EFM32WG Datasheet, PDF (731/834 Pages) List of Unclassifed Manufacturers – The EFM32WG Wonder Gecko is the ideal choice for demanding 8-, 16-, and 32-bit energy sensitive applications.

...the world's most energy friendly microcontrollers
Figure 30.7. Cascaded Inverting PGA Overview
POS0
VIN
R1
+
-
R2
POS1
+
-
POS2
+
-
VOUT3= -(VOUT2-POS3) x R2/R1 + POS3
R1
R2
VOUT2= -(VOUT1-POS1) x R2/R1 + POS1
R1
R2
VOUT1= -(VIN-POS0) x R2/R1 + POS0
Table 30.5. Cascaded Inverting PGA Configuration
OPA
OPA0
OPA0
OPA0
OPA0
OPA1
OPA1
OPA1
OPA1
OPA2
OPA2
OPA2
OPA bit-fields
POSSEL
NEGSEL
RESINMUX
NEXTOUT
POSSEL
NEGSEL
RESINMUX
NEXTOUT
POSSEL
NEGSEL
RESINMUX
OPA Configuration
POSPAD0
OPA0TAP
NEGPAD0
1
POSPAD1
OPATAP
OPA0INP
1
POSPAD2
OPATAP
OPA1INP
30.3.2.6 Cascaded Non-inverting PGA
This mode enables the opamp signals to be internally configured to cascade two or three opamps in non-
inverting mode as shown in Figure 30.8 (p. 731) . In both cases the negative input for all opamps will be
connected to the resistor ladder by setting the OPAxNEGSEL bit-field to OPATAP. In addition the resistor
ladder input must be set to VSS or NEGPADx in the OPAxRESINMUX in DACn_OPAxMUX. When
cascaded, the positive input on OPA0 is configured by the OPA0POSSEL bit-field. The output from OPA0
can be connected to OPA1 to create the second stage by setting NEXTOUT in DACn_OPA0MUX. To
complete the stage, the OPA1POSSEL bit-field must be set to OPA0INP in DACn_OPA1MUX. Similarly,
the last stage can be created by setting NEXTOUT in DACn_OPA1MUX and OPA2POSSEL bit-field to
OPA1INP in DACn_OPA2MUX.
Figure 30.8. Cascaded Non-inverting PGA Overview
VIN
+
-
VOUT1= VIN(1+ R2/R1)
+
VOUT2= VIN(1+ R2/R1)
+
VOUT3= VIN(1+ R2/R1)
-
-
R1
R2
R1
R2
R1
R2
2013-05-08 - Wonder Gecko Family - d0233_Rev0.50
731
www.energymicro.com