Datasheet

LTC491
10
491fa
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Fault Protection
All of LTC’s RS485 products are protected against ESD
transients up to 2kV using the human body model (100pF,
1.5kΩ). However, some applications need more
protection. The best protection method is to connect a
bidirectional TransZorb
®
from each line side pin to ground
(Figure 16).
A TransZorb is a silicon transient voltage suppressor that
has exceptional surge handling capabilities, fast response
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 break-
down voltage higher than the common mode voltage
Figure 16. ESD Protection with TransZorbs
LTC491 • F16
120Ω
DRIVER
Z
Y
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
U
PACKAGE DESCRIPTIO
N Package
14-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
N14 1002
.020
(0.508)
MIN
.120
(3.048)
MIN
.130 ± .005
(3.302 ± 0.127)
.045 – .065
(1.143 – 1.651)
.065
(1.651)
TYP
.018 ± .003
(0.457 ± 0.076)
.005
(0.125)
MIN
.255 ± .015*
(6.477 ± 0.381)
.770*
(19.558)
MAX
31
2
4
5
6
7
8910
11
1213
14
.008 – .015
(0.203 – 0.381)
.300 – .325
(7.620 – 8.255)
.325
+.035
–.015
+0.889
–0.381
8.255
()
NOTE:
1. DIMENSIONS ARE
INCHES
MILLIMETERS
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
.100
(2.54)
BSC