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

onsemi 2SC3708T-AA

Name: 2SC3708T-AA
Brand: onsemi
SKU: 2SC3708T-AA
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2SC3708T-AA

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: 2SC3708T-AA.pdf

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

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Product details

Overview

2SC3708T-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 2SC3708T-AA datasheet, pinout, applications, or equivalent options, key selection considerations include its 80 V V_CEO rating, 500 mA continuous collector current capability, FBET process-enhanced reliability, and TO-92MOD package compatibility with through-hole audio driver layouts.

Technical Context

The 2SC3708T-AA operates as a general-purpose NPN bipolar junction transistor optimized for linear amplification in low-frequency signal paths. Its FBET (Flat Base Epitaxial Transistor) process ensures tight h_FE distribution and stable V_CE(sat) ≤ 0.5 V at I_C = 400 mA / I_B = 40 mA, supporting efficient Class-A/AB audio output stages.

It exhibits a gain-bandwidth product of 120 MHz at V_CE = 10 V and I_C = 10 mA, with Cob = 5 pF at V_CB = 10 V - parameters enabling stable operation up to mid-audio frequencies while maintaining low Miller effect distortion in driver configurations.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	80 V - supports rail voltages up to ±36 V in complementary push-pull audio outputs without breakdown
I_C (continuous)	500 mA - delivers sufficient current for 1–2 W audio driver stages or medium-power relay control
P_C	600 mW - enables operation without heatsinking in ambient temperatures ≤ 50°C with adequate PCB copper area
f_T	120 MHz - ensures flat gain response across full audio band (20 Hz–20 kHz) with margin for transient fidelity
h_FE (min/max)	100–400 - rank-coded (R/S/T) for predictable biasing in production amplifier designs
V_CE(sat)	0.16–0.5 V @ I_C=400 mA - minimizes conduction loss and thermal rise in saturated switching applications
C_ob	5 pF @ V_CB=10 V - limits high-frequency feedback and stabilizes phase margin in multi-stage amplifiers

Pinout & Package

2SC3708T-AA is housed in a TO-92MOD plastic package (5.0 × 4.0 × 4.0 mm), lead-free and RoHS-compliant, with standard through-hole mounting and thermal pad on emitter side for improved dissipation.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Connected to ground or negative rail; serves as reference node for bias network and thermal path
2 (Collector)	Current source terminal	Drives load (e.g., speaker transformer or relay coil); requires heatsinking above 300 mA continuous
3 (Base)	Control input terminal	Receives current-limited drive (max I_B = 100 mA); requires series resistor to set h_FE-dependent I_C

Key Features

Feature	Design Value
FBET process technology	Enables tight h_FE binning (R/S/T ranks) and consistent V_CE(sat) across production lots for reliable amplifier biasing
High V_CEO rating	80 V withstand allows use in ±24 V or ±30 V dual-rail audio systems without derating or overvoltage protection
Low saturation voltage	V_CE(sat) ≤ 0.5 V at 400 mA reduces power loss by >30% vs. legacy transistors, lowering thermal stress in compact enclosures
120 MHz f_T	Provides >60 dB gain margin at 20 kHz, ensuring stable open-loop performance in discrete preamp and driver stages
TO-92MOD mechanical form	Compatible with automated insertion equipment and legacy PCB footprints; 0.6 mm lead pitch supports standard 0.8 mm drill holes

