MAX13442E Datasheet, PDF (16/18 Pages) Maxim Integrated Products – ±15kV ESD-Protected, ±80V Fault-Protected, Fail-Safe RS-485/J1708 Transceivers

±15kV ESD-Protected, ±80V Fault-Protected,
Fail-Safe RS-485/J1708 Transceivers
J1708 Applications
The MAX13444E is designed for J1708 applications. To
configure the MAX13444E, connect DE and RE to GND.
Connect the signal to be transmitted to TXD. Terminate
the bus with the load circuit as shown in Figure 14. The
drivers used by SAE J1708 are used in a dominant-
mode application. DE is active low; a high input on DE
places the outputs in high impedance. When the driver is
disabled (TXD high or DE high), the bus is pulled high by
external bias resistors R1 and R2. Therefore, a logic-level
high is encoded as recessive. When all transceivers are
idle in this configuration, all receivers output logic high
because of the pullup resistor on A and pulldown resistor
on B. R1 and R2 provide the bias for the recessive state.
C1 and C2 combine to form a lowpass filter, effective for
reducing FM interference. R2, C1, R4, and C2 combine
to form a 1.6MHz lowpass filter, effective for reducing
AM interference. Because the bus is unterminated, at
high frequencies, R3 and R4 perform a pseudotermina-
tion. This makes the implementation more flexible, as no
specific termination nodes are required at the ends of
the bus.
DI
D
120Ω
B
DE
A
RO
R
RE
MAX13442E
MAX13443E
B
A
R
D
DI
DE RO RE
Figure 13. MAX13442E/MAX13443E Typical RS-485 Network
120Ω
B
B
A
A
R
D
DI
DE RO RE
DE
D
DI
R
RO
RE
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