ST7FLITEU0ICD View Datasheet(PDF) - STMicroelectronics

Part Name

Description

MFG CO.

ST7FLITEU0ICD

8-bit low cost, low pin-count MCU for automotive, with single voltage Flash memory, ADC, timers

STMicroelectronics 

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Interrupts

ST7LUS5, ST7LU05, ST7LU09

Note: 1 These 8 bits can be written only when the I bit in the CC register is set.

2 Changing the sensitivity of a particular external interrupt clears this pending interrupt. This

can be used to clear unwanted pending interrupts. Refer to section External interrupt

function on page 66.

3 IS4[1:0] = 01 is the only safe configuration to avoid a spurious interrupt in Halt and AWUFH

modes.

Table 18. Interrupt sensitivity bits

ISx1

ISx0

External interrupt sensitivity

0

0

Falling edge and low level

0

1

) 1

0

t(s 1

1

Rising edge only

Falling edge only

Rising and falling edge

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System integrity management (SI)

The system integrity management block contains the low voltage detector (LVD) function. It

is managed by the SICSR register.

A reset can also be triggered following the detection of an illegal opcode or prebyte code.

Refer to Illegal opcode reset on page 99 for further details.

Low voltage detector (LVD)

The low voltage detector function (LVD) generates a static reset when the VDD supply

voltage is below a VIT-(LVD) reference value. This means that it secures the power-up as well

as the power-down keeping the ST7 in reset.

The VIT-(LVD) reference value for a voltage drop is lower than the VIT+(LVD) reference value

for power-on in order to avoid a parasitic reset when the MCU starts running and sinks

current on the supply (hysteresis).

The LVD Reset circuitry generates a reset when VDD is below:

● VIT+(LVD) when VDD is rising

● VIT-(LVD) when VDD is falling

The LVD function is illustrated in Figure 19.

The high voltage threshold can be activated by option byte. See Section 14.1 on page 131.

Provided the minimum VDD value (guaranteed for the oscillator frequency) is above VIT-(LVD),

the MCU can only be in two modes:

● under full software control

● in static safe reset

In these conditions, secure operation is always ensured for the application 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.

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