MAX3535E Maxim, MAX3535E Datasheet - Page 17

• Manufacturer Part Number: MAX3535E
• Description: +3V to +5V / 2500VRMS Isolated RS-485/RS-422 Transceivers with 15kV ESD Protection
• Manufacturer: Maxim

When not actively driving RE, it functions as the fault
indicator (Table 3). A low on RE indicates the part is
functioning properly, while a high indicates a fault is
present. The four causes of a fault indication are:
1) The voltage on V
2) The voltage on V
3) There is a problem that prevents the MAX3535E/
4) The die temperature exceeds +150°C nominally,
When a fault occurs, RO1 is switched to a logic-high
state if RE is low (Table 3). Open-circuit or short-circuit
conditions on the receiver inputs do not generate fault
conditions; however, any such condition also puts RO1
in a logic-high state (see the Fail Safe section).
Figure 10. Reading a Fault Condition
out threshold (2.69V nominal)
out threshold (2.80V nominal)
MXL1535E from communicating across its isolation
barrier
causing the part to go into thermal shutdown
+3V to +5V, 2500V
BIDIRECTIONAL MICROCONTROLLER I/O
RE
OE
FAULT
TRI-STATED BUFFER/
Transceivers with ±15kV ESD Protection
______________________________________________________________________________________
D
CC1
CC2
R
is below its undervoltage-lock-
is below its undervoltage-lock-
RO1
RE
DE
DI
MAX3535E
MXL1535E
GND1
V
V
CC1
CC1
RMS
Isolated RS-485/RS-422
Read RE for fault conditions by using a bidirectional
microcontroller I/O line or a tri-stated buffer as shown in
Figure 10. When using a tri-stated buffer, enable the
driver whenever the voltage on RE needs to be forced
to a logic-high or logic-low. To read RE for a fault con-
dition, disable the driver.
The SLO input selects between a fast and a slow slew
rate for the driver outputs. Connecting SLO to GND2
selects the slow slew-rate option that minimizes EMI
and reduces reflections caused by improperly terminat-
ed cables at data rates up to 400kbps. This occurs
because lowering the slew rate decreases the rise and
fall times for the signal at the driver outputs, drastically
reducing the high-frequency components and harmon-
ics at the output. Floating SLO or connecting it to V
selects the fast slew rate, which allows high-speed
operation.
OE
FAULT
DRIVER OUTPUT BECOMES HIGH IMPEDANCE
FAULT DETECTED
Slew-Rate Control Logic
CC2
17