147
Clock Generator
Chapter 4
Preliminary User’s Manual U17566EE1V2UM00
(3)
SCFMC - SSCG frequency modulation control register
The 8-bit SCFMC register controls the frequency modulation of the SSCG in
dithering mode (when CKC.DEN = 1).
Access
This register can be read/written in 8-bit or 1-bit units.
Address
FFFF F82A
H
.
Initial Value
00
H
. The register is initialized by any reset.
Note
1.
This register can only be rewritten with a new value if the SSCG is
switched off. Refer to the explanation at the beginning of this section.
2.
The given modulation ranges and frequencies are typical values. Refer
also to the Electrical Target Specification.
In dithering mode, the SSCG output frequency f
SSCG
varies according to the
FM range, specified by SCFMC[4:2], around it’s center value:
f
SSCG
= f
SSCGc
± (FM range)
The time of one full cycle is given by the period of the modulation frequency
specified in SCFMC[1:0].
7
6
5
4
3
2
1
0
0
0
0
SCFMC4
SCFMC3
SCFMC2
SCFMC1
SCFMC0
R
R
R
R/W
R/W
R/W
R/W
R/W
Table 4-11
SCFMC register contents
Bit position
Bit name
Function
4 to 2
SCFMC[4:2] Frequency modulation range control:
SCFMC4
SCFMC3
SCFMC2
FM range
0
0
0
± 0.5 % (typical value)
0
0
1
± 1.0 % (typical value)
0
1
0
± 2.0 % (typical value)
0
1
1
± 3.0 % (typical value)
1
0
0
± 4.0 % (typical value)
1
0
1
± 5.0 % (typical value)
other settings
prohibited
1 to 0
SCFMC[1:0] Frequency modulation frequency control:
SCFMC1
SCFMC0
Modulation frequency
0
0
40 kHz (typical value)
0
1
50 kHz (typical value)
1
0
60 kHz (typical value)
1
1
prohibited
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