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

onsemi BC237CG

Name: BC237CG
Brand: onsemi
SKU: BC237CG
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC237CG

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: BC237CG.pdf

Description:: TRANS NPN 45V 0.1A TO92

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BC237CG from onsemi is an NPN silicon general-purpose amplifier transistor in TO-92 package, rated for V_CEO = 45 V, I_C = 100 mA, P_D = 350 mW at T_A = 25°C, with h_FE = 200–500 (BC237C grade), and f_T = 150–200 MHz - used in low-noise audio preamplifiers, signal switching, and biasing circuits.

For engineers reviewing the BC237CG datasheet, pinout, applications, or equivalent options, key selection considerations include its Pb-free TO-92 packaging, verified DC current gain range, saturation voltage performance at 10 mA/0.5 mA drive, thermal resistance (R_JA = 357°C/W), and compatibility with legacy BC237-series designs requiring RoHS compliance.

Technical Context

The BC237CG is a discrete NPN bipolar junction transistor optimized for linear amplification and low-current switching. Its design emphasizes stable h_FE across collector currents (10 µA to 100 mA), low noise figure (NF = 2.0 dB at 1 kHz), and predictable V_CE(sat) ≤ 0.2 V at I_C/I_B = 10.

It operates within −55°C to +150°C junction temperature range, features C_obo = 4.5 pF and C_ibo = 8.0 pF for RF-stable biasing, and maintains f_T ≥ 150 MHz under standard test conditions (I_C = 0.5 mA, V_CE = 3.0 V), confirming suitability for HF analog stages up to ~100 MHz.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	45 V - Maximum safe collector-emitter voltage before breakdown; defines headroom for 24–36 V supply rail applications.
I_C (max)	100 mA - Continuous collector current limit; supports small-signal amplification and driver-stage operation.
h_FE range	200–500 - Verified DC current gain at I_C = 2.0 mA, V_CE = 5.0 V; enables predictable bias point setting in Class-A amplifiers.
f_T	150–200 MHz - Current-gain bandwidth product; confirms usable gain at VHF frequencies in tuned amplifier designs.
V_CE(sat)	≤ 0.2 V @ I_C = 10 mA, I_B = 0.5 mA - Low saturation voltage ensures minimal power loss in switching configurations.
R_JA	357°C/W - Junction-to-ambient thermal resistance; determines required PCB copper area for thermal management at full power.
NF	2.0 dB @ I_C = 0.2 mA, f = 1 kHz - Confirmed low-noise performance critical for microphone preamp and sensor interface stages.

Pinout & Package

BC237CG is housed in a Pb-free TO-92 (Case 29-11, Style 17) plastic package with standardized lead configuration and JEDEC-compliant dimensions (A = 4.45–5.20 mm, B = 4.32–5.33 mm).

Pin/Terminal	Circuit Role	Design Meaning
1	Collector	Main current output terminal; connects to load or next stage input; requires heat-sinking consideration at >100 mW dissipation.
2	Base	Control electrode; accepts bias current to regulate collector current; high-impedance node sensitive to layout-induced noise.
3	Emitter	Current return path; typically grounded or connected to emitter resistor for stable DC biasing and AC feedback.

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.
Guaranteed h_FE range (200–500)	Enables consistent gain matching across production batches without individual device binning or trim resistors.
Low V_CE(sat) ≤ 0.2 V	Reduces conduction loss in active-load switches and improves efficiency in battery-powered signal routing.
Verified f_T ≥ 150 MHz	Supports stable small-signal amplification up to FM broadcast band (88–108 MHz) with adequate gain margin.
Low noise figure (2.0 dB)	Meets requirement for first-stage amplification of weak signals from piezoelectric sensors or electret microphones.

Applications

Audio Preamp Stage	Signal Switching Node
Use Scenario: Amplifying low-level output from electret condenser microphone before ADC sampling. IC Role / Device Role / Timing Role: Discrete NPN transconductance amplifier providing 20–40 dB voltage gain with minimal added noise. Use Value: Achieves SNR > 65 dB at 1 kHz due to NF = 2.0 dB and stable h_FE, avoiding need for costly op-amps in cost-sensitive consumer audio.	Use Scenario: Enabling/disabling analog signal path between MCU GPIO and sensor output line. IC Role / Device Role / Timing Role: Low-power NPN switch operating in saturation/cutoff modes controlled by logic-level base drive. Use Value: Delivers <100 ns turn-on/off with V_CE(sat) ≤ 0.2 V, minimizing signal distortion and crosstalk in multiplexed sensor interfaces.
DC Bias Generator	RF Detector Load
Use Scenario: Providing precise quiescent current to set operating point of JFET or op-amp input stage. IC Role / Device Role / Timing Role: Constant-current source configured with emitter resistor and base bias network. Use Value: Maintains ±5% current stability over −25°C to +70°C ambient due to matched h_FE and low R_JA-limited self-heating.	Use Scenario: Acting as active load in AM demodulator or RF envelope detector circuit. IC Role / Device Role / Timing Role: Nonlinear current sink modulated by RF input amplitude at collector node. Use Value: Leverages f_T ≥ 150 MHz and C_obo = 4.5 pF to preserve detector response up to 30 MHz without parasitic resonance.

Audio Preamp Stage

Signal Switching Node

Use Scenario: Amplifying low-level output from electret condenser microphone before ADC sampling.

IC Role / Device Role / Timing Role: Discrete NPN transconductance amplifier providing 20–40 dB voltage gain with minimal added noise.

