MAX13041
when battery voltage is first applied to VBAT. When the
PWON flag is set, UVNOM is cleared and sleep mode is
disabled. The primary function of the PWON flag is to pre-
vent the MAX13041 from entering sleep mode (and there-
by disabling external voltage regulators) before the
protocol controller establishes control through EN and
STB. The PWON flag is externally indicated as a logic-low
on
ERR when the MAX13041 is placed into PWON/listen-
only mode from standby mode, go-to-sleep command
mode, or sleep mode. The PWON flag is cleared when
the MAX13041 enters normal mode.
Wake-Up Flag
The wake-up flag is set when a local or remote wake-up
request is detected. A local wake-up request is gener-
ated when the logic level on WAKE changes and
remains stable for tWAKE. A remote wake-on CAN
request is generated upon the detection of two domi-
nant bus cycles, each followed by a recessive bus
cycle (see Figure 5.) Each bus cycle must exceed
tBUS(DOM). The wake-up flag can only be set in stand-
by mode, go-to-sleep command mode, or sleep mode.
Setting the wake-up flag resets UVNOM, and wake-up
requests are not detected during the UVNOM flag wait-
ing time immediately after UVNOM has been set. The
wake-up flag is immediately available as a logic-low on
ERR and RXD, provided that VI/O and VCC are both
present. The wake-up flag is cleared when the
MAX13041 enters normal mode.
Wake-Up Source Flag
The wake-up source flag is set concurrently with the
wake-up source flag when a local wake-up event is
detected. The wake-up source flag can only be set
after the PWON flag has been cleared. The flag is
cleared when the MAX13041 leaves normal mode and
during initial power-on. The wake-up source flag is
externally indicated on
ERR when the MAX13041 is in
±80V Fault-Protected High-Speed CAN Transceiver
with Low-Power Management and Wake-On CAN
14
______________________________________________________________________________________
CANH
CANL
DOMINANT
RECESSIVE
DOMINANT
RECESSIVE
tBUSDOM
Figure 5. Wake-On-CAN Timing
INTERNAL FLAG
FLAG AVAILABLE ON
ERR
CONDITIONS TO CLEAR FLAG
UVNOM
No
Set PWON or wake-up flags
UVBAT
No
Recovery of VBAT
PWON
In PWON/listen-only mode (changing from
standby, go-to-sleep command, or sleep modes)
Entering normal mode
Wake-Up
In standby, go-to-sleep command, and sleep
modes (provided VI/O and VCC are present)
Entering normal mode or setting PWON or UVNOM
flag
Wake-Up Source
In normal mode (before the fourth dominant to
recessive edge on TXD, Note 10)
Leaving normal mode or setting PWON flag
Bus Failure
In normal mode (after the fourth dominant to
recessive edge on TXD, Note 10)
Re-entering normal mode
Local Failure
In PWON/listen-only mode (coming from normal
mode)
Entering normal mode or whenever RXD is
dominant while TXD is recessive (and all local
failures are resolved)
Table 2. Flag Signaling on
ERR
Note 10: Allow for a dominant time of at least 4s per dominant-recessive cycle.