MAX3058/MAX3059
Receiver
The receiver reads differential input from the bus lines
(CANH, CANL) and transfers this data as a single-
ended output (RXD) to the CAN controller. It consists of
a comparator that senses the difference
V = (CANH -
CANL) with respect to an internal threshold of 0.7V. If
this difference is positive (i.e.,
V > 0.7), a logic low is
present at RXD. If negative (i.e.,
V < 0.7V), a logic
high is present. The receiver always echoes the CAN
BUS data.
The CANH and CANL common-mode range is -7V to
+12V for the MAX3058, and 0V to VCC for the
MAX3059. RXD is logic high when CANH and CANL
are either shorted, or terminated and undriven.
Mode Selection
High-Speed Mode
Connect RS to ground to set the MAX3058/MAX3059 to
high-speed mode. When operating in high-speed
mode, the MAX3058/MAX3059 can achieve transmis-
sion rates of up to 1Mbps. In high-speed mode, use
shielded twisted-pair cable to avoid EMI problems.
Slope-Control Mode
Connect a resistor from RS to ground to select slope-
control mode (Table 3). In slope-control mode, CANH
and CANL slew rates are controlled by the resistor con-
nected to the RS pin. Maximum transmission speeds
are controlled by RRS, and range from 40kbps to
500kbps. Controlling the rise and fall slopes reduces
EMI and allows the use of an unshielded twisted pair or
a parallel pair of wires as bus lines. The transfer func-
tion for selecting the resistor value is given by:
RRS (k
) ≈ 12,500/(maximum speed in kbps)
See the Slew Rate vs. RRS graph in the Typical Oper-
ating Characteristics.
Standby Mode
If a logic-high level is applied to RS, the MAX3058
enters a low-current standby mode. In this mode, the
transmitter is switched off and the receiver is switched
to a low-current/low-speed state. If dominant bits are
detected, RXD switches to low level. The microcon-
troller should react to this condition by switching the
transceiver back to normal operation.
When the MAX3058 enters standby mode, RXD goes
high for 4s (max) regardless of the BUS state.
However, after 4s, RXD goes low only when the BUS is
dominant; otherwise, RXD remains high (when the BUS
is recessive). For proper measurement of standby to
receiver active time (tSBRXDL), the BUS should be in a
dominant state (see Figure 2).
Shutdown Mode
Drive SHDN high to enter shutdown mode on the
MAX3058. Connect SHDN to ground or leave it floating
for normal operation. On the MAX3059, drive RS high to
enter shutdown.
TERM
Drive TERM high (to VCC) or leave it floating to termi-
nate the MAX3059 with 120
resistor connected across
the CANH and CANL. Connect TERM to ground to dis-
connect this resistor.
Thermal Shutdown
If the junction temperature exceeds +160
°C, the device
is switched off. The hysteresis is approximately 25
°C,
disabling thermal shutdown once the temperature
drops to +135
°C. In thermal shutdown, CANH and CANL
go recessive and all IC functions are disabled.
5V, 1Mbps, Low Supply Current
CAN Transceivers
10
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CONDITION FORCED AT PIN RS
MODE
RESULTING CURRENT AT RS (A)
VRS < 0.3 x VCC
High speed
|IRS| < 500
0.4 x VCC <VRS < 0.6 x VCC
Slope control
10A < |IRS| < 200
VRS > 0.75 x VCC
Standby (MAX3058)
|IRS| < 10
VRS > 0.75 x VCC
Shutdown (MAX3059)
|IRS| < 10
Table 3. Mode Selection Truth Table