ST7PLITEU09M3TR View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

ST7PLITEU09M3TR

8-bit MCU with single voltage Flash memory, ADC, timers

STMicroelectronics 

ST7LITEU05 ST7LITEU09

SYSTEM INTEGRITY MANAGEMENT (Cont’d)

Figure 20. Reset and Supply Management Block Diagram

RESET

WATCHDOG

TIMER (WDG)

STATUS FLAG

RESET SEQUENCE

MANAGER

(RSM)

SYSTEM INTEGRITY MANAGEMENT

AVD Interrupt Request

SICSR

01

1

0

0

LVD AVD AVD

RF F IE

7

0

LOW VOLTAGE

VSS

DETECTOR

VDD

(LVD)

AUXILIARY VOLTAGE

DETECTOR

(AVD)

8.4.2 Auxiliary Voltage Detector (AVD)

The Voltage Detector function (AVD) is based on

an analog comparison between a VIT-(AVD) and

VIT+(AVD) reference value and the VDD main sup-

ply voltage (VAVD). The VIT-(AVD) reference value

for falling voltage is lower than the VIT+(AVD) refer-

ence value for rising voltage in order to avoid par-

asitic detection (hysteresis).

The output of the AVD comparator is directly read-

able by the application software through a real

time status bit (AVDF) in the SICSR register. This

bit is read only.

8.4.2.1 Monitoring the VDD Main Supply.

The AVD threshold is selected by the AVD[1:0]

bits in the AVDTHCR register.

If the AVD interrupt is enabled, an interrupt is gen-

erated when the voltage crosses the VIT+(AVD) or

VIT-(AVD) threshold (AVDF bit is set).

In the case of a drop in voltage, the AVD interrupt

acts as an early warning, allowing software to shut

down safely before the LVD resets the microcon-

troller. See Figure 21.

The interrupt on the rising edge is used to inform

the application that the VDD warning state is over

Note: Make sure the right combination of LVD and

AVD thresholds is used as LVD and AVD levels

are not correlated. Refer to section 13.3.2 on page

77 and section 13.3.3 on page 77 for more details.

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