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AMC1300: how to implement the low pass filter for AMC130x

Part Number: AMC1300
Other Parts Discussed in Thread: AMC1301,

Hi team,

For the low pass filter, i see in AMC1301 datasheet, the schematic don't show a front stage low pass filter, but in AMC1300 datasheet, there is a differential low pass filter structure, so 

1) what's the difference of AMC1301 and AMC1300 for the input implemention?

2) Is a front differential low pass filter structure is recommended by you side? if the AMC1301 could implement a front LPF?

Regards

Robin Liu 

  • Hi Robin,

    Thanks for your post!

    1) The input implementation will be the same. The AMC1301 and AMC1300 are pin to pin compatible with comparable specifications.

    2) Input filters are typically recommended for systems that require high accuracy and want to reduce noise. LPFs are typically designed with a cutoff frequency 1 decade (10x) past the frequency of the input signal. So if you have a 1kHz input signal that your LPF should be designed to have a cutoff frequency around 10kHz.

    The equation is: cutoff frequency = 1/(2*pi*R*C) for single ended or 1/(2*pi*2*R*C) for differential.

    Typically a small R value is preferred due to the thermal noise that the resistor generates. For example, if we pick a value of 100oHm for R, we can calculate C accordingly.

    Differential: 10kHz = 1/(2*pi*2*100ohM*C); C = 80nF