Part Number: ADS1220
Hi ,
I am using ADS1220 in one of my design. I/P to ADC is 0 to 2V . I would like to determine count range for ADC. Internal reference is used. Can we use std. ADC equation for count
Dout = Vin/ Vref ( 2 ^N ) or there is some other equation for ADS1220 should be used? Is there any calculator for this?
Is there any ref design which explains this?
Thanks in Advance !!
Amod
Amod,
Section 8.5.2 covers the data format. Basically all data coverters will use the equation Vin/LSB. LSB=FSR/2^N, and for this device the FSR = 2*Vref/Gain. The factor of 2 is used because the ADC allows bipolar signals so it accounts for both postative and negative range. For example, if the internal voltage reference of 2.5V is used, and Gain = 1, the posative full scale range is 2.5V and the negative full scale range is -2.5V for an overall FSR = 5V. You can also use the analog engineers calculator to help with this conversion. For a 2V input, the output code is 6,710,886 decmal, or 0x666666.
Best regards,
Art
Amond,
In general, you will look at full scale range for determining the resolution of a Analog-to-Digital converter. The full-scale range is normally set by the reference. Sometimes there is a multiplicative factor in the calculation. In this case FSR is a function of the reference and gain. For the calculation I did above, the reference used is 2.5V. Below is the same calculation for the internal 2.048V reference, and a gain of 1.
Best regrds, Art
