The ULN2003 (ULN2003a)  microcircuit is essentially a set of powerful composite keys for use in inductive load circuits. It can be used to control high-power loads, including electromagnetic relays, DC motors, electromagnetic valves, in control circuits for various stepper motors , and others.

ULN2003 microcircuit 

 The ULN2003a is a Darlington transistor assembly with high-power output keys, having protective diodes at the outputs, which are designed to protect the control circuits from reverse voltage surge from the inductive load.

Each channel (Darlington pair) in the ULN2003 is rated for 500 mA and can handle a maximum current of 600 mA. The inputs and outputs are located opposite each other in the chip housing, which greatly simplifies the PCB layout.

ULN2003 belongs to the ULN200X family of microcircuits. Different versions of this microcircuit are designed for specific logic. In particular, the ULN2003 microcircuit is designed to work with TTL logic (5V) and CMOS logic devices. ULN2003 has found wide application in control circuits of a wide range of loads, as relay drivers, display drivers, linear drivers, etc. ULN2003 is also used in stepper motor drivers.

Characteristics

• The nominal collector current of one key is 0.5 A;
• Maximum output voltage up to 50 V;
• Protective diodes at the outputs;
• The input is adapted to all kinds of logic;
• Possibility of application for relay control.