ST72321R7-Auto datasheet(241/243 Pages) STMICROELECTRONICS

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ST72321xx-Auto

Known limitations

Doc ID 13829 Rev 1

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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 VDD is approximately

between 0.8V and 1.5V. As a consequence, the I/Os may toggle when VDD 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 VDD ramp up speed the AVD may not start. As a result it

cannot generate interrupts when VDD 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.

1.5V

VIT+

0.8V

LVD RESET

V D

Window

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