ULN2803A Introduction

ULN2803A is an 8-channel Darlington transistor array, mainly used to drive high current and high voltage loads such as relays, stepper motors, LED displays, solenoid valves, etc. Each channel consists of a pair of Darlington transistors, with high current amplification capability, and can handle load currents up to 500mA. Manufacturers such as Texas Instruments (TI), STMicroelectronics, and Toshiba produce this model.

ULN2803A Parameters

ULN2803A Similar Prodcuts Comparison

ULN2803A vs MC1413BPG Comparison

Parameter	ULN2803A	MC1413BPG
Image
Manufacturer	STMicroelectronics	ON Semiconductor
Type	Darlington Transistor Array	Darlington Transistor Array
Channels	8 Channels	7 Channels
Input Type	TTL-Compatible	TTL-Compatible
Output Type	Open Collector (Sinking)	Open Collector (Sinking)
Output Current (per channel)	500 mA (max)	500 mA (max)
Peak Output Current	2.5A (per channel)	2.5A (per channel)
Voltage Rating	50V (max)	50V (max)
Saturation Voltage	1.4V (typical)	1.4V (typical)
Package Type	DIP-18, SOIC-18, SSOP-20	DIP-16, SOIC-16
Operating Temperature	-40°C to +85°C	-40°C to +85°C
Internal Flyback Diodes	Yes (for inductive load protection)	Yes (for inductive load protection)
Power Supply	5V to 30V (for input)	5V to 30V (for input)
Control Input Voltage	2.4V (minimum for activation)	2.4V (minimum for activation)
Typical Applications	Driving relays, lamps, motors, solenoids	Driving relays, lamps, motors, solenoids

The ULN2803A is a more versatile option if you need 8 channels for controlling more devices. It is commonly used in industrial and automotive control systems, as well as for general-purpose switching tasks.

The MC1413BPG is a slightly more compact solution with 7 channels, but otherwise provides very similar features and performance to the ULN2803A. It is suitable for designs with space constraints or where fewer control channels are needed.

ULN2803A working principle:

ULN2803A is an array based on Darlington transistor pairs, and each channel consists of two NPN transistors in series. With this configuration, high gain can be provided, allowing the input of a small current drive to control a large current output.

Each channel has built-in reverse diode protection, which is suitable for driving inductive loads such as relays and motors to prevent damage to the device by reverse electromotive force.

ULN2803A Application

Relay drive: suitable for controlling high current relays triggered by various low voltage signals.

LED driver: suitable for controlling large LED displays or multi-channel LED drivers.

Stepper motor driver: can be used to drive multiple windings of stepper motors.

Solenoid valve control: used for solenoid valve driving in industrial automation.

ULN2803A Pinout

ULN2803A pins, transistor matrix

ULN2803A advantages:

Internally integrated reverse diode protection makes it safer and more reliable when driving inductive loads.

Compatible with TTL and CMOS logic level inputs, suitable for direct interface with microcontrollers or other digital circuits.

The output current of each channel is up to 500 mA, which can drive most small and medium-sized relays and motors.

ULN2803A package:

ULN2803A uses DIP-18 package (dual in-line package), which is suitable for insertion into PCB boards through through holes and soldering, and is widely used in prototype development and industrial applications.

ULN2803A Video

Working principle, characteristics and applications of ULN2803A integrated circuit.

ULN2803A Datasheet PDF and Reference Manual

Download datasheets and manufacturer documentation for ULN2803A

ULN2803A Datasheet

FAQs for ULN2803A

1.What is the ULN2803A?

A: The ULN2803A is an 8-channel Darlington transistor array suitable for driving high current, high voltage loads. It can be used in high power applications such as relays, stepper motors, solenoid valves, LED arrays, etc.

2.What is the maximum output current of ULN2803A?

A: The maximum output current of each channel is 500 mA. In high current applications, multiple channels can be connected in parallel to obtain higher current capacity.

3.What is the operating voltage range of ULN2803A?

A: ULN2803A can handle load voltages up to 50V. The input logic level can be TTL or CMOS standard.

4.What loads can ULN2803A drive?

A: ULN2803A can drive a variety of loads, especially high current and inductive loads, such as:

Relays

Stepper motors

Solenoid valves

High power LED arrays

Buzzers and small motors

5.What is the input voltage range of ULN2803A?

A: The input of ULN2803A is compatible with TTL and CMOS logic levels, and the typical input voltage is 5V. When the input logic is high, the transistor pair of the corresponding channel is turned on and the output drives the load.

6.Does ULN2803A have built-in protection function?

A: Yes, ULN2803A has built-in reverse voltage protection diode, which is particularly suitable for driving inductive loads (such as relays and motors) to absorb the reverse electromotive force generated when the load is powered off to prevent device damage.

7.Can ULN2803A be used for PWM control?

A: Yes. ULN2803A can be used for PWM (pulse width modulation) control, which is suitable for adjusting the brightness of LEDs or controlling the speed of motors. Just input the PWM signal to the input of ULN2803A, and it will adjust the output according to the signal.

8.How many output channels does ULN2803A support?

Answer: ULN2803A provides 8 independent output channels, each channel can drive a load separately, suitable for multi-channel parallel control applications.

9.What is the difference between ULN2803A and ULN2003?

A: ULN2803A has 8 channels, while ULN2003 has only 7 channels. Other functions are basically the same, and both can be used to drive high current loads.

10.Can ULN2803A be used for stepper motor control?

A: Yes, ULN2803A is very suitable for stepper motor control. Through independent control of 8 channels, ULN2803A can provide drive signals for each winding of the stepper motor for precise control.

11.Does ULN2803A support parallel use?

A: Yes. When higher current is required, multiple channels of ULN2803A can be used in parallel to drive a single load to increase the total output current.

12.What are the alternatives to ULN2803A?

A: Common alternatives to ULN2803A include:

ULN2803ADWR: Surface mount version of ULN2803A.

TBD62083AFG: 8-channel Darlington array produced by Toshiba, with similar functions.

13. What is the difference between ULN2803A and ULN2803ADWR?

A: ULN2803A is a DIP-18 package suitable for through-hole soldering; while ULN2803ADWR is a SOIC-18 package suitable for surface mounting. The functions and electrical parameters of the two are basically the same, and the only difference is the package form and operating temperature range.