Texas Instruments ULN2003ADRG3

Overview

ULN2003ADRG3 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 directly with 3.3V/5V TTL or CMOS logic - widely used in relay and stepper motor control circuits.

For engineers reviewing the ULN2003ADRG3 datasheet, ULN2003ADRG3 pinout, ULN2003ADRG3 application, or ULN2003ADRG3 equivalent, key selection criteria include per-channel sink current capability, integrated flyback diode configuration, thermal derating at elevated ambient temperatures, and compatibility with low-voltage GPIO drivers in industrial I/O and motion control systems.

Technical Context

The ULN2003ADRG3 implements seven independent Darlington pairs, each with a 2.7kΩ series input resistor enabling direct interface to 3.3V/5V logic without external biasing. Its open-collector outputs share a common emitter (pin 8) and a common cathode clamp node (pin 9), allowing simultaneous suppression of inductive kickback across all channels when COM is tied to the load supply rail.

Each Darlington stage achieves current gain up to 10,000 A/A, permitting 500μA–1.35mA input drive to fully saturate the output at 300mA load current. Switching performance is characterized by 0.25–1μs propagation delay (tPLH/tPHL) at 25°C, with V_CE(sat) ≤1.6V at 350mA and II = 500μA - critical for minimizing power loss in high-duty-cycle solenoid or lamp driver applications.

Key Specifications

Pinout & Package

ULN2003ADRG3 is housed in a 16-pin SOIC (D) package with standard 1.27mm pitch, measuring 9.90mm × 3.91mm including leads. Thermal resistance R_θJA is 88.6°C/W, supporting moderate power dissipation with standard PCB copper area.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ULN2003ADR, ULN2003ADRG3 offers identical performance with enhanced traceability for automotive-grade supply chains; versus ST ULN2003A, it provides superior thermal headroom and tighter saturation voltage control - critical for energy-efficient industrial motor drives.

Availability

ULN2003ADRG3 is available at Aetrix Electronics and suitable for relay drivers, stepper motor controllers, and industrial lamp drivers requiring stable component supply across long production lifecycles.

Supply support for ULN2003ADRG3 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 connectivity technologies with over 50 years of industrial-grade component development.

The ULN200x family was engineered for robust, low-complexity interface between digital logic and high-voltage/high-current electro-mechanical loads - targeting reliability-critical applications in factory automation, building controls, and appliance systems.

FAQ

What is the maximum continuous current per channel for ULN2003ADRG3?

The ULN2003ADRG3 supports 500mA continuous collector current per Darlington channel under recommended operating conditions (T_A ≤ 70°C, proper PCB copper area). Derating is required above 70°C ambient, with maximum total current dropping to ~350mA at 105°C case temperature per Figure 5-4 in the datasheet. This rating assumes use of the internal clamp diodes with COM tied to the load supply.

Does ULN2003ADRG3 require external flyback diodes when driving relays?

No, ULN2003ADRG3 does not require external flyback diodes when driving relays. It integrates seven common-cathode clamp diodes connected to pin 9 (COM). To activate protection, connect COM to the same positive supply rail as the relay coil - this provides a path for inductive kickback current, preventing voltage spikes that could damage the IC or upstream logic.

Can ULN2003ADRG3 be used with 3.3V microcontroller GPIOs?

Yes, ULN2003ADRG3 is fully compatible with 3.3V GPIOs. Its 2.7kΩ internal base resistors allow direct connection: at 3.3V input, typical input current is ~1.2mA, sufficient to saturate the Darlington pair for loads up to 300mA. Verified V_I(on) is 2.4V min at I_C = 200mA, ensuring reliable turn-on across voltage and temperature extremes.

What is the purpose of pin 8 (E) and pin 9 (COM) on ULN2003ADRG3?

Pin 8 (E) is the common emitter node - internally tied to all seven Darlington emitter terminals and must be connected to system ground. Pin 9 (COM) is the common cathode of the integrated clamp diodes - connect it to the positive supply of the inductive load (e.g., +12V relay coil rail) to enable flyback current recirculation. Leaving COM unconnected disables diode protection and risks voltage overshoot.

How does thermal performance differ between ULN2003ADRG3 and ULN2003ADR?

ULN2003ADRG3 and ULN2003ADR share identical die, SOIC-16 package construction, and thermal metrics: both have R_θJA = 88.6°C/W and operate from –40°C to 105°C. The suffix "G3" denotes green (halogen-free) packaging and specific tape-and-reel compliance - no electrical or thermal differentiation exists between the two variants in actual circuit operation.