What is open collector comparator?
An open collector output is an output device that is attached to an open collector of a transistor. A perfect example of an open collector output are voltage comparators. Pretty much all voltage comparator chips, such as the LM311, the LM393, and the LM339 all function as output collector outputs.
Why is the output of the comparator made with an open collector?
The main reason for using open-collector is so that several comparators can have their output connected together in a wired OR gate. All the open collectors can be tied together to a single resistor without any conflicts between comparators.
How do you use open collector output?
An open-collector output is used to connect one side of the device being controlled to ground. The other side of the device will be connected to power. If you look at the CRICKIT “drive” outputs you will see that this is exactly what they are.
What is the function of the comparator in the ADC?
A comparator is normally used in applications where some varying signal level is compared to a fixed level (usually a voltage reference). Since it is, in effect, a 1-bit analog-to-digital converter (ADC), the comparator is a basic element in all ADCs.
How does the comparator work?
The comparator circuit work by simply taking two analog input signals, comparing them and then produce the logical output high “1” or low “0“. When the analog input on non-inverting is less than the analog input on inverting input, then the comparator output will swing to the logical low.
Why do they usually make comparators open collector?
The main reason for using open-collector is so that several comparators can have their output connected together in a wired OR gate. All the open collectors can be tied together to a single resistor without any conflicts between comparators. This would not have been easy to do when your comparator has also the capability…
Is it OK to use an open collector output?
An open collector output is simple and flexible but relatively slow compared to other logic outputs. Since most comparators are slow, it is OK to use open collector outputs for them. Fast comparators may have other types of outputs.
What’s the difference between a comparator and an opamp?
The difference is that the comparator output is a logic output that can only be on or off, and the opamp output is analog. An open collector output is simple and flexible but relatively slow compared to other logic outputs. Since most comparators are slow, it is OK to use open collector outputs for them.
How is a voltage comparator connected to a power supply?
Here, the open collector output from the voltage comparator is connected to a voltage source via a single pull-up resistor (and an LED for indication) which pulls the single output high to the power supply. When the output switch is HIGH it creates a high impedance path, therefore no current flows as V OUT = Vcc.