卤80V Fault-Protected, 2Mbps, Low Supply
Current CAN Transceivers
MAX3050/MAX3057
Detailed Description
The MAX3050/MAX3057 interface between the protocol
controller and the physical wires of the bus lines in a
CAN. They are primarily intended for automotive appli-
cations requiring data rates up to 2Mbps and feature
卤80V fault protection against shorts in high-voltage sys-
tems. This fault protection allows the devices to with-
stand up to 卤80V with respect to ground with no
damage to the device. The built-in fault tolerance
allows the device to survive in industrial and automotive
environments with no external protection devices. The
devices provide differential transmit capability to the
bus and differential receive capability to the CAN con-
troller (Figure 4).
The device has four modes of operation: high speed,
slope control, standby, and shutdown. In high-speed
mode, slew rates are not limited, making 2Mbps transmis-
sion speeds possible. Slew rates are controlled in slope-
control mode, minimizing EMI and allowing use of
unshielded twisted or parallel cable. In standby mode,
receivers are active and transmitters are in high imped-
ance. In shutdown mode, transmitters and receivers are
turned off.
The transceivers are designed to operate from a single
+5V supply and draw 56mA of supply current in domi-
nant state and 3.6mA in recessive state. In standby
mode, supply current is reduced to 125碌A. In shutdown
mode, supply current is 15碌A.
CANH and CANL are output short-circuit current limited
and are protected against excessive power dissipation
by thermal-shutdown circuitry that places the driver
outputs into a high-impedance state.
Fault Protection
The MAX3050/MAX3057 feature 卤80V fault protection.
This extended voltage range of CANH and CANL bus
lines allows use in high-voltage systems and communi-
cation with high-voltage buses. If data is transmitting at
2Mbps, the fault protection is reduced to 卤70V.
Transmitter
The transmitter converts a single-ended input (TXD)
from the CAN controller to differential outputs for the
bus lines (CANH, CANL). The truth table for the trans-
mitter and receiver is given in Table 1.
V
CC
MAX3050
THERMAL
SHUTDOWN
CANH
TXD
TRANSMITTER
CONTROL
CANL
RS
MODE
SELECTION
GND
RXD
RECEIVER
0.75V
WAKE
7.5V
AutoShutdown
SHDN
Figure 4. Functional Diagram
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