ST72T311R6T1 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
ST72T311R6T1
STMicroelectronics
'ST72T311R6T1' PDF : 164 Pages View PDF
ST72311R, ST72511R, ST72512R, ST72532R
5.1 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 VDD supply voltage is below a VIT- reference
value. This means that it secures the power-up as
well as the power-down keeping the ST7 in reset.
The VIT- reference value for a voltage drop is lower
than the VIT+ reference value for power-on in order
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
VDD is below:
– VIT+ when VDD is rising
– VIT- when VDD is falling
The LVD function is illustrated in Figure 10.
Provided the minimum VDD value (guaranteed for
the oscillator frequency) is below VIT-, the MCU
can only be in two modes:
Figure 10. Low Voltage Detector vs Reset
– under full software control
– in static safe reset
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 when ordering the device (ordering informa-
tion).
VDD
VIT+
VIT-
Vhys
RESET
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