Use Value: Achieves SNR > 65 dB at 1 kHz due to NF = 2.0 dB and stable h_FE, avoiding need for costly op-amps in cost-sensitive consumer audio.

Use Scenario: Enabling/disabling analog signal path between MCU GPIO and sensor output line.

IC Role / Device Role / Timing Role: Low-power NPN switch operating in saturation/cutoff modes controlled by logic-level base drive.

Use Value: Delivers <100 ns turn-on/off with V_CE(sat) ≤ 0.2 V, minimizing signal distortion and crosstalk in multiplexed sensor interfaces.

DC Bias Generator

RF Detector Load

Use Scenario: Providing precise quiescent current to set operating point of JFET or op-amp input stage.

IC Role / Device Role / Timing Role: Constant-current source configured with emitter resistor and base bias network.

Use Value: Maintains ±5% current stability over −25°C to +70°C ambient due to matched h_FE and low R_JA-limited self-heating.

Use Scenario: Acting as active load in AM demodulator or RF envelope detector circuit.

IC Role / Device Role / Timing Role: Nonlinear current sink modulated by RF input amplitude at collector node.

Use Value: Leverages f_T ≥ 150 MHz and C_obo = 4.5 pF to preserve detector response up to 30 MHz without parasitic resonance.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN amplifier transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC237C	Same electrical specs but SnPb lead finish; not RoHS-compliant; identical TO-92 mechanical outline.	Acceptable where Pb exemption applies (e.g., legacy industrial repair); unsuitable for new EU-market designs.	Select BC237C only if Pb-free compliance is waived per customer specification or regional regulation.
BC547C	Higher h_FE (420–800), same V_CEO/I_C, slightly higher C_obo (6 pF); TO-92 compatible pinout.	Better suited for high-gain, low-input-current amplifier stages; may require layout review for RF stability at >50 MHz.	Choose BC547C when gain consistency above 400 is required and noise floor is secondary to signal level.

Compared with BC237C and BC547C, the BC237CG delivers guaranteed RoHS compliance without sacrificing gain-bandwidth or noise performance - making it the preferred choice for new designs targeting EU, UK, and APAC markets where Pb-free enforcement is mandatory.

Availability

BC237CG is available at Aetrix Electronics and suitable for audio preamplifiers, sensor interface circuits, and low-power switching applications requiring stable component supply, RoHS compliance, and legacy BC237-series interoperability.

Supply support for BC237CG 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 BC237CG belongs to onsemi's legacy general-purpose bipolar transistor family, designed specifically for cost-sensitive, high-reliability linear and switching applications in consumer, industrial, and communications equipment.

FAQ

What is the maximum collector-emitter voltage rating for BC237CG?

The BC237CG has a maximum collector-emitter voltage (V_CEO) rating of 45 Vdc, tested at I_C = 2.0 mA with base open. This rating defines the absolute upper limit for safe DC or peak AC voltage applied between collector and emitter terminals without risking avalanche breakdown or long-term reliability degradation.

Is BC237CG RoHS-compliant and what does the 'G' suffix indicate?

Yes, BC237CG is RoHS-compliant. The 'G' suffix explicitly denotes Pb-free (lead-free) construction per EU Directive 2011/65/EU, confirmed in the official onsemi datasheet BC237/D Rev. 4. The device uses matte tin-plated leads and halogen-free molding compound, validated for standard reflow profiles including J-STD-020D.

What is the typical DC current gain (h_FE) range for BC237CG at 2.0 mA collector current?

The BC237CG exhibits a guaranteed h_FE range of 200 to 500 when measured at I_C = 2.0 mA and V_CE = 5.0 V, per the BC237/D datasheet. This range reflects the 'C' grade variant and is tighter than BC237B (120–200), enabling more predictable bias design in production-grade amplifiers.

Can BC237CG replace BC237C in existing designs without layout changes?

Yes, BC237CG is a direct drop-in replacement for BC237C in terms of pinout, package dimensions, and electrical specifications. The only difference is the Pb-free finish; all thermal, mechanical, and electrical parameters - including V_CEO, h_FE, f_T, and R_JA - are identical, allowing seamless substitution in legacy PCBs.

What is the thermal resistance junction-to-ambient (R_JA) for BC237CG in free-air conditions?

The BC237CG has a specified thermal resistance junction-to-ambient (R_JA) of 357°C/W under standard test conditions (TO-92 mounted on FR-4 board with no copper pour). This value assumes natural convection cooling and guides minimum PCB copper area requirements to maintain T_J ≤ 150°C at full 350 mW dissipation.

BC237CG 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:: 600mV @ 5mA, 100mA

Current - Collector Cutoff (Max):: 15nA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 380 @ 2mA, 5V

Power - Max:: 350 mW

Frequency - Transition:: 200MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

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

BC237CG FAQ

1.How can I place an order for BC237CG through Aetrix?

Please submit a Request for Quotation (RFQ) for BC237CG 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 BC237CG reliable?

The price and inventory of BC237CG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC237CG is usually 5 days.

3.What payment methods are accepted for BC237CG?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC237CG transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC237CG?

BC237CG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC237CG 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 BC237CG?

For technical support, including BC237CG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC237CG requirements.

6.How does Aetrix verify that BC237CG is sourced from the original manufacturer or authorized distributors?

All BC237CG 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 BC237CG meets industry standards.

7.What is the process for return or replacement of BC237CG?

All BC237CG units undergo pre-shipment inspection (PSI). If there is an issue with BC237CG, 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 BC237CG part is unused and in its original packaging.

Return procedure for BC237CG:

1.Submit a request within 90 days.

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

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