2SC945Q

NPN small-signal transistor, 50V VCEO, 150mA IC, 190MHz fT, TO-92 package, Q grade hFE (135-270), for audio amplification and high-frequency oscillator applications.

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Manufacturer Part：

2SC945Q

Package：

TO-92

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Description

Product Overview

The 2SC945Q is an NPN silicon epitaxial small-signal transistor designed for general-purpose audio frequency amplification and high-frequency oscillator applications. With a 50V collector-emitter voltage rating, 150mA collector current capacity, and a transition frequency of 190MHz typical, this device is well-suited for low-power signal amplification, high-frequency oscillation, and small-signal switching circuits. The ‘Q’ suffix designates the hFE grade of 135 to 270, providing medium-to-high current gain. Packaged in the widely-used TO-92 through-hole format, the 2SC945Q is a versatile general-purpose transistor used in a wide range of consumer and industrial electronic applications. Its complementary PNP counterpart is the 2SA733 series.

Key Specifications

Parameter Value
Transistor Type NPN Silicon Epitaxial Planar
Collector-Base Voltage (VCBO) 60 V
Collector-Emitter Voltage (VCEO) 50 V
Emitter-Base Voltage (VEBO) 5 V
Collector Current (IC) 150 mA
Base Current (IB) 50 mA
Collector Power Dissipation (PC) 750 mW (Tc=25°C)
DC Current Gain (hFE) 135 to 270 (Q grade)
Collector-Emitter Saturation Voltage 0.3 V (max) @ IC=100mA, IB=10mA
Transition Frequency (fT) 190 MHz (typ) @ IC=50mA
Output Capacitance (Cob) 3.0 pF (max)
Noise Figure (NF) 6.0 dB (max) @ f=100Hz
Junction Temperature +125°C (max)
Storage Temperature -55 to +150°C
Package TO-92 (3-Pin Through Hole)

Features

  • High transition frequency: 190MHz typical, suitable for RF and high-frequency applications
  • High hFE linearity for consistent gain across current levels
  • Low collector-emitter saturation voltage: 0.3V max at 100mA
  • Low output capacitance: 3pF typical for high-frequency performance
  • Q grade hFE: 135 to 270 (medium-high gain classification)
  • Available in multiple hFE grades: R (90-180), Q (135-270), P (200-400), K (300-600)
  • TO-92 package for through-hole mounting, widely available
  • Complementary to 2SA733 (PNP) for push-pull designs
  • Lead-free and RoHS compliant options available

Applications

  • Audio frequency pre-amplifiers and signal amplification
  • High-frequency oscillator circuits
  • Small-signal switching applications
  • Driver stages for medium-power transistors
  • Consumer electronics and home appliances
  • Radio frequency (RF) circuits up to VHF range
  • General-purpose electronic circuits

The 2SC945Q is a versatile NPN silicon epitaxial small-signal transistor widely used in general-purpose electronic circuits, audio amplification, and high-frequency oscillator applications. Manufactured using epitaxial planar technology, this device offers excellent high-frequency performance with a transition frequency of 190MHz typical, making it suitable for applications ranging from audio frequencies up to VHF radio circuits. The ‘Q’ suffix indicates the medium-high DC current gain grade, with hFE ranging from 135 to 270, providing designers with a predictable gain range for circuit optimization. The full hFE grading system includes R (90-180), Q (135-270), P (200-400), and K (300-600), allowing precise selection based on application requirements. With a collector-emitter voltage of 50V and collector current of 150mA, the 2SC945Q handles most small-signal amplification and low-power switching tasks effectively. The low collector-emitter saturation voltage of 0.3V maximum ensures efficient switching operation, while the low output capacitance of 3pF typical supports high-frequency circuit operation. Packaged in the industry-standard TO-92 through-hole format, this transistor is widely available and easy to prototype with. Its complementary PNP counterpart is the 2SA733 series, enabling complementary push-pull designs at low power levels. The 2SC945Q finds applications across consumer electronics, industrial control circuits, audio pre-amplifiers, oscillator circuits, and general-purpose signal processing.

