4.4 Feedback Mode Selection

The Feedback Mode Select (FMS) bits of OPAxCON3 are used to select how the internal feedback is connected to the internal resistor network. There are three configurations for FMS:

  • Connected to OPAxOUT
    • Internally, feedback goes from the output of the operational amplifier (OPAxOUT) to the resistor ladder. This is often used in conjunction with the internal resistor ladder for setting the OPA module’s gain.
  • Connected to VDD
    • There is no feedback through the multiplexer. However, the top of the resistor ladder is connected to VDD, which can be used to create a programmable resistor divider.
  • No Connection
    • There is no feedback through the multiplexer, and the top of the resistor ladder is floating. This mode is recommended when external components are connected to the feedback network of the amplifier(1).
    Important:
    1. Leaving FMS enabled may introduce a resistor in parallel with external feedback elements.