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

onsemi 2SC3950D

Name: 2SC3950D
Brand: onsemi
SKU: 2SC3950D
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2SC3950D

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-225AA, TO-126-3

Datasheet:: 2SC3950D.pdf

Description:: TRANS NPN 20V 0.5A TO-126ML

Quantity:: RFQ Add To RFQ list

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Product details

Overview

2SC3950D from SANYO Semiconductor is an NPN epitaxial planar silicon transistor designed for high-definition CRT display video output stages and wide-band amplification. It delivers f_T = 2.0 GHz, I_C = 500 mA continuous, V_CEO = 20 V, and operates in TO-126ML plastic package with micaless construction.

For engineers reviewing the 2SC3950D datasheet, pinout, applications, or equivalent options, key selection criteria include high-frequency gain-bandwidth performance, video-output stage saturation voltage (V_CE(sat) ≤ 0.8 V at I_C = 300 mA), and thermal dissipation capability (P_C = 5 W at T_c = 25°C).

Technical Context

This transistor employs epitaxial planar process technology to achieve stable high-frequency operation up to 2.0 GHz f_T, optimized for analog video signal amplification where bandwidth, linearity, and low distortion are critical. Its DC current gain spans h_FE1 = 40–200 (at I_C = 50 mA) and h_FE2 = 20 (at I_C = 500 mA), supporting both small-signal and high-current drive modes.

Designed for video output buffer and driver stages, it features low output capacitance (C_ob = 6.0 pF at V_CB = 10 V) and reverse transfer capacitance (C_re = 4.6 pF), minimizing signal feedback and phase shift in wideband configurations. Saturation characteristics-V_CE(sat) ≤ 0.8 V and V_BE(sat) ≤ 1.2 V at I_C/I_B = 10-enable efficient switching and linear Class-A/AB operation.

Key Specifications

Parameter	Value and Actual Design Meaning
f_T	2.0 GHz - enables stable amplification of HD video signals up to ~100 MHz fundamental with margin
I_C (continuous)	500 mA - supports high-current video output drive into low-impedance CRT deflection or anode loads
V_CEO	20 V - suitable for CRT anode supply rails and horizontal deflection stage biasing
C_ob	6.0 pF at V_CB = 10 V - limits Miller effect and preserves bandwidth in common-emitter video amps
V_CE(sat)	0.3–0.8 V at I_C = 300 mA, I_B = 30 mA - ensures low power loss and minimal voltage headroom consumption
P_C (T_c = 25°C)	5 W - allows high-power video output operation with external heatsinking
h_FE2	20 at I_C = 500 mA - defines minimum current gain under full-load video drive conditions

Pinout & Package

2SC3950D uses the TO-126ML plastic package-a micaless variant of TO-126 with integrated mounting tab and standardized footprint for through-hole PCB assembly and heatsink attachment.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Connected to ground or low-impedance return path in video output emitter-follower or common-emitter stages
2 (Collector)	Current source terminal	Drives CRT anode load or horizontal deflection coil; electrically tied to heatsink tab in TO-126ML
3 (Base)	Control input	Receives amplified video signal or drive current; requires current-limiting resistor due to low V_BE(sat) threshold

Key Features

Feature	Design Value
High f_T performance	2.0 GHz gain-bandwidth product ensures flat frequency response across HD video bandwidth (up to 30–50 MHz)
Micaless TO-126ML package	Eliminates insulating mica washer-reduces thermal resistance and simplifies mechanical mounting
Low saturation voltage	V_CE(sat) ≤ 0.8 V at 300 mA enables >95% efficiency in Class-AB video output stages
High pulse current rating	I_CP = 1000 mA supports transient CRT flyback and retrace current demands
Low output capacitance	C_ob = 6.0 pF minimizes high-frequency instability and improves amplifier stability margin

