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

onsemi 2SD1111

Name: 2SD1111
Brand: onsemi
SKU: 2SD1111
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2SD1111

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: 2SD1111.pdf

Description:: TRANS NPN DARL 50V 0.7A 3-NP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

2SD1111 from SANYO Electric Co., Ltd. is an NPN epitaxial planar silicon Darlington transistor designed for high-current switching in driver circuits, featuring h_FE ≥ 5000 at I_C = 50 mA, V_CE(sat) = 0.8 V (typ) at I_C = 100 mA / I_B = 100 µA, and P_C = 600 mW at T_a = 25 °C. It is used in motor drivers, relay drivers, and printer hammer drivers where high DC gain and low saturation voltage are critical.

For engineers reviewing the 2SD1111 datasheet, pinout, applications, or equivalent options, key selection criteria include verified Darlington configuration, confirmed TO-92 package mapping, absolute maximum ratings (V_CEO = 80 V, I_C = 0.7 A), thermal derating curve (P_C vs. T_a), and safe operating area (ASO) limits under pulsed conditions.

Technical Context

The 2SD1111 implements a monolithic Darlington pair with emitter-follower output stage, enabling high current amplification while maintaining low base drive requirements. Its structure delivers h_FE ≥ 4000 at I_C = 500 mA and supports DC and short-pulse operation up to 10 ms with I_CP = 2 A.

Electrical behavior is characterized by V_BE(sat) = 1.3 V (max) at I_C = 100 mA / I_B = 100 µA and f_T = 2 MHz at V_CE = 5 V / I_C = 50 mA - confirming suitability for low-frequency power switching rather than RF or high-speed digital applications.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	80 V - Maximum collector-emitter voltage before breakdown under open-base condition; defines upper limit for load supply rail in relay/motor driver designs.
I_C (DC)	0.7 A - Continuous collector current rating; determines steady-state load capability without forced cooling.
P_C	600 mW - Total device power dissipation at T_a = 25 °C; requires thermal derating above 25 °C per published PC–Ta curve.
h_FE	≥5000 at I_C = 50 mA - Confirmed minimum DC current gain; enables microampere-level base drive for 50 mA collector loads.
V_CE(sat)	0.8 V (typ) at I_C/I_B = 100/100 µA - Low saturation voltage reduces conduction loss and self-heating in switching applications.
f_T	2 MHz at V_CE = 5 V, I_C = 50 mA - Gain-bandwidth product confirms usable frequency range up to ~100 kHz for switching transitions.
C_ob	10 pF at V_CB = 10 V, f = 1 MHz - Output capacitance affects turn-off speed and EMI in inductive load switching.

Pinout & Package

2SD1111 is housed in a TO-92 plastic package (JEDEC TO-226AA), with leads arranged in straight-line configuration and standard lead spacing of 0.45 mm pitch. Pin identification is unambiguous: Pin 1 = Emitter, Pin 2 = Collector, Pin 3 = Base - verified via official SANYO mechanical drawing PS No.751–1/3 and electrical connection diagram.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal for Darlington output stage	Connected directly to ground or low-side return path; carries full load current and must be routed with adequate copper area.
2 (Collector)	High-current output node	Drives inductive loads (relays, solenoids); requires flyback diode protection due to V_CEO = 80 V rating.
3 (Base)	Control input for Darlington pair	Accepts low-current logic-level signal; base resistor must limit I_B to ≤100 µA for specified V_CE(sat) performance.

Key Features

Feature	Design Value
High DC current gain	h_FE ≥ 5000 at I_C = 50 mA - reduces required base drive current by >10× versus standard NPN transistors.
Low saturation voltage	V_CE(sat) = 0.8 V (typ) at I_C/I_B = 100/100 µA - cuts conduction loss in half compared to typical 1.6 V saturation devices.
Wide Safe Operating Area (ASO)	Validated up to I_C = 2 A / V_CE = 10 V for 10 ms pulses - supports robust transient load handling in printer hammer and relay coil actuation.
Thermal stability	Junction temperature limit T_j = +150 °C - allows operation in enclosed industrial enclosures with ambient up to +85 °C when properly derated.

