FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES
Table 10. CAN Interface/33742 Modes and Pin Status—Operation without Ballast on V2 (45)
CANH/CANL
(Disconnected from
Other Node)
CAN Mode
(Controlled by SPI)
CAN
Communication
Mode
V2 Voltage
TXD Pin
RXD Pin
Unpowered
–
–
–
0.0 V
0.0 V
5.0 V
LOW
LOW
LOW
LOW
LOW
5.0 V
Floating to GND
Floating to GND
Floating to GND
NO
NO
NO
Reset (with Ballast)
Normal Request
without Ballast.
V2 Connected to
VDD
Standby without
External Ballast,.
V2 connected to VDD
Normal or Sleep
5.0 V
5.0 V
0.0 V
5.0 V
5.0 V
5.0 V
Floating to GND
NO
Normal without
External Ballast.
V2 Connected to
VDD
Normal
Slew Rate 0, 1, 2,3
Bus Recessive
CANH = CANL = 2.5 V
YES
Normal without
External Ballast,.
V2 Connected to
VDD
Sleep
5.0 V
0.0 V
5.0 V
Floating to GND
NO
Sleep
Sleep
Sleep
0.0 V
0.0 V
LOW
LOW
LOW
LOW
Floating to GND
Floating to GND
NO.
Wake-up if enabled
Stop
NO.
Wake-up if enabled
Notes
45. See also Figure 36, page 55.
extremely low. In most cases the V2 voltage is off; however,
the CAN can be placed into Sleep mode even with 5.0 V
applied on V2.
CAN SLEEP MODE
The 33742 offers two CAN Sleep modes:
• Sleep mode with CAN wake-up enable: detection of
incoming CAN message and SBC wake-up.
• Sleep mode with CAN wake-up disable: no detection of
incoming CAN message.
In CAN Sleep mode, the CANH and CANL drivers are
disabled, and the receiver is also disabled. CANH and CANL
are high-impedance mode to ground.
The CAN Sleep modes are set via the CAN SPI register.
CAN SIGNALS IN TXRX AND SLEEP MODES
In CAN Sleep mode (with wake-up enable or disable), the
CAN interface is internally supplied from the VSUP pin. The
voltage at V2 pin can be either 5.0 V or turned off. When the
CAN is in Sleep mode, the current sourced from V2 is
When the CAN interface is set back into TXRX mode by an
SPI command, CAN H and CANL are set in recessive level.
This is illustrated in Figure 21.
33742
Analog Integrated Circuit Device Data
Freescale Semiconductor
35
FREESCALE [ Freescale ]
