Specifications
28 Control and Automation Solutions Guide
Isolated RS-485 Transceiver Reduces BOM
Complexity
MAX3535E
Galvanic isolation between the PLC’s backplane and the eldbus is required
due to the harsh conditions and large common-mode voltages that can occur
between remotely located subsystems. Maxim oers RS-485 transceivers with
integrated isolation based on capacitors, transformers, and optical techniques.
The MAX3535E RS-485 transceiver is designed for applications where galvanic
isolation is required up to ±2500V. By integrating the full half-bridge driver and
rectier, the MAX3535E oers ease of use. It provides extended ESD protection
up to ±15kV.
Benefits
• Complete isolation solution in one
package; saves board space
◦ 2500V
RMS
RS-485 bus isolation using
on-chip high-voltage capacitors
• Rugged design protects against ESD
strikes and other faults for enhanced
reliability
◦ Integrated ±15kV HBM ESD
◦ Short-circuit protected
◦ Fail-safe receiver inputs
• Easy interfacing with multivoltage
systems provides design flexibility
◦ 3.0V to 5.5V operation
◦ Hot-swap-protected driver-enable
input
28
27
1
2 3 11 14
26
25
4
420kHz
GND1
V
CC
10µF
ST1
GND2
A
B
RO2
Y
Z
SLO
V
CC2
ST2
RO
TWISTED-PAIR
CABLE
RE
DE
DI
16
15
17
13
12
18
RS-485/RS-422 BUS
VOLTAGE
REGULATOR
R
D
MAX3535E
Block diagram of the MAX3535E. Dashed line signifies isolation barrier.