Questions tagged [open-drain]
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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Can a voltage divider be used to safely lower pull-up voltage?
I'm working with an LTC2950 pushbutton on/off chip that's meant to toggle the enable pins of voltage regulators based presses from a momentary pushbutton. The LTC's enable pin is open drain and is ...
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Thermal analysis of a step down regulator
LTM8053 datasheet
I tried to plot the thermal graphic (watt-celcius) for this buck converter in MATLAB. The main goal is to find losses which turn into heat. Reasons for heat most of time switching ...
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How to multiplex open drain sensors
I have 64 digital hall effect sensors with open drain outputs (A3144), and would like to read their outputs with an MCU. Is there a simple way to multiplex these sensors to limit the number of IOs ...
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Type of output of this AND Gate
I am unable to find whether the output of this IC is a push-pull output or an open drain output.
I didn't notice either words in the datasheet. Hence, can someone help me to tell which output type is ...
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Why should an open drain/collector comparator go low when pull up is not connected if it is essentially a floating node?
As we know the open drain/collector output stage of a comparator looks something like this:
This is essentially a high impendance floating node. If we fail to connect pull up, the output does not go ...
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Calculation of pull-up resistor for open-drain output - multiple loads
Link to voltage supervisor
Link to AND gate
I would like to drive an open-drain output to multiple (5) loads, all of the same type.
I calculated the pull-up resistor range needed and wanted to double ...
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Open-drain Input mode
I have a GPIO expander (namely the MAX7317+ from Maxim Intergrated).
The I/O is open-drain.
I want to configure these I/O as Input mode.
Can I just connect them directly to my switch like this so that ...
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Common-output WS2812 LED strip alternative control
I try to build an RPi controlled LED strip, however, while the Linux is booting, I still want a minimal effect on the LED strip. So my idea is that once the device gets voltage, a cheap ...
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88
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Can I/O pins on a PLD (e.g. ATF16V8B) be configured to act as an open-drain output that is usable in a wired-OR circuit?
I designed a peripheral card for an 8-bit home computer which uses an ATF16V8B for address decoding and glue logic.
I want this card to be able to generate interrupt requests by driving the system's /...
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How to use an open drain signal to power a relay/MOSFET package?
I have a controller with a particular signal output (open drain, which I believe provides a ground when activated?) with an internal circuit breaker limiting to 175 mA that I want to use to drive a ...
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Open drain output with parasitic indicator LED
I'm designing a "minimal parts / as simple as possible" open drain NOR gate (also known as 2 N-MOSFETs and a wire), but I'd like it to have an output state LED.
I was thinking of having ...
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Converting Open-Drain to Active-Low
My question is very similar to Converting Open-Drain to Active-High, however instead of an active high, I want an active low.
I am trying to interface TI BQ51050B (QI receiver + LiPo Charger) and TI ...
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247
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Calculating hysteresis with an open drain comparator
I have a circuit as follows which will compare an input voltage to a 2.5 V (actually 2.3 V) reference. In one of the documents, it mentions that the feedback resistor must be 100 × Rpullup. If my ...
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Using an open drain buffer as a logic level step down converter
I'm trying to convert a 3V3 UART to 1V8 UART with an open drain buffer, but the output of the buffer is always high.
See the schematic below for the circuit. On the input to the buffer, there is a 0V -...
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Can the 74LVC06A input be connected to an open-drain output?
The picture above is the SN74LS06 schematic from Texas Instruments. It appears that the input of the SN74LS06 can be connected to an open-drain output.
I purchased the 74LVC06APW from Nexperia. But I ...
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Connecting Led to push-pull instead of open-drain
I am using the PCA10056 Nordic dev board which integrate a nRF52840.
The following LEDs are wired to some of the MCU GPIOs.
Currently, my MCU firmware configures those GPIOs as Push-pull output.
But I ...
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383
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Open-drain output using N-channel MOSFET in addition to pull-up resistor
I'm trying to understand a design in an evaluation board and I need some assistance.
In the above schematic, the PG output pin is open-drain so it requires a pull-...
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How many loads can I have on an open drain output?
So I am using this AND gate which has an open drain output. I am trying to determine how many loads that I can place on this output.
I see in the datasheet, that the Iol is over 1mA, but I am unsure ...
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Difference between open drain and push-pull modes
The figures show diagrams of line signals: the first in the open-drain + pull up mode, the second push-pull + pull-down.
There are several questions:
Why does a push pull output have a faster slope ...
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169
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Is a pull-up on open drain required when output is not used?
On a LTC3886-1 I can read this:
I see that all open-drain outputs are tied to VDD on the following application schematics:
Is there a reason why pull-ups seem required when the output is not used?
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What is meant by "monotonic reset"?
Can someone tell me what does it mean by Monotonic Reset? I read this below paragraph from this document and got this doubt.
A reset generator / voltage monitor is one option to provide a proper ...
user220456
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How many times larger should the gate resistors be than the drain resistor?
I was asked this question in class and could not come to a concise answer. This is question was asked in terms of MOSFET design. Are there any general rules or guidelines to follow?
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Can I connect a pull-up to a open drain output with current source ? Using LTC4124 charge controller
On the LTC4124 there is a CHRG pin connected to an LED. Datasheet says it is a open drain but indicates a current source between source and ground. Could I use a pull up resistor connected to VCC and ...
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MOSFET parasitic capacitance (Cds) behavior when the source is floating (open)?
I recently looked into an interesting circuit designed by some other guys 6 years ago.
The I2C SCL/SDA looks weird.
The SDA is an open drain output but somehow it was designed this way, connected to a ...
