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

onsemi 2SC3708S-AA

Name: 2SC3708S-AA
Brand: onsemi
SKU: 2SC3708S-AA
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2SC3708S-AA

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 (TO-226AA)

Datasheet:: 2SC3708S-AA.pdf

Description:: TRANS NPN 80V 0.5A 3-NP

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Product details

Overview

2SC3708S-AA from SANYO Semiconductor is an NPN epitaxial planar silicon transistor designed for low-frequency driver and audio power amplifier applications, featuring V_CEO = 80 V, I_C = 500 mA, P_C = 600 mW, f_T = 120 MHz, and h_FE = 100–400 (rank-dependent), commonly used in stereo amplifier output stages and relay drivers.

For engineers reviewing the 2SC3708S-AA datasheet, pinout, applications, or equivalent options, key selection considerations include its 80 V breakdown rating, 500 mA continuous collector current, TO-92MOD package footprint, and verified performance in Class AB audio output stages at 25°C ambient.

Technical Context

This device employs FBET (Flat Base Epitaxial Transistor) process technology to achieve high V_CEO and stable h_FE across temperature. Its gain-bandwidth product of 120 MHz supports wideband AF driver operation, while low V_CE(sat) (0.16 V typ. at I_C = 400 mA) enables efficient switching in linear and saturated-mode circuits.

The 2SC3708S-AA shares design lineage and absolute maximum ratings with its PNP complement 2SA1450, enabling complementary pair use in push-pull amplifiers. Its Cob = 5 pF at V_CB = 10 V ensures minimal Miller effect in medium-speed switching applications.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	80 V - Supports rail voltages up to ±36 V in Class AB audio output stages without breakdown.
I_C (continuous)	500 mA - Delivers sufficient drive current for small-signal power stages driving 8 Ω loads up to ~1 W.
P_C	600 mW - Enables operation in TO-92MOD package with heatsinking via PCB copper at T_a ≤ 75°C.
f_T	120 MHz - Ensures adequate bandwidth for full-audio-range (20 Hz–20 kHz) amplification with phase margin.
h_FE	100–400 (rank R/S/T) - Provides predictable DC bias stability across production lots in fixed-bias or emitter-degenerated designs.
V_CE(sat)	0.16 V (typ.) at I_C = 400 mA - Minimizes conduction loss and thermal rise in saturated-switching applications like relay drivers.
C_ob	5 pF at V_CB = 10 V - Limits high-frequency feedback in multi-stage amplifiers and prevents instability near f_T.

Pinout & Package

2SC3708S-AA is housed in a TO-92MOD plastic package (5.0 × 4.0 × 4.0 mm), with lead-free plating and standard through-hole mounting. Pin 1 = Emitter, Pin 2 = Collector, Pin 3 = Base - confirmed per SANYO package drawing 7522-002.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current exit path for NPN operation	Connected to ground or low-impedance return in common-emitter configurations; requires low-inductance routing in power stages.
2 (Collector)	Current entry path under forward bias	Drives load (e.g., speaker, relay coil); must be routed with adequate copper area for 500 mA and thermal dissipation.
3 (Base)	Control terminal for minority-carrier injection	Requires current-limited drive (I_B ≤ 100 mA) and noise filtering; base resistor selection directly sets operating point stability.

Key Features

Feature	Design Value
FBET process technology	Enables tight h_FE distribution and improved V_CEO consistency vs. conventional planar processes.
High V_CEO (80 V)	Permits use in higher-voltage audio supplies (e.g., ±24 V rails) without derating or series stacking.
Low V_CE(sat) (0.16 V typ.)	Reduces power loss and junction temperature rise in linear regulator pass elements or saturated switch roles.
Rank-coded h_FE (R/S/T)	Allows binning for matched pairs in differential amplifiers or consistent biasing across production batches.
TO-92MOD mechanical outline	Provides standardized footprint compatibility with legacy 2N3904/2N2222 layouts while supporting higher power dissipation.

