Picking Pull-Up Resistor Values | AO #25

Common question that comes up about pull-up resistors: what value do you pick and why not just use a piece of wire? In this follow-up electronics tutorial, the bald engineer looks at how to pick pull-up resistor values.

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#resistors #pull-up #electronics

[idogendel]

Was that the "Up Goer 5" poster on the wall? :-)

[Probotg]

I have struggled to understand the reasoning behind pullup values for specific applications (CAN, I2C, SPI, etc.). This video not only explains it well but it's much easier to understand than I thought. I never considered the length of the wire as a major factor until now. Thank you!

[jon_raymond]

Great explanation and that was a fancy "cut to second camera" feature!

[garycrockett]

Thank you! Finally a clear, understandable explanation of what a pull-up resistor is. I appreciate your time and effort!

[waltercomunello]

I actually grasped more about pullups in these 2 videos (a grand total of maybe 7mins) than in all those months I wasted trying to figure out how to pick them, reading from multiple sources.

[joost]

Your videos/explanations are always so clear, well illustrated and easy to follow. Very helpful!

[mithrandirthegrey]

This is so good. Finally somebody who actually explains the values.

[devdylan]

I always send people here when they start working with micro-controllers. you do the BEST job at elaborating this for people new to it.

[FindLiberty]

Another consideration is attempting to help keep CLOSED switch contacts, "clean" by using a lower
resistor value in order to pass higher current. The Phone company called it, sealing current"
(also called wetting current or fritt current), usually 10 to 14 ma to keep contacts, splices and
connections working instead of allowing them to become oxidized or dirty. Since the switch
contacts sit OPEN most of the time, that constant sealing current won't flow as a preventative
measure, though it may benefit from the micro arc as the button is pressed... Prolly not! lol

[nate]

Also look at your BOM if you are not using a 1K resistor anywhere else but you using lots of 5K resistors just go ahead use the 5K resistor.

[azmrblack]

Great, clear, no filler explanation. Loved it!

[johncronk]

Great video man. Learned the answer to my question in less than 4 minutes, and I have been on Google for probably an hour reading different sites and getting my head wrapped around this. Thanks. I look forward to watching more of your videos. 👍

[loucostello]

I watch electronic engineering tutorials all the time. AddOhms tutorials are the best.

[patprop]

2021, i just found your channel, you explain very clearly, i hope you come back and keep making more videos like these.

[denishnatiuk]

Your explanations are so intuitive. Brilliant.

[DarkWolf]

Bro. You actually helped me to understand this topic in 4 mins! My lecturer isn't that great I see :P

[gtag]

Oh man ! Good tutorial. I just came into electronics a few months back and never knew what a resist does in this particular application. Thank you for sharing. Any hopes on doing opamp tutorials 😊

Your explanations are very simple and easy to grasp.

[Roobotics]

One thing you could definitely elaborate on, is what happens when your pull-up/down is too weak of a ratio from the internal resistor. Assuming they are pulling opposite directions, you get a voltage divider effectively. Then your resulting voltage can be referenced to the input high/low specifications to see if you are going to make the guaranteed voltage levels for a certain state.

[jasonhanjk]

If I need a fast response, I use 3k3 ohm and pull up to 3V3. Which give me a nice 1mA sink when using I2C, beware it uses lot's of power. Or just slow down the clock speed and use 10k pull up instead.
Strong pull up is required if the boards have lot's of capacitance on the trace.

For push button you can use 100k pull up and 1nF COG / NPO to ground.

[nikosadie]

very good explanation! I am still new to electronics and this helps way more than books..