LTC1485IS8#TR Linear Technology, LTC1485IS8#TR Datasheet - Page 7

• Manufacturer Part Number: LTC1485IS8#TR
• Description: IC TXRX BUS/LINE RS485 LP 8SOIC
• Manufacturer: Linear Technology
• Type: Transceiverr

Specifications of LTC1485IS8#TR

• 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

Typical Application
A typical connection of the LTC1485 is shown in Figure 9.
Two twisted pair wires connect up to 32 driver/receiver
pairs for half duplex data transmission. There are no
restrictions on where the chips are connected to the wires
and it isn’t necessary to have the chips connected at the
ends. However, the wires must be terminated only at the
A
S
WITCHI
PPLICATI
RX
DX
2
3
4
1
U
LTC1485
G
DRIVER
RECEIVER
O
TI
U
S
W
E WAVEFOR
I FOR ATIO
U
RO
RE
RO
V
V
3V
0V
5V
0V
OH
OL
6
7
120
W
t
1.5V
ZH
t
ZL
Figure 8. Receiver Enable and Disable Times
1.5V
1.5V
W
Figure 9. Typical Connection
f = 1MHz; t
U
S
OUTPUT NORMALLY HIGH
OUTPUT NORMALLY LOW
r
10ns; t
7
6
ends with a resistor equal to their characteristic imped-
ance, typically 120 . The input impedance of a receiver is
typically 20k to GND, or 0.6 unit RS485 load, so in practice
50 to 60 transceivers can be connected to the same wires.
The optional shields around the twisted pair help reduce
unwanted noise, and are connected to GND at one end.
f
10ns
RECEIVER
DRIVER
LTC1485
120
t
t
HZ
LZ
1.5V
0.5V
0.5V
3
4
1
2
DX
RX
1485 F08
RECEIVER
DRIVER
LTC1485
LTC1485
1485 F09
4
1
2
3
RX
DX
7