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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Why do they usually make comparators open collector?

I never see open collector opamps while I frequently see open collector comparators. What is reason for preferring open collector output in comparators? (Inside of LM193.)
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Why does the I2C interface use the open-collector/open-drain?

The open-collector adds inconveniences like requiring an external pull-up resistor and slows down the throughput. Why did the I2C designers choose to use open-collector/open-drain?
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Open Collector Circuit Needs Pull-Up Resistor to Measure Frequency?

I need a little help determining what I need in order to measure frequency from an Encoder containing the attached Open Collector Output. The 5 Volts will actually be 24 Volts in my scenario (this is ...
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1answer
148 views

Correctly Configuring and Using DAQ Device Digital TTL I/O

I am using a National Instruments USB-6000 DAQ to control some equipment that accepts TTL inputs. Specifically, I have to pull a pin (normally 5V) to low. As I understand it, to do this, I can use my ...
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4answers
843 views

Open collector microcontroller output

I am building the following circuit, in order to control the P channel MOSFET as a high side switch for my load. The input of this circuit will be from a microcontroller (maybe an STM32F103), and I ...