SBASAT2 December 2024 AMC0386
PRODUCTION DATA
Connect a filter capacitor to the SNSP pin to improve signal-to-noise performance of the signal path. Input noise with a frequency close to the ΔΣ modulator sampling frequency (typically 10MHz) is folded back into the low-frequency range by the modulator. The purpose of the RC filter is to attenuate high-frequency noise below the desired noise level of the measurement. In practice, a cutoff frequency that is two orders of magnitude lower than the modulator frequency yields good results.
The cut-off frequency of the input filter is determined by the internal sensing resistor R2 and the external filter capacitor C5. The cut-off frequency is calculated as 1 / (2 x π x R2 x C5). For example, R2 =12.5kΩ and C5 = 100pF results in a cutoff frequency of 127kHz.