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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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2answers
112 views

Did I get this BJT configurations correct?

I'm trying to learn what kind of BJT transistors are this: Did I get them right?
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What is an open collector?

I am new to electronics, and I'm reading a book on embedded systems and bumped into an "Open Collector". I know that a transistor has a base, which acts like a switch for the current to flow from ...
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Adapting the 74LS170 open-collector “register file” to active-high TTL input

This is a question related to swapping a 74LS170 4 x 4 register file chip for a 74LS173 single 4-bit register. In the other question I wonder if there are even simpler ways to Turn a positive clock ...
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Connecting unused input 74LS07 gate

This is open collector gate. I can not find the amount of the leakage current through the input. Also not clear what output configuration must be to minimize current: leaving it floating - then with ...
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78 views

PNP Open Collector output series resistor

I have the following circuit to drive a logical output (the input is driven by an MCU): The issue I have is that because of R4, when I want to draw a few mA from the output, the voltage drops. Right ...
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99 views

Open Collector to drive PNP without Pull-Up

I need to generate a current signal between 12V and GND, which has to have galvanic isolation. For this, I want to use an optocoupler. Maximum permittable rise / fall time: < 1µs Output side Vcc: ...
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85 views

Why is open collector output is called high impedance and what determines the upper limit of the pull-up resistor?

Is calling open collector output as high impedance due to the value of pull up resistor or due to the fact that the IC itself do not source any current? And what determines the upper limit value of ...
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1answer
79 views

IR2110 - Open Collector Output Problem

I'm trying to design an inverter and I'm using 2 IR2110 as gate drivers but my MCU board PWM outputs are open collector, I've added a pull-up and transistor to feed IR2110 with 5V pulses but it's not ...
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146 views

ULN 2003 open collector

I have searched for troubleshooting the ULN and did not find any solution. I use a ULN chip in a motor inverter for controlling precharge relay and main relay. The problem is when the motor inverter ...
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3answers
150 views

Are activated open-collector and open-drain circuits wasting energy?

Consider the following reference circuit for a 6N137 optocoupler. My understanding is that this circuit uses a pull-up resistor on the output node so when the optocoupler led is activated, the ...
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1answer
171 views

Identify this open collector serial protcol

I'm trying to analyze the serial link between two devices, respectively a motor controller board and a Li-Po battery manager, which battery powers both devices. The application is a battery-powered ...
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493 views

connecting Open drain and Push pull outputs to drive the same pin

I am designing a circuit in which has a voltage supervisor (MCP121-33)with active low output nRST connected to RESET input of the microcontroller which is straightforward. Also, there is a another ...
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52 views

LP311 collector remains at ~11V when “low”

Okay, I'm trying to monitor current going to a device, and in case current is drawn, light a led and provide a low signal (<5V) to a microcontroller. The current goes through a half-ohm resistor ...
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1answer
264 views

Connect two different sources with two Digital Ouptuts using an Adam 4055

I would like to operate an Adam 4055 module to control two different applications having their own power supply. Adam 4055 is Digital Input/Output control module over RS-485, I use only the DO part ...
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1answer
118 views

prox sensor with NPN open collector output or a dry contact

I am totally new in this field. I want to use a 5 V / TTL signal from a National Instrument to switch on/off a Red lion PXU series temperature controller. But this controller required a dry contact ...
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1answer
275 views

How connect a open collector output to led and to GPIO?

I want to use this Single Cell Li-Ion Solar Battery Charger (BQ24210). The pins /CHG and /PG are an open collector outputs and it will be connected to two low power LEDs as shown in the schematic. If ...
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239 views

Using open collector output from fan sensor to opto-isolator for MCU GPIO

I have a cooling system that uses an external temperature sensor to turn on two HDF4020L-12HHB 12VDC fans and I need to use the locked rotor sensor outputs from the fans as inputs to a MCU (5V logic) ...
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1answer
91 views

Is this optocoupler-based circuit design reliable?

Hello, I have designed this optocoupler interface to an stepper driver. However, I'm not sure if it's all right. For R1 I made (5-3.3)/10mA ≈ 180 ohms. 3.3V taking into account the two leds voltage ...
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1answer
1k views

May I connect two open collector outputs in parallel

May I connect two open collectors like this in parallel? simulate this circuit – Schematic created using CircuitLab
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738 views

Using Raspberry Pi to read open collector outputs from tally connector

Please forgive my ignorance, I'm a software programmer who is new to the electrical and hardware side. Our Panasonic HS300G video switcher has a Tally connector. Below is the pin diagram and circuit ...
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91 views

Confusion with the reasons collector area being greater than the emitter region

Often I come up with the following reasoning when it comes to why collector has larger area than the emitter: For less power dissipation collector area should be more. In other words, when area ...
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2answers
1k views

How can I interface a Raspberry PI GPIO to an open collector circuit to send / receive data?

I have a GPIO from a Raspberry PI connected to a Nintendo 64 system like so: From what I've gathered and observed, the data line on the N64 system is an open-collector output. The line is tied high ...
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1answer
344 views

How does the Nintendo 64 detect a controller is connected?

