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.

Filter by
Sorted by
Tagged with
1
vote
1answer
296 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 ...
5
votes
6answers
1k views

Difference between no input and a zero input in digital electronics

I'm new to digital electronics and try to understand how logic gates works. In books many times Zeroes​ and ones are referred as Low and High respectively, is Low and High used as an indication of ...
0
votes
2answers
51 views

Minimizing pulled open collector output rise time on 74LS09

I have a circuit that calls for one open collector buffer for driving a shared line (/WAIT via Zilog Z80) and one typical AND gate. I've consolidated these into a single 74LS09 open collector quad 2-...
5
votes
4answers
1k views

Why are the outputs of these gates tied together in the Apollo Guidance Computer?

In looking at the AGC schematics, I'm finding a lot of instances where the outputs of some of the NOR gates are tied together when feeding into another gate. The most dramatic example being here, ...
0
votes
2answers
129 views

Open-Collector to Push-Pull

In a project I am using a 74LS05 to provide an ESP32 microcontroller with 6 open-collector outputs. Actually this is fine for 5 of the outputs, but for the remaining one I'd rather have a full push-...
1
vote
1answer
106 views

Purpose of base-collector resistor in open-collector opto-isolated GPIO output

I've been working with an opto-isolated output for a high-speed camera I'm interfacing with and was a little puzzled by the circuit they were using for an opto-isolated open collector output. As far ...
3
votes
2answers
240 views

When using an open-drain output to drive an NPN transistor, can the base resistor be replaced by a pull-up?

Assuming the value of R1 is the correct value for the base resistor for the given motor L1, is it okay to omit the additional base resistor, used in push-pull applications, for an open-collector ...
1
vote
1answer
61 views

Define the purpose of these components in the operation of this low side driver

I am trying to understand the operation of the following low side driver circuit I found in a schematic of an old pinball machine (redrawn for clarity): L1 is a Solenoid and Q1 is a Darlington BJT (...
0
votes
2answers
58 views

Can this be done with the TLP2368 optocoupler (open collector)? (Toshiba)

I have tried to write to Toshiba technical service, but no one responds. I have the layout of this optocoupler (TLP2368). According to the datasheets, the VCC voltage to GND is a maximum of 6V, so I ...
1
vote
0answers
67 views

Open Collector Output connection to a relay

Hey sorry if this question is too simple, as i am not an expert in this. I have a device ( industrial router, works at 0- 30vdc) which has a Galvanically isolated Open collector ( External 0-30 VDC, 0....
1
vote
1answer
55 views

Does the 74LS09 have an adequate internal input pullup?

I want to feed an output of the 74LS05 open collector inverter into one of the inputs of the 74LS09 AND gate. The internal schematics in the datasheet shows that there is an internal resistor and 2 ...
3
votes
4answers
761 views

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 ...
1
vote
2answers
291 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 ...
0
votes
3answers
88 views

Connection of two open drain outputs to control common LEDs by PIC32MZ

I want to use this Single Cell Li-Ion Battery Charger (MCP73833). The pins STAT1 STAT2 and /PG are an open collector outputs and it will be connected to low power LEDs as shown in the schematic. If I ...
0
votes
1answer
86 views

How to drive pin to open drain/collector?

I'm looking at a datasheet for a bit of hardware I am adding to a design. However, one of the pins on the chip is listed as: ON/OFF - 1.8V must be driven to open drain/collector It does not specify ...
0
votes
1answer
89 views

Help understanding open collector comparator

I am working on a simple circuit based on the LM311 comparator. It has an open collector, which is not something that I've used before, and I have a few questions. First, my understanding of the open ...
0
votes
1answer
107 views

Explanation for parallel darlington behavior

I've built and simulated the circuit below in real life, LTSpice and Stack-Echange-Spice. It behaves in a similar fashion in all of these Environments. When the "LAMP2" load is disconnected, the Base ...
1
vote
1answer
124 views

What is the purpose of this schottky diode reversed across the BJT base resistor?

In a design for the popular "gotek" floppy drive emulator, as per the standard, the outputs from the floppy emulator are open-collector. An STM32 is used as the processor. This drives a 74HC04, which ...
2
votes
1answer
61 views

Help on translating 5V rotary signal output to interface with lathe's cnc controller!

I have a hall sensor (OH137 - open collector) as an index signal on my lathe’s spindle. I have the sensor pulled high by a 1k resistor and can’t change it because they’re both glued in epoxy. This ...
0
votes
0answers
37 views

5 wire, Logic Output Photointerupter/Slotted Optical Switch

I am trying to get a digital output from a 5 wire photointerupter. The p/n is OPB903w55z, it is configured as an inverted open collector. I have used 4 terminal transistor output photointerupters ...
0
votes
1answer
238 views

Open collector and open drain logical gates

Can somebody explain what open collector and open drain mean? I'm a CS student, and I'm really a newbie in terms of electronics and I only managed to find some "expert level" explanations, which I ...
1
vote
1answer
96 views

Open collector / drain question

I'm trying to to find the best way to force an inverting amplifier to postive saturation with a gate input, but otherwise leave the function of the op-amp intact. I've come up with a few ways to do ...
0
votes
1answer
76 views

Simplest way to short two leads with GPIO

I have a piece of hardware that has an open collector GPIO as shown below: I'd like to have use the open-collector output to short two floating wires together -- they're essentially two leads from a ...
0
votes
1answer
937 views

Proper use of open collector to switch an output

I'm working with a pre-existing piece of consumer hardware that has an open collector GPIO output, as shown below: The Open Collector is able to source up to 100 mA. I'd like to switch a relay (a ...
0
votes
1answer
125 views

MCU PIN Open Drain Protection

I am trying to control a PC fan using a micro-controller(STM32F0) According Intel's PWM fan spec, the fan will pull up the PWM signal to up to 5.25V. ...
0
votes
2answers
190 views

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 ...
0
votes
2answers
86 views

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 ...
0
votes
2answers
348 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 ...
0
votes
1answer
477 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: ...
0
votes
2answers
300 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 ...
0
votes
3answers
443 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 ...
4
votes
1answer
199 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 ...
0
votes
2answers
737 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
votes
2answers
79 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 ...
10
votes
1answer
390 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 ...
0
votes
1answer
157 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 ...
0
votes
1answer
467 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
votes
0answers
451 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) ...
4
votes
2answers
6k 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 ...
1
vote
1answer
132 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 ...
3
votes
1answer
2k 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
1
vote
3answers
1k 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 ...
1
vote
0answers
134 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 ...
1
vote
2answers
2k 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 ...
6
votes
1answer
539 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 ...
1
vote
3answers
2k 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 ...
1
vote
1answer
850 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 ...
0
votes
3answers
1k 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 ...
5
votes
6answers
3k 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 ...
0
votes
2answers
704 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 ...