Opamp Vdac Combination - Silicon Laboratories EFR32xG14 Wireless Gecko Reference Manual

24.3.4.10 Common Reference
It is possible to configure all opamps to have a common reference by setting the RESINMUX to COMPAD in VDACn_OPAx_MUX.
When RESINMUX of all opamps is set to COMPAD mode, the NEGPAD input of OPA0 is used.
24.3.4.11 Dual Buffer ADC Driver
It is possible to use any two of the opamps to form a Dual Buffer ADC driver as shown in
on page 810. Both opamps used must be configured in the same way. The positive input is configured by setting the 0PAx POSSEL
to PAD, and the negative input is connected to the resistor ladder by setting NEGSEL to OPATAP in VDACn_OPAx_MUX. The output
from the opamps can be configure to drive pins through the alternative output network or the APORT. The ADC can sample pins that
the opamps are driving through the APORT.
VIP
+
-
R1
OPA
OPAx
OPAx
OPAx

24.3.5 Opamp VDAC Combination

Since two of the OPAMPs are part of the VDAC, it is not possible to use both VDAC channels and all 2 OPAMPs at the same time. If
both VDAC channels are used, OPA0 and OPA1 can not be used as stand-alone opamp. However, it is possible to use one of the
VDAC channels in combination with OPA0 or OPA1. OPA1 is available when VDAC channel 0 is in use, and OPA0 is available when
VDAC channel 1 is used.
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V1
V2
Figure 24.11. Instrumentaion Amplifier Overview
VOUTP=VIP(1+ R2/R1)
or
VOUTP = VIP (Unity Gain)
R2
Figure 24.12. Dual Buffer ADC Driver Overview
Table 24.14. Dual Buffer ADC Driver Configuration
OPA Bitfields
POSSEL
NEGSEL
RESINMUX
VOUT
+
OPA0
-
R2
R1
R1
R2
+
OPA1
-
VOUT
Figure 24.12 Dual Buffer ADC Driver Overview
VIN
+
-
R1 R2
OPA Configuration
POSPADx, APORT[1-4]X
OPATAP
VSS
Reference Manual
OPAMP - Operational Amplifier
VOUTN=VIN(1+ R2/R1)
or
VOUTN = VIN (Unity Gain)
Rev. 1.1 | 810