CRD44800-ST-FB View Datasheet(PDF) - Cirrus Logic
Part Name
Description
Manufacturer
CRD44800-ST-FB Datasheet PDF : 76 Pages
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CS44600
7.33.2 Decimator Scale (DEC_SCALE[18:0])
Default = 25868h
Function:
These bits are used to scale the power supply reading (Decimator Outd (addresses 3Bh, 3Ch, 3Dh)) dur-
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 Decimator Shift
(DEC_SHIFT[2:0]) register description and “Recommended PSR Calibration Sequence” on page 44.
DEC_SCALE[18:0] DEC_SHIFT[2:0]
20000h=0.5
28851h=0.6331
001b=1
010b=2
Calculated Coefficient (CPSR)
0.5*2^(1)=1
0.6331*2^(2)=2.5325
Table 18. Decimator Shift/Scale Coefficient Calculation Examples
7.34 Decimator Outd (addresses 3Bh, 3Ch, 3Dh)
7
DEC_OUTD23
7
DEC_OUTD15
7
DEC_OUTD07
6
DEC_OUTD22
6
DEC_OUTD14
6
DEC_OUTD06
5
DEC_OUTD21
5
DEC_OUTD13
5
DEC_OUTD05
4
DEC_OUTD20
4
DEC_OUTD12
4
DEC_OUTD04
3
DEC_OUTD19
3
DEC_OUTD11
3
DEC_OUTD03
2
DEC_OUTD18
2
DEC_OUTD10
2
DEC_OUTD02
1
DEC_OUTD17
1
DEC_OUTD09
1
DEC_OUTD01
0
DEC_OUTD16
0
DEC_OUTD08
0
DEC_OUTD00
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 44.
DS633F1
71
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