiency white LEDs in portable lighting modules.

IC Role / Device Role / Timing Role: Linear current regulator using emitter-follower topology with sense resistor feedback.

Use Value: V_CE(sat) ≤ 0.25 V minimizes dropout voltage and extends battery life; 100 mA I_C rating supports multi-LED strings.

Use Scenario: Switching 12 V/50 mA relay coils in home automation controllers and PLC I/O modules.

IC Role / Device Role / Timing Role: Low-side switch with flyback diode protection and base resistor limiting.

Use Value: Guaranteed h_FE ≥ 200 ensures full saturation with ≤ 0.5 mA base drive; TO-92 footprint simplifies manual assembly and repair.

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
BC547B	Same electrical specs but SnPb lead finish; not RoHS-compliant.	Legacy designs requiring Pb-based soldering or exempted industrial use.	Select BC547B only if Pb-free compliance is not required and existing PCBs were qualified with SnPb process.
MMBT3904LT1G	SMT SOT-23 package; identical V_CEO, I_C, h_FE, and f_T; slightly lower P_D (310 mW).	Space-constrained PCBs where through-hole TO-92 is impractical.	Choose MMBT3904LT1G for automated assembly and higher-density layouts; verify thermal margin due to lower power rating.

Compared with BC547B, BC547BG adds RoHS compliance without electrical trade-offs; versus MMBT3904LT1G, it offers higher power dissipation and through-hole serviceability but requires larger board area.

Availability

BC547BG is available at Aetrix Electronics and suitable for audio preamplifiers, sensor interface circuits, and LED driver bias networks requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for BC547BG 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 management, analog, sensing, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

The BC547BG belongs to onsemi's legacy general-purpose bipolar transistor product line, designed for cost-sensitive, high-volume applications demanding reliability, wide temperature operation, and standardized through-hole packaging.

FAQ

What is the maximum collector-emitter voltage rating for BC547BG?

The BC547BG has a guaranteed V_CEO rating of 45 Vdc, meaning it can safely withstand up to 45 volts between collector and emitter with base open. This rating is confirmed in the Absolute Maximum Ratings table of the official onsemi datasheet (Rev. 8, August 2021) and defines the upper voltage limit for reliable operation in amplifier or switching circuits using BC547BG.

Is BC547BG RoHS-compliant and what does the 'G' suffix indicate?

Yes, BC547BG is RoHS-compliant. The 'G' suffix explicitly denotes a Pb-free (lead-free) version of the BC547B transistor, manufactured per onsemi's Pb-free strategy and qualified for lead-free reflow soldering processes. This is documented in the Ordering Information section (page 5) and Pb-Free Packages footnote on page 1 of the BC546/D datasheet.

What is the typical DC current gain (h_FE) range for BC547BG at I_C = 2 mA?

The BC547BG exhibits a minimum h_FE of 200 and a maximum of 450 when tested at I_C = 2 mA and V_CE = 5.0 V, as specified in the Electrical Characteristics table (page 2) of the onsemi datasheet. This range ensures predictable base drive requirements across manufacturing lots and supports stable biasing in linear amplifier and switching applications using BC547BG.

Can BC547BG replace BC547B in existing designs without layout changes?

Yes, BC547BG is a direct drop-in replacement for BC547B in terms of pinout, package dimensions (TO-92), and all electrical specifications - the only difference is the Pb-free finish. Mechanical drawings confirm identical Case 29-11 outline, and the datasheet states "BC547BG" appears in the same ordering table as "BC547B" with identical ratings, making BC547BG fully compatible with BC547B footprints and schematics.

What is the thermal resistance from junction to ambient (R_JA) for BC547BG?

The thermal resistance from junction to ambient (R_JA) for BC547BG is 200°C/W, as specified in the Thermal Characteristics table (page 1) of the onsemi datasheet. This value applies to the device mounted on a standard FR-4 PCB with minimal copper area and natural convection cooling, and must be used to calculate junction temperature rise under actual operating power dissipation conditions for BC547BG.

BC547BG 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):: 45 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)

BC547BG FAQ

1.How can I place an order for BC547BG through Aetrix?

Please submit a Request for Quotation (RFQ) for BC547BG 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 BC547BG reliable?

The price and inventory of BC547BG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC547BG is usually 5 days.

3.What payment methods are accepted for BC547BG?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC547BG transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC547BG?

BC547BG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC547BG 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 BC547BG?

For technical support, including BC547BG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC547BG requirements.

6.How does Aetrix verify that BC547BG is sourced from the original manufacturer or authorized distributors?

All BC547BG 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 BC547BG meets industry standards.

7.What is the process for return or replacement of BC547BG?

All BC547BG units undergo pre-shipment inspection (PSI). If there is an issue with BC547BG, 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 BC547BG part is unused and in its original packaging.

Return procedure for BC547BG:

1.Submit a request within 90 days.

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

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