
M0A21/M0A23 Series
May 06, 2022
Page
131
of 746
Rev 1.02
M0
A21
/M
0
A
2
3
SE
RIES
TEC
H
NICAL
RE
FEREN
C
E
M
ANUAL
V
REF
Control Register (SYS_VREFCTL)
Register
Offset
R/W
Description
Reset Value
SYS_VREFCTL
0x28
R/W
V
REF
Control Register
0x0000_0100
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
PRELOADSEL
Reserved
ADCPRESEL
VREFCTL
Bits
Description
[31:7]
Reserved
Reserved.
[6]
PRELOADSEL
Pre-load Timing Selection (Write Protect)
0 = Pre-load time is 60us for 0.1uF Capacitor.
1 = Pre-load time is 310us for 1uF Capacitor.
Note:
These bits is write protected. Refer to the SYS_REGLCTL register.
[5]
Reserved
Reserved.
[4]
ADCPRESEL
ADC Voltage Reference
0 = ADC positive reference voltage comes from AV
DD
(voltage of V
DD
pin)
1 = ADC positive reference voltage comes from internal or external V
REF
.
Note:
These bits is write protected. Refer to the SYS_REGLCTL register.
[3:0]
VREFCTL
V
REF
Control Bits (Write Protect)
0000 = V
REF
is from external pin.
0001 = V
REF
is internal 1.536V.
0011 = V
REF
is internal 2.048V.
0101 = V
REF
is internal 2.56V.
0111 = V
REF
is internal 3.072V.
1001 = V
REF
is internal 4.096V.
Others = Reserved.
Note 1:
GPA1 needs to keep folating if Internal voltage reference is enabled.
Note 2:
These bits are write protected. Refer to the SYS_REGLCTL register.