The 2SC945Q is an NPN bipolar junction transistor that operates on the principle of current-controlled current amplification. When a small current flows into the base terminal (forward-biasing the base-emitter junction), it controls a proportionally larger current flowing between the collector and emitter terminals. The DC current gain hFE of the Q grade ranges from 135 to 270, meaning the collector current is 135 to 270 times the base current. In common-emitter configuration (the most widely used topology), the input signal is applied to the base-emitter junction and the amplified output is taken from the collector. The high transition frequency (190MHz) means the gain remains substantial well into the radio frequency range, enabling use in RF amplifier and oscillator circuits. The epitaxial planar construction provides a thin base region, which contributes to both high gain and good high-frequency response. In audio applications, the transistor’s high hFE linearity ensures that the gain remains consistent across the signal current range, minimizing distortion. For switching applications, the low saturation voltage ensures that power dissipation in the ON state is minimized, while the fast switching characteristics support operation at moderate frequencies. The noise figure of 4 to 6dB makes it suitable for low-level signal amplification where noise performance is important.

Pin Number Pin Name Description
1 Emitter (E) Emitter terminal – reference terminal for common-emitter circuits; connected to ground or lower supply rail
2 Collector (C) Collector terminal – connected to the positive supply through a load resistor or matching network; output is taken from this pin in common-emitter configuration
3 Base (B) Base terminal – input signal is applied here; small base current controls the collector-emitter current flow
  • Audio pre-amplifier stages and headphone amplifiers
  • High-frequency oscillator circuits (Colpitts, Hartley, RC oscillators)
  • Small-signal switching and logic level translation
  • Driver stages for medium-power output transistors
  • Radio frequency (RF) amplifier circuits up to VHF band
  • Consumer electronics: televisions, radios, audio equipment
  • Industrial control and sensor signal conditioning circuits
Model Manufacturer Key Difference
2N3904 ON Semiconductor / Fairchild Industry-standard NPN small-signal transistor, 40V/200mA, TO-92
BC337 ON Semiconductor / NXP 45V/800mA NPN general-purpose transistor, TO-92, higher current
2SC1815 Toshiba 60V/150mA NPN transistor, TO-92, similar audio amplifier application
KSC945 ON Semiconductor Direct equivalent, 60V/150mA, TO-92, manufacturer cross-reference
MMBT3904 ON Semiconductor Surface-mount SOT-23 version of 2N3904, SMD alternative
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Quality Assurance

Quality is the core foundation of our long-term global cooperation. With over 20 years of experience in the electronic component industry, Materialparts has built a strict and standardized quality management system covering component sourcing, incoming inspection, full-batch testing, packaging and delivery. We are committed to delivering 100% genuine, high-reliability electronic components for industrial control, automotive electronics, consumer electronics and medical device industries, and fully safeguarding your production and R&D projects.

1. Authorized & Genuine Sourcing Promise

All of our electronic components are procured from official authorized distributors and original manufacturers. We strictly reject counterfeits, refurbished parts, disassembled components and gray-market goods. Every product is guaranteed to be brand-new original parts and fully consistent with the original technical parameters. For branded products such as NXP IC series, we maintain complete supply channel documents to realize full product traceability.

2. Strict Full-batch Quality Inspection

We implement 100% full-batch quality control for all goods before shipment. Our professional QC team conducts multi-dimensional tests including appearance inspection, electrical parameter testing, performance verification and packaging check. Each batch of components is attached with complete inspection reports and batch records. We stick to zero-tolerance standards for defective products to ensure every piece of component meets industrial application requirements.

3. Industry Standard Compliance

Our products comply with a variety of international industry quality standards to adapt to high-standard application scenarios:
  • Automotive Electronics: All automotive-grade components pass AEC-Q series certification, featuring excellent stability and durability to adapt to complex vehicle operating environments.
  • Medical Devices: High-reliability components meet medical industry safety and compliance regulations, ensuring stable operation for medical equipment.
  • Industrial Control & Consumer Electronics: Products conform to universal international electronic industry standards, suitable for long-term continuous operation of various equipment.

4. Professional Reliability Control

For static-sensitive, moisture-sensitive and precision components such as ICs, PCBs, sensors and connectors, we carry out reliability screening in advance. Combined with standardized ESD anti-static packaging and vacuum moisture-proof packaging, we avoid component damage caused by static electricity, dampness or collision during storage and transportation, and retain the original performance of products.

