st62t25cn6 STMicroelectronics, st62t25cn6 Datasheet - Page 23

• Manufacturer Part Number: st62t25cn6
• Description: 8-bit Mcus With A/d Converter, Two Timers, Oscillator Safeguard & Safe Reset
• Manufacturer: STMicroelectronics

5.2 LOW VOLTAGE DETECTOR (LVD)
The on-chip Low Voltage Detector is enabled by
setting a bit in the option bytes (refer to the Option
Bytes section of this document).
The LVD allows the device to be used without any
external RESET circuitry. In this case, the RESET
pin should be left unconnected.
If the LVD is not used, an external circuit is manda-
tory to ensure correct Power On Reset operation,
see figure in the Reset section. For more details,
please refer to the application note AN669.
The LVD generates a static Reset when the supply
voltage is below a reference value. This means
that it secures the power-up as well as the power-
down keeping the ST6 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).
Figure 12. Low Voltage Detector Reset
RESET
IT-
V
V
reference value for a voltage drop is lower
IT+
IT-
IT+
reference value for power-on in order
V
DD
The LVD Reset circuitry generates a reset when
V
– V
– V
The LVD function is illustrated in
If the LVD is enabled, the MCU can be in only one
of two states:
– Over the input threshold voltage, it is running un-
– Below the input threshold voltage, it is in static
In these conditions, secure operation is guaran-
teed without the need for external reset hardware.
During a Low Voltage Detector Reset, the RESET
pin is held low, thus permitting the MCU to reset
other devices.
V
DD
der full software control
safe reset
hyst
IT+
IT-
is below:
when V
when V
DD
DD
is falling
is rising
ST6215C/ST6225C
Figure
12.
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