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What is open-drain port?
Glossary Term: Open-drain 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).
Which port pins are open-drain in 8051?
PORT 0 of 8051 microcontroller: Port 0 is 8 open drain bi-directional IO port, Open drain simply means a transistor that connects to Gnd. Bi-directional means this PORT may be configured as input or output. P0 register is used for accessing PORT0.
What is open-drain interface?
An open drain terminal is connected to ground when a high voltage (logic 1) is applied to the gate, yet presents a high impedance when a low voltage (logic 0) is applied to the gate.
What are the disadvantages of open sewer?
Harmful Effects of Open Drains
- Spread of diseases.
- Build-up of toxic chemicals.
- Road deterioration.
- Contamination of water sources.
- Breeding sites of mosquitoes.
- Bad odor and unsightly.
- Cause unnecessary traffic jam.
- Normal life disruption.
How does an open drain output work on a microcontoller?
An open drain output is just an open-switch connected to 0V. To pass current through it you need to feed current into it and this can be done with a pull-up resistor. If you don’t pass current into the pin you will not be able to see a voltage: – Here are two devices sharing the same open-drain output – notice the pull-up resistor to +5V.
What happens when output is set to open drain?
If output port is set into open-drain mode then we don’t require any circuit to pull down the output value of the pin. The open-drain output configuration turns off all pull-ups and only drives the pull-down transistor of the port pin when the port latch contains logic “0”.
What does an open drain on an IC mean?
If you are working with an integrated circuit (IC) and the datasheet mentions an open drain or open collector, that’s engineering speak for a current sink on an output pin. For those unfamiliar with the terminology, a “current sink” means that the current is flowing into the pin (or node, etc.), not out of the pin.
What’s the difference between an open drain and an open collector?
The term “open drain” means there’s a current sink, but on a FET device, for example, a MOSFET. (A MOSFET is like a transistor that can handle higher voltages but operates in much the same way.) The term “open collector” refers to a current sink on a transistor output. If an NPN transistor is left unconnected, or open but connected