Tagged Questions

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 ...

learn more… | top users | synonyms

0
votes
1answer
141 views

How to replace bulb with LED in a PWM circuit (car)?

I want to replace a light bulb in a Peugeot 308 SW with a LED. The bulb works (lights) normally, but the LED blinks. I thought they are controlling the bulb in alternative current but my digital ...
2
votes
4answers
141 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.)
2
votes
4answers
421 views

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 ...
1
vote
2answers
89 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 ...
0
votes
1answer
84 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 ...
1
vote
2answers
463 views

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 ...
1
vote
2answers
180 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 ...
1
vote
1answer
304 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
votes
2answers
104 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: ...
1
vote
2answers
775 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 ...
7
votes
1answer
453 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 ...
0
votes
3answers
588 views

Fast opto-isolation with open collector output without VCC

I have a two wire communication channel, with a data line and a ground line, with the data line being pulled high via a resistor on the receiving end. I am supposed to send information on this line by ...
2
votes
1answer
327 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 ...
1
vote
2answers
464 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 ...
4
votes
4answers
626 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 ...
2
votes
2answers
2k 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 ...
8
votes
1answer
2k 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 ...