In this mode, OPAMP0 and OPAMP1 are configured as voltage followers. The OPAMPCTRLx register can be configured as follows:
| MUXPOS | MUXNEG | RES1MUX | POTMUX | RES2VCC | RES2OUT | RES1EN | ANAOUT | |
|---|---|---|---|---|---|---|---|---|
| OPAMP0 | 0000 | 011 | 010 | 010 | 0 | 1 | 1 | 0 |
| OPAMP1 | 0000 | 011 | 011 | 000 | 0 | 0 | 0 | 0 |
| OPAMP2 | 0111 | 001 | 010 | 010 | 0 | 1 | 1 | 0 |
The resistor ladders associated with OPAMP0 and OPAMP2 must be configured as follows in order to select the appropriate gain:
| OPAMPCTRL0.POTMUX | OPAMPCTRL2.POTMUX | GAIN |
|---|---|---|
| 0x7 | Reserved | Reserved |
| 0x6 | 0x0 | 1/7 |
| 0x5 | Reserved | Reserved |
| 0x4 | 0x1 | 1/3 |
| 0x3 | Reserved | Reserved |
| 0x2 | 0x2 | 1 |
| 0x1 | 0x4 | 3 |
| 0x0 | 0x6 | 7 |
Note: Either the DAC or GND must be the
reference, selected by the OPAMPCTRL0.RES1MUX bits. Refer to the OPAMP Control 'x' register
(OPAMPCTRL) for details.
Figure 1. Instrumentation amplifier
