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TLE6251-3G Datasheet, PDF (14/36 Pages) Infineon Technologies AG – High Speed CAN-Transceiver with Wake and Failure Detection | |||
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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 VS power supply.
In typical applications the power supplies VCC and VIO 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 VCC and VIO 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 âRecessiveâ to âDominantâ, followed by a âDominantâ
signal for the time t > tWake initiates a bus Wake-Up (see Figure 6).
CANH
CANL
t < tWake
t > tWake
âRecessiveâ to âDominantâ
change
No Wake-Up
Wake-Up
t
INH
Normal
Operation
mode
Go-To
Sleep
command
Sleep mode
t
Stand-By mode
Figure 6 Remote Wake-Up
In case the time of the âDominantâ signal on the CAN bus is shorter than the filtering time tWake, no bus Wake-Up
occurs. The filter time is implemented to protect the HS CAN transceiver TLE6251-3G against unintended bus
Wake-Upâs, triggered by spikes on the CAN bus. The signal change on the CAN bus from âRecessiveâ to
âDominantâ is mandatory, a permanent âDominantâ 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
âLowâ 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 VS to the
external circuitry.
Data Sheet
14
Rev. 1.1, 2011-06-06
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