Datasheet

Functional overview STM32L052x6 STM32L052x8
30/143 DocID025936 Rev 8
3.14 Ultra-low-power comparators and reference voltage
The STM32L052x6/8 embed 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 ultra low consumption
• One comparator with rail-to-rail inputs, fast or slow mode.
• The threshold can be one of the following:
– DAC output
– External I/O pins
– Internal reference voltage (V
REFINT
)
– submultiple of Internal reference voltage(1/4, 1/2, 3/4) for the rail to rail
comparator.
Both comparators can wake up the devices 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).
3.15 System configuration controller
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, TIM21, TIM22 and LPTIM timer input captures. It also controls the
routing of internal analog signals to the USB internal oscillator, ADC, COMP1 and COMP2
and the internal reference voltage V
REFINT
.
3.16 Touch sensing controller (TSC)
The STM32L052x6/8 provide a simple solution for adding capacitive sensing functionality to
any application. These devices offer up to 24 capacitive sensing channels distributed over 8
analog I/O groups.
Capacitive sensing technology is able to detect the presence of a finger near a sensor which
is protected from direct touch by a dielectric (such as glass, plastic). The capacitive variation
introduced by the finger (or any conductive object) is measured using a proven
implementation based on a surface charge transfer acquisition principle. It consists of
charging the sensor capacitance and then transferring a part of the accumulated charges
into a sampling capacitor until the voltage across this capacitor has reached a specific
threshold. To limit the CPU bandwidth usage, this acquisition is directly managed by the
hardware touch sensing controller and only requires few external components to operate.
The touch sensing controller is fully supported by the STMTouch touch sensing firmware
library, which is free to use and allows touch sensing functionality to be implemented reliably
in the end application.
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