LT1785/LT1785A/
LT1791/LT1791A
60V Fault Protected
RS485/RS422 Transceivers
Fea T Descrip T
n
Protected from Overvoltage Line Faults to 60V
The LT 1785/LT1791 are half-duplex and full-duplex differ-
n
Pin Compatible with LTC485 and LTC491
ential bus transceivers for RS485 and RS422 applications
n
High Input Impedance Supports Up to 128 Nodes
which feature on-chip protection from overvoltage faults
n
No Damage or Latchup to ESD
on the data transmission lines. Receiver input and driver
n
IEC-1000-4-2 Level 4: 15kV Air Discharge
output pins can withstand voltage faults up to 60V with
n
IEC-1000-4-2 Level 2: 4kV Contact Discharge
respect to ground with no damage to the device. Faults
n
Controlled Slew Rates for EMI Emissions Control
may occur while the transceiver is active, shut down or
n
Guaranteed High Receiver Output State for Floating,
powered off.
Shorted or Inactive Inputs (LT1785A/LT1791A)
Data rates to 250kbaud on networks of up to 128 nodes
n
Outputs Assume a High Impedance When Off or
are supported. Controlled slew rates on the driver out-
Powered Down
putscontrol EMI emissions and improve data transmis-
n
Drives Low Cost, Low Impedance Cables
sion integrity on improperly terminated lines. Drivers are
n
Short-Circuit Protection on All Outputs
specified to operate with inexpensive cables as low as
n
Thermal Shutdown Protection
72 characteristic impedance.
n
Guaranteed Operation to 125C
The LT1785A/LT1791A devices have fail-safe receiver
inputs to guarantee a receiver output high for shorted, open
a T
or inactive data lines. On-chip ESD protection eliminates
n need for external protection devices.
Industrial Control Data Networks
n
CAN Bus Applications
The LT1785/LT1785A are available in 8-lead DIP and SO
n
HVAC Controls
packages and the LT1791/LT1791A in 14-lead DIP and
L, LT, LTC, LTM, Module, Linear Technology and the Linear logo are registered trademarks of
SO packages.
Linear Technology Corporation. All other trademarks are the property of their respective owners.
Typical a T
Normal Operation Waveforms at 250kBaud
V
CC1
RO1
RX
RO
RE1
LT1785 R
TERM
DE1
DI1 TX
Y-Z
GND1
DI
V
CC2
RO2
RX
RE2
R
LT1785 TERM 178591 TA02
DE2
DI2
TX
GND2
178591 TA01
178591fd
1
For more information www.linear.com/LT1785
ion pplica
ions pplica
ion uresLT1785/LT1785A/
LT1791/LT1791A
(Note 1)
a Te Maxi Mu M r a T
Supply Voltage (V ) ................................................18V Operating Temperature Range
CC
Receiver Enable Input Voltage ...................... 0.3V to 6V LT1785C/LT1791C/
Driver Enable Input Voltage .......................... 0.3V to 6V LT1785AC/LT1791AC .................................... 0C to 70C
Driver Input Voltage ................................... 0.3V to 18V LT1785I/LT1791I/
Receiver Input Voltage ................................ 60V to 60V LT1785AI/LT1791AI .................................. 40C to 85C
Driver Output Voltage .................................. 60V to 60V LT1785H/LT1791H/
Receiver Output Voltage ...................0.3V to (V + 6V) LT1785AH/LT1791AH ............................. 40C to 125C
CC
Storage Temperature Range ................... 65C to 150C
Lead Temperature (Soldering, 10 sec) .................. 300C
p in c F T
TOP VIEW
TOP VIEW
14
NC 1 V
CC
RO 2 R 13 NC
RO 1 V
8
CC
R
RE 3 12 A
RE 2 7 B
DE 4 11 B
DE 3 6 A
D DI 5 10
Z
DI 4 5 GND
D
GND 6 9 Y
N8 PACKAGE S8 PACKAGE
GND 7 8 NC
8-LEAD PDIP 8-LEAD PLASTIC SO
T = 150C, = 130C/W (N8)
JMAX JA
N PACKAGE S PACKAGE
T = 150C, = 150C/W (S8)
JMAX JA 14-LEAD PDIP 14-LEAD PLASTIC SO
T = 150C, = 130C/W (N)
JMAX JA
T = 150C, = 150C/W (S)
JMAX JA
Der in F Ma T
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT1785CN8#PBF LT1785CN8#TRPBF 1785 8-Lead PDIP 0C to 70C
LT1785CS8#PBF LT1785CS8#TRPBF 1785 8-Lead Plastic SO 0C to 70C
LT1785IN8#PBF LT1785IN8#TRPBF 1785I 8-Lead PDIP 40C to 85C
LT1785IS8#PBF LT1785IS8#TRPBF 1785I 8-Lead Plastic SO 40C to 85C
LT1785ACN8#PBF LT1785ACN8#TRPBF 1785A 8-Lead PDIP 0C to 70C
LT1785ACS8#PBF LT1785ACS8#TRPBF 1785A 8-Lead Plastic SO 0C to 70C
LT1785AIN8#PBF LT1785AIN8#TRPBF 1785AI 8-Lead PDIP 40C to 85C
LT1785AIS8#PBF LT1785AIS8#TRPBF 1785AI 8-Lead Plastic SO 40C to 85C
LT1785HN8#PBF LT1785HN8#TRPBF 1785H 8-Lead PDIP 40C to 125C
LT1785HS8#PBF LT1785HS8#TRPBF 1785H 8-Lead Plastic SO 40C to 125C
LT1785AHN8#PBF LT1785AHN8#TRPBF 1785AH 8-Lead PDIP 40C to 125C
LT1785AHS8#PBF LT1785AHS8#TRPBF 1785AH 8-Lead Plastic SO 40C to 125C
LT1791CN#PBF LT1791CN#TRPBF 1791 14-Lead PDIP 0C to 70C
LT1791CS#PBF LT1791CS#TRPBF 1791 14-Lead Plastic SO 0C to 70C
178591fd
2
For more information www.linear.com/LT1785
ion or or
ion igura on
ings bsolu