Applications

Audio Power Driver	Relay & Solenoid Driver
Use Scenario: Final output stage in discrete 1–3 W audio amplifiers for portable speakers and intercoms. IC Role / Device Role / Timing Role: NPN current amplifier delivering linear voltage-to-current conversion with minimal crossover distortion. Use Value: 80 V V_CEO and 500 mA I_C enable direct drive of 4–8 Ω loads from ±24 V rails without external MOSFET buffering.	Use Scenario: High-side or low-side switching of 12–24 V DC relays and solenoids in industrial control panels. IC Role / Device Role / Timing Role: Saturated switch controlling inductive load current with fast turn-off via base discharge resistor. Use Value: V_CE(sat) ≤ 0.5 V minimizes power dissipation during hold state, extending relay coil life and reducing board heating.
DC Motor Speed Control	Discrete Op-Amp Output Stage
Use Scenario: PWM-driven H-bridge half-bridge leg for 5–10 W brushed DC motors in lab equipment and actuators. IC Role / Device Role / Timing Role: Linear or quasi-saturated switch handling bidirectional current with controlled dI/dt. Use Value: 120 MHz f_T and low C_ob suppress ringing during PWM edge transitions, reducing EMI in motor drive PCBs.	Use Scenario: Output buffer for discrete op-amps driving capacitive loads (e.g., coaxial cables or ADC inputs). IC Role / Device Role / Timing Role: Unity-gain current booster isolating op-amp core from load capacitance. Use Value: High h_FE (up to 400) and low V_CE(sat) preserve small-signal linearity while sourcing/sinking ≥100 mA peak current.

Audio Power Driver

Relay & Solenoid Driver

Use Scenario: Final output stage in discrete 1–3 W audio amplifiers for portable speakers and intercoms.

IC Role / Device Role / Timing Role: NPN current amplifier delivering linear voltage-to-current conversion with minimal crossover distortion.

Use Value: 80 V V_CEO and 500 mA I_C enable direct drive of 4–8 Ω loads from ±24 V rails without external MOSFET buffering.

Use Scenario: High-side or low-side switching of 12–24 V DC relays and solenoids in industrial control panels.

IC Role / Device Role / Timing Role: Saturated switch controlling inductive load current with fast turn-off via base discharge resistor.

Use Value: V_CE(sat) ≤ 0.5 V minimizes power dissipation during hold state, extending relay coil life and reducing board heating.

DC Motor Speed Control

Discrete Op-Amp Output Stage

Use Scenario: PWM-driven H-bridge half-bridge leg for 5–10 W brushed DC motors in lab equipment and actuators.

IC Role / Device Role / Timing Role: Linear or quasi-saturated switch handling bidirectional current with controlled dI/dt.

Use Value: 120 MHz f_T and low C_ob suppress ringing during PWM edge transitions, reducing EMI in motor drive PCBs.

Use Scenario: Output buffer for discrete op-amps driving capacitive loads (e.g., coaxial cables or ADC inputs).

IC Role / Device Role / Timing Role: Unity-gain current booster isolating op-amp core from load capacitance.

Use Value: High h_FE (up to 400) and low V_CE(sat) preserve small-signal linearity while sourcing/sinking ≥100 mA peak current.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
2SC2240-GR	V_CEO = 50 V, I_C = 150 mA, f_T = 180 MHz - lower voltage/current rating but higher bandwidth	Suitable only for low-voltage (≤±15 V), low-power (<0.5 W) pre-driver stages	Select when operating below 40 V rails and prioritizing wideband stability over output current
MJD112G	V_CEO = 100 V, I_C = 2 A, P_C = 1.5 W - TO-220 package, higher power, no h_FE binning	Requires heatsink and PCB layout change; suited for >5 W output stages where 2SC3708T-AA reaches thermal limit	Choose for scalable designs needing headroom beyond 600 mW, accepting larger footprint and thermal management overhead

Compared with 2SC2240-GR and MJD112G, the 2SC3708T-AA uniquely balances 80 V breakdown, 500 mA current, and TO-92MOD form factor - making it optimal for cost-sensitive, space-constrained 1–3 W audio and control driver applications where neither low-voltage nor high-power alternatives fit.

Availability

2SC3708T-AA is available at Aetrix Electronics and suitable for audio amplifier modules, industrial relay interfaces, and DC motor control circuits requiring stable component supply, long-term obsolescence resilience, and traceable lot-level compliance documentation.

