
DocID024597 Rev 5
673/1830
RM0351
Voltage reference buffer (VREFBUF)
674
21.3.2 VREFBUF
calibration
control register (VREFBUF_CCR)
Address offset: 0x04
Reset value: 0x0000 00XX
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Res
Res
Res
Res
Res
Res
Res
Res
Res
Res
Res
Res
Res
Res
Res
Res
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Res
Res
Res
Res
Res
Res
Res
Res
Res
Res
Res
Res
VRR
VRS
HIZ
ENVR
r
rw
rw
rw
Bits 31:4 Reserved, must be kept at reset value.
Bit 3
VRR:
Voltage reference buffer ready
0: the voltage reference buffer output is not ready.
1: the voltage reference buffer output reached the requested level.
Bit 2
VRS
: Voltage reference scale
This bit selects the value generated by the voltage reference buffer.
0: Voltage reference set to V
REF_OUT1
(around 2.048 V).
1: Voltage reference set to V
REF_OUT2
(around 2.5 V).
Bit 1
HIZ:
High impedance mode
This bit controls the analog switch to connect or not the VREF+ pin.
0: VREF+ pin is internally connected to the voltage reference buffer output.
1: VREF+ pin is high impedance.
Refer to
Table 138: VREFBUF buffer modes
for modes descriptions depending on ENVR bit
configuration.
Bit 0
ENVR:
Voltage reference buffer enable
This bit is used to enable the voltage reference buffer.
0: Internal voltage reference disable.
1: Internal voltage reference enable.
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Res
Res
Res
Res
Res
Res
Res
Res
Res
Res
Res
Res
Res
Res
Res
Res
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Res
Res
Res
Res
Res
Res
Res
Res
Res
Res
TRIM[5:0]
rw
rw
rw
rw
rw
rw
Bits 31:6 Reserved, must be kept at reset value.
Bits 5:0
TRIM[5:0]
: Trimming code
These bits are automatically initialized after reset with the trimming value stored in the Flash
during production test. Writing into these bits allows to tune the internal reference buffer
voltage.