Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Pull up resistor and power supply to controLler

Status
Not open for further replies.
V

venkates2218

Full Member level 6
Full Member level 6
Joined
Sep 30, 2016
Messages
354
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,298
Visit site
Activity points
4,306
In my project i used 1K resistor as pullup resistor for pic microcontroller on PORTB and enabled internal pullup resistor also...

is 1k is suitbale for pullup operation..?
Or i need to change the value...?
 

Pullup resistor for what ? Button circuit ? You can use 1k. I use 4.7k to 22k.
 

i used 1K resistor as pullup resistor for pic microcontroller on PORTB and enabled internal pullup resistor also...
Click to expand...
In this way you are parallelizing to resistors. Doesn't make sense. The internal pull-up should be sufficient.
 

for battery powered circuits alone..?
Or we have to care leakage current in all forum power supply circuits..?
 

Hi,

how is your "pull up" resistor related to "power supply" circuits?
It isn´t clear to me.

A simple drawing could clarify.

Klaus
 

i dono know about it..?
Easyrider83 mentioned liked below,so i'm asking is their any relationship between the pull-up resistors and type of power supply..?
For battey powered device you should care about leakege current. For other causes use Ohm's law, please.
 

sorry i can't understand your answer OKADA...
Can you explain it please..?

- - - Updated - - -

i'm going to use 7A DC 12V battery as power supply...
Is any problem will created due to pull-up resistors to battery..?
 

Use 22k resistor in battery powered devices for pull-up resistor. When higher value pullups are used very less current flows. This saves battery current. If battery 150 mAh then you nned to save more current.

Say current will be flowing in the internal circuit. If 1k resistor is used with 5V then 5V/1k = 0.005A flows. If 22k resistor is used then 2.27 * 10^-4 A current flows.

I thought Li-Ion battery stacked to get 5V.

Assuming some current flows in the internal circuitary of MCU when button is not pressed and internal resistance is 0 and only pull-up resistance is considered.

Image 2. Assume the meters are inside the MCU.


1k resistor and 5V

current = 5 mA

Power in resistor = 0.025W

22k resistor and 5V


current = 227 uA

power in resistor = 0.001134W
 

Attachments

  • currents.png
    currents.png
    13.3 KB · Views: 171
  • currents2.png
    currents2.png
    13 KB · Views: 172
Last edited:
Hi,

i'm going to use 7A DC 12V battery as power supply...Is any problem will created due to pull-up resistors to battery..?
Click to expand...
even more confusing.

Is your pullup resistor connected to 12V battery? .. Or why do you mention battery voltage?

I don´t like guessing. If you are interested in an answer, then post a simple circuit drawing....

Klaus
 

normal citcuit using pic micocontroller...
In that i'm using pull-up resistor for push button ..
If battery is used as powersupply means it will affect the battery life or something else...
Because by using pullup resistor we are shorting positive and negative power supply when the button is pressed....
 

Pullup resistor value decides the current drawn from the battery. High resistance, lesser current and more battery life.
 

Use the internal pull-up. It is tenths of KOhms. No external resisitor is required. Even for low power. External or internal, there will be power loss. But someone will press it for a couple of seconds and then he will release it. So it is not a big deal.
 
Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top