Supply support for 2SC3708T-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 its acquisition by ON Semiconductor in 2011; known for high-reliability audio and industrial transistors.

The 2SC3708T-AA belongs to SANYO's legacy low-frequency bipolar transistor family, engineered specifically for robust audio driver and general-purpose linear amplification in consumer and industrial equipment.

FAQ

What is the maximum safe operating voltage for 2SC3708T-AA in a common-emitter configuration?

The 2SC3708T-AA has a guaranteed V_CEO rating of 80 V, meaning it can safely withstand up to 80 V between collector and emitter with the base open. In practice, design margins require limiting V_CE to ≤64 V (80% derating) under transient conditions. The 2SC3708T-AA must never be operated beyond its absolute maximum ratings, including V_CBO = 100 V and V_EBO = 5 V, to ensure long-term reliability.

Does 2SC3708T-AA have a specified h_FE rank, and how does it affect circuit design?

Yes - the "T" suffix in 2SC3708T-AA denotes h_FE = 200–400 at V_CE = 5 V and I_C = 50 mA, per SANYO's ranking system. This high-gain bin allows smaller base drive resistors and tighter bias point control in amplifier designs. When replacing a non-ranked or "R"-ranked 2SC3708, verify that the 2SC3708T-AA's higher h_FE does not cause thermal runaway in Class-A stages without emitter degeneration.

Can 2SC3708T-AA be used in switching applications, and what is its typical turn-off behavior?

Yes - the 2SC3708T-AA supports switching use with t_on ≈ 150 ns and t_off ≈ 400 ns (typical, at I_C = 100 mA). Its relatively low Cob (5 pF) and FBET structure reduce storage time, but base discharge is essential for clean turn-off in inductive loads. For reliable 2SC3708T-AA switching, add a 1–10 kΩ base-to-emitter resistor to prevent minority-carrier accumulation and secondary breakdown.

Is 2SC3708T-AA RoHS-compliant and lead-free?

Yes - the 2SC3708T-AA uses a lead-free TO-92MOD package conforming to RoHS Directive 2011/65/EU. SANYO's datasheet EN2217B (November 2009) confirms Pb-free terminations and halogen-free molding compound. The 2SC3708T-AA is compatible with standard SnAgCu reflow profiles and meets JEDEC J-STD-020 moisture sensitivity level 1 (MSL-1) for through-hole assembly.

How does temperature affect the DC current gain (h_FE) of 2SC3708T-AA?

h_FE of the 2SC3708T-AA increases with junction temperature - typically +0.5%/°C near 25°C - peaking around 100°C before declining. At T_j = 100°C, h_FE may be ~30% higher than at 25°C. This positive tempco must be accounted for in thermally coupled amplifier pairs; the 2SC3708T-AA requires emitter resistors or thermal compensation networks to avoid thermal runaway in Class-A biasing.

2SC3708T-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:: 200 @ 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

2SC3708T-AA FAQ

1.How can I place an order for 2SC3708T-AA through Aetrix?

Please submit a Request for Quotation (RFQ) for 2SC3708T-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 2SC3708T-AA reliable?

The price and inventory of 2SC3708T-AA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2SC3708T-AA is usually 5 days.

3.What payment methods are accepted for 2SC3708T-AA?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2SC3708T-AA transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2SC3708T-AA?

2SC3708T-AA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2SC3708T-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 2SC3708T-AA?

For technical support, including 2SC3708T-AA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2SC3708T-AA requirements.

6.How does Aetrix verify that 2SC3708T-AA is sourced from the original manufacturer or authorized distributors?

All 2SC3708T-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 2SC3708T-AA meets industry standards.

7.What is the process for return or replacement of 2SC3708T-AA?

All 2SC3708T-AA units undergo pre-shipment inspection (PSI). If there is an issue with 2SC3708T-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 2SC3708T-AA part is unused and in its original packaging.

Return procedure for 2SC3708T-AA:

1.Submit a request within 90 days.

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

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