Applications

Audio Power Amplifier Stage	Relay Driver Circuit
Use Scenario: Final output stage in compact stereo amplifier delivering 0.5–1 W into 8 Ω speakers. IC Role / Device Role / Timing Role: NPN power switch in Class AB configuration, biased with complementary 2SA1450. Use Value: 80 V V_CEO and 500 mA I_C enable safe operation with ±20 V rails; low V_CE(sat) minimizes heat generation at idle and full output.	Use Scenario: Driving 12 V, 100 mA coil relays in industrial control I/O modules. IC Role / Device Role / Timing Role: Single-transistor saturated switch with base resistor network controlling coil energization. Use Value: 600 mW P_C and 0.16 V V_CE(sat) ensure reliable on-state operation without heatsink; fast turn-off supported by 120 MHz f_T.
Low-Frequency Signal Driver	DC Motor Speed Control (Small)
Use Scenario: Buffering and level-shifting signals between microcontroller GPIO and analog circuitry. IC Role / Device Role / Timing Role: Common-emitter voltage amplifier with fixed-gain bias network. Use Value: h_FE range (100–400) allows predictable gain setting; 120 MHz f_T preserves fidelity up to 100 kHz.	Use Scenario: PWM-driven H-bridge half-bridge element controlling 3–6 V, 200 mA brushed DC motors in portable devices. IC Role / Device Role / Timing Role: Low-side switching transistor modulated at 1–20 kHz PWM frequency. Use Value: 500 mA I_C and 80 V V_CEO accommodate motor back-EMF spikes; TO-92MOD allows compact board layout.

Audio Power Amplifier Stage

Relay Driver Circuit

Use Scenario: Final output stage in compact stereo amplifier delivering 0.5–1 W into 8 Ω speakers.

IC Role / Device Role / Timing Role: NPN power switch in Class AB configuration, biased with complementary 2SA1450.

Use Value: 80 V V_CEO and 500 mA I_C enable safe operation with ±20 V rails; low V_CE(sat) minimizes heat generation at idle and full output.

Use Scenario: Driving 12 V, 100 mA coil relays in industrial control I/O modules.

IC Role / Device Role / Timing Role: Single-transistor saturated switch with base resistor network controlling coil energization.

Use Value: 600 mW P_C and 0.16 V V_CE(sat) ensure reliable on-state operation without heatsink; fast turn-off supported by 120 MHz f_T.

Low-Frequency Signal Driver

DC Motor Speed Control (Small)

Use Scenario: Buffering and level-shifting signals between microcontroller GPIO and analog circuitry.

IC Role / Device Role / Timing Role: Common-emitter voltage amplifier with fixed-gain bias network.

Use Value: h_FE range (100–400) allows predictable gain setting; 120 MHz f_T preserves fidelity up to 100 kHz.

Use Scenario: PWM-driven H-bridge half-bridge element controlling 3–6 V, 200 mA brushed DC motors in portable devices.

IC Role / Device Role / Timing Role: Low-side switching transistor modulated at 1–20 kHz PWM frequency.

Use Value: 500 mA I_C and 80 V V_CEO accommodate motor back-EMF spikes; TO-92MOD allows compact board layout.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
2SC2274	V_CEO = 60 V (lower), h_FE = 120–240 (narrower range), same TO-92MOD package	Not suitable for ±24 V rail systems; limited headroom for transient overvoltage in relay coils	Select only when supply voltage ≤ ±18 V and tighter h_FE tolerance is required.
MJD2955T4	TO-220 package, I_C = 10 A, V_CEO = 60 V - higher power but larger footprint and lower voltage rating	Over-specified for <1 W audio; requires PCB cutout and heatsink; incompatible pinout	Use only if >1 W output or forced-air cooling is needed; not a drop-in replacement.

Compared with 2SC2274 and MJD2955T4, the 2SC3708S-AA uniquely balances 80 V breakdown, 500 mA current, TO-92MOD form factor, and rank-binned h_FE, making it optimal for space-constrained, medium-voltage audio and driver applications where thermal budget and layout density are critical.

Availability

2SC3708S-AA is available at Aetrix Electronics and suitable for audio power amplifier stages, relay driver circuits, low-frequency signal drivers, and small DC motor speed control requiring stable component supply and long-term obsolescence management.

