ATA6623 datasheet(9/24 Pages) ATMEL

9 / 24 page

4957H–AUTO–05/10

ATA6623/ATA6625

Figure 4-5.

LIN Wake-up Diagram from Sleep Mode

4.4

Fail-safe Mode

At system power-up the device automatically switches to Fail-safe Mode. The voltage regulator

is switched on (V

CC = 3.3V/5V/50 mA), (see Figure 6-1 on page 11). The NRES output switches

to low for t

res = 4 ms and gives a reset to the microcontroller. LIN communication is switched off.

The IC stays in this mode until EN is switched to high, and changes then to the Normal Mode. A

power down of V

Batt (VS < 4V) during Silent- or Sleep Mode switches the IC into the Fail-safe

Mode after power up. A logic low at NRES switches the IC into Fail-safe Mode directly.

4.5

Unpowered Mode

If you connect battery voltage to the application circuit, the voltage at the VS pin increases

according to the block capacitor (see Figure 6-1 on page 11). After VS is higher than the VS

undervoltage threshold VS

th, the IC mode changes from Unpowered Mode to Fail-safe Mode.

The VCC output voltage reaches its nominal value after t

VCC. This time, tVCC, depends on the

VCC capacitor and the load.

NRES is low for the reset time delay t

Reset; no mode change is possible during this time.

Regulator wake-up time

Off state

On state

Low

Fail-safe Mode

Normal Mode

EN High

Microcontroller

start-up time delay

Reset

time

Low or floating

NRES

VCC

voltage

regulator

RXD

LIN bus

Bus wake-up filtering time

tbus

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