Rainbow Electronics ATA6670 - Manual (Page 9)

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9204C–AUTO–09/11
Atmel ATA6670 [Preliminary]
3.13 Local WAKE-up via Pin WAKE2 (Only Available at Transceiver 2)
A falling edge at pin WAKE2 followed by a low level maintained for a certain period of time
(> t
WAKE
) results in a local wake-up request. According to ISO 7637, the wake-up time ensures
that no transients create a wake-up. The transceiver 2 then switches to fail-safe mode. Pin
INH2 is activated (switches to VS2) and the internal slave termination resistor is switched on.
The local wake-up request is indicated by a low level at pin RXD for interrupting the microcon-
troller and by a strong pull-down at pin TXD. (see
Figure 3-5 ).
The voltage threshold for a wake-up signal is 3V below the VS2 voltage with an output current
of typically –3µA. Even in the case of a continuos low at pin WAKE2 it is possible to switch the
transceiver 2 into sleep mode via a low level at pin EN2. The transceiver 2 will remain in sleep
mode for an unlimited time. To generate a new wake-up at pin WAKE2, a high signal for > 6µs
is required. A negative edge then restarts the wake-up filtering time.
Figure 3-5. LIN Transceiver 2: Wake-up from Wake-up Switch (WAKE2)
W a ke2 Pin
INH2
RXD2
TXD2
EN2
S t a te ch a nge
Low or flo a ting
Node in s leep s t a te
Microcontroller s t a rt- u p
del a y time
High
Low Low
EN High
We a k
p u ll-down
Node in
oper a tion
TXD s trong p u ll-down
High or flo a ting
TXD we a k p u ll-down re s i s tor
W a ke filtering time
t
WAKE