ST72C334J4TAE STMicroelectronics, ST72C334J4TAE Datasheet - Page 27

• Manufacturer Part Number: ST72C334J4TAE
• Description: 8-bit MCU for automotive with single voltage Flash/ROM memory, ADC, 16-bit timers, SPI, SCI interfaces
• Manufacturer: STMicroelectronics

8.1 LOW VOLTAGE DETECTOR (LVD)
To allow the integration of power management
features in the application, the Low Voltage Detec-
tor function (LVD) generates a static reset when
the V
value. This means that it 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 the
Provided the minimum V
the oscillator frequency) is above V
can only be in two modes:
Figure 12. Low Voltage Detector vs Reset
DD
– V
– V
– under full software control
– in static safe reset
RESET
is below:
DD
IT-
IT+
IT-
V
V
IT+
IT-
reference value for a voltage drop is lower
when V
supply voltage is below a V
when V
IT+
reference value for power-on in order
V
DD
DD
DD
is falling
is rising
DD
value (guaranteed for
Figure
IT-
IT-
, the MCU
reference
ST72334xx-Auto, ST72314xx-Auto, ST72124Jx-Auto
12.
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:
1. The LVD allows the device to be used without
any external RESET circuitry.
2. Three different reference levels are selectable
through the option byte according to the applica-
tion requirement.
LVD application note
Application software can detect a reset caused by
the LVD by reading the LVDRF bit in the CRSR
register.
This bit is set by hardware when a LVD reset is
generated and cleared by software (writing zero).
V
hyst
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