ON Semiconductor NCV7341 Manual page 7

Table 3. OPERATION MODES
Undervoltage
Pin STB Pin EN
X X
Low Low
Low High
High Low
High High
Normal Mode
In Normal mode, the transceiver is able to communicate
via the bus lines. The CAN controller can transmit data to the
bus via TxD pin and receive data from the bus via Pin RxD.
The bus lines (CANH and CANL) are internally biased to
V /2 via the common−mode input resistance. Pin V
CC
is also providing voltage V
to externally stabilize the common mode voltage of the bus
– see Figure 2 and Figure 3. Pin INH is active (pulled high)
so that the external regulators controlled by INH Pin are
switched on.
Receive−Only Mode
In Receive−only mode, the CAN transmitter is disabled.
The CAN controller can still receive data from the bus via
RxD Pin as the receiver part remains active. Equally to
normal mode, the bus lines (CANH and CANL) are
internally biased to V /2 and Pin V
CC
voltage V /2. Pin INH is also active (pulled high).
CC
Standby Mode
Standby mode is a low−power mode. Both the transmitter
and the receiver are disabled and a very low−power
differential receiver monitors the CAN bus activity. Bus
lines are biased internally to ground via the common mode
input resistance and Pin V
SPLIT
A wake−up event can be detected either on the CAN bus or
on the WAKE Pin. A valid wake−up is signaled on pins ERR
and RxD. Pin INH remains active (pulled high) so that the
external regulators controlled by INH Pin are switched on.
Go−To−Sleep Mode
Go−To−Sleep mode is an intermediate state used to put the
transceiver into sleep mode in a controlled way.
Go−To−Sleep mode is entered when the CAN controller
Conditions
V /V VBAT
CC IO
Undervoltage
Flag Flag
Set X
Reset Set
Reset Reset
Reset Reset
Reset Reset
Reset Reset
SPLIT
/2 which can be further used
CC
is providing
SPLIT
is high−impedant (floating).
http://onsemi.com
NCV7341
Power−up or
Wakeup Flag
X
Set
Reset If in sleep, then no change
Set
Reset If in sleep, then no change
Set
Reset
If in sleep, then no change
X
X
puts pin EN to High and STB Pin to Low. If the logical state
of Pins EN and STB is kept unchanged for minimum period
of t and neither a wake−up nor a power−up event occur
h(min)
during this time, the transceiver enters sleep mode. While in
go−to−sleep mode, the transceiver behaves identically to
stand−by mode.
Sleep Mode
Sleep mode is a low−power mode in which the
consumption is further reduced compared to stand−by
mode. Sleep mode can be entered via go−to−sleep mode or
in case an undervoltage on either V
longer than the under−voltage detection time. The
transceiver behaves identically to standby mode, but the
INH Pin is deactivated (left floating) and the external
regulators controlled by INH Pin are switched off. In this
way, the V consumption is reduced to a minimum. The
BAT
device will leave sleep mode either by a wake−up event (in
case of a CAN bus wake−up or via Pin WAKE) or by putting
Pin STB high (as long as an under−voltage on V
is not detected).
Internal Flags
The transceiver keeps several internal flags reflecting
conditions and events encountered during its operation.
Some flags influence the operation mode of the transceiver
(see Figure 5 and Table 3). Beside the undervoltage and the
TxD dominant timeout flags, all others can be read by the
CAN controller on Pin ERR. Pin ERR signals internal flags
depending on the operation mode of the transceiver. An
overview of the flags and their visibility on Pin ERR is given
in Table 4. Because the ERR Pin uses negative logic, it will
be pulled low if the signaled flag is set and will be pulled
high if the signaled flag is reset.
7
Transceiver Behavior
Operating Mode
Sleep
Standby
otherwise stand−by
Stand−by
otherwise stand−by
Stand−by
otherwise go−to−sleep
Receive−only
Normal
or V
CC IO
Pin INH
Floating
High
Floating
High
High
Floating
High
High
Floating
High
High
High
occurs for
or V
CC IO