JAJSDU5A August 2017 – February 2020 ADS114S06B , ADS114S08B
PRODUCTION DATA.
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At a gain of 1, the device can be configured to disable and bypass the low-noise PGA. Disabling the PGA lowers the overall power consumption and also removes the restrictions of Equation 5 for the input voltage range. If the PGA is bypassed, the ADC absolute input voltage range extends beyond the AVDD and AVSS power supplies, allowing input voltages at or below ground. Equation 6 shows the absolute input voltage range when the PGA is bypassed:
In order to measure single-ended signals that are referenced to AVSS (AINP = VIN, AINN = AVSS), the PGA must be bypassed. The PGA is bypassed and powered down by setting the PGA_EN[1:0] bits to 00 in the gain setting register (03h).
For signal sources with high output impedance, external buffering may still be necessary. Active buffers introduce noise and also introduce offset and gain errors. Consider all of these factors in high-accuracy applications.