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

onsemi 2SD1838

Name: 2SD1838
Brand: onsemi
SKU: 2SD1838
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2SD1838

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-220-3 Full Pack

Datasheet:: 2SD1838.pdf

Description:: TRANS NPN DARL 50V 5A TO-220ML

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Product details

Overview

2SD1838 from SANYO Semiconductor is an NPN triple-diffused planar silicon Darlington transistor designed for high-current switching in inductive loads, featuring V_CEO = 50 V, I_C = 5 A continuous, and on-chip 60 ± 10 V Zener diode between collector and base. It delivers h_FE = 1000–4000 at I_C = 2.5 A and supports motor drivers, relay drivers, and printer hammer drivers.

For engineers reviewing the 2SD1838 datasheet, pinout, applications, or equivalent options, key selection criteria include its 50 mJ inductive load energy handling (E_s/b), TO-220ML micaless package, V_CE(sat) ≤ 1.5 V at 2.5 A, and guaranteed V_(BR)CEO ≥ 50 V with tight process-controlled breakdown uniformity.

Technical Context

This Darlington transistor uses a triple-diffused planar structure to achieve high DC current gain and wide Active Safe Operating Area (ASO). Its integrated 60 ± 10 V collector-to-base Zener enables self-clamping during inductive turn-off, eliminating external snubbers in many driver circuits.

The device is optimized for fast switching in pulsed inductive loads: t_on = 0.6 μs, t_stg = 4.0 μs, and t_f = 1.5 μs under standardized test conditions (V_CC = 200 V, I_C = 3.0 A, I_B1 = –I_B2 = 6 mA), with f_T = 20 MHz confirming usable bandwidth for medium-speed switching.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	50 V - Maximum collector-emitter voltage before breakdown; defines safe operating ceiling for inductive flyback suppression.
I_C	5 A continuous - Sustained current-handling capability at T_c = 25°C; enables direct drive of medium-power solenoids and motors.
h_FE	1000–4000 at V_CE = 3 V, I_C = 2.5 A - High DC gain reduces required base drive current, easing microcontroller interface.
E_s/b	50 mJ at L = 100 mH, R_BE = 100 Ω - Quantified inductive energy absorption per switching cycle without failure.
V_CE(sat)	≤1.5 V at I_C = 2.5 A, I_B = 5 mA - Low saturation voltage minimizes conduction loss and thermal stress in high-duty-cycle operation.
f_T	20 MHz - Gain-bandwidth product confirms suitability for switching frequencies up to several hundred kHz with stable gain.

Pinout & Package

2SD1838 is housed in a micaless TO-220ML package (SANYO designation), enabling direct mounting to heatsinks without insulating washers. The case serves as the collector terminal.

Pin/Terminal	Circuit Role	Design Meaning
1 (Base)	Control input	Receives low-current drive signal; requires I_B ≤ 0.5 A max; internal Zener referenced to this node.
2 (Collector)	High-current output / case	Electrically connected to metal tab; must be isolated from chassis unless circuit ground reference permits.
3 (Emitter)	Power return path	Serves as common emitter node; carries full load current; connects to system ground or low-side switch return.

Key Features

Feature	Design Value
On-chip Zener clamping	60 ± 10 V C–B Zener eliminates need for external flyback diode or TVS in many L-load applications.
Micaless TO-220ML	Direct-mount heatsink interface reduces thermal resistance and assembly cost vs. insulated packages.
Uniform V_(BR)CEO	Tight 50–70 V distribution due to accurate impurity diffusion ensures consistent turn-off behavior across production lots.
High ASO	Wide Safe Operating Area supports simultaneous high V_CE and I_C during transient overload, critical for relay coil switching.