Applications

High-Definition CRT Video Output	Wide-Band RF Driver
Use Scenario: Final-stage amplification of RGB or composite video signals driving CRT anode or grid electrodes. IC Role / Device Role / Timing Role: NPN video output transistor operating in Class-AB push-pull or single-ended configuration. Use Value: Delivers 500 mA continuous current with 2.0 GHz f_T to maintain edge fidelity and minimize rise-time degradation in HD video waveforms.	Use Scenario: Medium-power broadband RF amplification in VHF/UHF test equipment or analog signal generators. IC Role / Device Role / Timing Role: Single-transistor wideband amplifier with fixed-gain topology and DC-coupled input. Use Value: Low C_ob (6.0 pF) and C_re (4.6 pF) reduce feedback-induced oscillation risk while sustaining >100 MHz usable bandwidth.
Horizontal Deflection Driver	Analog Signal Reconstruction
Use Scenario: Driving horizontal deflection yoke in CRT monitors requiring high peak current and fast switching. IC Role / Device Role / Timing Role: Switching transistor in quasi-resonant or linear horizontal output stage. Use Value: I_CP = 1000 mA and V_CEO = 20 V support safe operation during flyback transients and retrace intervals.	Use Scenario: Reconstructing high-fidelity analog waveforms from DAC outputs in precision test instrumentation. IC Role / Device Role / Timing Role: Unity-gain buffer or low-distortion voltage follower for signal conditioning. Use Value: V_CE(sat) ≤ 0.8 V and h_FE ≥ 20 at full load preserve signal amplitude integrity and minimize harmonic distortion.

High-Definition CRT Video Output

Wide-Band RF Driver

Use Scenario: Final-stage amplification of RGB or composite video signals driving CRT anode or grid electrodes.

IC Role / Device Role / Timing Role: NPN video output transistor operating in Class-AB push-pull or single-ended configuration.

Use Value: Delivers 500 mA continuous current with 2.0 GHz f_T to maintain edge fidelity and minimize rise-time degradation in HD video waveforms.

Use Scenario: Medium-power broadband RF amplification in VHF/UHF test equipment or analog signal generators.

IC Role / Device Role / Timing Role: Single-transistor wideband amplifier with fixed-gain topology and DC-coupled input.

Use Value: Low C_ob (6.0 pF) and C_re (4.6 pF) reduce feedback-induced oscillation risk while sustaining >100 MHz usable bandwidth.

Horizontal Deflection Driver

Analog Signal Reconstruction

Use Scenario: Driving horizontal deflection yoke in CRT monitors requiring high peak current and fast switching.

IC Role / Device Role / Timing Role: Switching transistor in quasi-resonant or linear horizontal output stage.

Use Value: I_CP = 1000 mA and V_CEO = 20 V support safe operation during flyback transients and retrace intervals.

Use Scenario: Reconstructing high-fidelity analog waveforms from DAC outputs in precision test instrumentation.

IC Role / Device Role / Timing Role: Unity-gain buffer or low-distortion voltage follower for signal conditioning.

Use Value: V_CE(sat) ≤ 0.8 V and h_FE ≥ 20 at full load preserve signal amplitude integrity and minimize harmonic distortion.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN high-frequency power transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
2SC3838	f_T = 1.2 GHz, I_C = 300 mA, V_CEO = 20 V, TO-126 package	Lower bandwidth and current capacity; suitable only for SD video or lower-power deflection	Select when system bandwidth < 50 MHz and peak current < 300 mA; verify thermal derating at T_c
2SC4110	f_T = 2.5 GHz, I_C = 600 mA, V_CEO = 25 V, TO-220 package	Higher voltage/current ratings and larger package; requires PCB layout change	Choose for upgraded HD+ systems needing >20 V headroom or >500 mA drive; not drop-in compatible

Compared with 2SC3950D, 2SC3838 offers reduced bandwidth and current handling but shares TO-126 mechanical compatibility, whereas 2SC4110 provides superior RF performance and voltage margin at the cost of package redesign and thermal interface requalification.

Availability

2SC3950D is available at Aetrix Electronics and suitable for high-definition CRT display video output, wide-band amplifier, and horizontal deflection driver applications requiring stable component supply and long-term industrial availability.