5. Traceability Management System

We establish a complete product traceability system. Each batch of goods corresponds to independent batch number, sourcing record, inspection record and delivery record. Customers can query the whole lifecycle information of components at any time. This system effectively solves quality risks and facilitates after-sales handling and production quality control for your company.

6. After-sales Quality Guarantee

If any product is confirmed to have non-conformity quality problems due to our reasons after receipt, we provide free return, exchange and supplementary delivery services. Our professional quality team will also conduct root cause analysis to optimize our quality control process. We respond to quality feedback within 24 hours to resolve your worries efficiently.

Contact Us

If you have inquiries about our quality standards, inspection procedures or product certification documents, please feel free to contact us:

 

Email: [email protected]
Tel / WhatsApp: +86 13760382860
Address: Room 2919, Guoli Building, Huaqiang North, Futian District, Shenzhen, Guangdong, China

 

Shipping & Payment

Materialparts is a professional global supplier of electronic components with over 20 years of industry experience. We provide one-stop supply of passive components, integrated circuits, as well as parts for industrial control, automotive electronics, consumer electronics and medical devices. Below are the unified shipping and payment policies applicable to all orders, samples and bulk purchases worldwide.

1. Payment Terms

We offer a variety of secure and convenient payment methods to meet diverse business cooperation needs. Details are as follows:
  1. Accepted Payment Methods
  • T/T (Bank Wire Transfer): The primary settlement method for bulk orders and a widely used international payment channel.
  • PayPal: Ideal for small orders, sample orders and quick payments.

  1. Settlement Currency

     

    US Dollar (USD) is the default settlement currency. RMB is available for domestic customers.

  2. Bank Charges

     

    All transfer fees, intermediary bank charges and other remittance-related expenses shall be borne by the buyer.

  3. Payment Requirements
  • Sample and small orders: Shipment will be arranged upon full payment.
  • In-stock bulk orders: Goods will be delivered within 2 to 3 working days after full payment.

2. Shipping & Delivery

We partner with leading global logistics providers to ensure safe and fast delivery worldwide. Relevant details are listed below:
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  • Economy Logistics: Air freight and sea freight for large-volume cargo
  • Domestic Delivery: SF Express, Yunda Express
  1. Order Processing Time
  • In-stock items: Orders confirmed and fully paid before 14:00 (GMT+8) will be shipped on the same day. All other orders will be dispatched within 1 to 2 working days.
  • Out-of-stock or sourced items: The delivery lead time will be confirmed separately according to brand and inventory status.
  1. Estimated Transit Time
  • International Express: 3 – 7 working days globally
  • Air Freight: 7 – 12 working days
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  • Free international express delivery is offered for large orders. Terms for long-term partners can be negotiated separately.
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    Within 24 hours after dispatch, we will send the tracking number, commercial invoice, packing list and other documents to your email or communication account. You may check the shipment status online in real time.

3. General Order Rules & Notes

  1. MOQ & Sample Service

     

    We support flexible minimum order quantities for samples, small-batch and large-batch orders. All sample orders shall comply with the above shipping and payment policies.

  2. Packaging Standard

     

    All electronic components are packed with professional anti-static and shockproof materials. Original factory packaging is available for branded chips and integrated circuits.

4. Customs & Liability Statement

  1. Import Duties & Taxes

     

    All import duties, customs clearance fees and local taxes incurred for international shipments shall be borne by the buyer. We will provide complete customs documents to assist you with clearance procedures.

  2. Handling of Lost or Damaged Goods
  • In case of loss or severe damage during transit, please contact us within 48 hours after receiving the tracking information. We will assist you in filing a claim with the logistics provider.
  • We shall not be liable for any losses caused by incorrect delivery address, wrong contact information or the buyer’s refusal to complete customs clearance.

5. Local Pickup in Shenzhen

Local pickup service is available for customers in Shenzhen and surrounding areas:
  • Address: Room 2919, Guoli Building, Huaqiang North, Futian District, Shenzhen, Guangdong Province, China
  • Business Hours: 09:00 – 18:00, Monday to Friday. Closed on weekends and official public holidays.
  • Notice: Please make an appointment via email or communication tools one day in advance, and present your order information upon pickup.

