PIC18f ADC voltage reference

Status
Not open for further replies.
A

amilaachala

Newbie level 6
Joined
Nov 15, 2012
Messages
11
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,356
hi guys,

I want to know about 'minimum external voltage references' that can be given to ADC.suppose i give external voltage references as " 0 V and 3.3 V " then a step size would be ( 3.3/1023 ) V rit????

thanks ........
 

Step Count = (VREF / (Total No. of Steps)) * ADC result

Step size = VREF/(Max count)
So, the step size would be (3.3/1024)

Be careful, total no. of steps is 1024, not 1023.

The minimum external voltage reference you can use is 3.0V (if VDD ≧ 3.0V) or 1.8V (if VDD < 3.0V).

Hope this helps.
Tahmid.
 
Last edited:
are you sure??? i mean to find a step size

step size = (Vmax - Vmin) / 1024

that will give you the voltage difference between 2 steps Right?????????
 

Hi,

Tahmid is correct.

step size = ( vmax 3v3 - vmin 0v) / 1024 = 3v3 / 1024 = 0.003226 v per single step

Also see the chips datasheet, section electrical charactristics, for the operating voltages of the ADC of your particular type of chip F or LF
 


If you look closely you will see that Tahmid has muliplied the equation you posted with an additional Vin.
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…