st72321j STMicroelectronics, st72321j Datasheet - Page 26

• Manufacturer Part Number: st72321j
• Description: 8-bit Mcu With Nested Interrupts, Flash, 10-bit Adc, 5 Timers, Spi, Sci, I2c Interface
• Manufacturer: STMicroelectronics

ST72321J
6.4 SYSTEM INTEGRITY MANAGEMENT (SI)
The System Integrity Management block contains
the Low Voltage Detector (LVD), Auxiliary Voltage
Detector (AVD) and Clock Security System (CSS)
functions. It is managed by the SICSR register.
6.4.1 Low Voltage Detector (LVD)
The Low Voltage Detector function (LVD) gener-
ates a static reset when the V
below a V
secures the power-up as well as the power-down
keeping the ST7 in reset.
The V
than the V
to avoid a parasitic reset when the MCU starts run-
ning and sinks current on the supply (hysteresis).
The LVD Reset circuitry generates a reset when
V
The LVD function is illustrated in
Figure 13. Low Voltage Detector vs Reset
26/179
DD
– V
– V
RESET
is below:
IT-
IT+
IT-
V
V
reference value for a voltage drop is lower
when V
when V
IT+
IT-
IT+
IT-
reference value for power-on in order
reference value. This means that it
V
DD
DD
DD
is falling
is rising
DD
supply voltage is
Figure
13.
Provided the minimum V
the oscillator frequency) is above V
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 allows the device to be used without any
external RESET circuitry.
The LVD is an optional function which can be se-
lected by option byte.
V
– under full software control
– in static safe reset
hys
DD
value (guaranteed for
IT-
, the MCU