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

onsemi BC372G

Name: BC372G
Brand: onsemi
SKU: BC372G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC372G

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: BC372G.pdf

Description:: TRANS NPN DARL 100V 1A TO92

Quantity:: RFQ Add To RFQ list

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Inventory:7,436

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Product details

Overview

BC372G from onsemi is an NPN silicon high-voltage Darlington transistor in TO-92 package, rated for V_CEO = 100 V, I_C = 1.0 A, and P_D = 625 mW at T_A = 25°C, with h_FE ≥ 8.0 (min) at I_C = 250 mA and V_CE = 5 V - used in relay drivers, lamp dimmers, and low-frequency switching power supplies.

For engineers reviewing the BC372G datasheet, pinout, applications, or equivalent options, key selection considerations include its 100 V V_CEO rating, Darlington gain structure, TO-92 thermal resistance (R_JA = 200 °C/W), saturation voltage behavior (V_CE(sat) ≤ 1.1 V), and Pb-free compliance per onsemi's Rev. 4 specification.

Technical Context

The BC372G implements a monolithic NPN Darlington pair with integrated base-emitter resistor network absent - requiring external base drive control. Its high V_CEO and V_CES (both 100 V) support operation in 80–100 V DC bus applications, while f_T = 100–200 MHz enables stable low-speed switching up to ~10 kHz without oscillation.

Thermal design relies on R_JC = 83.3 °C/W and R_JA = 200 °C/W, limiting continuous dissipation to 625 mW at ambient; derating is 5.0 mW/°C above 25°C. C_ob = 10–25 pF and NF = 2.0 dB (1 kHz) confirm suitability for audio-level amplification and noise-sensitive analog switching.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	100 V - supports direct switching of 80–100 V DC loads without external snubbing
I_C (max)	1.0 A - enables driving relays, solenoids, or incandescent lamps up to 100 W at 100 V
h_FE	8.0–160 - Darlington gain allows microampere-level base current to switch >100 mA collector load
V_CE(sat)	≤1.1 V @ I_C/I_B = 100 - limits conduction loss to <1.1 W at full 1 A load
f_T	100–200 MHz - ensures stable turn-off response in PWM dimming below 20 kHz
R_JA	200 °C/W - requires heatsinking or airflow for >300 mW sustained dissipation in still air

Pinout & Package

BC372G is housed in a Pb-free TO-92 (Case 29, Style 1) package with straight leads, 3-pin through-hole mounting, and standard pinout: Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink output node	Connected to ground or low-side return path; must handle full load current and tolerate V_EB ≤ 12 V
2 (Base)	Control input terminal	Receives current-limited drive (typically 1–10 mA); no internal bias resistor - external R_B required
3 (Collector)	High-voltage switched output	Connects to positive rail or inductive load; withstands 100 V transient spikes during turn-off

Key Features

Feature	Design Value
High-voltage Darlington architecture	Enables single-transistor 100 V, 1 A switching without cascaded stages or external gain boost
Pb-free TO-92 packaging	Complies with RoHS Directive 2011/65/EU and JEDEC J-STD-609A Class 3 moisture sensitivity
Low V_CE(sat) at high I_C	Reduces power loss to ≤1.1 W at 1 A, easing thermal management in compact enclosures
Wide T_J range (−55 to +150°C)	Supports deployment in automotive under-hood, industrial motor controls, and outdoor lighting environments

Applications

Relay Driver Circuits	Lamp Dimming Controls
Use Scenario: Driving 12–48 VDC electromagnetic relays in PLC I/O modules and HVAC controllers. IC Role / Device Role / Timing Role: High-current, high-voltage switch interfacing microcontroller GPIO to relay coil. Use Value: Eliminates need for discrete driver transistors or optocoupler+MOSFET combos due to integrated Darlington gain and 100 V rating.	Use Scenario: Phase-angle dimming of incandescent and halogen lamps in residential and commercial lighting. IC Role / Device Role / Timing Role: Main AC line-switching element synchronized to zero-cross detection. Use Value: Withstands 100 V peak reverse voltage across collector-emitter during half-cycle blocking, enabling direct mains-connected TRIAC gate drive.
Low-Frequency Power Supplies	Industrial Solenoid Actuators
Use Scenario: Linear regulator pass elements or flyback converter primary switches operating below 20 kHz. IC Role / Device Role / Timing Role: Voltage-controlled current source regulating output voltage or storing energy in transformer primary. Use Value: f_T ≥ 100 MHz ensures clean turn-off with minimal tail current, reducing switching losses and EMI in unregulated SMPS designs.	Use Scenario: On/off control of 24–100 VDC solenoid valves in factory automation and fluid control systems. IC Role / Device Role / Timing Role: Final-stage power switch activated by PLC output or isolated digital signal. Use Value: V_CEO = 100 V accommodates inductive kickback suppression without clamping diodes in many valve configurations.

Relay Driver Circuits

Lamp Dimming Controls

Use Scenario: Driving 12–48 VDC electromagnetic relays in PLC I/O modules and HVAC controllers.

IC Role / Device Role / Timing Role: High-current, high-voltage switch interfacing microcontroller GPIO to relay coil.

Use Value: Eliminates need for discrete driver transistors or optocoupler+MOSFET combos due to integrated Darlington gain and 100 V rating.

Use Scenario: Phase-angle dimming of incandescent and halogen lamps in residential and commercial lighting.

