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

onsemi TN6705A

Name: TN6705A
Brand: onsemi
SKU: TN6705A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: TN6705A

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: TN6705A.pdf

Description:: TRANS NPN 45V 1.5A TO-226-3

Quantity:: RFQ Add To RFQ list

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Inventory:5,597

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Product details

Overview

TN6705A from Fairchild Semiconductor is an NPN general-purpose bipolar junction transistor (BJT) designed for linear amplification and switching applications up to 1.2 A collector current, with V_CEO = 45 V, h_FE ≥ 40 at I_C = 50 mA, and TO-226 package. It serves as a discrete power/signal amplifier in low-to-medium-power analog stages and relay drivers.

For engineers reviewing the TN6705A datasheet, pinout, applications, or equivalent options, key selection criteria include its 45 V V_CEO, 1.5 A I_C continuous rating, 50 °C/W R_θJA, h_FE range across operating currents, and suitability for DC-coupled amplifier and saturated-switch designs.

Technical Context

The TN6705A is a silicon planar NPN BJT fabricated in Fairchild's Process 38, optimized for general-purpose linear and switching operation. Its design supports stable DC current gain (h_FE = 40–250) across I_C = 50–500 mA at V_CE = 2.0 V, with guaranteed V_CE(sat) ≤ 1.0 V at I_C = 1.0 A / I_B = 100 mA.

Thermal performance is defined by R_θJA = 50 °C/W and R_θJC = 125 °C/W, enabling operation from –55 °C to +150 °C junction temperature. Small-signal f_T is not specified, but h_fe = 2.5–20 at 20 MHz confirms usable RF capability in narrowband low-frequency amplifiers.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	45 V - Maximum safe collector-emitter voltage under open-base conditions; sets upper rail limit for switch/amplifier stage.
I_C (cont.)	1.5 A - Continuous collector current rating; supports 1.2 A typical switching loads with thermal margin.
h_FE	40–250 - DC current gain range at V_CE = 2.0 V; enables predictable base drive sizing for linear or saturated operation.
V_CE(sat)	0.5–1.0 V - Saturation voltage at I_C = 500 mA–1.0 A; determines conduction loss and heat generation in switching mode.
R_θJA	50 °C/W - Junction-to-ambient thermal resistance; defines required PCB copper area and airflow for thermal management.
C_cb	30 pF - Collector-base capacitance at 10 V; impacts high-frequency gain roll-off and stability in amplifier layouts.

Pinout & Package

Package: TO-226 (also known as TO-92), through-hole, epoxy-molded plastic case with 3 leads. Standard lead configuration: Emitter (E), Base (B), Collector (C) - viewed from flat side with leads down, left-to-right is E-B-C.

Pin/Terminal	Circuit Role	Design Meaning
E (Emitter)	Current sink terminal for NPN operation	Reference node for biasing; connects to ground or low-side return path in common-emitter configurations.
B (Base)	Control input for minority-carrier injection	Requires current-limited drive (e.g., via series resistor); base-emitter turn-on ~1.5 V at 1.0 A I_C.
C (Collector)	Current source terminal	Connects to load and supply rail; must withstand 45 V transient spikes and dissipate up to 1.0 W at 25°C ambient.

Key Features

Feature	Design Value
Process 38 fabrication	Ensures consistent h_FE distribution and breakdown voltage stability across production lots.
V_CEO = 45 V / V_CBO = 60 V	Supports 36 V nominal supply rails with 20% margin against transients in industrial control interfaces.
h_FE ≥ 40 at I_C = 500 mA	Enables reliable saturation with modest base drive (e.g., 10–12 mA), reducing MCU GPIO loading.
R_θJA = 50 °C/W	Allows operation at full I_C without heatsink on 1-in² 2-oz copper with minimal airflow.

Applications

DC Power Switching	Low-Frequency Amplifier
Use Scenario: Driving 12 V/500 mA solenoid or relay coil from microcontroller GPIO. IC Role / Device Role / Timing Role: NPN switch in common-emitter configuration, operated in saturation region. Use Value: Low V_CE(sat) (≤1.0 V) minimizes power loss and self-heating during sustained on-state.	Use Scenario: Single-stage audio preamplifier for electret microphone signal conditioning. IC Role / Device Role / Timing Role: Class-A common-emitter amplifier with emitter degeneration resistor. Use Value: h_FE ≥ 40 ensures stable bias point and gain reproducibility across units and temperature.
Industrial Sensor Interface	LED Driver
Use Scenario: Level-shifting and current buffering for 4–20 mA loop transmitter output stage. IC Role / Device Role / Timing Role: Linear current source with active feedback control. Use Value: V_CEO = 45 V accommodates 24 V loop supply plus safety margin for cable drop and surge.	Use Scenario: Constant-current driver for high-brightness indicator LEDs in panel meters. IC Role / Device Role / Timing Role: Saturated switch regulating LED current via emitter resistor. Use Value: 1.5 A I_C rating allows parallel LED strings or overdrive margin for aging compensation.

DC Power Switching

Low-Frequency Amplifier

Use Scenario: Driving 12 V/500 mA solenoid or relay coil from microcontroller GPIO.

IC Role / Device Role / Timing Role: NPN switch in common-emitter configuration, operated in saturation region.