Applications

Motor Driver Circuits	Relay Driver Modules
Use Scenario: Driving brushed DC motors in industrial printers and copiers where rapid start/stop cycles generate high back-EMF. IC Role / Device Role / Timing Role: High-current NPN Darlington switch controlling motor power path; handles repetitive 50 mJ inductive spikes. Use Value: On-chip Zener clamping prevents voltage overshoot beyond 70 V, protecting upstream logic and reducing BOM count by one external component.	Use Scenario: Energizing 24 VDC industrial relays with 100–200 Ω coils in PLC output modules. IC Role / Device Role / Timing Role: Low-input-drive power switch turning relay coils on/off; leverages h_FE ≥ 1000 to accept 5 mA MCU GPIO drive. Use Value: V_CE(sat) ≤ 1.5 V at 2.5 A limits power dissipation to < 3.75 W, enabling compact heatsinking in dense I/O card layouts.
Printer Hammer Drivers	Industrial Solenoid Controllers
Use Scenario: Actuating impact print hammers requiring precise 10–20 ms pulses with peak currents up to 4 A. IC Role / Device Role / Timing Role: Fast-switching Darlington delivering controlled current pulses; t_on/t_f < 2 μs ensures sharp edge definition. Use Value: 20 MHz f_T and low storage time (t_stg = 4.0 μs) enable clean pulse fidelity without tailing, critical for dot-matrix print quality.	Use Scenario: Controlling pneumatic valve solenoids in factory automation systems subject to frequent cycling and ambient temperatures up to 85°C. IC Role / Device Role / Timing Role: Robust load switch rated for continuous 5 A at elevated case temperatures; PC = 25 W at T_c = 25°C. Use Value: Wide ASO and 150°C junction rating allow reliable operation in thermally constrained enclosures without derating below 4 A at 85°C ambient.

Motor Driver Circuits

Relay Driver Modules

Use Scenario: Driving brushed DC motors in industrial printers and copiers where rapid start/stop cycles generate high back-EMF.

IC Role / Device Role / Timing Role: High-current NPN Darlington switch controlling motor power path; handles repetitive 50 mJ inductive spikes.

Use Value: On-chip Zener clamping prevents voltage overshoot beyond 70 V, protecting upstream logic and reducing BOM count by one external component.

Use Scenario: Energizing 24 VDC industrial relays with 100–200 Ω coils in PLC output modules.

IC Role / Device Role / Timing Role: Low-input-drive power switch turning relay coils on/off; leverages h_FE ≥ 1000 to accept 5 mA MCU GPIO drive.

Use Value: V_CE(sat) ≤ 1.5 V at 2.5 A limits power dissipation to < 3.75 W, enabling compact heatsinking in dense I/O card layouts.

Printer Hammer Drivers

Industrial Solenoid Controllers

Use Scenario: Actuating impact print hammers requiring precise 10–20 ms pulses with peak currents up to 4 A.

IC Role / Device Role / Timing Role: Fast-switching Darlington delivering controlled current pulses; t_on/t_f < 2 μs ensures sharp edge definition.

Use Value: 20 MHz f_T and low storage time (t_stg = 4.0 μs) enable clean pulse fidelity without tailing, critical for dot-matrix print quality.

Use Scenario: Controlling pneumatic valve solenoids in factory automation systems subject to frequent cycling and ambient temperatures up to 85°C.

IC Role / Device Role / Timing Role: Robust load switch rated for continuous 5 A at elevated case temperatures; PC = 25 W at T_c = 25°C.

Use Value: Wide ASO and 150°C junction rating allow reliable operation in thermally constrained enclosures without derating below 4 A at 85°C ambient.

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-current Darlington switching applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BD679	V_CEO = 80 V, I_C = 4 A, no integrated Zener; TO-126 package.	Higher voltage margin but lower current and no built-in clamping; requires external flyback protection.	Choose BD679 when >60 V flyback suppression is needed and board space allows discrete Zener + diode.
TIP122	V_CEO = 100 V, I_C = 5 A, integrated 50 V Zener; TO-220 package with electrically isolated tab.	Higher V_CEO and same current rating, but Zener tolerance wider (±20%); tab is insulated, requiring thermal pad.	Choose TIP122 when 100 V rating is mandatory and isolation from heatsink is required; verify Zener clamping meets EMI requirements.

Compared with BD679 and TIP122, the 2SD1838 offers tighter V_(BR)CEO uniformity, micaless mounting, and precisely specified 60 ± 10 V clamping-making it optimal for cost-sensitive, high-volume L-load drivers where predictable flyback control and thermal simplicity are prioritized.

