AN3248

Analog voltage monitoring

Doc ID 17758 Rev 3

5/17

Figure 2 shows how to connect a sensor output to an STM32L1 device using comparator 1

(COMP1). COMP1 shares the same inputs as the ADC which reduces the number of

Figure 2.

Sensor output connection to COMP1

1.

Legend for Figure 2

COMP1_INP/ADC CHx: comparator 1 non-inverting input shared with ADC channel x

2.

Only if required.

Figure 3 shows the gain in power consumption in an analog monitoring application.

Figure 3.

Power consumption in an analog voltage monitoring application

1.

Legend for Figure 3

S: Stop mode

R: Run mode

The input analog voltage can be connected either to PB4 or PB5. The analog threshold can

PB3. DAC channel 1 and channel 2 (DAC_OUT1 and DAC_OUT2 respectively) cannot be

used in such application cases since the DAC channels are powered off in Stop mode.

Ai18734

Sensor

Analog

voltage

COMP1_INP/

STM32L1 device

S

R

S

R

S

R

S

Input analog voltage

Analog threshold

Time

MCU state

Time

Time

MCU current consumption

Few mA

Few μA

ai17492