AN3248
Analog watchdog during Stop mode
Doc ID 17758 Rev 1
9/19
In an analog watchdog application, COMP1 is configured through external interrupt line 21
(EXTI line 21) to exit the MCU from Stop mode when the analog input voltage exceeds
V
REFINT
. COMP2 is set, through EXTI line 22, to exit the MCU from Stop mode when the
analog voltage goes below the lower threshold. Throughout the time the analog voltage is
within the defined thresholds, the MCU is in Stop mode and power consumption is reduced.
When the analog voltage exceeds the defined thresholds, average power consumption can
be reduced by switching to Run mode.
Figure 6
gives an overview of an analog watchdog application with threshold1 higher than
threshold2.
Figure 6.
Analog watchdog during stop mode
1.
While the MCU is in Stop mode, the input voltage exceeds threshold1 and the MCU exits Stop mode.
2.
While the MCU is in Run mode, the input voltage goes downthreshold1 and the MCU enters Stop mode.
3.
While the MCU is in Stop mode, the input voltage goes down threshold2 and the MCU exits Stop mode.
Note:
In Stop mode, only COMP1, COMP2 and V
REFINT
continue to consume power. Please refer
to the specific device datasheet for power consumption values.
Note:
No hysteresis is implemented on either comparator inputs.
-#5STATE
4IME
-#5EXITS
3TOPMODE
3ENSOROUTPUT
VOLTAGE
6
4IME
4HRESHOLD
62%&).4
-#5EXITS
3TOPMODE
-#5ENTERS
3TOPMODE
AI
4HRESHOLD
