Rainbow Electronics ATA6662 - Manual (Page 5)

5
4916E–AUTO–02/07
ATA6662 [Preliminary]
3.10 Operation Modes
1. Normal mode
This is the normal transmitting and receiving mode. All features are available.
2. Sleep mode
In this mode the transmission path is disabled and the device is in low power mode.
Supply current from V
Batt
is typically 10 µA. A wake-up signal from the LIN bus or via pin
WAKE will be detected and will switch the device to pre-normal mode. If EN then
switches to high, normal mode is activated. Input debounce timers at pin WAKE
(T
WAKE
), LIN (T
BUS
) and EN (T
sleep
,T
nom
) prevent unwanted wake-up events due to auto-
motive transients or EMI. In sleep mode the INH pin is left floating. The internal
termination between pin LIN and pin V
S
is disabled to minimize the power dissipation in
case pin LIN is short-circuited to GND. Only a weak pull-up current (typical 10 µA)
between pin LIN and pin V
S
is present. The sleep mode can be activated independently
from the actual level on pin LIN or WAKE, guaranteeing that the lowest power con-
sumption is achievable even in the case of a continuous dominant level on pin LIN or a
continuous LOW on pin WAKE.
3. Pre-normal mode
At system power-up, the device automatically switches to pre-normal mode. It switches
the INH pin to a high state, to the V
S
level. The microcontroller of the application will
then confirm the normal mode by setting the EN pin to high.
3.11 Remote Wake-up via Dominant Bus State
A voltage less than the LIN pre-wake detection V
LINL
at pin LIN activates the internal LIN
transceiver.
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 pre-normal mode. Pin INH is activated (switches to V
S
) and the internal
termination 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 on page 7 ).
3.12 Local Wake-up via Pin WAKE
A falling edge at pin WAKE, followed by a low level maintained for a certain time period (T
WAKE
),
results in a local wake-up request. The wake-up time (T
WAKE
) ensures that no transient, accord-
ing to ISO7637, creates a wake-up. The device switches to pre-normal mode. Pin INH is
activated (switches to V
S
) and the internal termination resistor is switched on. The local wake-up
request is indicated by a low level at pin RXD to interrupt the microcontroller and a strong
pull-down at pin TXD (see
Figure 3-3 on page 7 ). The voltage threshold for a wake-up signal is
3V below the VS voltage with an output current of typical –3 µA. Even in the case of a continu-
ous low at pin WAKE it is possible to switch the IC into sleep mode via a low at pin EN. The IC
will stay in sleep mode for an unlimited time. To generate a new wake up at pin WAKE it needs
first a high signal > 6 µs before a negative edge starts the wake-up filtering time again.