IC Role / Device Role / Timing Role: Main AC line-switching element synchronized to zero-cross detection.

Use Value: Withstands 100 V peak reverse voltage across collector-emitter during half-cycle blocking, enabling direct mains-connected TRIAC gate drive.

Low-Frequency Power Supplies

Industrial Solenoid Actuators

Use Scenario: Linear regulator pass elements or flyback converter primary switches operating below 20 kHz.

IC Role / Device Role / Timing Role: Voltage-controlled current source regulating output voltage or storing energy in transformer primary.

Use Value: f_T ≥ 100 MHz ensures clean turn-off with minimal tail current, reducing switching losses and EMI in unregulated SMPS designs.

Use Scenario: On/off control of 24–100 VDC solenoid valves in factory automation and fluid control systems.

IC Role / Device Role / Timing Role: Final-stage power switch activated by PLC output or isolated digital signal.

Use Value: V_CEO = 100 V accommodates inductive kickback suppression without clamping diodes in many valve configurations.

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage Darlington transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC372	Same die, non-Pb-free TO-92 package; identical electrical specs and pinout	No RoHS compliance; unsuitable for EU/China export or new medical/industrial designs	Select BC372G when Pb-free compliance and traceable sourcing are mandatory
MJD122G	TO-220 package, higher P_D = 1.5 W, same V_CEO = 100 V, h_FE = 1000–4000 (higher gain)	Requires PCB footprint change and heatsink; better for >500 mA continuous loads	Choose MJD122G only when thermal budget exceeds TO-92 capability or gain >1000 is needed

Compared with BC372 and MJD122G, the BC372G offers RoHS-compliant TO-92 packaging with verified 100 V/1 A capability and predictable Darlington saturation behavior - making it optimal for cost-sensitive, space-constrained, and regulatory-compliant relay and lamp driver designs where thermal load stays below 625 mW.

Availability

BC372G is available at Aetrix Electronics and suitable for relay driver circuits, lamp dimming controls, low-frequency power supplies, and industrial solenoid actuators requiring stable component supply and full RoHS compliance.

Supply support for BC372G 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 delivering energy-efficient, high-performance silicon solutions for automotive, industrial, cloud, medical, and IoT applications.

The BC372G belongs to onsemi's legacy bipolar transistor product line, designed specifically for high-voltage, medium-current linear and switching applications where Darlington gain, ruggedness, and TO-92 manufacturability are prioritized over RF performance or ultra-low saturation.

FAQ

What is the maximum continuous collector current for BC372G?

The BC372G has a maximum continuous collector current (I_C) of 1.0 A at T_A = 25°C. Derating applies above 25°C at 5.0 mW/°C, and actual usable current depends on PCB copper area, ambient temperature, and airflow. At 70°C ambient, safe continuous I_C drops to approximately 0.55 A assuming no heatsink.

Does BC372G include a built-in base-emitter resistor?

No, the BC372G does not integrate any base-emitter resistor. It is a bare Darlington pair requiring external base current limiting - typically via a series resistor between microcontroller GPIO and Pin 2 (Base). This allows precise control of gain and switching speed, unlike biased transistors such as the MMBT5401.

What is the typical V_CE(sat) of BC372G at 1 A collector current?

The BC372G specifies V_CE(sat) ≤ 1.1 V at I_C = 250 mA and I_B = 2.5 mA (I_C/I_B = 100). At 1 A, V_CE(sat) rises to ~1.3–1.5 V depending on junction temperature and base drive level - confirmed by Figure 2 in the onsemi BC372/D datasheet.

Can BC372G replace BC373G in a 100 V circuit?

No - BC373G is rated for V_CEO = 80 V only, while BC372G is rated for 100 V. Substituting BC372G for BC373G is acceptable if voltage stress remains ≤80 V, but replacing BC373G with BC372G in a 100 V design is valid and improves margin. The reverse substitution risks breakdown.

Is BC372G suitable for audio amplifier applications?

The BC372G can be used in low-fidelity, low-power audio preamplifier or driver stages due to its 2.0 dB noise figure at 1 kHz and f_T > 100 MHz, but it is not optimized for linearity or low distortion. For Hi-Fi audio, purpose-built small-signal transistors like BC549C or 2N5088 are preferred; BC372G suits cost-sensitive speaker protection or mute-switch circuits instead.

BC372G 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 - Darlington

Current - Collector (Ic) (Max):: 1 A

Voltage - Collector Emitter Breakdown (Max):: 100 V

Vce Saturation (Max) @ Ib, Ic:: 1.1V @ 250µA, 250mA

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 10000 @ 100mA, 5V

Power - Max:: 625 mW

Frequency - Transition:: 200MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

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

BC372G FAQ

1.How can I place an order for BC372G through Aetrix?

Please submit a Request for Quotation (RFQ) for BC372G 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 BC372G reliable?

The price and inventory of BC372G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC372G is usually 5 days.

3.What payment methods are accepted for BC372G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC372G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC372G?

BC372G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC372G 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 BC372G?

For technical support, including BC372G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC372G requirements.

6.How does Aetrix verify that BC372G is sourced from the original manufacturer or authorized distributors?

All BC372G 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 BC372G meets industry standards.

7.What is the process for return or replacement of BC372G?

All BC372G units undergo pre-shipment inspection (PSI). If there is an issue with BC372G, 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 BC372G part is unused and in its original packaging.

Return procedure for BC372G:

1.Submit a request within 90 days.

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

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