11.5.6 CMU_HFXOSTARTUPCTRL - HFXO Startup Control
Offset
Bit Position
0x02C
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Reset
0x0A0
0x20
Access
R
W
R
W
Name
Bit
Name
Reset
Access Description
31:20
Reserved
To ensure compatibility with future devices, always write bits to 0. More information in
19:11
CTUNE
0x0A0
RW
Sets Oscillator Tuning Capacitance
This CTUNE value is applied during the startup phase of the HFXO. Capacitance on HFXTAL_N and HFXTAL_P (pF) =
Ctune = Cpar + CTUNE<8:0> X 40fF. Max Ctune 25pF (CLmax ~12.5pF). CL(DNLmax)=50fF ~ 0.6ppm (12.5ppm/pF).
10:7
Reserved
To ensure compatibility with future devices, always write bits to 0. More information in
6:0
IBTRIMXOCORE
0x20
RW
Sets the Startup Oscillator Core Bias Current
This IBTRIMXOCORE value is applied during the startup phase of the HFXO. Current (uA) = IBTRIMXOCORE X 40uA.
Bits 6 and 5 may only me high in the crystal oscillator startup phase.
Reference Manual
CMU - Clock Management Unit
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