Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [pulldown]

A pull-down resistor brings a line down to a voltage (typically ground potential) when the line isn't being driven to a specific voltage. It prevents the line from "floating" with an unknown voltage on it.

A pull-down resistor brings a line down to a voltage (typically ground potential), while still allowing the line to be driven to a higher voltage.

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294 questions
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How is a "smart pull-down" implemented

Some devices have a smart pull-down resistor. It is active until the user drives the pin, and as soon as a threshold is reached, the pull-down is deactivated. How is this implemented, e.g. if I wanted to design a smart pull-down or pull-up for a…
trevor
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Pull Down resistors value for unused pin for MCU

According to the datasheet, it is preferred to have MCU's unused pins connected to GND. That's the only thing suggested in the datasheet. I think it would not be a wise decision to directly connect the unused pins to GND. I am planning to use a…
Z0iS
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Reduce current through a pull-down resistor when chip power is removed

For a battery-powered application, I'm trying to reduce the current draw of a chip when its voltage rail is removed. What is the current through the enable pin's pull-down resistor when the 5V USB-supplied rail is removed? In particular, I'm using…
EarthIsHome
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Pull-down resistors on 7447 input pins

I have a simple circuit with a 7447 chip driving a 7-segment LED. The 7447 input pins A=1, B=2, C=4, D=8 apparently float high as logic 1. Using momentary pushbutton switches, I short various combinations of the pins to ground, and I get the…
Carsten1
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Adjusting the drive strength of level-sensitive interrupt signal

In my current environment, the interrupt source comes from an FPGA on a daughter board and connects to a GPIO pin on an EVB: daughter board (interrupt output signal from SD controller)--> EVB(GPIO pin with interrupt enabled). The GPIO interrupt…
bruin
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Am I calculating a pull-down resistor correctly?

I'm working on a board with a MAX3221. I chose this device because you can disable the DOUT-RS232 output and the RIN-RS232 input which is very important, and critical, for my application. In order to achieve this, the MAX3221 /FORCEOFF input shall…
m4l490n
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Replace Switch to power AV Receiver

How to close a circuit using a 5V power signal? Essentially the goal is turn on an AV receiver, using the internal power ON/OFF switch, to activate using a 5V control signal. The receiver now uses a mechanical switch to bridge a signal wire to…
Michael Reno
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Why is pull down resistor path of least resistance for the "floating" noise?

This question often pops up from people learning about pull up/pull down resistors. Why people ask it, is easy to see, it is a logical question to ask. If the pull-down resistor is bypassed at logic high voltage, because it is not the path of least…
LearningBasicComputerScience
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