Contents
Why do we need a driver IC in driving a relay?
It is difficult to use a number of relays with transistors, so, relay driver IC ULN2003A can be used for availing more relays. Based on the signals received from the microcontroller the relay driver circuit drives the relay or relays ON and OFF, such that controlling the operation of loads connected to these relays.
What is the use of relay?
Relays are used to provide time delay functions. They are used to time the delay open and delay close of contacts. Relays are used to control high voltage circuits with the help of low voltage signals. Similarly they are used to control high current circuits with the help of low current signals.
What is meant by driver circuit?
In electronics, a driver is a circuit or component used to control another circuit or component, such as a high-power transistor, liquid crystal display (LCD), stepper motors, and numerous others. Typically the driver stage(s) of a circuit requires different characteristics to other circuit stages.
How to test the working of ULN2003 IC?
The below circuit is a simple circuit that can be used to test the working of ULN2003 IC. In the circuit consider the LED to be the loads and the logic pins (blue colour) as the pins connected to the Digital circuit or Microcontroller like Arduino.
How many relays can I use with ULN2003?
We can use seven relays with relay driver circuit using ULN2003 and the relay driver circuit using ULN2803 enables to use eight relays. The above circuit represents the interfacing of PIC microcontroller (PIC16F877A) with relays using a relay driver circuit with ULN2003.
Why does the ULN2003 IC not have a VCC pin?
It might be surprising to note that this IC does not have any Vcc (power) pin; this is because the power required for the transistors to work will be drawn from the input pin itself. The below circuit is a simple circuit that can be used to test the working of ULN2003 IC.
How many transistors are in an uln3002 circuit?
Its contains seven Darlington pair of a transistor which have high voltage and high current carrying capability. Its mean ULN3002 can drive up to seven relays at a time. A diode is used with each pair of NPN Darlington transistor.