Figure 159. Standalone Mode: External Gain Setting Mode - ST STM32L4 5 Series Reference Manual

RM0351
23.3.4 OPAMP modes
The operational amplifier inputs and outputs are all accessible on terminals. The amplifiers
can be used in multiple configuration environments:
•
Standalone mode (external gain setting mode)
•
Follower configuration mode
•
PGA modes
Note: The amplifier output pin is directly connected to the output pad to minimize the output
impedance. It cannot be used as a general purpose I/O, even if the amplifier is configured
as a PGA and only connected to the ADC channel.
Note: The impedance of the signal must be maintained below a level which avoids the input
leakage to create significant artifacts (due to a resistive drop in the source). Please refer to
the electrical characteristics section in the datasheet for further details.
Standalone mode (external gain setting mode)
The procedure to use the OPAMP in standalone mode is presented hereafter.
Starting from the default value of OPAMP_CSR, and the default state of GPIOx_MODER,
configure bit OPA_RANGE according the V
the two input pins and the output pin are connected to the operational amplifier.
This default configuration uses the factory trimming values and operates in normal mode
(highest performance). The behavior of the OPAMP can be changed as follows:
•
OPALPM can be set to "operational amplifier low-power" mode in order to save power.
• USERTRIM can be set to modify the trimming values for the input offset.

Figure 159. Standalone mode: external gain setting mode

DocID024597 Rev 5
Operational amplifiers (OPAMP)
voltage. As soon as the OPAEN bit is set,
DDA
689/1830
699