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

onsemi 2SD1685G

Name: 2SD1685G
Brand: onsemi
SKU: 2SD1685G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2SD1685G

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-225AA, TO-126-3

Datasheet:: 2SD1685G.pdf

Description:: TRANS NPN 20V 5A TO-126ML

Quantity:: RFQ Add To RFQ list

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Product details

Overview

2SD1685G from onsemi is an NPN bipolar junction transistor (BJT) designed for medium-power switching applications, featuring V_CEO = 20 V, I_C = 5 A continuous, and low V_CE(sat) = 220–500 mV at I_C = 3 A / I_B = 60 mA. It is commonly used in relay drivers, lamp drivers, and voltage regulators where robust current handling and fast turn-on/turn-off are required.

For engineers reviewing the 2SD1685G datasheet, pinout, applications, or equivalent options, key selection criteria include its TO-126ML package thermal performance, h_FE rank G (280–560 at I_C = 500 mA), f_T = 120 MHz, and Pb-free compliance - all critical for industrial control and strobe circuit design.

Technical Context

This device operates as a single NPN switch with a maximum junction temperature of 150°C and a storage range of –55°C to +150°C. Its low saturation voltage enables reduced conduction losses in DC-DC regulators and lamp driver stages, while its 120 MHz f_T supports reliable operation in pulse-width modulated (PWM) control up to several hundred kHz.

The TO-126ML package provides 10 W power dissipation at T_C = 25°C and eliminates need for electrical insulation during heatsink mounting due to plastic-covered leadframe. Switching times - t_on = 30 ns, t_stg = 300 ns, t_f = 40 ns - reflect optimized charge storage for high-duty-cycle switching.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	20 V - Maximum safe collector-emitter voltage under open-base conditions; defines upper limit for DC bus voltage in relay/lamp driver designs.
I_C (continuous)	5 A - Continuous collector current rating; supports load switching up to ~60 W at 12 V with adequate heatsinking.
V_CE(sat)	220–500 mV @ I_C=3 A, I_B=60 mA - Low saturation voltage minimizes power loss and self-heating in saturated-switch applications.
h_FE (Rank G)	280–560 @ V_CE=2 V, I_C=500 mA - High DC gain reduces required base drive current, easing microcontroller GPIO interface design.
f_T	120 MHz - Gain-bandwidth product enabling stable operation in high-frequency PWM and strobe timing circuits.
t_on/t_f	30 ns / 40 ns - Fast switching transitions reduce switching losses and EMI generation in repetitive pulse applications.
P_C @ T_C=25°C	10 W - Package-level power dissipation capability; requires mechanical mounting to heatsink for sustained >1.5 W operation.

Pinout & Package

2SD1685G is housed in a TO-126ML plastic package (JEITA/JEDEC-compliant TO-126), with exposed collector tab for direct heatsink attachment and no insulator required. The package weighs 0.97 g and measures 15.5 mm × 11.0 mm × 3.3 mm (L×W×H).

Pin/Terminal	Circuit Role	Design Meaning
1	Emitter	Current return path; connected to ground or low-side reference in common-emitter configurations.
2	Collector	Main output terminal; electrically tied to heatsink tab; must be isolated from chassis unless system ground referenced.
3	Base	Control input; requires current-limited drive (e.g., 60 mA typical for 3 A switching) to ensure full saturation.

Key Features

Feature	Design Value
Low V_CE(sat)	220–500 mV enables <1.5 W conduction loss at 3 A, improving thermal margin in compact relay driver PCBs.
High h_FE Rank G	280–560 gain reduces base drive requirement by >2× vs. standard-grade transistors, simplifying gate-driver IC selection.
Fast switching (t_on/t_f)	30 ns / 40 ns allows clean square-wave operation up to 1 MHz repetition rate without significant distortion.
Insulator-free mounting	Plastic-covered leadframe permits direct metal-to-metal heatsink contact, reducing thermal resistance by ~2–3°C/W vs. insulated mounting.

