Open Collector Output

An Open Collector output is an NPN transistor. An NPN transistor allows the sinking of current to common. It can be thought of as a switch that allows the circuit, after the load, to be connected to common. This means that a source is required for the output to work.

What is open collector output in VFD?

The Open-Collector Output is a transistor circuit configuration used in a wide variety of electronic designs includ- ing many integrated circuits (ICs). Three parts make up a transistor: the emitter, the base and the collector.

What is the advantage of open collector output?

The advantage of open collector outputs, or open drain outputs is that the load to be switched or controlled can be connected to a voltage supply which is independant, and/or different from the supply voltage used by the controlling circuit, and that they can “sink” or “source” an externally-supplied voltage depending

What is open collector signal?

Open-collector devices are commonly used to connect multiple devices to one interrupt request signal or a shared bus such as I²C. This enables one device to drive the bus without interference from the other inactive devices.

Are Arduino outputs open collector?

Just like sourcing current is an output. There is no open drain or open collector configuration in an arduino. If you want one you have to use an external transistor or FET.

Why is it called open collector?

The term “open collector” refers to a current sink on a transistor output. If an NPN transistor is left unconnected, or open but connected to an external pin, it's an open collector.

What is the difference between open drain and open collector?

An “open collector” is functionally the same as an “open drain”. An “open collector” refers to a current sink on a BJT transistor output, while an “open drain” refers to a current sink on a FET output.

Is open collector a dry contact?

A "dry contact input" generally expects that its two contacts will be shorted to each other to activate it -- and NOT shorted to anything else. An "open collector output" is one that is open-circuit when inactive, and shorted to ground when active.

What is push pull vs open drain?

While a push-pull sensor has two MOSFETs that alternately conduct to provide high or low output signals, an open drain sensor has only one MOSFET. When a magnetic field turns the open-drain sensor on, the MOSFET conducts, allowing current to sink through the pull-up resistor to ground.

Why open drain is used?

An open-drain is commonly found in many integrated circuits. This helps multiple devices to connect with the usage of single wire which is in a mode of pull-down operation.

Why I2C lines are open drain?

I2C is multi-master and multi-slave protocol. If the lines are not open drain then there may chance that one slave pulling the device low and other slave is trying to pull the same line high. This situation is called as the bus contention.

What is an open collector input and why is it used on sensors?

The open-collector output of a power supply is a method of control circuitry used to output the state (status) and other information of the power supply. The output of a power supply is controlled by an open collector to turn it on and off externally.

What is a 3 state output?

A three-state, or Tri-State™, output has three electrical states: One, zero, and "Hi-Z," or "open." The hi-Z state is a high-impedance state in which the output is disconnected, leaving the signal open, to be driven by another device (or to be pulled up or down by a resistor provided to prevent an undefined state).

What is PNP output?

A PNP output is commonly called a “sourcing” output. When it senses an object it will connect the output to the positive supply. If you're unsure of which output type you need, a number of manufactures produce sensors with configurable outputs. In this case the sensor can be configured to operate as an NPN or PNP type.

Does open collector need a pull-up resistor?

Open collector outputs require a pull-up resistor (R in the image above) for the output to be able to properly “output high”. The pull-up resistor is connected between the output pin and the output voltage (Vcc in the image above) that is desired for a high state.

What is open drain drivers?

An open-drain or open-collector output pin is driven by a single transistor, which pulls the pin to only one voltage (generally, to ground). When the output device is off, the pin is left floating (open, or hi-z).

Are Arduino pins push pull?

But is there a function to configure the pin in open drain or push pull ? Only if the processor supports it. On the AVR-based Arduinos (UNO, Nano, Mini, Mega, Leonardo, Micro) the outputs are all Push-Pull.

What does a collector do in a transistor?

Collector – The section which collects the major portion of the majority charge carrier supplied by the emitter is called a collector. The collector-base junction is always in reverse bias. Its main function is to remove the majority charges from its junction with the base.

Is open drain input or output?

In both of the scenarios, the point to be noted is that the open drain/collector is a part of the output transistor which is directly connected out to a pin that is on the external side of the integrated circuit.

How an open collector TTL operates?

Open Collector Output With any of the input at logic low, the corresponding emitter-base junction is forward biased and the voltage drop across the base of Q1 is around 0.9V, not enough for the transistors Q2 and Q3 to conduct. Thus the output is either floating or Vcc, i.e. High level.