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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16
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1answer
14k views

Open Drain vs Open Collector

Is there a practical difference between Open Drain and Open Collector outputs, or are the terms used interchangably? If they are indeed different, what are the contexts where each is advantageous? My ...
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1answer
256 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 ...
7
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1answer
821 views

Open collectors & 74LVC245

I am trying to interface a PS/2 keyboard to a MSP430 for a toy. The PS/2 keyboard runs off 5V, but the MSP430 microcontroller runs off 3.3V. So I have a 74LVC245 level shifter to convert between the ...
6
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1answer
334 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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4answers
7k views

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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2answers
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SPI and pullups. Is it ever used in open collector configuration

Is SPI ever wired as open collector in devices calling for the use of pullup resistors? Everything seems to point to it usually being totem pole but I wonder if there are exceptions. The only pullup ...
5
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6answers
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 ...
4
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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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4answers
3k views

Using an open-collector output from one IC to trigger a level change on the input pin of another IC?

So my problem is simple: I have an IC that provides an output pin to alert you when some condition is met. The output pin is open-collector, high-impedance when active. I want to monitor this output ...
4
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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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4answers
933 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
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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4answers
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Purpose of pullup resistor in BJT LED driver circuit

One answer to this question suggests the following circuit to drive a LED from an open collector output of a 74LS47: simulate this circuit – Schematic created using CircuitLab What is the ...
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3answers
889 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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2answers
4k views

Simulate tach signal of PWM fan

I have a power supply that uses a PWM fan with 4 wires. Wires: 12V (red), GND (black), PWM Control (brown), TACH Sig (white) The fan speed is controlled by the PWM control wire (brown). Fan speed is ...
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3answers
678 views

Is controlling a voltage regulator's EN/SHDN terminal directly by 3.3V microcontroller possible?

Let's take the LT1763. The datasheet says that "The SHDN pin can be driven either by 5V logic or open-collector logic with a pull-up resistor." On the other hand the chart "SHDN Pin Threshold Off-to-...
2
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2answers
8k views

difference between dry contact mode output and open collector output

We have a device which can work with dry contact input and a device which gives open collector output. Will it inter-operate? Is there any difference between dry contact mode output and open ...
2
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2answers
374 views

Question regarding 7402 IC

I want to create a SR latch using 7402 IC. I would like to read the output (i.e. Q value) from the IC using an ADAM-6066 which has the following specs for digital input: Wet contacts: Logic level 0: ...
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2answers
1k views

PIC18F2550 I2C Open Drain?

As far as I have read, the I2C pins are Open Drain or Open collector, but in the PIC18F2550 the datasheet doesnt say anything about those pins, and even says they are a digital output if you select ...
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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 ...
2
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1answer
3k views

Interfacing PS/2 Keyboard to 3.3V inputs

I have had wonderful success with my new Mojo FPGA, so I decided to try something more difficult, interfacing with a PS/2 keyboard, but I cannot get it to work. Of course, I took the proper ...
2
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1answer
1k views

Do you have to set the TRIS register when using open collector outputs on Microchip microcontrollers?

I'm using a dsPIC33FJ series microcontroller from Microchip. It has dedicated open-collector outputs/registers. I've read the documentation and it is extremely brief. Does setting the ODCx register ...
2
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2answers
430 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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2answers
366 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 ...
2
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1answer
936 views

Controlling 2 relays with 1 Open-Collector output

I had a board with open/collector output pins, and i need to control 2 relays syncronioulsy (open and close at the same time) with 1 open collector output. So how can make the connectıon from pin to ...
2
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1answer
229 views

How to control bi-directional logic line bypassing the open-collector stage?

The uBlox Leon G100 GSM modem has a bi-directional RESET_N line (active-low) that controls the reset of the modem but also indicates whether the modem is up or down (modem out MCU in). Because the ...
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3answers
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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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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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4answers
2k views

Wired-or open drain with open collector outputs

I have a comparator with open collector output (LM311) and a gate with open drain output (SN74LVC1G06). I want join these two outputs to make a wired-or, with a pull-up resistor tied to +3.3V. In a ...
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2answers
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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3answers
700 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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2answers
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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1answer
532 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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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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2answers
865 views

Using open collector as regular 5v output

I'm trying to use the following IC: SN74S289BJ so that the output is 5v when HIGH and ~0v when LOW, however I'm having problems due to the open collector nature of it, as I've written data to a ...
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1answer
90 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
81 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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2answers
279 views

Arduino + LS7407N to shift logic levels in serial communication

I'm trying to drive a device that uses 12-0V levels for serial communication. I decided to use LS7407N, a buffer with open-collector, so that I can use Arduino's TTL levels to send commands to the ...
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1answer
71 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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2answers
132 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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0answers
88 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
727 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 ...
0
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1answer
118 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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2answers
800 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 "...
0
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1answer
884 views

How to get the full Vcc output from comparator?

I am working on a circuit using a comparator for a school project, but in testing it is not acting as expected. Specifically, the output is not going all the way to the higher rail voltage attached ...
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3answers
133 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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2answers
474 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 ...
0
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2answers
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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1answer
263 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 ...
0
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1answer
512 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 ...