ZHCSES1B March 2016 – October 2018 ADS1282-SP
PRODUCTION DATA.
The voltage reference for the ADS1282-SP is the differential voltage between VREFP and VREFN: VREF = VREFP – VREFN. The reference inputs use a structure similar to that of the analog inputs with the circuitry of the reference inputs shown in Figure 35. The average load presented by the switched capacitor reference input can be modeled with an effective differential impedance of REFF = tSAMPLE / CIN (tSAMPLE = 1/ƒMOD). The effective impedance of the reference inputs loads the external reference.
The ADS1282-SP reference inputs are protected by ESD diodes. In order to prevent these diodes from turning on, the voltage on either input must stay within the range shown in Equation 7:
The minimum valid input for VREFN is AVSS – 0.1 V and maximum valid input for VREFP is AVDD + 0.1 V.
A high-quality 5 V reference voltage is necessary for achieving the best performance from the ADS1282-SP. Noise and drift on the reference degrade overall system performance, and it is critical that special care be given to the circuitry generating the reference voltages in order to achieve full performance. See Application Information for reference recommendations.