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NUC126
Aug. 08, 2018
Page
195
of 943
Rev 1.03
NUC12
6 S
E
RI
E
S
T
E
CH
NI
CA
L R
E
F
E
RE
NCE
MA
NUA
L
PLL Control Register (CLK_PLLCTL)
The PLL reference clock input is from the 4~24 MHz external high speed crystal oscillator (HXT) clock
input or from the 22.1184 MHz internal high speed RC oscillator (HIRC). This register is used to control
the PLL output frequency and PLL operation mode.
Register
Offset
R/W
Description
Reset Value
CLK_PLLCTL
0x20
R/W
PLL Control Register
0x008D_8418
31
30
29
28
27
26
25
24
Reserved
23
22
21
20
19
18
17
16
STBSEL
Reserved
PLLSRC
OE
BP
PD
15
14
13
12
11
10
9
8
OUTDIV
INDIV
FBDIV
7
6
5
4
3
2
1
0
FBDIV
Bits
Description
[31:24]
Reserved
Reserved.
[23]
STBSEL
PLL Stable Counter Selection
0 = PLL stable time is 6144 PLL source clock (suitable for source clock is equal to or less
than 12MHz).
1 = PLL stable time is 12288 PLL source clock (suitable for source clock is larger than
12MHz).
[22:20]
Reserved
Reserved.
[19]
PLLSRC
PLL Source Clock Selection
0 = PLL source clock from external 4~24 MHz high-speed crystal (HXT).
1 = PLL source clock from internal 22.1184 MHz high-speed oscillator (HIRC).
[18]
OE
PLL OE (FOUT Enable) Control
0 = PLL FOUT Enabled.
1 = PLL FOUT is fixed low.
[17]
BP
PLL Bypass Control
0 = PLL is in normal mode (default).
1 = PLL clock output is same as PLL input clock FIN.
[16]
PD
Power-down Mode
If set PDEN(CLK_PWRCTL[7]) bit to 1, the PLL will enter Power-down mode, too.
0 = PLL is in normal mode.
1 = PLL is in Power-down mode (default).
[15:14]
OUTDIV
PLL Output Divider Control
Refer to the formulas below the table.
[13:9]
INDIV
PLL Input Divider Control