To give some context, I am trying to emulate controller input to the N64 via a GPIO pin on the Raspberry PI. In an attempt to accomplish this, I have one of the PI's GPIO's in a pull-up configuration ...
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3answers
1k views

Open Drain Serial TX output on Arduino

I have been trying to implement an open drain Serial output using a Arduino Nano. In the following example I have used 2 Arduino Nanos (both operating at 5V Vcc), using one Arduino as the transmitter ...
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1answer
530 views

Why is there no open-collector OR-gate in the 7400 series? [closed]

I searched in the "List of 7400 series integrated circuits" on Wikipedia for a open-collector OR-gate, but couldn't find any. The list looks complete, so I assume there is no such chip in the 7400 ...
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757 views

Open-collector comparator with hysteresis and LED indicator at output

I am trying to choose the correct resistor values to make Vout go high when Vbatt falls below 18V and go low when Vbatt rises above 20V. I've built the actual circuit and my measured values are 18.0V ...
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2k views

Why do I2C lines use open drain driver instead of tri-state drivers?

My understanding is that I2C lines use pull-up resistors to passively pull up the bus to logic high because the drivers used on the bus are active drivers, namely open collector/open-drain. Since open ...
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2answers
503 views

Impedance matching open collector output

I am designing a circuit that will receive a 20 MHz square wave (LVDS), convert the LVDS to single ended, and drive a 75 Ohm line. I've found some 75 Ohm drivers from TI, but the applications ...
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1answer
548 views

Voltage protection of PNP Open-Collector Pull-Down Resistor Circuit

Circuit Consider the following U-Shaped Micro Photoelectric Sensor Panasonic PM-T54P with two PNP Open-Collector Transistor outputs: I chose the supply voltage to be 12V DC. In the place of the two ...
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3answers
2k views

Open Collector/Drain vs Push pull

Given the situation where an LED is being used for a status indicator or similar, not toggling quickly. Which is the best configuration for the IO pin, push pull or open drain? As I see it either ...
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3answers
411 views

Understanding Proper Implementation Of Open-Collector

I am confused about the implementation of an open-collector circuit. From what I've read, there are many ways to incorrectly wire up an open-collector circuit. Before I explain my confusion, let me ...
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1answer
153 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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750 views

Optoisolator With LED in series not working

I'm using an FODM8061 Optoisoltor with and open collector Logic Output. I'm referencOptoisolator Logic Output Question Here's my current circuit: LED 1(on the left) connects to an open-collector ...
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3k views

Totem pole vs open collector configuration

Can anyone please explain for power consumption view point only whether totem pole or open collector should be preferred with a bit explanation?
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85 views

Which side of SPI link harness to locate SDO pull-up?

I'm looking for some help/insight into a decision I am making about whether to change a circuit I have built. My slave device requires a pull-up on its SDO (MISO) pin which is open collector. When ...
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1answer
1k views

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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438 views

Open Collector Comparator for Voltage Glitch Detection

I recently ran a round of PCBs which included an experimental circuit to detect short glitches in my input voltages. I attached the schematic for reference: The intent is that C29, in parallel with ...
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3answers
916 views

Interfacing open-collector optoisolator to 3.3V microcontroller

I have a bit of a puzzle on my hands trying to interface a Fairchild MID400 optoisolator (popular "logic level" optoisolator for mains detection) to a 3.3V GPIO pin. The MID400 is a 5V part [*] and ...
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2k views

Adding Low Pass Filter to Open Collector Hall Sensor

I'm using a gear tooth sensor to create pulses when a metal object passes the sensor. There's a lot of noise on the signal so I decided a simple low pass filter would suffice(f-cutoff = appx.400hz). ...
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4answers
1k views

Input pins hardware interface uC

I am trying to figure out how to interface a A2235-H GPS module. The datasheet says that one pin(nRST) must be connected to open collector or open drain output of uC while an other one(ON_OFF) must ...
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2answers
368 views

Open collector with Atmega48

After looking at this, I think I already know the answer, but I just wanted some clarification. Open collector microcontroller output I have a part that is going to drive my mosfet at 15V. I have ...
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1answer
119 views

Open collector to high-z

Keeping it completely analog, is there a way to high-z an open collector output? An open collector always allows a path to or from a specific voltage potential and this is complicating a rather simple ...
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825 views

Open-collector current measurement

I have come across a gate driver circuit (proprietary) that measures open-collector current and sets a flag if the current exceeds a threshold (say 20 mA) to protect the NPN transistor. This is the "...
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1answer
84 views

How to handle Digital Input Interface

Below in right side there is an discrete output signal circuit implementation and as a platform i need to read this signal somehow. I have a discrete input interface. My question is how can use my ...
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97 views

What is the output type of the sn74lvc1g04?

It doesn't seem to clearly say totem-pole, open-collector, open-drain, etc. I wanted to place a pull-up at the output to guarantee a default state, but I feel like this is a bad decision. datasheet
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1k views

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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960 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 ...
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1answer
650 views

How does an open-collector gate work by using resistors?

I understand that that the purpose is to drive multiple signals to a wire bi-directionally. The two logic states are either 0 or flow (high-impedance). However, how do resistors come into play for the ...
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1answer
8k views

What's the difference between a 74LS05 hex inverter and a 74LS04 hex inverter?

It looks like the 74LS05 has "open collector outputs" (not sure what that is) and the 04 does not. Plus, it appears the ...
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707 views

Handling Open/Ground Input

I have an open collector output interfaced board using that how should I control an input of another equipment with below characteristics: 0 Ground 1 Open Thanks.