12 remote wake-up via dominant bus state – Rainbow Electronics ATA6664 User Manual
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9146E–AUTO–03/11
Atmel ATA6663/ATA6664
3.12
Remote Wake-up via Dominant Bus State
A voltage lower than the LIN pre-wake detection V
LINL
at pin LIN activates the internal LIN
receiver and starts the wake-up detection timer.
A falling edge at pin LIN, followed by a dominant bus level V
BUSdom
maintained for a certain
time period (> t
BUS
) and a rising edge at pin LIN results in a remote wake-up request. The
device switches to fail-safe mode. Pin INH is activated (switches to V
S
) and the internal termi-
nation resistor is switched on. The remote wake-up request is indicated by a low level at pin
RXD to interrupt the microcontroller (see
Figure 3-2.
LIN Wake-up Waveform Diagram
In sleep mode the device has a very low current consumption, even during short-circuits or
floating conditions on the bus. A floating bus can arise if the Master pull-up resistor is missing,
e.g., in case it is switched off when the LIN Master is in sleep mode or if the power supply of
the Master node is switched off.
To minimize the current consumption I
VS
during voltage levels at the LIN-pin below the LIN
pre-wake threshold, the receiver is activated only for a specific time t
mon
. If t
mon
elapses while
the voltage at the bus is lower than pre-wake detection low (V
LINL
) and higher than the LIN
dominant level, the receiver is switched off again and the circuit reverts to sleep mode. The
current consumption is then the result of I
VSsleep
plus I
LINwake
. If a dominant state is reached on
the bus no wake-up will occur. Even if the voltage exceeds the pre-wake detection high
(V
LINH
), the IC will remain in sleep mode (see
).
This means the LIN bus must be above the Pre-wake detection threshold V
LINH
for a few
microseconds before a new LIN wake-up is possible.
Microcontroller
s
t
a
rt-
u
p
del
a
y time
B
us
w
a
ke-
u
p filtering time
(t
BU
S
)
Off
s
t
a
te
Node in
s
leep
s
t
a
te
High or flo
a
ting
Low or flo
a
ting
Low
High
EN High
Norm
a
l
Mode
Reg
u
l
a
tor w
a
ke-
u
p time del
a
y
INH
Extern
a
l
volt
a
ge
reg
u
l
a
tor
EN
RXD
LIN
bus