Texas Instruments ULN2003AIPWRG4

Overview

ULN2003AIPWRG4 from Texas Instruments is a 7-channel high-voltage, high-current NPN Darlington transistor array designed for logic-level interfacing to inductive and resistive loads. It features 500mA per channel collector current capability, 50V output voltage rating, integrated common-cathode clamp diodes, 2.7kΩ input base resistors for direct TTL/5V CMOS compatibility, and operates across –40°C to 70°C ambient temperature - widely deployed in relay and stepper motor control circuits.

For engineers reviewing the ULN2003AIPWRG4 datasheet, ULN2003AIPWRG4 pinout, ULN2003AIPWRG4 application, or ULN2003AIPWRG4 equivalent, key selection criteria include verified sink-current derating at elevated duty cycles, thermal resistance (RθJA = 114.1°C/W) in TSSOP-16 package, COM pin connection requirements for inductive suppression, and input current vs. logic voltage behavior at 3.3V/5V drive levels.

Technical Context

The ULN2003AIPWRG4 integrates seven independent Darlington pairs with monolithic 2.7kΩ series base resistors, enabling direct interface to standard 5V TTL and CMOS logic without external biasing. Each channel provides open-collector sinking output with internal flyback diodes tied to a shared COM terminal, supporting safe turn-off of solenoids, relays, and DC motors.

Its functional architecture relies on cascaded NPN transistors delivering β² current gain (up to ~10⁴), allowing <1.4mA input current at 5V to sustain 350mA output current while maintaining VCE(sat) ≤1.6V. The device requires no external power supply beyond the load rail and COM connection - emitter (E) is internally tied to ground reference.

Key Specifications

Pinout & Package

TSSOP-16 package (5.00mm × 4.40mm), 16-pin surface-mount, lead-free and RoHS-compliant. Pin 1 marked via dot or bevel; pins numbered counter-clockwise from top-left corner when viewed top-down with marking dot in upper-left.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ULN2003AIPWRG4, ULN2003ADR offers lower thermal resistance for improved power handling in SOIC layout, while ULQ2003AIPWR extends operational reliability in warmer environments - neither is pin-compatible with 100V SN75468 nor CMOS-optimized ULN2004A variants.

Availability

ULN2003AIPWRG4 is available at Aetrix Electronics and suitable for relay drivers, stepper motor interfaces, and industrial lamp control requiring stable component supply and long-term manufacturing continuity.

Supply support for ULN2003AIPWRG4 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 logic-to-load interfacing in automation, instrumentation, and electromechanical control - prioritizing integration, reliability, and ease of use over programmability or digital intelligence.

FAQ

What is the maximum continuous current per channel for ULN2003AIPWRG4?

The ULN2003AIPWRG4 supports 500mA continuous collector current per channel under recommended operating conditions. Derating is required above 70°C ambient or with >50% duty cycle due to thermal limits of the TSSOP-16 package (RθJA = 114.1°C/W). At 70°C ambient and 100% duty, single-channel operation remains within safe junction temperature if VCE(sat) ≤1.6V and load voltage ≤50V. ULN2003AIPWRG4 datasheet Figure 5-5 confirms 0.5A max for DYY package at 70°C - TSSOP-16 shares this rating.

How should the COM pin be connected when using ULN2003AIPWRG4 with a relay?

The COM pin of ULN2003AIPWRG4 must be connected directly to the positive supply rail of the relay coil (e.g., +12V or +24V). This completes the internal clamp diode path, allowing stored inductive energy to recirculate safely during turn-off and preventing voltage spikes that could damage the Darlington outputs or upstream logic. Leaving COM unconnected or grounding it disables flyback protection and risks device failure. ULN2003AIPWRG4 functionality depends on correct COM routing per TI SLRS027T Section 7.4.1.

Can ULN2003AIPWRG4 drive 3.3V logic directly?

Yes, ULN2003AIPWRG4 accepts 3.3V logic inputs directly due to its 2.7kΩ internal base resistors. At VI = 3.3V, input current is ~1.22mA (3.3V ÷ 2.7kΩ), sufficient to saturate the Darlington pair for loads up to 350mA (per ULN2003AIPWRG4 datasheet Section 5.6). No level shifter or external resistor is needed. This makes ULN2003AIPWRG4 compatible with modern low-voltage MCUs while retaining full 500mA sink capability.

What is the purpose of the E (emitter) pin on ULN2003AIPWRG4?

The E pin (Pin 8) on ULN2003AIPWRG4 is the common emitter connection for all seven Darlington pairs and must be tied to system ground. It establishes the reference potential for input logic thresholds and output saturation voltage (VCE(sat)). Unlike discrete transistors, E is not floating - incorrect grounding causes improper biasing, elevated VCE(sat), or complete failure to switch. ULN2003AIPWRG4 thermal and electrical performance assumes E is solidly connected to PCB ground plane per TI SLRS027T Pin Function Table 4-1.

Does ULN2003AIPWRG4 support parallel operation of multiple channels?

Yes, ULN2003AIPWRG4 channels can be paralleled to increase total sink current capacity - for example, two channels in parallel support up to 1A (derated for thermal balance). TI documentation confirms this in Section 3 ("Darlington pairs can be paralleled for higher current capability") and Figure 5-2 shows VCE(sat) behavior under combined loading. Ensure matched trace lengths and symmetric layout to avoid current imbalance; ULN2003AIPWRG4's identical internal structure enables predictable sharing without external ballasting resistors.