Instrumentation Amplifier

In this mode, OPAMP0 and OPAMP1 are configured as voltage followers. The OPAMPCTRLx register can be configured as follows:

Table 1. Instrumentation Amplifier Configuration
  MUXPOS MUXNEG RES1MUX POTMUX RES2VCC RES2OUT RES1EN ANAOUT
OPAMP0 000 010 11 010 0 1 1 0
OPAMP1 000 010 11 000 0 0 0 0
OPAMP2 110 001 10 010 0 1 1 0

The resistor ladders associated with OPAMP0 and OPAMP2 must be configured as follows in order to select the appropriate gain:

Table 2. Instrumentation Amplifier Gain Selection
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 OPAMPCTRL0, OPAMPCTRL1 and OPAMPCTRL2 for details.
Figure 1. Instrumentation amplifier