Datasheet

Data Sheet 14 Rev. 1.1, 2011-06-06
TLE6251-3G
Wake-Up Functions
6 Wake-Up Functions
There are several possibilities for a mode change from Sleep mode to another operation mode.
• Remote Wake-Up via a message on the CAN bus.
• Local Wake-Up via a signal change on the pin WK.
• A status change of the logical signals applied to the mode control pins EN and NSTB.
• An under-voltage detection on the
V
S
power supply.
In typical applications the power supplies
V
CC
and V
IO
are turned off in Sleep mode, meaning a mode change can
only be caused by an external event, also called Wake-Up. In case the
V
CC
and V
IO
power supply are available, a
mode change can be simple caused by changing the status on the mode control pins EN and NSTB.
6.1 Remote Wake-Up
A remote Wake-Up or also called bus Wake-Up occurs via a CAN bus message and changes the operation mode
from Sleep mode to Stand-By mode. A signal change from “Recessive” to “Dominant”, followed by a “Dominant”
signal for the time t >
t
Wake
initiates a bus Wake-Up (see Figure 6).
Figure 6 Remote Wake-Up
In case the time of the “Dominant” signal on the CAN bus is shorter than the filtering time
t
Wake
, no bus Wake-Up
occurs. The filter time is implemented to protect the HS CAN transceiver TLE6251-3G against unintended bus
Wake-Up’s, triggered by spikes on the CAN bus. The signal change on the CAN bus from “Recessive” to
“Dominant” is mandatory, a permanent “Dominant” signal would not activate any bus Wake-Up.
In Stand-By mode the RxD output pin and the NERR output pin display the CAN bus Wake-Up event by a logical
“Low” signal (Details see Chapter 8). Once the HS CAN Transceiver TLE6251-3G has recognized the Wake-Up
event and has changed to Stand-By mode, the INH output pin becomes active and provides the voltage
V
S
to the
external circuitry.
CANH
CANL
INH
t > t
Wake
Go-To
Sleep
command
Stand-By mode
Normal
Operation
mode
t
t
Sleep mode
„Recessive“ to „Dominant“
change
t < t
Wake
No Wake-Up
Wake-Up