Rainbow Electronics ATA6624 - Manual (Page 10)

10
4986F–AUTO–07/08
ATA6622/ATA6624/ATA6626
The VCC regulator is activated, and the internal LIN slave termination resistor is switched on.
The remote wake-up request is indicated by a low level at the RXD pin to interrupt the microcon-
troller (see
Figure 4-5 on page 11 ).
EN high can be used to switch directly from Sleep/Silent to Fail-safe Mode. If EN is still high after
VCC ramp up and undervoltage reset time, the IC switches to the Normal Mode.
Figure 4-4. Switch to Sleep Mode
4.4 Fail-safe Mode
The device automatically switches to Fail-safe Mode at system power-up. The voltage regulator
is switched on (VCC = 3.3V/5V/2%/50 mA) (see
Figure 5-1 on page 14 ). 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. The IC then changes to Nor-
mal Mode. A power down of V
Batt
(V
S
< 4V) during Silent or Sleep Mode switches the IC into
Fail-safe Mode after power up. A low at NRES switches into Fail-safe Mode directly. During
Fail-safe Mode the TXD pin is an output and signals the last wake-up source.
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 5-1 on page 14 ). 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, t
VCC
, depends on the
VCC capacitor and the load.
The NRES is low for the reset time delay t
reset
. During this time, t
reset
, no mode change is
possible.
Delay time sleep mode
t
d_sleep
= maximum 20 µs
LIN switches directly to recessive mode
t
d
= 3.2 µs
LIN
VCC
NRES
TXD
EN
Sleep Mode Normal Mode
Mode select window