Supply support for 2SC3708S-AA 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 was a Japanese semiconductor manufacturer specializing in analog, power, and discrete devices before integration into ON Semiconductor in 2011; known for high-reliability audio and power transistors.

The 2SC3708S-AA belongs to SANYO's low-frequency driver transistor family, engineered specifically for cost-sensitive, thermally constrained audio output and industrial interface applications requiring robust V_CEO and consistent h_FE.

FAQ

What is the maximum collector-emitter voltage rating for the 2SC3708S-AA?

The 2SC3708S-AA has a guaranteed minimum collector-to-emitter breakdown voltage V(BR)_CEO of 80 V at I_C = 1 mA with open-base condition. This rating is validated per SANYO datasheet No.2217, allowing safe operation in circuits with DC supply rails up to ±36 V when appropriate safety margins are applied. Exceeding this voltage risks irreversible avalanche failure.

Does the 2SC3708S-AA have a specified gain-bandwidth product (f_T)?

Yes, the 2SC3708S-AA has a typical gain-bandwidth product f_T of 120 MHz, measured at V_CE = 10 V and I_C = 10 mA. This value is confirmed in the "Electrical Characteristics" table on page 2 of the official SANYO datasheet No.2217, ensuring usable bandwidth well beyond the audio spectrum for stable amplifier design.

What package type does the 2SC3708S-AA use, and what are its pin assignments?

The 2SC3708S-AA uses the TO-92MOD plastic package (dimensions 5.0 × 4.0 × 4.0 mm). Pin 1 is Emitter, Pin 2 is Collector, and Pin 3 is Base - as defined in SANYO package drawing 7522-002. This matches standard TO-92 orientation but with modified lead spacing optimized for automated insertion and thermal performance.

Is the 2SC3708S-AA suitable for use in complementary pairs with the 2SA1450?

Yes, the 2SC3708S-AA is explicitly designed as the NPN complement to the PNP 2SA1450, sharing identical absolute maximum ratings, thermal characteristics, and package dimensions. SANYO data sheet No.2217 confirms matched V_CEO/V_CBO, h_FE ranges, and f_T behavior - enabling direct pairing in Class AB push-pull output stages without bias recalibration.

What is the typical collector-emitter saturation voltage (V_CE(sat)) for the 2SC3708S-AA?

The 2SC3708S-AA exhibits a typical V_CE(sat) of 0.16 V at I_C = 400 mA and I_B = 40 mA, with a maximum of 0.5 V under those same conditions. This low saturation voltage is critical for minimizing power loss in relay driver and linear regulator applications, and is verified in the "Electrical Characteristics" section of the SANYO datasheet.

2SC3708S-AA Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 (TO-226AA)

Packaging:: Bulk

Product Status:: Active

Transistor Type:: NPN

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

Voltage - Collector Emitter Breakdown (Max):: 80 V

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 40mA, 400mA

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 140 @ 50mA, 5V

Power - Max:: 600 mW

Frequency - Transition:: 120MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 3-NP

2SC3708S-AA FAQ

1.How can I place an order for 2SC3708S-AA through Aetrix?

Please submit a Request for Quotation (RFQ) for 2SC3708S-AA 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 2SC3708S-AA reliable?

The price and inventory of 2SC3708S-AA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2SC3708S-AA is usually 5 days.

3.What payment methods are accepted for 2SC3708S-AA?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2SC3708S-AA transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2SC3708S-AA?

2SC3708S-AA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2SC3708S-AA 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 2SC3708S-AA?

For technical support, including 2SC3708S-AA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2SC3708S-AA requirements.

6.How does Aetrix verify that 2SC3708S-AA is sourced from the original manufacturer or authorized distributors?

All 2SC3708S-AA 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 2SC3708S-AA meets industry standards.

7.What is the process for return or replacement of 2SC3708S-AA?

All 2SC3708S-AA units undergo pre-shipment inspection (PSI). If there is an issue with 2SC3708S-AA, 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 2SC3708S-AA part is unused and in its original packaging.

Return procedure for 2SC3708S-AA:

1.Submit a request within 90 days.

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

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