Datasheet

DocID027096 Rev 2 29/137
STM32L073xx Functional overview
36
3.13.2 V
LCD
voltage monitoring
This embedded hardware feature allows the application to measure the V
LCD
supply voltage
using the internal ADC channel ADC_IN16. As the V
LCD
voltage may be higher than V
DDA
,
and thus outside the ADC input range, the ADC input is connected to LCD_VLCD2 (which
provides 1/3V
LCD
when the LCD is configured 1/3Bias and 1/4V
LCD
when the LCD is
configured 1/4Bias or 1/2Bias).
3.14 Digital-to-analog converter (DAC)
Two 12-bit buffered DACs can be used to convert digital signal into analog voltage signal
output. An optional amplifier can be used to reduce the output signal impedance.
This digital Interface supports the following features:
• One data holding register (for each channel)
• Left or right data alignment in 12-bit mode
• Synchronized update capability
• Noise-wave generation
• Triangular-wave generation
• Dual DAC channels with independent or simultaneous conversions
• DMA capability (including the underrun interrupt)
• External triggers for conversion
• Input reference voltage V
REF+
Six DAC trigger inputs are used in the STM32L073xx. The DAC channels are triggered
through the timer update outputs that are also connected to different DMA channels.
3.15 Ultra-low-power comparators and reference voltage
The STM32L073xx 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).
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