Datasheet

TJA1055 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet Rev. 5 — 6 December 2013 7 of 26
NXP Semiconductors
TJA1055
Enhanced 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. Pins RXD and ERR
will signal the wake-up interrupt even
in case V
CC
is not present.
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.
[1] Wake-up interrupts are released when entering normal operating mode.
[2] For TJA1055T a diode is added in series with the high-side driver of ERR
and RXD to prevent a reverse
current from ERR
to V
CC
in the unpowered state.
[3] For TJA1055T/3, ERR
and RXD are open-drain.
[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
dom(CANH)
or t
dom(CANL)
in it is required.
Table 5. Normal operating and low power modes
Mode Pin STB Pin EN Pin ERR Pin RXD Pin RTL
switched
to
LOW HIGH LOW HIGH
Goto-sleep
command
LOW HIGH wake-up
interrupt
signal
[1]
[2][3]
wake-up
interrupt
signal
[1]
[2][3]
V
BAT
Sleep LOW LOW
[4]
Standby LOW LOW
Power-on
standby
HIGH LOW V
BAT
power-on
flag
[5]
wake-up
interrupt
signal
[1]
V
BAT
Normal
operating
HIGH HIGH error flag no error
flag
dominant
received
data
recessive
received
data
V
CC