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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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 using LM70880-Q1 buck.
There is power good pin is available. I want to make use of this pin. It is a open collector output that goes low if the Vout is ...
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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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Why should an open drain/collector comparator go low when pull up is not connected if it is essentially a floating node?
As we know the open drain/collector output stage of a comparator looks something like this:
This is essentially a high impendance floating node. If we fail to connect pull up, the output does not go ...
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Pulling 5 V signal line down to 0.5 V
I want to pull a 5 V signal line down to 0.5 V via an open-collector NPN BJT.
I intend to implement a simple voltage divider by using a resistor between emitter and ground. The base is driven by a 5 V ...
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Open collector circuit input to logic gate
I'm designing a simple circuit where I intercept and read an open collector pulse signal from an external machine and let it pass through to an optocoupler. In addition to that, I can also output a ...
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Open Collector config ULN2003
Are open collector configurations like those found in ULN2003 always in saturation (when Sufficient Base voltage is applied)? Can they never go into the active region?
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