LTC1966
Production
The LTC1966 is a true RMS-to-DC converter that utilizes an innovative patented ?S computational technique. The internal delta sigma circuitry of the LTC1966...
Datasheet
LTC1966 on Analog.com
hii my name is aied and i want to use the LTC1966 trms converter
so i built circuit in lt spice and used an a capacitor of 0.1uf at the output in order to get the response time at the output .
and i feed the LTC with a sine wave with an a amplitude of 0.25v and frequency of 50 hz
sense TRMS converter is suppose ti measure the heat value of the signal i expected to see on a 0.25VPP sine wave a dc output around 1 volt .
i calculated the area between the X axis and the sine with the 0.25v amp graph from 0 to 2*pi and i got an answer of 1.
so i am suppose to see in output of 1 v .(SENCE THE TRMS is the area between the graph and the x axis )
but i got a different result a ripple with about 200mv max and 100mv min
i expected to see a dc voltage of 1v with much more smaller ripple
i attached picture from the lt spice and i wonder if i did something wrong ?
my goal is to measure a TRUE RMS signal with an amplitude ranges from 0 to 3.3volts and frequency of 50 to 60 hz max ,i would be very thankful for your help .
Hi aiedb:
In your circuit, IN1 is being driven negative while the LTC1966 does not have a negative supply. In order to use LTC1966 on a single supply, use the circuit shown in the datasheet, Figure 9b.
Also, with a 250mVpk (500mVpp) sinusoid, the correct RMS/DC level to expect from the LTC1966 is 1/root2*250mV = 176.8mV.
hii, thanks for your reply
yes you are right i fixed my design by adding a negative voltage supply in the VSS pin.
and indeed the expected value is as you said 176mv.
from what i sa
do have any recommendation for me if i want to measure TRMS of a sine wave with non leaner distortions on the wave i need the output to suttle up a least in 100ms .
hii, thanks for your reply
yes you are right i fixed my design by adding a negative voltage supply in the VSS pin.
and indeed the expected value is as you said 176mv.
from what i sa
do have any recommendation for me if i want to measure TRMS of a sine wave with non leaner distortions on the wave i need the output to suttle up a least in 100ms .