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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open-drain reliability problems

I've built a run of simple boards like the one shown below to control LEDs in automobiles. The boards have twenty of the NX3008 mosfets in an open-drain configuration as shown, which are controlled by ...
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0answers
19 views

NMOS open drain output vs PMOS open drain output

I'm reading HT1632C LED driver datasheet and it has on the first page in the features section: Selectable NMOS open drain output driver and PMOS open drain output driver for commons Does it ...
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1answer
73 views

Very odd open-drain output design

I ran across a open-drain design and am baffled by the resistor between the nFET source and ground. There are only two purposes that I see it could serve. 1) It's series source termination, matching ...
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0answers
39 views

Why are pullups needed on eMMC data lines?

The JEDEC spec for eMMC shows pullups on both CMD and DAT lines. The pullup for the CMD line is obviously necessary as it sometimes operates in open drain mode, this necessity is represented by Rod ...
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2answers
45 views

Can I use an open-drain NXP 74LVC07A output as level translator for an 8V CMOS input?

I'm designing circuitry that uses an NXP 74HC4051 analog mux with a +8V supply. An MCU with 3.3V GPIOs needs to control the mux S0-S2 selection inputs. I am wondering whether an NXP 74LVC07A, powered ...
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1answer
33 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.
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3answers
68 views

How does open drain io act as bidirectional

Could someone explain how open drain io acts as bidirectional. Whether it is actually bidirectional or it can act only as input or output at a time.
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1answer
93 views

Connecting Open-Drain inputs or outputs together with one resistor

I had a couple of quick questions. I am designing a board using 10 IO expanders which I'll use as inputs. Each has an !INT pin which is open drain and pulled high to 5v through a resistor. Can I ...
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4answers
118 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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3answers
86 views

How does this voltage detector IC work in a circuit? What does open drain vs. CMOS output mean?

I'm evaluating the Rohm BD48/BD49 series voltage detector. I'm having trouble understanding the data sheet. I want to generate a high signal when the input voltage is above a desired threshold (3.0 ...
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3answers
148 views

Diode Drop vs Open Drain Output Tolerance

I have an LED Driver IC that states a 5.5V tolerant Open Drain Output. It's Absolute Maximum section indicates 6.5V with a note saying "The input negative-voltage and output voltage ratings may be ...
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0answers
160 views

Voltage Sag with PIC24 PWM Open-Drain Configuration

I'm experiencing some major voltage sag with an open-drain PWM output into an RC servo. I'm pulling up to +5V with an external pull-up resistor. I've tried using everything from a 1k-100kOhm resistor, ...
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2answers
245 views

STM32F3 Discovery 5V output

I want to use a STM32F3 GPIO (3.6V) to drive another device using 5V input. Which is the correct way to do so? I know that is possible to use the open drain mode on the GPIO, but I'm not sure if I ...
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1answer
202 views

PIC24 Open-Drain Config for 5V PWM Operation

I'm running a PIC24HJ series processor with a supply voltage of 3.3V. I need my PWM signal to be 0-5V, not 0-3.3V. Can I simply connect the PWM line to a 5V supply with a pull-up resistor? Or do I ...
2
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1answer
139 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?
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2answers
213 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
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3answers
3k 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 ...
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2answers
217 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 ...
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2answers
660 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 ...
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1answer
531 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 ...
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3answers
673 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
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1answer
227 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 ...
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2answers
611 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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1answer
4k 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 ...