7 Detailed Description

7.1 Overview

This standard device has proven ubiquity and versatility across a wide range of applications. This is due to

integration of 7 Darlington transistors of the device that are capable of sinking up to 500 mA and wide GPIO

range capability.

The ULN2003A device comprises seven high-voltage, high-current NPN Darlington transistor pairs. All units

feature a common emitter and open collector outputs. To maximize their effectiveness, these units contain

suppression diodes for inductive loads. The ULN2003A device has a series base resistor to each Darlington pair,

thus allowing operation directly with TTL or CMOS operating at supply voltages of 5 V or 3.3 V. The ULN2003A

device offers solutions to a great many interface needs, including solenoids, relays, lamps, small motors, and

LEDs. Applications requiring sink currents beyond the capability of a single output may be accommodated by

paralleling the outputs.

This device can operate over a wide temperature range (–40°C to 105°C).

7.2 Functional Block Diagrams

All resistor values shown are nominal. The collector-emitter diode is a parasitic structure and should not be

used to conduct current. If the collectors go below GND, an external Schottky diode should be added to clamp

negative undershoots.

COM

Output C

E

Input B

10.5 NŸ

7.2 NŸ

3 NŸ

7 V

Figure 7-1. ULN2002A Block Diagram

COM

Output C

E

Input B

RB

2.7 NŸ

7.2 NŸ

3 NŸ

Figure 7-2. ULN2003A, ULQ2003A and ULN2003AI

Block Diagram

COM

Output C

E

Input B

RB

10.5 NŸ

7.2 NŸ

3 NŸ

Figure 7-3. ULN2004A and LQ2004A Block Diagram

www.ti.com

ULN2002A, ULN2003A, ULN2003AI

ULQ2003A, ULN2004A, ULQ2004A

SLRS027S – DECEMBER 1976 – REVISED JUNE 2024

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Product Folder Links: ULN2002A ULN2003A ULN2003AI ULQ2003A ULN2004A ULQ2004A