LTC1485CS8 Linear Technology, LTC1485CS8 Datasheet - Page 10

• Manufacturer Part Number: LTC1485CS8
• Description: IC TXRX DIFFERNTIAL BUS 8-SOIC
• Manufacturer: Linear Technology
• Type: Transceiverr

Specifications of LTC1485CS8

• Number Of Drivers/receivers: 1/1
• Protocol: RS422, RS485
• Voltage - Supply: 4.75 V ~ 5.25 V
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

LTC1485
The termination resistors are used to generate a DC bias
which forces the receiver output to a known state, in this
case a logic 0. The first method consumes about 208mW
and the second about 8mW. The lowest power solution is
to use an AC termination with a pull-up resistor. Simply
swap the receiver inputs for data protocols ending in
logic 1.
Fault Protection
All of LTC’s RS485 products are protected against ESD
transients up to 2kV using the human body model
(100pF, 1.5k ). However, some applications need more
protection. The best protection method is to connect a
bidirectional TransZorb
(Figure 15).
A TransZorb is a silicon transient voltage suppressor that
has exceptional surge handling capabilities: fast response
TYPICAL
10
A
PPLICATI
A
PPLICATI
O
U
S
®
from each line side pin to ground
I FOR ATIO
U
O
U
S
W
RS232
RS232 to RS485 Level Translator with Hysteresis
IN
5.6k
RS232
HYSTERESIS = 10k • V
U
IN
10k
RS232 Receiver
220k
5.6k
DRIVER
time and low series resistance. They are available from
General Semiconductor Industries and come in a variety
of breakdown voltages and prices. Be sure to pick a
breakdown voltage higher than the common-mode volt-
age required for your application (typically 12V). Also,
don’t forget to check how much the added parasitic
capacitance will load down the bus.
TransZorb is a registered trademark of General Instruments, GSI
RECEIVER
A
– V
B
1485 TA02
A
B
R 19 (k • VOLT)/R
120
Figure 15. ESD Protection with TransZorbs
DRIVER
RX
1485 TA03
A
B
120
1485 F15