Availability

2SD1838 is available at Aetrix Electronics and suitable for motor drivers, relay drivers, printer hammer drivers, and industrial solenoid controllers requiring stable component supply and long-term obsolescence management.

Supply support for 2SD1838 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 industrial-grade transistors.

The 2SD1838 belongs to SANYO's high-current Darlington transistor family engineered specifically for robust inductive load switching in office automation, industrial controls, and electromechanical actuation systems.

FAQ

What is the maximum continuous collector current rating for the 2SD1838?

The 2SD1838 has a maximum continuous collector current (I_C) of 5 A at case temperature T_c = 25°C. At higher case temperatures, derating applies per the PC–T_c curve; for example, at T_c = 80°C, the usable I_C drops to approximately 3.2 A to maintain safe junction temperature. The 2SD1838 also supports 8 A pulsed current (I_CP) under specified duty cycle conditions.

Does the 2SD1838 include an integrated protection diode?

No, the 2SD1838 does not include an integrated flyback diode. Instead, it integrates a 60 ± 10 V Zener diode between collector and base to clamp inductive flyback voltage. This provides self-limiting clamping action during turn-off, reducing or eliminating the need for an external diode in many L-load applications. The 2SD1838 relies on this Zener for voltage suppression-not a standard PN junction diode.

What package type is used for the 2SD1838 and how does it affect thermal design?

The 2SD1838 uses the TO-220ML package, a micaless variant of TO-220 where the metal tab (collector) is electrically exposed and designed for direct mounting to a heatsink without insulating hardware. This lowers thermal resistance and simplifies mechanical assembly. Because the tab is live (connected to collector), PCB layout must ensure no unintended shorting to ground or other potentials, unlike insulated TO-220 variants.

How is the 2SD1838's inductive load capability quantified, and what test conditions apply?

Inductive load capability for the 2SD1838 is quantified as E_s/b = 50 mJ, measured under standardized conditions: L = 100 mH, R_BE = 100 Ω, and specified test circuit per datasheet Figure "Es/b Test Circuit". This value represents the maximum single-pulse inductive energy the device can safely absorb during turn-off without failure. It is not a continuous rating and assumes proper base drive and thermal management.

Can the 2SD1838 replace the TIP122 in existing designs without layout changes?

No-the 2SD1838 cannot be used as a drop-in replacement for the TIP122 without verifying mechanical and electrical compatibility. Although both are TO-220 Darlington transistors rated for 5 A, the 2SD1838 has a micaless tab (collector-connected), whereas the TIP122 tab is electrically isolated. Substituting the 2SD1838 may create a short if the original design grounds the heatsink. Additionally, Zener voltage tolerance differs (±10% vs. ±20%), affecting clamping precision. Always validate thermal, electrical, and safety margins before substitution.

2SD1838 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-220-3 Full Pack

Packaging:: Bulk

Product Status:: Active

Transistor Type:: NPN - Darlington

Current - Collector (Ic) (Max):: 5 A

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

Vce Saturation (Max) @ Ib, Ic:: 1.5V @ 5mA, 2.5A

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 1000 @ 2.5A, 3V

Power - Max:: 2 W

Frequency - Transition:: 20MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220ML

2SD1838 FAQ

1.How can I place an order for 2SD1838 through Aetrix?

Please submit a Request for Quotation (RFQ) for 2SD1838 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 2SD1838 reliable?

The price and inventory of 2SD1838 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2SD1838 is usually 5 days.

3.What payment methods are accepted for 2SD1838?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2SD1838 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2SD1838?

2SD1838 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2SD1838 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 2SD1838?

For technical support, including 2SD1838 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2SD1838 requirements.

6.How does Aetrix verify that 2SD1838 is sourced from the original manufacturer or authorized distributors?

All 2SD1838 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 2SD1838 meets industry standards.

7.What is the process for return or replacement of 2SD1838?

All 2SD1838 units undergo pre-shipment inspection (PSI). If there is an issue with 2SD1838, 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 2SD1838 part is unused and in its original packaging.

Return procedure for 2SD1838:

1.Submit a request within 90 days.

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

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