Questions about Open-Drain devices and protocols. Open-Drain connections have two states, Open/Floating, or Drain to ground. Typically require Pullup resistors.

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2
votes
1answer
54 views

How to measure open-drain vs. hi-z with multimeter

I have an output pin configured to be either open-drain or hi-z. How can I use my multimeter to tell which mode it is in?
1
vote
2answers
101 views

Resistance values for open drain

I am trying to establish SPI connection between C8051F931 and SD card. One of the sample programs I have found contains the following comments. ...
2
votes
3answers
735 views

Open-drain microcontoller ports

I want to understand the concept of open-drain ports like port P0 of the 8051 microcontroller. Why do we need to connect pull up resistors to the port P0? I have basic knowledge of MOSFETs and other ...
0
votes
2answers
144 views

Can Transmission gates be used to implement 3 State Logic?

In my application i need to use a common line shared between two peripherals, i have to indicate to the devices whenever the bus is free or not, hence i can't have push-pull output where the output is ...
0
votes
2answers
333 views

Voltage level in an open drain bus (I2C)

I have a setup as seen in this image: The question is what will the voltage at the line on the left size (marked with [Volt ??] ) be when the open-drain logic is active? The goal is to have a logic ...
1
vote
1answer
299 views

Using Open drain to get +5V

I have a legacy board in my product that has 1 temperature input with 2 rtd temperature probes. Until the new boards are ready the manufacturer has used a relay already mounted on the board to switch ...
4
votes
3answers
312 views

DS1307-breakout-board

I want to build an RTC clock for the Raspberry Pi. Adafruit has a guide to accomplish this with Dallas DS1307. On the schematic they put a 2.2K resistor between VCC and SCL and do the same for VCC and ...
2
votes
1answer
172 views

PWM drivers of Shift registers that are not open drain?

I am need of a 16 channel PWM Serial based LED driver, or serial in – parallel out shiftregister. I had been looking at TLC5940 and TLC59025 respectively. But for my current set up the ouptuts ...
1
vote
2answers
357 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 ...
8
votes
1answer
1k 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 ...