Cirrus-logic CS4245 Manuel d'utilisateur télécharger pdf (Page 33)

DS656F3 33

CS4245

The high-pass filter continuously subtracts a measure of the DC offset from the output of the decimation

filter. If the HPFFreeze bit (See “ADC High-Pass Filter Freeze (Bit 1)” on page 45.) is set during normal op-

eration, the current value of the DC offset for the each channel is frozen and this DC offset will continue to

be subtracted from the conversion result. This feature makes it possible to perform a system DC offset cal-

ibration by:

1. Running the CS4245 with the high-pass filter enabled until the filter settles. See the ADC Digital Filter

Characteristics section for filter settling time.

2. Disabling the high-pass filter and freezing the stored DC offset.

A system calibration performed in this way will eliminate offsets anywhere in the signal path between the

calibration point and the CS4245.

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Cirrus-logic CS4245 Manuel d'utilisateur Page 33