Rainbow Electronics ATA6624 - Manual (Page 12)

12
4986F–AUTO–07/08
ATA6622/ATA6624/ATA6626
5. Wake-up Scenarios from Silent or Sleep Mode
5.1 Remote Wake-up via Dominant Bus State
A voltage less than the LIN Pre_Wake detection V
LINL
at the LIN pin activates the internal LIN
receiver.
A falling edge at the LIN pin followed by a dominant bus level V
BUSdom
maintained for a certain
time period (t
BUS
) and a rising edge at pin LIN result in a remote wake-up request. The device
switches from Silent or Sleep Mode to Fail-safe Mode. The VCC voltage regulator is/remains
activated, the INH pin is switched to high, and the internal slave termination resistor is switched
on. The remote wake-up request is indicated by a low level at the RXD pin to generate an inter-
rupt for the microcontroller. A low level at the LIN pin in the Normal Mode starts the bus wake-up
filtering time, and if the IC is switched to Silent or Sleep Mode, it will receive a wake-up after a
positive edge at the LIN pin.
5.2 Local Wake-up via Pin WAKE
A falling edge at the WAKE pin followed by a low level maintained for a certain time period
(t
WAKE
) results in a local wake-up request. The device switches to Fail-safe Mode. The internal
slave termination resistor is switched on. The local wake-up request is indicated by a low level at
the RXD pin to generate an interrupt in the microcontroller and a strong pull down at TXD. When
the Wake pin is low, it is possible to switch to Silent or Sleep Mode via pin EN. In this case, the
wake-up signal has to be switched to high > 10 µs before the negative edge at WAKE starts a
new local wake-up request.
5.3 Local Wake-up via Pin KL_15
A positive edge at pin KL_15 followed by a high voltage level for a certain time period (> t
KL_15
)
results in a local wake-up request. The device switches into the Fail-safe Mode. The internal
slave termination resistor is switched on. The extra long wake-up time ensures that no transients
at KL_15 create a wake up. The local wake-up request is indicated by a low level at the RXD pin
to generate an interrupt for the microcontroller and a strong pull down at TXD. During high-level
voltage at pin KL_15, it is possible to switch to Silent or Sleep Mode via pin EN. In this case, the
wake-up signal has to be switched to low > 250 µs before the positive edge at KL_15 starts a
new local wake-up request. With external RC combination, the time is even longer.
5.4 Wake-up Source Recognition
The device can distinguish between a local wake-up request (Wake or KL_15 pins) and a
remote wake-up request (dominant LIN bus state). The wake-up source can be read on the TXD
pin in Fail-safe Mode. A high level indicates a remote wake-up request (weak pull up at the TXD
pin); a low level indicates a local wake-up request (strong pull down at the TXD pin). The
wake-up request flag (signalled on the RXD pin), as well as the wake-up source flag (signalled
on the TXD pin), is immediately reset if the microcontroller sets the EN pin to high (see
Figure
4-2 on page 8 and Figure 4-3 on page 9 ) and the IC is in Normal Mode. The last wake-up source
flag is stored and signalled in Fail-safe Mode at the TXD pin.