Questions tagged [open-collector]
An open collector is a common type of output found on many integrated circuits (IC).Instead of outputting a signal of a specific voltage or current, the output signal is applied to the base of an internal NPN transistor whose collector is externalized (open) on a pin of the IC. The emitter of the transistor is connected internally to the ground pin. If the output device is a MOSFET the output is called open drain and it functions in a similar way.
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Digital output (open collector)
I have a controller with a digital output configured as open collector. The wiring diagram in the manual is shown in the image below. The manual indicates that the diagram is internal (if I'm ...
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Why is the output on ULN2803 0V when the input is LOW?
i have the next circuit:
The purpose is to drive a seven segment display using a pic16f877A and ULN2803 for driving power
I have read the datasheet and shows the next diagram for this IC:
So i know ...
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How to use a negative voltage to switch betwen positive voltage and ground
Basically the title, I want the output to be a positive voltage when the control voltage is negative and the output should either be ground or open when there is no control signal (it is left floating)...
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Constant volatge at the output of LM311
I made a PCB based on the following schematic.
The inputs of the comparator work as expected (i.e., the capacitor voltage or the voltage at the non-inverting pin gradually increases and, after a few ...
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Transistor switching speed
I want to be able to identify the speed of a transistor in terms of switching. Most datasheets don't indicate that but I found this transistor from ST-Electronics. Is it the maximum switching ...
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What types of outputs apart from Open Drain/Open Collector exist?
I am trying to grasp the idea of an Open Circuit/Open Drain, but I haven't been able to find, which other types of outputs exist ("Closed Circuits", so to speak). It would be helpful, if you ...
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Watching an open-collector input without disturbing it
I'm trying to control an opto-isolator (actually a photorelay such as a TLP354x but it doesn't really matter here).
The problem lie in an external device (black magic box) which is also controlled by ...
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How to calculate pull up resistor for Power Good Pin?
I am learning to design buck converter, and I'm using a LM70880-Q1 buck.
There is power good pin available and I want to make use of this pin. It is an open collector output that goes low if the Vout ...
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How can I make a non-inverting open-collector (or open drain) with a single transistor?
I had a PCB made for a homebrew SBC but while waiting for the boards I discovered a bug. I have a 74HC138 output (I believe this is just normal push-pull) that I need to hook up to a CPU pin but I ...
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Why don't we use decoupling capacitors for open-drain outputs?
If an IC with open-drain outputs (and hence pull-up resistors) is used, we of course put decoupling capacitors on the IC supply, but why don't we also add decoupling capacitors between the power pin ...
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7407 functional schematic question
I was trying to understand the role of the left-most transistor.
... as illustrated in the datasheet:
SNx407 and SNx417 Hex Buffers and Drivers With Open-Collector High-Voltage Outputs
If there is a '...
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Thoroughly confused about open drain
I've been reading a tutorial on open drain and I'm thoroughly confused.
First, the terminology makes little sense. How can a resistor pull up or pull down current when its job is to resist current? ...
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Can I drive a relay with a PCF8575?
I would like to drive a relay using a PCF8575, which has "quasi-bidirectional input/output (I/O)" ports. If I understood properly, they are open-drain ports. Is this diagram OK? Do I need ...
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Best way to use Driveay alert output (Open Collector NPN)
I'm learning as I go on this project.
I have a beam-break driveway alert that I would like to get the output from on a device like an Arduino or Raspberry Pi and need some guidance on the best ...
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Control WS2812x from open collector output
I have a board with digital output that is based on open collector Darlington driver (providing up to 500mA) and I want to use that output to control WS2812x LED strip.
What should the circuit look ...
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