onsemi 2SD1801T-TL-E

Overview

2SD1801T-TL-E from onsemi is an NPN bipolar junction transistor (BJT) designed for general-purpose switching and amplification in low-voltage, medium-current applications. It features a DC current gain (h_FE) of 200–400 at I_C = 500 mA, V_CE = 2 V; maximum collector-emitter voltage (V_CEO) of 20 V; continuous collector current (I_C) rating of 1 A; and a power dissipation (P_D) of 1 W at T_A = 25 °C. It is commonly used in relay drivers, LED drivers, and small-signal amplifier stages in consumer and industrial control circuits.

For engineers reviewing the 2SD1801T-TL-E datasheet, pinout, applications, or equivalent options, key selection criteria include its guaranteed h_FE range at 500 mA bias, TO-220AB package thermal performance, saturation voltage (V_CE(sat)) ≤ 0.5 V at I_C/I_B = 500 mA/50 mA, and suitability for linear or saturated-mode operation in discrete power interface stages.

Technical Context

The 2SD1801T-TL-E operates as a silicon NPN BJT with epitaxial base construction, optimized for stable DC current amplification and fast switching in non-RF, non-high-frequency analog/digital interface roles. Its specified h_FE range (200–400) is guaranteed at I_C = 500 mA and V_CE = 2 V, and its V_CE(sat) is characterized at high drive ratio (I_C/I_B = 10), supporting reliable turn-on in logic-driven switch configurations.

Thermal design relies on its TO-220AB package's 62.5 °C/W junction-to-ambient thermal resistance (R_θJA) under standard PCB mounting conditions, and its safe operating area (SOA) is defined up to 10 ms pulse width at 25 °C ambient-enabling robust transient handling in relay coil and solenoid drive applications.

Key Specifications

Pinout & Package

The 2SD1801T-TL-E is housed in a TO-220AB plastic package with three leads, featuring a metal tab electrically connected to the collector terminal and intended for mechanical mounting and thermal transfer to a heatsink.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 2SD1801T-TL-E, 2SC4793-O offers higher voltage headroom but reduced current gain consistency, while MJD122G provides much greater power handling in a different package-neither matches the exact 20 V/1 A/TO-220AB balance of the 2SD1801T-TL-E for cost-sensitive, thermally constrained low-voltage driver designs.

Availability

2SD1801T-TL-E is available at Aetrix Electronics and suitable for relay drivers, LED current amplifiers, DC motor control stages, and linear power supply pass elements requiring stable component supply and proven thermal behavior in TO-220AB packages.

Supply support for 2SD1801T-TL-E 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 is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The 2SD1801T-TL-E belongs to onsemi's general-purpose bipolar transistor product line, engineered for reliable, cost-effective discrete switching and amplification in consumer, industrial, and infrastructure equipment where thermal robustness and parameter consistency are prioritized.

FAQ

What is the maximum collector-emitter voltage rating for the 2SD1801T-TL-E?

The 2SD1801T-TL-E has a maximum collector-emitter voltage (V_CEO) rating of 20 V. This value is measured with the base open and defines the absolute upper limit for voltage applied between collector and emitter before risk of avalanche breakdown. Designers must ensure that transient spikes and operating voltages remain below this threshold, especially in inductive load switching applications where flyback voltages may occur. The 2SD1801T-TL-E is therefore best suited for 12 V and lower DC systems.

Does the 2SD1801T-TL-E have a built-in base-emitter resistor?

No, the 2SD1801T-TL-E is a standard NPN bipolar junction transistor without any integrated resistors. It requires an external base current-limiting resistor to establish proper biasing and prevent excessive base current. Unlike digital transistors (BRTs), which integrate base resistors, the 2SD1801T-TL-E gives full design flexibility for optimizing h_FE-dependent drive conditions-but mandates careful calculation of R_B based on target I_C, V_CC, and guaranteed h_FE range.

What is the typical saturation voltage of the 2SD1801T-TL-E under rated conditions?

The typical saturation voltage (V_CE(sat)) of the 2SD1801T-TL-E is ≤ 0.5 V when operated at I_C = 500 mA and I_B = 50 mA (I_C/I_B = 10). This low V_CE(sat) directly reduces conduction losses and self-heating during on-state operation, making the 2SD1801T-TL-E well-suited for efficient switching in relay drivers and LED current boosters. Actual measured values may vary slightly depending on junction temperature and manufacturing lot.

Is the metal tab of the 2SD1801T-TL-E electrically connected to any internal terminal?

Yes, the metal tab of the 2SD1801T-TL-E is internally connected to the collector terminal. This connection is inherent to the TO-220AB package construction and must be accounted for in PCB layout and mechanical mounting. If the heatsink or chassis is grounded, electrical isolation (e.g., mica washer + insulating sleeve) is required to prevent shorting the collector to ground. Failure to isolate may damage the 2SD1801T-TL-E or disrupt circuit functionality.

Can the 2SD1801T-TL-E be used in linear amplifier configurations?

Yes, the 2SD1801T-TL-E is suitable for linear amplifier applications such as Class-A audio preamplifiers or precision current sources, provided operating conditions remain within its Safe Operating Area (SOA) and thermal limits. Its specified h_FE range (200–400) and low V_CE(sat) support stable biasing, but designers must ensure adequate heatsinking-especially at higher V_CE × I_C products-and avoid operation near secondary breakdown boundaries. The 2SD1801T-TL-E is not optimized for RF or high-frequency analog use.