What are the transfer functions of LPF1 and LPF2 for LSM6DSOX?

[lgi000]

I am interested in calibrating precisely the delay introduced by the filter chain (LPF1 and/or LPF2) of the LSMDSOX (or DSO/DSM - I presume they are the same). I have found the settling times in Table 13 of App Note AN-5272, which is a good start, but is there more information available on the actual transfer functions of LPF1 and LPF2?

Can the self-test be used as a clean step function on the input, as a way to characterize the overall transfer function? The AN-5272 App Note suggests to wait 100 ms for a stable output, but it is not clear whether this is due to the settling time of the filters, or if it is imposed by some other stabilization of the self-test circuitry itself.

Thanks in advance,

Best regards,

Laurent

[Eleon BORLINI · Accepted solution]

Hi Laurent @lgi000​ ,

we -as ST- cannot disclose the detailed transfer functions of the internal filters, but I can point you a similar frequency response.

Consider the IIS3DWB datasheet, p. 20: here the transfer function (frequency response) of the filter is the following one:

There are 2 main parameters of this filter that you can adjust: the frequency pole, which is determined by ODR/2 (which is fixed at 13.33kHz for the IIS3DWB but can vary for the LSM6DSOX), and the slope of the filter, which is determined by the (adjustable) cut-off frequency (the -3dB frequency), that can be ODR/4, ODR/10 and ODR/20 for the IIS3DWB, and as described in the Table 72. (at p.63 of the datasheet) for the LSM6DSOX:

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-Eleon

[tlifschitz]

Hi Eleon

Is it possible to have the frequency response plots of all the cutoff configurations? As you mentioned, on the datasheet only the first three curves are shown.

Thank you

Tobías