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M451
May. 4, 2018
Page
586
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1006
Rev.2.08
M4
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RTC 32K Oscillator Control Register (RTC_LXTCTL)
Register
Offset
R/W
Description
Reset Value
RTC_LXTCTL
0x100
R/W
RTC 32.768 kHz Oscillator Control Register
0x0000_000E
31
30
29
28
27
26
25
24
Reserved
23
22
21
20
19
18
17
16
Reserved
15
14
13
12
11
10
9
8
Reserved
7
6
5
4
3
2
1
0
Reserved
GAIN
LXTEN
Bits
Description
[31:4]
Reserved
Reserved.
[3:1]
GAIN
Oscillator Gain Option
User can select oscillator gain according to crystal external loading and operating
temperature range. The larger gain value corresponding to stronger driving capability and
higher power consumption.
000 = L0 mode.
001 = L1 mode.
010 = L2 mode.
011 = L3 mode.
100 = L4 mode.
101 = L5 mode.
110 = L6 mode.
111 = L7 mode (Default).
[0]
LXTEN
Backup Domain 32K Oscillator Enable Bit
0 = Oscillator is Disabled.
1 = Oscillator is Enabled.
This bit controls 32 kHz oscillator on/off. User can set either LXTEN in RTC battery power
domain or system manager control register CLK_PWRCTL[1] (LXTEN) to enable 32 kHz
oscillator. If this bit is set 1, X32 kHz oscillator keep running after system core power is
turned off, if this bit is clear to 0, oscillator is turned off when system core power is turned
off.