Contact Information

Email: [email protected]

Tel / WhatsApp: +86 13760382860

Service & Packaging

Materialparts is a professional electronic component supplier based in Shenzhen, China, with over 20 years of global trading experience. We integrate component procurement, quality inspection, technical support, customized packaging, and global delivery services to provide one-stop supply chain solutions. Our business covers industrial control, automotive electronics, consumer electronics, medical devices and other industries. We always adhere to genuine sources, stable supply and considerate after-sales service.

Core Services

1. One-stop Sourcing & BOM Support

We specialize in a full range of passive and active electronic components, including SMD resistors, power resistors, connectors, aviation connectors, LED beads, flexible circuit boards, printed circuit boards, and integrated circuits. Our professional team provides BOM list consolidation, component matching, and alternative model recommendation services. We support sample orders, small-batch trial production, and mass production orders with flexible MOQs to meet diverse procurement needs.

2. Genuine Product Guarantee & Full-process Quality Inspection

All products are sourced from official authorized channels and are 100% original genuine parts. Every batch of goods undergoes strict full-process quality inspection before delivery, with complete batch records and traceability documents provided. Our products comply with AEC-Q standards for automotive electronics and high-reliability specifications for medical devices. We eliminate counterfeits, refurbished parts and defective products from the source to secure your project production.

3. Fast Quotation & Order Processing

Our customer service team responds promptly to inquiries and quotation requests. All in-stock orders will be processed within one working day. We provide stocking reservation services for long-term cooperative customers, effectively solving problems such as component shortages and unstable supply chains.

4. Professional Technical Support

Our senior engineer team provides free technical consultation, model selection guidance and original manufacturer datasheets. We assist customers in solving problems related to product R&D, circuit design and component application, providing reliable technical support for project progress.

5. Sourcing for Special Components

Relying on our global supply chain network, we professionally source scarce components, obsolete parts and customized special components to efficiently solve your procurement difficulties.

6. Global Logistics & Document Services

We cooperate with mainstream international logistics providers including DHL, FedEx, UPS and TNT to achieve fast global delivery. We can provide complete export documents such as customs declaration files, commercial invoices and packing lists to ensure smooth customs clearance for international shipments. Local pickup is also available for customers in Shenzhen, China.

Professional Packaging Standards

Electronic components are sensitive to static electricity, collision, moisture and dust. We adopt industry-standard anti-static packaging solutions to fully ensure the integrity of goods during transportation and storage.

1. General Packaging Specifications

  • All components are packed separately to avoid damage caused by friction and collision;
  • Shockproof buffer materials are added for fragile products to ensure transportation safety;
  • Each package is clearly marked with part number, quantity, batch number and specifications for easy inventory counting and management.

2. Classified Professional Packaging

  • Anti-static Packaging: Static-sensitive components such as chips, circuit boards and sensors are packaged with anti-static bags, shielding boxes and conductive foam in strict accordance with international anti-static standards to prevent static damage.
  • Vacuum Moisture-proof Packaging: Moisture-sensitive components are vacuum-sealed with desiccants to isolate humid air, suitable for ocean transportation and long-term storage.
  • Original Factory Packaging: Integrated circuits of brands such as NXP are delivered with original reels, trays or tubes by default, retaining complete original packaging and adapting to automated SMT production lines.
  • Discrete Device Packaging: Discrete devices such as SMD resistors, power resistors and LEDs are quantitatively and classifiedly packaged with accurate quantity and clear marking.
  • Connector / Aviation Connector Packaging: Hard outer packaging is adopted to prevent pin bending and structural deformation.

3. Custom Packaging Services

We provide value-added services including personalized packaging, custom labeling and re-reeling according to customer requirements, fully matching your production and warehouse management standards.

Contact Information

For service consultation or packaging customization, please feel free to contact us:
Email: [email protected]
Tel / WhatsApp: +86 13760382860
Address: Room 2919, Guoli Building, Huaqiang North, Futian District, Shenzhen, Guangdong, China
 

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