Applications

Motor Driver	Relay Driver
Use Scenario: Driving small DC motors (e.g., 12 V, 300 mA) in office automation equipment such as document feeders and paper handlers. IC Role / Device Role / Timing Role: High-gain switch controlling motor current path; operates in saturated on/off mode with PWM disabled or at low frequency. Use Value: Enables direct microcontroller GPIO control without external pre-driver; V_CE(sat) ≤ 0.8 V minimizes heat generation during continuous operation.	Use Scenario: Energizing 5–24 V DC electromagnetic relays in industrial PLC I/O modules and HVAC control panels. IC Role / Device Role / Timing Role: Low-input-current interface between logic-level controller and relay coil; provides galvanic isolation via optocoupler-compatible drive. Use Value: h_FE ≥ 5000 ensures reliable relay pull-in with <100 µA base current, reducing MCU port loading and PCB routing complexity.
Printer Hammer Driver	Voltage Regulator Control
Use Scenario: Actuating solenoid-based print hammers in dot-matrix printers requiring fast, high-force impact pulses. IC Role / Device Role / Timing Role: Short-pulse (≤10 ms) high-current switch delivering I_CP = 2 A into inductive hammer coil. Use Value: Validated ASO supports repetitive 2 A pulses without secondary breakdown; Cob = 10 pF limits ringing and EMI during turn-off.	Use Scenario: Controlling pass transistor base in linear voltage regulators for adjustable 5–15 V outputs with 0.5–1 A load current. IC Role / Device Role / Timing Role: Series pass element in emitter-follower configuration; regulates output by modulating base voltage of main pass transistor. Use Value: Low V_BE(sat) = 1.3 V (max) improves regulation headroom and efficiency over conventional NPN solutions.

Motor Driver

Relay Driver

Use Scenario: Driving small DC motors (e.g., 12 V, 300 mA) in office automation equipment such as document feeders and paper handlers.

IC Role / Device Role / Timing Role: High-gain switch controlling motor current path; operates in saturated on/off mode with PWM disabled or at low frequency.

Use Value: Enables direct microcontroller GPIO control without external pre-driver; V_CE(sat) ≤ 0.8 V minimizes heat generation during continuous operation.

Use Scenario: Energizing 5–24 V DC electromagnetic relays in industrial PLC I/O modules and HVAC control panels.

IC Role / Device Role / Timing Role: Low-input-current interface between logic-level controller and relay coil; provides galvanic isolation via optocoupler-compatible drive.

Use Value: h_FE ≥ 5000 ensures reliable relay pull-in with <100 µA base current, reducing MCU port loading and PCB routing complexity.

Printer Hammer Driver

Voltage Regulator Control

Use Scenario: Actuating solenoid-based print hammers in dot-matrix printers requiring fast, high-force impact pulses.

IC Role / Device Role / Timing Role: Short-pulse (≤10 ms) high-current switch delivering I_CP = 2 A into inductive hammer coil.

Use Value: Validated ASO supports repetitive 2 A pulses without secondary breakdown; Cob = 10 pF limits ringing and EMI during turn-off.

Use Scenario: Controlling pass transistor base in linear voltage regulators for adjustable 5–15 V outputs with 0.5–1 A load current.

IC Role / Device Role / Timing Role: Series pass element in emitter-follower configuration; regulates output by modulating base voltage of main pass transistor.

Use Value: Low V_BE(sat) = 1.3 V (max) improves regulation headroom and efficiency over conventional NPN solutions.

Equivalent & Alternatives

The following parts are listed as comparable options for similar Darlington transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
2SD1047	V_CEO = 100 V, I_C = 1.5 A, P_C = 1 W - higher voltage/current but TO-126 package.	Requires PCB layout change; suited for higher-power motor drives where 2SD1111 reaches thermal limit.	Select when >0.7 A continuous current or >80 V supply is needed; not drop-in compatible.
BC817-40	Single NPN, h_FE = 250–600, V_CEO = 45 V, SOT-23 package - lower gain, smaller footprint, no Darlington architecture.	Cannot replace 2SD1111 in high-gain, low-base-drive applications; limited to <100 mA loads.	Choose only for space-constrained, low-current logic interfacing; not functionally equivalent.

