MC33742EP Freescale, MC33742EP Datasheet - Page 45

• Manufacturer Part Number: MC33742EP
• Manufacturer: Freescale

Specifications of MC33742EP

• Data Rate: 1000Kbps
• Number Of Transceivers: 1
• Standard Supported: CAN 2.0
• Operating Supply Voltage (max): 27V
• Operating Supply Voltage (typ): 5/9/12/15/18/24V
• Operating Supply Voltage (min): 4.5V
• Supply Current: 45mA
• Operating Temperature (max): 125C
• Operating Temperature (min): -40C
• Operating Temperature Classification: Automotive
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Compliant

RXD FAILURE DETECTION
HIGH transition of the differential receiver. Excluding internal
propagation delay, RXD output should be LOW when the
differential receiver is LOW. In the event RXD is shorted to
5.0V (e.g., to VDD), RXD will be tied to a high level and the
RXD short to 5.0V can be detected at the next LOW-to-HIGH
transition of the differential receiver. Compete detection
requires three samples.
CAN driver is disabled. The error is reported through the SPI
register LPC, bit RXPR.
RECOVERY CONDITION
sampling for a correct low level at TXD, as illustrated in
Figure
RXD driver is deactivated and a weak pulldown current
source is activated in order to allow recovery conditions. The
driver stays disabled until the failure is cleared (RXD no
longer permanent recessive) and the bus driver is activated
by an SPI register command (write 1 to the CANCLR bit in the
CAN register).
Diff Output
RXD Output
RXD Flag
Analog Integrated Circuit Device Data
Freescale Semiconductor
Note RXD Flag is neither the RXPR bit in the LPC register
The SBC senses the RXD output voltage at each LOW-to-
When the error is detected, an error flag is latched and the
The SBC will try to recover from a bus fault condition by
As soon as an RXD permanent recessive is detected, the
CANH
CANL
nor the CANF bit in INTR register.
26.
RXD Flag Latched
Figure 26. RXD Recovery Conditions
RXD Short to V
DD
Sampling
RXD no longer shorted to V
Sampling
DD
TXD PERMANENT DOMINANT FAILURE
PRINCIPLE
bus is set into dominant level, and no communication is
possible. The SBC has a TXD permanent timeout detector.
After timeout, the bus driver is disabled and the bus is
released in a recessive state. The TXD permanent dominant
failure is reported in the TIM1 register.
RECOVERY
in case of TXD short to RXD. The recovery condition for TXD
permanent dominant (recovery means the reactivation of the
CAN drivers) is done by an SPI command and is controlled
by the MCU.
no longer permanent dominant) and the bus driver is
activated by an SPI register command (write logic [1] to
CANCLR bit in the CAN register).
TXD TO RXD SHORT CIRCUIT FAILURE
PRINCIPLE
CAN message is received, the RXD will be at a LOW.
Consequently, the TXD pin is LOW and drives CANH and
CANL into the dominant state. The bus is stuck in dominant
mode and no further communication is possible.
DETECTION AND RECOVERY
and release the CANL and CANH drivers. However, at the
next incoming dominant bit, the bus will be stuck again in
dominant. In order to avoid this situation, the recovery from a
failure (recovery means the reactivation of the CAN drivers)
is done by an SPI command and controlled by the MCU.
INTERNAL ERROR OUTPUT FLAGS
protection is activated or over-current detection occurs on the
CANL or CANH pins (THERM-CUR bit). The errors are
reported in the CAN register.
In the event TXD is set to a permanent low level, the CAN
The TXD permanent dominant is used and activated also
The driver stays disabled until the failure is cleared (TXD
In the event the TXD is shorted to RXD when an incoming
The TXD permanent dominant timeout will be activated
There are internal error flags to signal whenever thermal
FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES
33742
45