ST7FLITE02 STMICROELECTRONICS [STMicroelectronics], ST7FLITE02 Datasheet - Page 33

• Manufacturer Part Number: ST7FLITE02
• Description: 8-BIT MICROCONTROLLER WITH SINGLE VOLTAGE FLASH MEMORY, DATA EEPROM, ADC, TIMERS, SPI
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

8.4 SYSTEM INTEGRITY MANAGEMENT (SI)
The System Integrity Management block contains
the Low voltage Detector (LVD) and Auxiliary Volt-
age Detector (AVD) functions. It is managed by
the SICSR register.
Note: A reset can also be triggered following the
detection of an illegal opcode or prebyte code. Re-
fer to
8.4.1 Low Voltage Detector (LVD)
The Low Voltage Detector function (LVD) gener-
ates a static reset when the V
below a V
it secures the power-up as well as the power-down
keeping the ST7 in reset.
The V
lower than the V
on in order to avoid a parasitic reset when the
MCU starts running and sinks current on the sup-
ply (hysteresis).
The LVD Reset circuitry generates a reset when
V
The LVD function is illustrated in
The voltage threshold can be configured by option
byte to be low, medium or high. See
on page
Figure 18. Low Voltage Detector vs Reset
DD
– V
– V
V
V
RESET
is below:
IT-
IT+
section 12.2.1 on page 79
IT+(LVD)
IT-(LVD)
IT-(LVD)
(LVD)
(LVD)
114.
IT-(LVD)
when V
when V
reference value for a voltage drop is
V
DD
IT+(LVD)
reference value. This means that
DD
DD
reference value for power-
is rising
is falling
DD
for further details.
Figure
supply voltage is
section 15.1
18.
Provided the minimum V
the oscillator frequency) is above V
MCU can only be in two modes:
In these conditions, secure operation is always en-
sured for the application without the need for ex-
ternal reset hardware.
During a Low Voltage Detector Reset, the RESET
pin is held low, thus permitting the MCU to reset
other devices.
Notes:
The LVD is an optional function which can be se-
lected by option byte. See
114.
It allows the device to be used without any external
RESET circuitry.
If the LVD is disabled, an external circuitry must be
used to ensure a proper power-on reset.
It is recommended to make sure that the V
ply voltage rises monotonously when the device is
exiting from Reset, to ensure the application func-
tions properly.
Caution: If an LVD reset occurs after a watchdog
reset has occurred, the LVD will take priority and
will clear the watchdog flag.
V
– under full software control
– in static safe reset
hys
ST7LITE0x, ST7LITESx
DD
section 15.1 on page
value (guaranteed for
IT-(LVD)
DD
33/125
, the
sup-
1