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Can I connect the pull-up resistors of I2C lines to 3.3 V on a 1.8 V device?
I need to use the following sensor in my project : AS7341 (ams). It is a spectrometer whose data are accessed through an I2C inteface. The datasheet can be found here.
It is stated that its power ...
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Power Consumption for Open Drain Communication
When using an open drain communication scheme, like I2C, it seems that the majority of power consumption comes from the sinking of current through the pull up resistor when a logic 0 is transmitted.
...
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235
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Expected behaviour of a non-inverting buffer IC
I am using an NL17SZ07 buffer w/ open drain. Is it to be expected that I need to pull the output high with a pull-up resistor to have the output behave as expected?
I would have anticipated that the ...
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On what factors does the I2C pull up resistor values depend upon
I was reading this Article regarding the pull up resistor calculation.
I understood that the value of the pull up resistors depend upon the currents, the supply voltage and the Logic Level voltages ...
user220456
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Can I leave an unused open-drain output disconnected?
I'm designing a circuit using the MAX22203 motor driver and it has a few open drain outputs to indicate current throttling. In my design I don't need to read these outputs, so my question is what ...
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763
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Using a series diode to protect input with pull-up resistor
I have a switch input that I need to protect from miswiring to 12V battery power, reverse wiring to power, ESD and transients.
I tried using a Zener diode circuit to handle the overvoltage:
Steering ...
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857
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How do open-drain I/O pins work on a PIC16 microcontroller?
I'm trying to understand how to operate an open-drain I/O port on an older PIC (PIC16F1718.) My goal is to use it for bit-banged bidirectional open-drain I2C communication.
I know how to enable and ...
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How to wire two open-drain logic outputs to a three pin bi-color LED
I am very new to working with electronics; my main experience is in programming. I am working on a project and intend to use this MCP73833/4 Li-Ion Charger. It has two "Charge Status Output" ...
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Confused about pull-up resistor
I'm a software guy trying to implement a 1-wire interface. I have modified a USB-to-UART device as indicated here, but I don't understand the "pull up" resistor concept. Googling "open-...
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How to drive an open drain/collector?
I'm connecting a Digi XBee radio to a Kinetis microcontroller and would like to know how to control reset. The XBee datasheet describes the reset pin 5 as both input and open drain output:
...
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Why have resistors on a signal line
I'm new to electronics so forgive me if this is an obvious question.
I'm making a small circuit to read out a digimatic caliper. There are many designs only and I'm wondering why some components are ...
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Why are open-drain outputs needed?
I have almost no knowledge in electronics and electricity. I've encountered the concept of open-drain output recently and I think I got the idea.
What I have understood is that it is a transistor ...
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What to do with unused open drain pins
I have a light sensor IC.
I have 2 questions:
The I2C Lines is connected between the microcontroller (3.3V domain) and the light sensor IC. The microcontroller is placed on a PCB and the light sensor ...
user220456
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STM32L1 GPIO pin configuration - Power supply current increase due to pin with open-drain setup
Setup
I have an STM32L151 mcu(application processor) and on its PB5 pin I have a peripheral (SARA-N3) connected. The requirements for the peripheral are that the pin is configured as an open drain ...
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Why do we need NMOS transistors for NAND gate?
I have a hard time understanding how gates are built from CMOS transistors. For example, I don't understand why do we need the NMOS transistors if the PMOS transistors will already produce the desired ...
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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 ...
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Trying to understand push-pull output mode and open-drain output mode in a MCU's GPIO pin
I have a MCU (STM32H7xx) whose GPIOs, when configured as output, can be configured either as open-drain or push-pull. Before seeing this, I though that open-drain meant hihg-Z, however I don't see how ...
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Understanding ECU Lowside Output Circuit
Hello StackExchange,
I'm trying to understand this low side output circuit so that I can interface it with a load.
I will have to add another MOSFET/Relay/Driver of some description on the lowside ...
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TLC5940 resets itself when driving certain DC motors
So I had the following setup:
I was just driving a small DC motor with this circuit by either sinking current on pin 0 or 1 on the TLC with a motor voltage of 5 volts and everything was fine. The ...
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Serial Communication with HV5623
I'm just trying to understand the communication protocol with the HV5623. Here is the Function table:
I want to be able to hold the HV output while I shift in the new states into the shift register, ...
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what will happen when providing two pull up resistors in same line
If two pull ups given in a situation one pull is 4.7 K-ohm and other pull up is 10 k-ohm was given to open-drain pin then what will happen? Imagine the open-drain was connecting to an IO pin of an ...
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192
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Understanding Master/Slave trigger configuration through open-drain GPIO
I am working with two industrial cameras that I want to trigger synchroniously through hardware triggering. For this the STROBE_OUT pin (which is an open drain pin) from one camera (Master camera) ...
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464
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Can several Ethernet PHYs cause damage to one another if they transmit on MDIO bus simultaneously?
I have 4 ethernet devices (1 PHY - AR8035; and 3 Dual PHYs - DP83849IFVS) on my custom PCB board. ICs are controlled by SoC AM335x via MDIO bus. Previous revisions of the board worked fine. New ...
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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 ...
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Question about open drain
In which region does a NMOS work when its drain is open circuit? Let's say the input is high voltage lavel, how can I determine whether it is saturation of triode region when drain is open?
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Why do they keep series resistor with each open drain output during Wired OR logic?
In a design schematic I have seen series resistors being used in WIRED OR logic.
All 4 input signals are open-drain signals and hence being represented as switches. Can anyone explain why we need R1-...
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