ST72321 datasheet(187/189 Pages) STMICROELECTRONICS

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ST72321

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15.4.2 LVD Startup behaviour

When the LVD is enabled, the MCU reaches its

authorized operating voltage from a reset state.

However, in some devices, the reset state is re-

leased 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 107. LVD Startup Behaviour

15.4.3 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.

15.4.4 Internal RC oscillator operation

Internal RC oscillator operation is not supported in

ROM devices.

15.4.5 External clock source with PLL

External clock source is not supported with the

PLL enabled.

15.4.6 Pull-up not present on PE2

Unlike ST72F321 Flash devices, ST72321 ROM

devices have no weak pull-up on port PE2.

In TQFP44 ROM devices, the PE2 pad is not con-

nected to an internal pull-up like other unbonded

pads (See note 4 under Table 1, “Device Pin De-

scription,” on page 10). It is recommended to con-

figure it as output push pull to avoid added current

consumption.

1.5V

VIT+

0.8V

LVD RESET

V D

Window

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