Applications

Relay Driver Circuits	Lamp Driver Stages
Use Scenario: Driving 12 V/5 A electromagnetic relays in PLC I/O modules with microcontroller GPIO control. IC Role / Device Role / Timing Role: NPN switch providing current amplification and isolation between logic-level control and inductive load. Use Value: Low V_CE(sat) limits coil driver loss to <1.5 W; fast turn-off suppresses back-EMF-induced contact arcing.	Use Scenario: Controlling incandescent or halogen lamps (up to 60 W) in automotive interior lighting or industrial signage. IC Role / Device Role / Timing Role: Saturated-mode power switch regulating lamp current via PWM duty cycle. Use Value: High h_FE Rank G ensures full saturation with ≤10 mA base drive, compatible with standard logic buffers.
Voltage Regulator Pass Element	Strobe Flash Control
Use Scenario: Linear pass transistor in adjustable 5–15 V, 3 A bench power supplies with thermal foldback protection. IC Role / Device Role / Timing Role: Series-pass element dissipating excess voltage as heat; controlled by error amplifier feedback loop. Use Value: 10 W T_C-rated dissipation supports 5 V dropout at 3 A without forced air; TO-126ML tab enables direct heatsink coupling.	Use Scenario: Triggering xenon flash tubes in camera modules or emergency signaling equipment with precise 20 μs pulse width. IC Role / Device Role / Timing Role: High-current pulse switch delivering 3–5 A peak current to flash capacitor discharge path. Use Value: 8 A pulse rating (I_CP) and 30 ns t_on ensure sub-microsecond trigger edge fidelity and consistent flash intensity.

Relay Driver Circuits

Lamp Driver Stages

Use Scenario: Driving 12 V/5 A electromagnetic relays in PLC I/O modules with microcontroller GPIO control.

IC Role / Device Role / Timing Role: NPN switch providing current amplification and isolation between logic-level control and inductive load.

Use Value: Low V_CE(sat) limits coil driver loss to <1.5 W; fast turn-off suppresses back-EMF-induced contact arcing.

Use Scenario: Controlling incandescent or halogen lamps (up to 60 W) in automotive interior lighting or industrial signage.

IC Role / Device Role / Timing Role: Saturated-mode power switch regulating lamp current via PWM duty cycle.

Use Value: High h_FE Rank G ensures full saturation with ≤10 mA base drive, compatible with standard logic buffers.

Voltage Regulator Pass Element

Strobe Flash Control

Use Scenario: Linear pass transistor in adjustable 5–15 V, 3 A bench power supplies with thermal foldback protection.

IC Role / Device Role / Timing Role: Series-pass element dissipating excess voltage as heat; controlled by error amplifier feedback loop.

Use Value: 10 W T_C-rated dissipation supports 5 V dropout at 3 A without forced air; TO-126ML tab enables direct heatsink coupling.

Use Scenario: Triggering xenon flash tubes in camera modules or emergency signaling equipment with precise 20 μs pulse width.

IC Role / Device Role / Timing Role: High-current pulse switch delivering 3–5 A peak current to flash capacitor discharge path.

Use Value: 8 A pulse rating (I_CP) and 30 ns t_on ensure sub-microsecond trigger edge fidelity and consistent flash intensity.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN medium-power switching applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
2SD1733G	V_CEO = 25 V, I_C = 5 A, h_FE Rank G = 280–560, same TO-126ML package	Higher V_CEO allows use in 24 V systems; otherwise functionally interchangeable in 12–20 V designs	Select 2SD1733G when operating above 20 V rail or requiring margin against transient overvoltage
MJD127G	V_CEO = 100 V, I_C = 5 A, h_FE = 1000–2500 (min), TO-252 package	Higher voltage rating and surface-mount format; significantly higher h_FE reduces base drive burden but requires PCB rework	Choose MJD127G only if upgrading to 100 V systems or transitioning to SMT assembly; not drop-in compatible

Compared with 2SD1685G, 2SD1733G offers extended voltage headroom in identical form factor, while MJD127G trades through-hole compatibility for higher voltage and SMT manufacturability - neither is pin-compatible, but both serve overlapping medium-power switching roles.

