Decimator Scale (Dec_Scale[18:0]); Decimator Outd (Addresses 3Bh, 3Ch, 3Dh); Decimator Outd (Dec_Outd[23:0]); Table 18. Decimator Shift/Scale Coefficient Calculation Examples - Cirrus Logic CS44600 Manual

7.33.2 Decimator Scale (DEC_SCALE[18:0])

Default = 25868h
Function:
These bits are used to scale the power supply reading
ing the PSR feedback calibration sequence. DEC_SCALE[18:0] has 19-bit precision, formatted as signed
1.18 with decimal values from -1 to 1-2^(-18). The combination of shift and scale factors
(DEC_SCALE[18:0]*2^(DEC_SHIFT[2:0])) can be viewed as a floating point coefficient. The floating point
coefficient will be determined during the PSR feedback calibration sequence. See
(DEC_SHIFT[2:0])
DEC_SCALE[18:0]
20000h=0.5
28851h=0.6331
7.34

Decimator Outd (addresses 3Bh, 3Ch, 3Dh)

7 6
DEC_OUTD23 DEC_OUTD22
7 6
DEC_OUTD15 DEC_OUTD14
7 6
DEC_OUTD07 DEC_OUTD06

7.34.1 Decimator Outd (DEC_OUTD[23:0])

Default = 000000h (Read Only)
Function:
These bits reflect the real-time power supply value as measured by the external PSR feedback circuit.
DEC_OUTD[23:0] has 24-bit precision, formatted as signed 2.22 with decimal values from -4 to 4-2^(-22).
Calibration needs to be done to correlate the value of DEC_OUTD[23:0] with the real power supply value.
A quiet DC power supply without any ripple is treated as 1.0 with DEC_OUTD[23:0] calibrated at 400000h.
See "Recommended PSR Calibration Sequence" on page
DS633F1
register description and
DEC_SHIFT[2:0]
001b=1
010b=2

Table 18. Decimator Shift/Scale Coefficient Calculation Examples

5 4
DEC_OUTD21 DEC_OUTD20
5 4
DEC_OUTD13 DEC_OUTD12
5 4
DEC_OUTD05 DEC_OUTD04
(Decimator Outd (addresses 3Bh, 3Ch,
"Recommended PSR Calibration Sequence" on page
Calculated Coefficient (C
0.5*2^(1)=1
0.6331*2^(2)=2.5325
3 2
DEC_OUTD19 DEC_OUTD18
3
DEC_OUTD11 DEC_OUTD10
3
DEC_OUTD03 DEC_OUTD02
44.
CS44600
Decimator Shift
)
PSR
1
DEC_OUTD17 DEC_OUTD16
2 1
DEC_OUTD09 DEC_OUTD08
2 1
DEC_OUTD01 DEC_OUTD00
3Dh)) dur-
44.
0
0
0
71