Texas Instruments ULN2003ADYYR

Overview

ULN2003ADYYR from Texas Instruments is a 7-channel high-voltage, high-current NPN Darlington transistor array optimized for inductive load switching. It delivers 500mA per channel, supports 50V collector-emitter voltage, integrates input base resistors (2.7kΩ), features built-in common-cathode clamp diodes, and operates across –40°C to 105°C - widely used in relay and stepper motor control interfaces.

For engineers reviewing the ULN2003ADYYR datasheet, ULN2003ADYYR pinout, ULN2003ADYYR application, or ULN2003ADYYR equivalent, key selection criteria include per-channel sink current capability, integrated flyback diode configuration, thermal performance in SOT-16 package, TTL/CMOS input compatibility, and parallel-output scalability for higher load currents.

Technical Context

The ULN2003ADYYR implements seven independent NPN Darlington pairs with internal 2.7kΩ series base resistors enabling direct drive from 3.3V or 5V logic. Each channel provides open-collector output with a shared common-cathode clamp diode node (COM) and common emitter (E) for inductive kickback suppression.

It operates in two primary functional modes: inductive load drive (COM tied to coil supply) and resistive load drive (COM floating, external pull-up required). Switching performance is characterized by 0.25–1μs propagation delay (25°C) and V_CE(sat) ≤1.6V at 350mA, with thermal resistance R_θJA = 123.1°C/W in its SOT-16 package.

Key Specifications

Pinout & Package

SOT-16 package (4.20mm × 2.00mm), surface-mount, 16-pin layout with exposed thermal pad (pin 8 = E, pin 9 = COM).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ULN2003ADYYR, ULN2003ADR offers superior thermal management in SOIC packaging for higher continuous current, while ULQ2003A provides automotive-grade reliability certification - neither is pin-compatible with ULN2003ADYYR's SOT-16 mechanical form factor.

Availability

ULN2003ADYYR is available at Aetrix Electronics and suitable for relay control, stepper motor interfacing, lamp driving, and industrial display applications requiring stable component supply and long-term industrial lifecycle support.

Supply support for ULN2003ADYYR 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and high-reliability silicon solutions for industrial, automotive, and communications markets.

The ULN2003ADYYR belongs to TI's legacy high-voltage Darlington array product line, engineered for robust, low-cost interface between microcontrollers and high-power electromechanical loads in harsh environments.

FAQ

What is the maximum continuous current per channel for ULN2003ADYYR?

The ULN2003ADYYR supports 500mA maximum collector current per channel under recommended operating conditions. Derating is required above 70°C ambient; Figure 5-5 in the datasheet shows duty-cycle-dependent limits - e.g., at 100% duty cycle and 70°C, max per-channel current is ~350mA in the SOT-16 package due to thermal constraints. Always verify power dissipation using R_θJA = 123.1°C/W.

How should the COM pin be connected when driving a relay with ULN2003ADYYR?

When driving an inductive relay coil with ULN2003ADYYR, connect the COM pin directly to the positive side of the relay coil supply (e.g., +24V). This ties the cathodes of all internal clamp diodes to the supply rail, allowing flyback current to recirculate safely through the diode during turn-off. The relay coil connects between COM and the corresponding collector output (e.g., 1C), while the emitter (E) remains grounded.

Can ULN2003ADYYR drive 3.3V logic inputs directly?

Yes, ULN2003ADYYR can drive 3.3V logic inputs directly because its 2.7kΩ internal input resistors allow sufficient base current to saturate the Darlington pair at VI = 3.3V. At 25°C, input current is ~0.93mA (typical) - well within standard GPIO sink capability. Confirm V_CE(sat) ≤1.1V at 100mA load ensures reliable low-level output for downstream logic sensing.

Is ULN2003ADYYR RoHS compliant and lead-free?

Yes, ULN2003ADYYR is RoHS compliant and lead-free. Texas Instruments certifies this part as meeting JEDEC J-STD-020 moisture sensitivity level 1 (MSL-1) and IPC/JEDEC J-STD-020D reflow profile requirements. The SOT-16 package uses matte tin lead finish, and full compliance documentation is available in TI's official product change notices and material declarations.

What is the purpose of the E (emitter) pin on ULN2003ADYYR?

The E pin (pin 8) is the common emitter connection for all seven Darlington pairs in ULN2003ADYYR. It must be connected to system ground to complete the current path. Unlike the COM pin (which serves clamp diode cathodes), E establishes the reference potential for transistor operation - leaving it unconnected prevents any channel from conducting. In PCB layout, E should be tied to a low-impedance ground plane to minimize voltage rise under high sink current.