SBASAY5 June 2024 ADS8681W
PRODUCTION DATA
The device features a differential input structure. Figure 6-1 shows the simplified circuit schematic for the AFE circuit, including the input overvoltage protection circuit, PGA, low-pass filter (LPF), and high-speed ADC driver.
The ADS868xW supports multiple unipolar or bipolar, single-ended and differential input voltage ranges based on the program register configurations. .As explained in the RANGE_SEL_REG register, configure the input voltage range to be bipolar or unipolar. The bipolar ranges are ±3V × VREF, ±2.5V × VREF, ±1.5V × VREF, ±1.25V × VREF, and ±0.625V × VREF. The unipolar ranges are 0V to 3V × VREF, 0V to 2.5V × VREF, 0V to 1.5 × VREF, and 0V to 1.25 × VREF. With the internal or external reference voltage set to 4.096V, configure the device input ranges to bipolar or unipolar ranges. The configured bipolar ranges are ±12.288V, ±10.24V, ±6.144V, ±5.12V, and ±2.56V. The configured unipolar ranges are 0V to 12.288V, 0V to 10.24V, 0V to 6.144V, and 0V to 5.12V.
The device samples the voltage difference between the AIN_P and the AIN_M pins. For optimum performance, make sure the input currents and impedances along each input path are matched. Route the two single-ended signals to AIN_P and AIN_M as symmetrically as possible from the signal source to the ADC input pins.
If the analog input pins (AIN_P) or (AIN_M) to the device are left floating, the output of the ADC corresponds to an internal biasing voltage. The output from the ADC is considered invalid if the device operates with floating input pins. This condition does not cause any damage to the device, which becomes fully functional when a valid input voltage is applied to the pins.