TJA1054A Datasheet, PDF (7/27 Pages) NXP Semiconductors – Fault-tolerant CAN transceiver

NXP Semiconductors
TJA1054A
Fault-tolerant CAN transceiver
7.2 Low power modes
The transceiver provides three low power modes which can be entered and exited via
STB and EN (see Table 5 and Figure 3).
The sleep mode is the mode with the lowest power consumption. Pin INH is switched to
HIGH-impedance for deactivation of the external voltage regulator. Pin CANL is biased to
the battery voltage via pin RTL. If the supply voltage is provided, pins RXD and ERR will
signal the wake-up interrupt.
The standby mode operates in the same way as the sleep mode but with a HIGH level on
pin INH.
The power-on standby mode is the same as the standby mode, however, in this mode the
battery power-on flag is shown on pin ERR instead of the wake-up interrupt signal. The
output on pin RXD will show the wake-up interrupt. This mode is only for reading out the
power-on flag.
Table 5.
Mode
Normal operating and low power modes
Pin STB Pin EN Pin ERR
LOW
HIGH
Goto-sleep LOW
command
Sleep
LOW
Standby LOW
Power-on HIGH
standby
HIGH
LOW^[4]
LOW
LOW
wake-up
interrupt
signal
[1][2][3]
V_BAT
power-on
flag^[1][5]
Normal
HIGH
operating
HIGH
error flag no error
flag
Pin RXD
LOW
HIGH
wake-up
interrupt
signal
[1][2][3]
Pin RTL
switched
to
V_BAT
wake-up
interrupt
signal
[1][2][3]
dominant
received
data
recessive
received
data
V_BAT
V_CC
[1] If the supply voltage V_CC is present.
[2] Wake-up interrupts are released when entering normal operating mode.
[3] A local or remote wake-up event will be signalled at the transceiver pins RXD and ERR if
V_BAT = 5.3 V to 27 V.
[4] In case the goto-sleep command was used before. When V_CC drops, pin EN will become LOW, but due to
the fail-safe functionality this does not effect the internal functions.
[5] V_BAT power-on flag will be reset when entering normal operating mode.
Wake-up requests are recognized by the transceiver through two possible channels:
• The bus lines for remote wake-up
• Pin WAKE for local wake-up
In order to wake-up the transceiver remotely through the bus lines, a filter mechanism is
integrated. This mechanism makes sure that noise and any present bus failure conditions
do not result into an erroneous wake-up. Because of this mechanism it is not sufficient to
simply pull the CANH or CANL bus lines to a dominant level for a certain time. To
guarantee a successful remote wake-up under all conditions, a message frame with a
dominant phase of at least the maximum specified t_(CANH) or t_(CANL) in it is required.
TJA1054A_5
Product data sheet
Rev. 05 — 29 September 2009
© NXP B.V. 2009. All rights reserved.
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