Operational amplifiers (OPAMP) RM0440
790/2126 RM0440 Rev 4
Follower configuration mode
The procedure to use the OPAMP in follower mode is presented hereafter.
• configure VM_SEL bits as “opamp_out connected to OPAMPx_VINM input”, 11
• configure VP_SEL bits as “GPIO connected to OPAMPx_VINP”, 00
• As soon as the OPAEN bit is set, the voltage on pin OPAMPx_VINP is buffered to pin
OPAMPx_VOUT.
Note: The pin corresponding to OPAMPx_VINM is free for another usage.
The signal on the OPAMP output is also seen as an ADC input. As a consequence, the
OPAMP configured in follower mode can be used to perform impedance adaptation on input
signals before feeding them to the ADC input, assuming the input signal frequency is
compatible with the operational amplifier gain bandwidth specification.
Figure 172. Follower configuration
STM32
+
-
VINM0
VINM1
MSv48040V1
VOUT
VINP3 or DACx_CHy
VINP2
VINP1
VINP0
1. opamp_out can be redirected internally to an ADC channel by setting OPAINTOEN bit.
In this case, the I/O on which is mapped the OPAMPx_VOUT is free and can be used for another purpose.
opamp_out
(1)
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