Hi all
I had attached an image that shows the output is open collector & has a resistor .Can anyone explain me what does the open collector means & how does it function and what is the use of resistor ?

MOD: trimmed your image.E

 

hi Md,
Welcome to AAC.
Open collector, means you have to add an external pull up resistor.
E

 

Open collector means the output transistor collector has no connection, thus the need for a pull-up resistor to the supply voltage to generate a voltage signal.

 

Open collector output (and open emitter output) means that the chip manufacturer intentionally omitted some essential components required to make a complete circuit. The manufacturer did not commit to a specific output voltage and load resistor.
It means that the circuit designer is free to apply a suitable load and supply voltage according to the needs of the specific application.

It also means that in digital systems, the designer can implement wired-OR (for negative logic) buses or party-line systems without the need for additional gates.

 

An additional advantage of an open collector output is, for example, the transistor may de driven from a 5V supply control circuit but it can switch a 24V load as the collector does not have a connection to that driving circuit.
The load voltage therefore is wholly dependant on the specs of the transistor. There are quite a few chips that have open collector outputs and are used to drive small motors as things like that. Very handy.

 

You can check the practical application of Open collector circuit.
PNP or NPN for plc and motor driver?