ST72340 datasheet(34/191 Pages) STMICROELECTRONICS

Part #	ST72340

Description	8-BIT MCU WITH UP TO 16K FLASH MEMORY, 10-BIT ADC, TWO 16-BIT TIMERS, TWO I2C, SPI, SCI

PDF	191 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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34 / 191 page

ST72340, ST72344, ST72345

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SYSTEM INTEGRITY MANAGEMENT (Cont’d)

7.5.2 Auxiliary Voltage Detector (AVD)

The AVD is used to provide the application with an

early warning of a drop in voltage. If enabled, an

interrupt can be generated allowing software to

shut down safely before the LVD resets the micro-

controller. See Figure 19.

The AVD function is active only if the LVD is ena-

bled through the option byte (see Section 15.1 on

page 181). The activation level of the AVD is fixed

at around 0.5 mV above the selected LVD thresh-

old.

In the case of a drop in voltage below VIT-(PVD), the

AVDF flag is set and an interrupt request is issued.

If VDD rises above the VIT+(AVD) threshold voltage

the AVDF bit is cleared automatically by hardware.

No interrupt is generated, and therefore software

should poll the AVDF bit to detect when the volt-

age has risen, and resume normal processing.

Figure 19. Using the AVD to Monitor VDD

VDD

VIT-(AVD)

AVDF bit

RESET VALUE

IF AVDIE bit = 1

AVD INTERRUPT

REQUEST

INTERRUPT PROCESS

VIT-(LVD)

LVD RESET

Early Warning Interrupt

(Power has dropped, MCU not

not yet in reset)

VIT+(AVD)

Vhys

ST72340 Datasheet(PDF) 34 Page - STMicroelectronics