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ST72321xx-Auto Known limitations
Doc ID 13829 Rev 1 241/243
Consequently, the LVD function is not guaranteed in the current silicon revision. For
complete security, an external reset circuit must be added.
22.3.2 LVD startup behavior
When the LVD is enabled, the MCU reaches its authorized operating voltage from a reset
state. However, in some devices, the reset state is released when V
DD
is approximately
between 0.8V and 1.5V. As a consequence, the I/Os may toggle when V
DD
is within this
window.
This may be an issue especially for applications where the MCU drives power components.
Figure 108. LVD startup behavior
22.3.3 AVD not supported
On some devices with a specific V
DD
ramp up speed the AVD may not start. As a result it
cannot generate interrupts when V
DD
rises and falls.
22.3.4 Internal RC oscillator operation
Internal RC oscillator operation is not supported in ROM devices.
22.3.5 External clock source with PLL
External clock source is not supported with the PLL enabled.
22.3.6 Pull-up not present on PE2
Unlike ST72F321 Flash devices, ST72321 ROM devices have no weak pull-up on port PE2.
In LQFP44 ROM devices, the PE2 pad is not connected to an internal pull-up like other
unbonded pads. It is recommended to configure it as output push-pull to avoid added
current consumption.
22.3.7 Readout protection with LVD
The LVD is not supported if readout protection is enabled.
5V
1.5V
V
IT+
0.8V
LVD RESET
V
D
D
Window
t
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