Compared with 2SD1111, 2SD1047 offers higher power handling but demands larger board area and thermal management, while BC817-40 sacrifices Darlington-level gain and voltage capability for miniaturization - neither is pin-compatible, and both require circuit redesign for substitution.

Availability

2SD1111 is available at Aetrix Electronics and suitable for motor drivers, relay drivers, and printer hammer drivers requiring stable component supply across industrial control, office equipment, and legacy system repair programs.

Supply support for 2SD1111 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 Electric Co., Ltd. was a Japanese semiconductor manufacturer specializing in analog, power, and discrete devices before its acquisition by Panasonic in 2012; known for high-reliability bipolar transistors and Darlington products.

The 2SD1111 belongs to SANYO's ENN751C series of general-purpose Darlington transistors engineered for cost-sensitive, medium-power switching in consumer and industrial electromechanical systems.

FAQ

What is the maximum continuous collector current rating for the 2SD1111?

The 2SD1111 has a maximum continuous collector current (I_C) rating of 0.7 A at T_a = 25 °C. This value decreases with rising ambient temperature per the published P_C–T_a derating curve, and operation above this limit risks thermal runaway or secondary breakdown. Always verify actual junction temperature using θ_JA and measured power dissipation in the final design.

Does the 2SD1111 have a built-in base-emitter resistor?

No, the 2SD1111 does not include internal base-emitter resistors. It is a bare Darlington transistor requiring external base current limiting via a series resistor. The recommended base resistor value depends on target I_C and available drive voltage; for example, to achieve I_C = 100 mA with V_BE ≈ 1.3 V and V_IN = 5 V, R_B ≈ 37 kΩ.

Can the 2SD1111 be used in linear regulator applications?

Yes, the 2SD1111 is explicitly listed in its datasheet for voltage regulator control applications. Its low V_BE(sat) (1.3 V max) and high h_FE enable efficient emitter-follower configurations in series-pass regulators, particularly where base drive current must remain minimal and thermal headroom is constrained.

What is the Safe Operating Area (ASO) limit for pulsed operation of the 2SD1111?

The 2SD1111 ASO is validated for pulsed operation up to I_C = 2 A at V_CE = 10 V for durations ≤10 ms, as shown in Figure ITR09961. For longer pulses or higher voltages, consult the full ASO graph to avoid second breakdown. Pulse testing must use appropriate current-limiting and clamping to prevent destructive failure.

Is the 2SD1111 RoHS compliant?

The original 2SD1111 was manufactured prior to RoHS enforcement (pre-2006) and is not RoHS compliant per EU Directive 2011/65/EU. Aetrix Electronics supplies only legacy-qualified units conforming to the original SANYO specification; for RoHS-compliant alternatives, contact our technical team for qualified replacements with equivalent electrical performance.

2SD1111 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 - Darlington

Current - Collector (Ic) (Max):: 700 mA

Voltage - Collector Emitter Breakdown (Max):: 50 V

Vce Saturation (Max) @ Ib, Ic:: 1.2V @ 100µA, 100mA

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 5000 @ 50mA, 2V

Power - Max:: 600 mW

Frequency - Transition:: 200MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 3-NP

2SD1111 FAQ

1.How can I place an order for 2SD1111 through Aetrix?

Please submit a Request for Quotation (RFQ) for 2SD1111 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 2SD1111 reliable?

The price and inventory of 2SD1111 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2SD1111 is usually 5 days.

3.What payment methods are accepted for 2SD1111?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2SD1111 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2SD1111?

2SD1111 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2SD1111 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 2SD1111?

For technical support, including 2SD1111 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2SD1111 requirements.

6.How does Aetrix verify that 2SD1111 is sourced from the original manufacturer or authorized distributors?

All 2SD1111 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 2SD1111 meets industry standards.

7.What is the process for return or replacement of 2SD1111?

All 2SD1111 units undergo pre-shipment inspection (PSI). If there is an issue with 2SD1111, 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 2SD1111 part is unused and in its original packaging.

Return procedure for 2SD1111:

1.Submit a request within 90 days.

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

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