ON Semiconductor NCV7341, Manual, Page: 9 / 18

NCV7341
http://onsemi.com
9
transmissions, an internal bus failure flag is set and made
immediately visible through a Low level on the ERR pin.
The transmission and reception circuitry continues to
function.
When four consecutive dominant transmissions succeed
without a bus line short being detected, the internal bus
failure flag is reset and ERR pin is released to High level.
Split Circuit
The V
SPLIT
Pin is operational only in normal and
receive − only modes. It is floating in standby and sleep
modes. The V
SPLIT
can be connected as shown in Figure 2
and Figure 3 and its purpose is to provide a stabilized DC
voltage of V
CC
/2 to the bus avoiding possible steps in the
common − mode signal, therefore reducing EME. These
unwanted steps could be caused by an unpowered node on
the network with excessive leakage current from the bus that
shifts the recessive voltage from its nominal V
CC
/2 level.
Wake − up
The transceiver can detect wake − up events in stand − by,
go − to − sleep and sleep modes. Two types of wake − up events
are handled – remote wake − up via the CAN bus or a local
wake − up via the WAKE pin. A valid remote wake − up is
recognized after two dominant states of the CAN bus of at
least t
dom
, each of them followed by a recessive state of at
least t
rec
.
A local wake − up is detected after a change of state (High
to Low, or Low to High) on WAKE Pin which is stable for
at least t
WAKE
. To increase the EMS level of the WAKE Pin,
an internal current source is connected to it. If the state of the
WAKE Pin is stable at least for t
WAKE
, the direction of the
current source follows (pulldown current for Low state,
pullup current for High state). It is recommended to connect
Pin WAKE either to GND or VBAT if it’s not used in the
application.
Fail Safe Features
Fail safe behavior is ensured by the detection functions
associated with the internal flags.
Furthermore, a current − limiting circuit protects the
transmitter output stage from damage caused by accidental
short circuit to either positive or negative supply voltage,
although power dissipation increases during this fault
condition.
The Pins CANH and CANL are protected from
automotive electrical transients (according to ISO 7637; see
Figure 9). Pins TxD is pulled high and Pins STB and EN are
pulled low internally should the input become disconnected.
Pins TxD, STB, EN and RxD will be floating, preventing
reverse supply should the V
IO
supply be removed.