Measure resistance with ADC

Status
Not open for further replies.
F

funghome

Newbie level 4
Joined
Oct 15, 2006
Messages
7
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Visit site
Activity points
1,323
adc measure resistance

I want to measure an unknown resistor resistance with ADC, and calculate the unknown value using below circuit.
But I don't know how to calcualate the value.
LTC2410 is a 24 bits adc.
If 820000 was read, what is the resistance?
 

how to measure resistance adc

Hi,

You can calculate the resistance R in K ohms as follows:

REFadc = VREF+ - VREF-
= Vcc - Vcc (10 + R )/ (20 + R)
= Vcc [ 1- (10+R)/(20+R)]
= Vcc [ (20+R-10-R)/(20+R)]
= Vcc [ 10/(20+R)]
Analog Input = Vcc * R/(20+R) = REFadc* (ADC Reading / ADC Full Scale)
So,
Vcc*R/(20+R) = Vcc[10/(20+R)] * 8,20,000 / 2^24

R = 10 * 8,20,000 / 2^24
= 0.48876 K ohms
= 488.76 ohms


Regards,
Laktronics
 

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…