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16-4 OA
16.2 OA Operation
The OA module is configured with user software. The setup and operation of
the OA is discussed in the following sections.
16.2.1 OA Amplifier
The OA is a configurable, low-current, rail-to-rail operational amplifier. It can
be configured as an inverting amplifier, or a non-inverting amplifier, or can be
combined with other OA modules to form differential amplifiers. The output
slew rate of the OA can be configured for optimized settling time vs. power
consumption with the OAPMx bits. When OAPMx = 00 the OA is off and the
output is high-impedance. When OAPMx > 0, the OA is on. See the
device-specific datasheet for parameters.
16.2.2 OA Input
The OA has configurable input selection. The signals for the + and − inputs are
individually selected with the OANx and OAPx bits and can be selected as
external signals or internal signals from one of the DAC12 modules. One of the
non-inverting inputs is tied together internally for all OA modules.
The OA input signal swing is software selectable with the OARRIP bit. When
OARRIP = 0, rail-to-rail input mode is selected and the OA uses higher
quiescent current. See the device datasheet for parameters.
16.2.3 OA Output
The OA has configurable output selection. The OA output signals can be
routed to ADC12 inputs A12 (OA0), A13 (OA1), or A14 (OA2) with the
OAADC0 bit. When OAADC0 = 1 and OAPMx > 0, the OA output is connected
to the corresponding ADC input internally, and the external ADC input is not
connected. The OA output signals can also be routed to ADC12 inputs A1
(OA0), A3 (OA1), or A5 (OA2) when OAFCx = 0, or when OAADC1 = 1. In this
case, the OA output is connected to both the ADC12 input internally, and the
corresponding pin on the device. The OA output is also connected to an
internal R-ladder with the OAFCx bits. The R-ladder tap is selected with the
OAFBRx bits to provide programmable gain amplifier functionality.