Availability

2SD1685G is available at Aetrix Electronics and suitable for relay drivers, lamp drivers, and voltage regulator pass elements requiring stable component supply, RoHS-compliant packaging, and consistent h_FE binning (Rank G).

Supply support for 2SD1685G 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

onsemi (formerly ON Semiconductor) is a global semiconductor manufacturer specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The 2SD1685G belongs to onsemi's general-purpose bipolar transistor product line, engineered for cost-sensitive, medium-power linear and switching applications where reliability, thermal performance, and consistent gain binning are essential.

FAQ

What is the h_FE range for 2SD1685G, and how is it binned?

The 2SD1685G is binned to Rank G, with DC current gain (h_FE) specified from 280 to 560 at V_CE = 2 V and I_C = 500 mA. This tight gain grouping ensures predictable base drive requirements across production lots, critical for consistent performance in relay and lamp driver circuits using the 2SD1685G.

Can 2SD1685G replace 2SD1685F in existing designs?

Yes, the 2SD1685G and 2SD1685F share identical TO-126ML packaging, pinout, and absolute maximum ratings. The only difference is h_FE binning: 2SD1685F is Rank F (160–320), while 2SD1685G is Rank G (280–560). Designers may substitute 2SD1685G where higher gain improves noise immunity or reduces base drive burden - no layout change needed.

What is the maximum allowable collector dissipation for 2SD1685G at 75°C case temperature?

The 2SD1685G datasheet specifies P_C = 10 W at T_C = 25°C, with derating required above that temperature. At T_C = 75°C, the maximum allowable collector dissipation is approximately 6.5 W, calculated using the linear derating slope of 40 mW/°C beyond 25°C - a value confirmed in the device's thermal characteristics curves on page 4 of the EN2042B datasheet.

Does 2SD1685G require an insulating washer when mounted to a heatsink?

No, the 2SD1685G uses a TO-126ML package with a plastic-covered leadframe, eliminating the need for electrical insulation between the collector tab and heatsink. This design reduces thermal resistance and simplifies mechanical assembly - a verified feature explicitly stated in the "Features" section of the 2SD1685G datasheet.

What are the recommended test conditions for measuring V_CE(sat) of 2SD1685G?

V_CE(sat) for the 2SD1685G is characterized at I_C = 3 A and I_B = 60 mA, with V_CE measured under saturated switching conditions. These conditions appear in the "Electrical Characteristics" table and correspond to the standard test setup shown in Figure 1 of the EN2042B datasheet, ensuring repeatable validation of low-saturation performance in the 2SD1685G.

2SD1685G Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-225AA, TO-126-3

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: NPN

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

Voltage - Collector Emitter Breakdown (Max):: 20 V

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 60mA, 3A

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 280 @ 500mA, 2V

Power - Max:: 1.5 W

Frequency - Transition:: 120MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-126ML

2SD1685G FAQ

1.How can I place an order for 2SD1685G through Aetrix?

Please submit a Request for Quotation (RFQ) for 2SD1685G 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 2SD1685G reliable?

The price and inventory of 2SD1685G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2SD1685G is usually 5 days.

3.What payment methods are accepted for 2SD1685G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2SD1685G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2SD1685G?

2SD1685G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2SD1685G 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 2SD1685G?

For technical support, including 2SD1685G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2SD1685G requirements.

6.How does Aetrix verify that 2SD1685G is sourced from the original manufacturer or authorized distributors?

All 2SD1685G 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 2SD1685G meets industry standards.

7.What is the process for return or replacement of 2SD1685G?

All 2SD1685G units undergo pre-shipment inspection (PSI). If there is an issue with 2SD1685G, 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 2SD1685G part is unused and in its original packaging.

Return procedure for 2SD1685G:

1.Submit a request within 90 days.

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

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