Datasheet

Functional overview STM32L15xCC STM32L15xRC STM32L15xUC STM32L15xVC
26/132 DocID022799 Rev 6
3.12 Operational amplifier
The STM32L15xxC embeds two operational amplifiers with external or internal follower
routing capability (or even amplifier and filter capability with external components). When
one operational amplifier is selected, one external ADC channel is used to enable output
measurement.
The operational amplifiers feature:
 Low input bias current
 Low offset voltage
 Low power mode
 Rail-to-rail input
3.13 Ultra-low-power comparators and reference voltage
The STM32L15xxC embeds two comparators sharing the same current bias and reference
voltage. The reference voltage can be internal or external (coming from an I/O).
 One comparator with fixed threshold
 One comparator with rail-to-rail inputs, fast or slow mode. The threshold can be one of
the following:
– DAC output
– External I/O
– Internal reference voltage (V
REFINT
) or a sub-multiple (1/4, 1/2, 3/4)
Both comparators can wake up from Stop mode, and be combined into a window
comparator.
The internal reference voltage is available externally via a low power / low current output
buffer (driving current capability of 1 µA typical).
3.14 System configuration controller and routing interface
The system configuration controller provides the capability to remap some alternate
functions on different I/O ports.
The highly flexible routing interface allows the application firmware to control the routing of
different I/Os to the TIM2, TIM3 and TIM4 timer input captures. It also controls the routing of
internal analog signals to ADC1, COMP1 and COMP2 and the internal reference voltage
V
REFINT
.
3.15 Touch sensing
The STM32L15xxC devices provide a simple solution for adding capacitive sensing
functionality to any application. These devices offer up to 23 capacitive sensing channels
distributed over 10 analog I/O groups. Both software and timer capacitive sensing
acquisition modes are supported.
Capacitive sensing technology is able to detect the presence of a finger near a sensor which
is protected from direct touch by a dielectric (glass, plastic, ...). The capacitive variation
introduced by the finger (or any conductive object) is measured using a proven