JAJSRV8 August 2024 AMC0136
ADVANCE INFORMATION
デバイスごとのパッケージ図は、PDF版データシートをご参照ください。
Place a RC filter in front of the isolated amplifier 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 at the input is to attenuate high-frequency noise below the desired noise level of the measurment. In pactice, a cutoff frequency that is two orders of magnitude lower than the modulator frequency yields good results.
Most voltage-sensing applications use high-impedance resistive dividers in front of the isolated modulator to scale down the input voltage. In this case, a single capacitor (as shown in Figure 7-2) is sufficient to filter the input signal. Assuming a 10kΩ sensing resistor (R2), a 100pF filter capacitor yields in a 160kHz cutoff frequency.