Use Value: Low V_CE(sat) (≤1.0 V) minimizes power loss and self-heating during sustained on-state.

Use Scenario: Single-stage audio preamplifier for electret microphone signal conditioning.

IC Role / Device Role / Timing Role: Class-A common-emitter amplifier with emitter degeneration resistor.

Use Value: h_FE ≥ 40 ensures stable bias point and gain reproducibility across units and temperature.

Industrial Sensor Interface

LED Driver

Use Scenario: Level-shifting and current buffering for 4–20 mA loop transmitter output stage.

IC Role / Device Role / Timing Role: Linear current source with active feedback control.

Use Value: V_CEO = 45 V accommodates 24 V loop supply plus safety margin for cable drop and surge.

Use Scenario: Constant-current driver for high-brightness indicator LEDs in panel meters.

IC Role / Device Role / Timing Role: Saturated switch regulating LED current via emitter resistor.

Use Value: 1.5 A I_C rating allows parallel LED strings or overdrive margin for aging compensation.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN general-purpose amplifier applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MPSA42	V_CEO = 300 V, h_FE = 50–250, R_θJA = 200 °C/W, TO-92	Higher voltage rating but lower thermal efficiency; unsuitable for >1 A continuous loads.	Prefer when high-voltage isolation is critical and current < 200 mA.
BC547B	V_CEO = 45 V, I_C = 100 mA, h_FE = 200–450, TO-92	Lower current capability and higher h_FE spread; limited to small-signal use.	Choose only for low-power amplification where I_C < 100 mA and gain consistency matters more than drive strength.

Compared with MPSA42 and BC547B, the TN6705A uniquely balances 45 V breakdown, 1.5 A current handling, and 50 °C/W thermal resistance in TO-92-making it optimal for medium-power switching and linear amplification where both voltage headroom and thermal robustness are required.

Availability

TN6705A is available at Aetrix Electronics and suitable for industrial sensor interfaces, DC power switching circuits, and LED driver modules requiring stable component supply and long-term manufacturability.

Supply support for TN6705A 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete devices before its acquisition by ON Semiconductor in 2016.

The TN6705A belongs to Fairchild's general-purpose bipolar transistor product line, engineered for cost-sensitive, medium-power linear and switching applications in industrial and consumer equipment.

FAQ

What is the maximum continuous collector current rating for the TN6705A?

The TN6705A has a maximum continuous collector current (I_C) rating of 1.5 A at T_A = 25°C. Derating applies above 25°C per the 8.0 mW/°C specification. In practice, sustained operation near 1.5 A requires careful thermal design due to its 50 °C/W R_θJA; typical switching use limits I_C to 1.2 A with adequate PCB copper.

Does the TN6705A have a specified transition frequency (f_T)?

No, the TN6705A datasheet does not specify f_T. However, its small-signal current gain h_fe is characterized at 20 MHz (2.5–20), indicating usable bandwidth for low-frequency amplification and switching up to several MHz. For RF applications beyond 10 MHz, a device with published f_T is recommended.

Can the TN6705A replace the TN6715A in a circuit?

The TN6705A and TN6715A share the same Process 38 and TO-226 package but differ in electrical characteristics: the TN6715A has higher h_FE and lower V_CE(sat). Substituting TN6705A for TN6715A may require adjusting base drive and verifying saturation margin, especially at I_C > 500 mA. Always consult the TN6715A datasheet for direct comparison before replacement.

What is the emitter-base breakdown voltage (V_EBR) of the TN6705A?

The TN6705A has a guaranteed V(BR)_EBO of 5.0 V minimum at I_E = 1.0 mA, IC = 0. This defines the maximum reverse voltage allowable between emitter and base. Exceeding this risks base-emitter junction damage, especially in circuits with inductive flyback or bidirectional signal coupling.

Is the TN6705A RoHS compliant?

Yes, the TN6705A manufactured by Fairchild Semiconductor meets RoHS Directive 2011/65/EU requirements. Lead-free finish and halogen-free packaging were standard for Fairchild's TO-92 devices post-2006. Confirm compliance using the date code and lot traceability provided with Aetrix Electronics' shipment.

TN6705A Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 1.5 A

Voltage - Collector Emitter Breakdown (Max):: 45 V

Vce Saturation (Max) @ Ib, Ic:: 1V @ 100mA, 1A

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 40 @ 250mA, 2V

Power - Max:: 1 W

Frequency - Transition:: -

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-226-3

TN6705A FAQ

1.How can I place an order for TN6705A through Aetrix?

Please submit a Request for Quotation (RFQ) for TN6705A 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 TN6705A reliable?

The price and inventory of TN6705A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TN6705A is usually 5 days.

3.What payment methods are accepted for TN6705A?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TN6705A transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TN6705A?

TN6705A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TN6705A 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 TN6705A?

For technical support, including TN6705A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TN6705A requirements.

6.How does Aetrix verify that TN6705A is sourced from the original manufacturer or authorized distributors?

All TN6705A 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 TN6705A meets industry standards.

7.What is the process for return or replacement of TN6705A?

All TN6705A units undergo pre-shipment inspection (PSI). If there is an issue with TN6705A, 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 TN6705A part is unused and in its original packaging.

Return procedure for TN6705A:

1.Submit a request within 90 days.

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

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