Supply support for 2SC3950D 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

SANYO Semiconductor Co., Ltd. was a Japanese semiconductor manufacturer specializing in analog, power, and display interface components before its acquisition by ON Semiconductor in 2011.

The 2SC3950D belongs to SANYO's high-frequency bipolar transistor product line, engineered specifically for analog video signal chain integrity in CRT-based display systems.

FAQ

What is the maximum collector current rating for the 2SC3950D?

The 2SC3950D has a continuous collector current rating of 500 mA and a pulsed collector current rating of 1000 mA. These values are specified at T_a = 25°C with appropriate heatsinking. Operation above 500 mA continuous requires verification of case temperature (T_c) and thermal design to avoid exceeding the 150°C junction limit. The 2SC3950D must be mounted on a heatsink when operating near its P_C = 5 W limit.

Does the 2SC3950D support high-definition video bandwidth requirements?

Yes, the 2SC3950D supports HD video bandwidth requirements via its 2.0 GHz f_T, low C_ob (6.0 pF), and fast saturation characteristics. These parameters enable flat gain response up to ~100 MHz, sufficient for preserving edge sharpness and timing fidelity in 1080i/p CRT video signals. The 2SC3950D is explicitly rated for high-definition CRT display video output per its original SANYO datasheet.

What is the pin configuration of the 2SC3950D in TO-126ML package?

The 2SC3950D uses a standard TO-126ML pinout: Pin 1 = Emitter, Pin 2 = Collector (connected to metal tab), Pin 3 = Base. This configuration is confirmed in the SANYO datasheet diagram (No.2441-2/4) and matches industry-standard TO-126 mechanical drawings. The collector-tab connection requires electrical isolation from chassis unless intentionally grounded per circuit design.

Is the 2SC3950D suitable for use in safety-critical or medical applications?

No, the 2SC3950D is intended for standard applications including home appliances, AV equipment, and industrial displays-not for safety-critical, life-sustaining, or medical equipment. SANYO explicitly excludes "special applications" such as medical devices, aerospace, nuclear control, or transportation systems. The 2SC3950D does not carry extended reliability qualification or failure rate certification required for such domains.

How does the micaless TO-126ML package affect thermal performance of the 2SC3950D?

The micaless TO-126ML package eliminates the insulating mica washer used in traditional TO-126 variants, reducing thermal resistance between the die and heatsink. This allows more efficient heat transfer and higher sustained power dissipation-critical for video output stages running continuously at elevated ambient temperatures. The 2SC3950D achieves P_C = 5 W at T_c = 25°C specifically due to this improved thermal path.

2SC3950D Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-225AA, TO-126-3

Packaging:: Bulk

Product Status:: Active

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 500 mA

Voltage - Collector Emitter Breakdown (Max):: 20 V

Vce Saturation (Max) @ Ib, Ic:: 800mV @ 30mA, 300mA

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 60 @ 50mA, 5V

Power - Max:: 1.3 W

Frequency - Transition:: 2GHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-126ML

2SC3950D FAQ

1.How can I place an order for 2SC3950D through Aetrix?

Please submit a Request for Quotation (RFQ) for 2SC3950D 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 2SC3950D reliable?

The price and inventory of 2SC3950D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2SC3950D is usually 5 days.

3.What payment methods are accepted for 2SC3950D?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2SC3950D transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2SC3950D?

2SC3950D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2SC3950D 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 2SC3950D?

For technical support, including 2SC3950D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2SC3950D requirements.

6.How does Aetrix verify that 2SC3950D is sourced from the original manufacturer or authorized distributors?

All 2SC3950D 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 2SC3950D meets industry standards.

7.What is the process for return or replacement of 2SC3950D?

All 2SC3950D units undergo pre-shipment inspection (PSI). If there is an issue with 2SC3950D, 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 2SC3950D part is unused and in its original packaging.

Return procedure for 2SC3950D:

1.Submit a request within 90 days.

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

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