VDAC0_OUT0
VDAC0_OUT1
Ch 1
AVDD
1.25 V Low Noise
2.5 V Low Noise
CH0DATA
CH1DATA
ADC / ACMP / Etc.
REFSEL
Ch 0
1.25 V
2.5 V
Pin Reference
OPA0
OPA1
OPA0_OUT
MAINOUTEN
VDAC0_OUT0ALTx
ALTOUTEN,
ALTOUTPADEN
APORT
APORTOUTEN
MAINOUTEN
VDAC0_OUT1ALTx
ALTOUTEN,
ALTOUTPADEN
APORT
APORTOUTEN
OPA1_OUT
Figure 23.1. VDAC Overview
23.3.1 Power Supply
The VDAC module power (V
OPA
) is derived from the AVDD supply pin.
23.3.2 I/O Pin Considerations
The maximum usable analog signal that can be seen on external VDAC outputs depends on several factors: whether the signal is rout-
ed through the APORT, whether overvoltage is enabled, and on the IOVDD/AVDD supply voltages, as shown in the
mum Usable IO Voltage on page 756
table.
Table 23.1. Maximum Usable IO Voltage
VDAC Pin
Maximum IO Voltage (APORT
USED and OVT Enabled/
Disabled)
Maximum IO Voltage (APORT
UNUSED, OVT Enabled)
Maximum IO Voltage (APORT UN-
USED, OVT Disabled)
VDAC External VREF In-
puts
N/A
MIN(AVDD, IOVDD)
MIN(AVDD, IOVDD)
VDAC Outputs
MIN(AVDD, IOVDD)
MIN(AVDD, IOVDD + 2 V)
MIN(AVDD, IOVDD)
23.3.3 Enabling and Disabling a Channel
A VDAC channel is enabled by writing 1 to the CHxEN and disabled by writing 1 to CHxDIS in VDACn_CMD. The channel enabled
status can be read by polling the CHxENS bit in VDACn_STATUS. This bit will go high immediately following a write to CHxEN. After
disabling a channel the CHxENS bit will stay high until the VDAC channel is completely disabled.
Software should configure the VDAC before enabling a channel. Software
must not
write to any of the following registers while
either
CH0ENS or CH1ENS are set:
• VDACn_CTRL
• VDACn_CHxCTRL
• VDACn_OPAxTIMER
A VDAC channel will not begin driving its output before it is enabled
and
has received a conversion trigger, see
. After a channel is enabled it will listen for trigger sources specified in TRIGMODE in VDACn_CHxCTRL. If TRIGMODE is set to
SW, SWPRS or SWREFRESH and a value was written to CHxDATA or COMBDATA before enabling the channel a conversion will start
immediately when the channel is enabled. When disabling a channel any pending triggers are flushed.
Reference Manual
VDAC - Digital to Analog Converter
silabs.com
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