ULN2803ADWR: A Comprehensive Overview | Heisener Electronics
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ULN2803ADWR: A Comprehensive Overview

Technology Cover
Post Date: 2024-06-07

ULN2803ADWR Introduction

The ULN2803ADWR is an application specific integrated circuit (IC) that is part of the ULN2803 series of high voltage, high current Darlington transistor arrays. It is typically used to interface between low level digital or microcontroller signals and high power devices such as relays, motors, solenoids, and lamps.

The ULN2803ADWR IC consists of eight Darlington pairs, which are essentially a combination of multiple transistors. Each Darlington pair consists of a driver transistor and a power transistor, enabling it to handle higher currents and voltages than a single transistor.

ULN2803ADWR Simplified Schematics

ULN2803ADWR Pinout

The ULN2803ADWR features a 16-pin configuration: Pins 1-8 are input pins compatible with TTL and CMOS logic, receiving signals from microcontrollers; Pins 11-18 are output pins connected to the loads (relays, LEDs, motors), each capable of handling up to 500mA with built-in flyback diodes for inductive kickback protection; Pin 10 is the common ground pin; and Pin 9 (COM) connects to the positive supply voltage for the freewheeling diodes. This design allows efficient control of multiple high-power loads with low-power digital signals.

ULN2803ADWR Specifications

Here's a detailed table of the specifications for the ULN2803ADWR:

Parameter Specification
Type Darlington Transistor Array
Number of Channels 8
Output Current per Channel 500 mA
Output Voltage Up to 50V
Input Voltage 2.4V (high) / 0.4V (low)
Input Current 1.35 mA (per channel)
Supply Voltage (Vcc) Not required (open collector outputs)
Logic Compatibility TTL, CMOS
Power Dissipation 2.25 W
Operating Temperature Range -40°C to 85°C
Pin Count 16
Integrated Diodes Yes (for inductive kickback protection)
Mounting Type Surface Mount
ESD Protection Yes
Propagation Delay 1 µs
Current Gain (hFE) 1000
Switching Speed Fast

ULN2803ADWR Features

- The output can handle voltages up to 50V, making it suitable for a variety of high voltage applications.

- The input pins are compatible with TTL and CMOS logic levels, ensuring easy interfacing with microcontrollers and other digital logic circuits.

- Available in a 16-pin small outline integrated circuit (SOIC) package for surface mount applications.

- The device operates reliably over a wide temperature range of -40°C to 85°C, making it suitable for a wide range of environments.

- Minimal input current (1.35 mA per channel) is required, reducing the load on the drive circuit.

- Propagation delay is only 1 µs, enabling fast response.

- High current gain (hFE) of 1000.

ULN2803ADWR Applications

U Relay Driver: Suitable for controlling multiple relays in automation and control systems.

LED Display Driver: Used to drive LED displays and signs.

Motor Control: Suitable for driving small DC motors in robots, toys, and industrial automation.

Inductive Load Driver: It can drive inductive loads such as solenoids and transformers.

Logic Buffer: Used as an interface between low-power logic circuits (such as microcontrollers) and high-power loads.

Lamp and Heater Control: Used to control incandescent lamps, heaters, and other resistive loads in home appliances and industrial equipment.

Printheads and Other Peripherals: Commonly used in printers and other peripherals to drive high-current components such as printheads and sensors.

Audio Amplifier: Used in audio applications to drive speakers and other audio output devices.

ULN2803ADWR Manufacturer

The ULN2803ADWR is manufactured by Texas Instruments (TI), a well-known and reputable company in the electronics industry. Texas Instruments specializes in designing and producing a wide range of semiconductor products, including integrated circuits for various applications. The ULN2803ADWR, part of their extensive lineup, is a robust Darlington transistor array commonly used for driving high-current and high-voltage loads.


ULN2803ADWR Circuit

ULN2803ADWR Package

The ULN2803ADWR is available in a surface-mount SOIC-18 (Small Outline Integrated Circuit) package. This package has 18 pins, which are arranged in a double row and spaced for surface mounting on a printed circuit board (PCB). The SOIC-18 package offers a compact form factor suitable for automated assembly processes, providing reliable performance in various applications requiring high-density component placement.

How To Use ULN2803ADWR?

Step 1: Connect the input pins (1-8) to the digital outputs of your microcontroller or control circuit. Each input pin controls a corresponding output pin.

Step 2: Connect the output pins (10-17) to the negative terminal of the load you want to drive. The positive terminal of the load should be connected to the power supply.

Step 3: Connect the COM pin (9) to the power supply of the load, making sure it matches the voltage requirements of the load.

Step 4: Connect the GND pin (18) to the ground of the control circuit to complete the circuit.

If you are driving an inductive load such as a relay or motor, add a diode for flyback protection.

FAQs about ULN2803ADWR

What is the maximum current rating per channel?

The ULN2803ADWR is an 8-channel Darlington transistor array designed to drive high-current, high-voltage loads with TTL or CMOS logic.

What is the purpose of the COM pin?

The COM pin is connected to the power supply for the loads and provides back EMF protection when driving inductive loads.


In conclusion, the ULN2803ADWR is a versatile and robust solution for driving high current, high voltage loads from low power digital circuits. By reading this article, you can learn the basic information and importance of this electronic component and how to use it.

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