RM0440 Rev 4 791/2126
RM0440 Operational amplifiers (OPAMP)
829
Programmable gain amplifier mode
The procedure to use the OPAMP as programmable gain amplifier is presented hereafter.
• configure VM_SEL bits as “Feedback resistor is connected to OPAMPx_VINM input”,
10
• configure PGA_GAIN bits as “internal Gain 2, 4, 8, 16,32, or 64”, 00000 to 00101
• 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 amplified by the
selected gain and visible on pin OPAMPx_VOUT.
Note: To avoid saturation, the input voltage must stay below V
DDA
divided by the selected gain.
Figure 173. PGA mode, internal gain setting (x2/x4/x8/x16/x32/x64),
inverting input not used
STM32
+
-
VINM0
VINM1
MSv48041V1
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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