Texas Instruments ULN2003AIPW

Overview

ULN2003AIPW from Texas Instruments is a 7-channel high-voltage, high-current NPN Darlington transistor array optimized for interfacing low-voltage logic (TTL/5V CMOS) with inductive loads. Each channel delivers 500mA sink current, supports 50V collector-emitter voltage, and integrates clamp diodes for flyback suppression. It is widely deployed in relay drivers, stepper motor control, and LED display interfaces.

For engineers reviewing the ULN2003AIPW datasheet, ULN2003AIPW pinout, ULN2003AIPW application, or ULN2003AIPW equivalent, key selection criteria include per-channel saturation voltage (≤1.6V at 350mA), input base resistor value (2.7kΩ), thermal resistance (114.1°C/W in TSSOP), common-emitter configuration, and compatibility with 3.3V/5V GPIO without external biasing.

Technical Context

The ULN2003AIPW implements seven independent Darlington pairs-each formed by cascaded NPN transistors-to achieve current gain up to 10,000 A/A. Its internal 2.7kΩ series base resistor enables direct drive from 3.3V or 5V logic, while the shared emitter (Pin 8) and common-cathode clamp diode node (Pin 9) support coordinated inductive load switching.

Operation requires tying the COM pin (Pin 9) to the inductive load supply rail to activate internal flyback diodes. The device operates across –40°C to 70°C ambient temperature, with absolute maximum ratings of 50V V_CE, 500mA per channel, and 2.5A total emitter current-enabling robust interface between microcontrollers and industrial actuators.

Key Specifications

Pinout & Package

TSSOP-16 package (5.00mm × 4.40mm), thin shrink small-outline package with exposed pad not specified; moisture sensitivity level (MSL) not provided in source data.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ULN2003AD and ULQ2003AIPW, the ULN2003AIPW offers the smallest footprint (TSSOP-16) and standard industrial temperature range (–40°C to +70°C), making it optimal for space-constrained consumer and embedded designs where thermal load remains moderate.

Availability

ULN2003AIPW is available at Aetrix Electronics and suitable for relay drivers, stepper motor interfaces, LED display systems, and lamp/solenoid control requiring stable component supply and long-term production continuity.

Supply support for ULN2003AIPW 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 delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and personal electronics markets.

The ULN200x family was engineered specifically for logic-level interfacing to high-voltage/high-current loads - enabling reliable, cost-effective replacement of discrete transistor arrays in relay, motor, and lamp driver applications.

FAQ

What is the maximum continuous current per channel for ULN2003AIPW?

The ULN2003AIPW supports 500mA maximum collector current per channel under recommended operating conditions. This rating assumes proper thermal management - for example, limiting ambient temperature and ensuring adequate PCB copper area for heat dissipation. At 350mA, V_CE(sat) remains ≤1.6V, keeping power dissipation within safe limits for the TSSOP-16 package's 114.1°C/W R_θJA.

Does ULN2003AIPW require external flyback diodes when driving relays?

No, ULN2003AIPW does not require external flyback diodes when driving relays. It integrates seven common-cathode clamp diodes connected to Pin 9 (COM). To activate them, connect COM to the positive supply rail of the inductive load - for example, +12V for a 12V relay coil. This internal path safely dissipates stored inductive energy during turn-off, protecting both the ULN2003AIPW and upstream logic.

Can ULN2003AIPW be used with 3.3V microcontrollers?

Yes, ULN2003AIPW is fully compatible with 3.3V microcontrollers. Its internal 2.7kΩ base resistors ensure sufficient input current (~1.2mA at 3.3V) to saturate each Darlington pair. Verified VI(on) is as low as 2.4V at 200mA load, confirming reliable turn-on from standard 3.3V GPIO. No level-shifting or external biasing is required.

How should the COM and E pins be connected in a typical ULN2003AIPW circuit?

In a typical ULN2003AIPW circuit, connect Pin 8 (E) directly to system ground - this is the common emitter reference for all channels. Connect Pin 9 (COM) to the positive supply rail of the inductive load (e.g., +24V for a 24V solenoid). For resistive loads like LEDs, COM may be left floating, but grounding it is acceptable and simplifies layout. Never leave E unconnected.

What is the thermal performance difference between ULN2003AIPW and ULN2003AD?

ULN2003AIPW (TSSOP-16) has a junction-to-ambient thermal resistance (R_θJA) of 114.1°C/W, while ULN2003AD (SOIC-16) is rated at 88.6°C/W. This means the SOIC version dissipates heat more effectively - allowing ~28% higher continuous power before reaching thermal limit. Choose ULN2003AIPW for space-constrained designs; select ULN2003AD when thermal headroom is critical and board area permits the larger package.