SLASF27A December 2023 – November 2024 TAC5242
PRODUCTION DATA
To remove the DC offset component and attenuate the undesired low-frequency noise content in the record data, the device supports a configurable high-pass filter (HPF) with a –3dB cut-off frequency of 0.000021 × fS or 0.00025 × fS. The HPF is not a channel-independent filter but is globally applicable for all the ADC channels. This HPF is constructed using the first-order infinite impulse response (IIR) filter and is efficient enough to filter out possible DC components of the signal. This configuration is only available in Target I2S or LJ modes of operation. In the Target TDM Mode of operation, MD3 is used to set slots for input and output data streams as described in Table 7-4 and in Controller Mode, MD3 is used as CCLK input as described in Table 7-9, and in these modes, the HPF is by default set to 0.000021 × fS. Additionally, as a lower frequency filter in digital requires a higher value capacitor as well for low droop at the cutoff frequency, the device also adjusts the input cap quick charge time along with the HPF cut-off with this configuration. Table 7-11 shows the MD3 configuration and –3dB cutoff frequency value and input cap quick charge setting. Figure 7-14 shows a frequency response plot for the HPF filter.
MD3 | INPUT CAP QUICK CHARGE | HPF –3dB CUT-OFF FREQUENCY | HPF –3dB CUTT-OFF FREQUENCY @ 48 kHz SAMPLE RATE |
---|---|---|---|
Low | Disabled (50ms time) | 0.000021 × fS | 1Hz |
High | Enabled (12.5ms time) | 0.00025 × fS | 12Hz |