Rainbow Electronics ATA6631 User Manual
Page 10
10
9165A–AUTO–11/09
ATA6629/ATA6631
4.4
Sleep or Silent Mode: Behavior at a Floating LIN-bus or a Short Circuited LIN to GND
In Sleep or in Silent Mode the device has a very low current consumption even during shortcir-
cuits or floating conditions on the bus. A floating bus can arise if the Master pull-up resistor is
missing, e.g., if it is switched off when the LIN- Master is in sleep mode or even if the power
supply of the Master node is switched off.
In order to minimize the current consumption I
VS
in sleep or silent mode during voltage levels at
the LIN-pin below the LIN pre-wake threshold, the receiver is activated only for a specific time
tmon. 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
changes back to sleep respectively Silent Mode. The current consumption is then the result of
I
VSsleep
or I
VSsilent
plus I
LINwake
. If a dominant state is reached on the bus no wake-up will occur.
Even if the voltage rises above the Pre-wake detection high (V
LINH
), the IC will stay in sleep
respectively silent mode (see
This means the LIN-bus must be above the Pre-wake detection threshold V
LINH
for a few micro-
seconds before a new LIN wake-up is possible.
Figure 4-6.
Floating LIN-bus During Sleep or Silent Mode
If the ATA6629/ATA6631 is in Sleep or Silent Mode and the voltage level at the LIN-bus is in
dominant state (V
LIN
< V
BUSdom
) for a time period exceeding t
mon
(during a short circuit at LIN, for
example), the IC switches back to Sleep Mode respectively Silent Mode. The V
S
current
consumption then consists of I
VSsleep
or I
VSsilent
plus I
LINWAKE
. After a positive edge at pin LIN the
IC switches directly to Fail-safe Mode (see
I
V
Ss
leep/
s
ilent
I
V
Ss
leep
I
V
S
f
a
il
+ I
LINw
a
ke
I
V
Ss
leep
V
BU
S
dom
V
LINL
I
V
S
t
mon
LIN Pre-w
a
ke
LIN domin
a
nt
s
t
a
te
LIN BU
S
Mode of
oper
a
tion
Int. P
u
ll-
u
p
Re
s
i
s
tor
RLIN
W
a
ke-
u
p Detection Ph
as
e
off (di
sab
led)
S
leep/
S
ilent Mode
S
leep/
S
ilent Mode