Operational amplifier (OPAMP)
RM0365
DocID025202 Rev 7
18
Operational amplifier (OPAMP)
18.1 OPAMP
introduction
STM32F302xB/C/D/E devices embed 2 operational amplifiers OPAMP1, OPAMP2 and
STM32F302x6/8 devices embed 1 operational amplifier OPAMP2. They can either be used
as standalone amplifiers or as follower / programmable gain amplifiers.
The operational amplifier output is internally connected to an ADC channel for measurement
purposes.
18.2
OPAMP main features
•
Rail-to-rail input/output
•
Low offset voltage
•
Capability of being configured as a standalone operational amplifier or as a
programmable gain amplifier (PGA)
•
Access to all terminals
•
Input multiplexer on inverting and non-inverting input
•
Input multiplexer can be triggered by a timer and synchronized with a PWM signal.
18.3
OPAMP functional description
18.3.1 General
description
On every OPAMP, there is one 4:1 multiplexer on the non-inverting input and one 2:1
multiplexer on the inverting input.
The inverting and non inverting inputs selection is made using the VM_SEL and VP_SEL
bits respectively in the OPAMPx_CSR register.
The I/Os used as OPAMP input/outputs must be configured in analog mode in the GPIOs
registers.
The connections with dedicated I/O are summarized in the table below and in
and
Table 105. Connections with dedicated I/O
OPAMP1 inverting
input
OPAMP1 non
inverting input
OPAMP2 inverting
input
OPAMP2 non
inverting input
PA3 (VM1)
PA1 (VP0)
PA5 (VM1)
PA7 (VP0)
PC5 (VM0)
PA7 (VP1)
PC5 (VM0)
PD14 (VP1)
PA5 (VP3)
PA3 (VP2)
-
PB0 (VP2)
-
-
-
PB14 (VP3)
(1)
1. Only in STM32F302xB/C/D/E devices.