Hello all,
Can anyone confirm that how many will be the output bits when I am using 32KSPS data rate and I only wants to see the output of channel 1. I am confused in two statements written in data sheet.
This is the paragaraph under the heading Readback Length (Page 53)
The number of bits in the data output depends on the number of channels and the number of bits per channel.
The data format for each channel data is twos complement and MSB first. For the ADS129x with 32-kSPS and
64-kSPS data rates, the number of data bits is 24 status bits + 16 bits per channel × 8 channels = 152 bits. For
all other data rates, the number of data bits is 24 status bits + 24 bits per channel × 8 channels = 216 bits. When
channels are powered down using the user-register setting, the corresponding channel output is set to 0.
However, the sequence of channel outputs remains the same. The ADS1294 outputs four channels of datam and
the ADS1296 outputs six channels of data.
This para is on the very next page under the heading Data Format
The ADS129x output 24 bits of data per channel in binary twos complement format, MSB first. The LSB has a
weight of VREF / (2^23 – 1). A positive full-scale input produces an output code of 7FFFFFh and the negative fullscale
input produces an output code of 800000h. The output clips at these codes for signals exceeding full-scale.
Table 13 summarizes the ideal output codes for different input signals. For DR[2:0] = 000 and 001, the device
has only 17 and 19 bits of resolution, respectively. The last seven (in 17-bit mode) or five (in 19-bit mode) bits
can be ignored.
In my case I am using 32 kSPS, so what will be the no of output bits ? 16 bits as explained in first paragraph or 17 bits as explained in second paragraph?
Also explain the total no of output bits. I am only using 3 channels CH1,CH2 and CH3 and I only wants to see the output of CH1. Rest of the channels are powered down and input shorted.
