CS5378 View Datasheet(PDF) - Cirrus Logic
Part Name
Description
MFG CO.
CS5378 Datasheet PDF : 88 Pages
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CS5378
1-bit
∆−Σ
Input
5th order
sinc1
8
4th order
sinc2
stage1
2
4th order
sinc2
stage2
2
5th order
sinc2
stage3
2
6th order
sinc2
stage4
2
4th order
sinc3
stage1
5
4th order
sinc3
stage2
5
4th order
sinc3
stage3
5
5th order
sinc3
stage4
5
5th order
sinc3
stage5
2
6th order
sinc3
stage6
3
6th order
sinc3
stage7
2
24-bit
Output
Figure 23. SINC Filter Block Diagram
12. SINC FILTER
The SINC filter primary purpose is to attenuate out-
of-band noise components from the ∆Σ modula-
tors. While doing so, they decimate 1-bit ∆Σ data
into lower frequency 24-bit data suitable for the
FIR and IIR filters.
The SINC filter has three cascaded sections,
SINC1, SINC2, and SINC3, which are each made
up of the smaller stages shown in Figure 23.
The selected output word rate in the FILTCFG reg-
ister automatically determines the coefficients and
decimation ratios selected for the SINC filters.
12.1 SINC1 Filter
The first section is SINC1, a single stage 5th order
fixed decimate by 8 SINC filter. This SINC filter
decimates the incoming 1-bit ∆Σ bit stream from
the modulators down to a 64 kHz rate.
12.2 SINC2 Filter
The second section is SINC2, a multi-stage, vari-
able order, variable decimation SINC filter. De-
pending on the selected output word rate in the
FILTCFG register, different cascaded SINC2 stag-
es are enabled, as shown in Table 11.
12.3 SINC3 Filter
The last section is SINC3, a flexible multi-stage
variable order, variable decimation SINC filter.
Depending on the selected output word rate in the
FILTCFG register, different SINC3 stages are en-
abled, as shown in Table 11.
12.4 SINC Filter Synchronization
The SINC filter is synchronized to the external sys-
tem by the MSYNC signal, which is generated
from the SYNC input. The MSYNC signal sets a
reference time (time 0) for all filter operations, and
the SINC filter is restarted to phase align with this
reference time.
DS639F2
40
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