Datasheet

Applications Information (Continued)
•
Balanced cables (e.g., twisted pair) are usually better
than unbalanced cables (ribbon cable, simple coax) for
noise reduction and signal quality.
•
For cable distances
<
0.5m, most cables can be made to
work effectively. For distances 0.5m ≤ d ≤ 10m, CAT 3
(category 3) twisted pair cable works well and is readily
available and relatively inexpensive. For distances
>
10m, and high data rates CAT 5 twisted pair is recom-
mended.
•
There are three Fail-Safe scenarios, open input pins,
shorted inputs pins and terminated input pins. The first
case is guaranteed for DS90LV019. A HIGH state on
R
OUT
pin can be achieved by using two external resistors
(one to V
CC
and one to GND) per Figure 10 (Terminated
Input Fail-Safe Circuit). R1 and R2 should be R
T
to limit
the loading to the LVDS driver . R
T
is selected to match
the impedance of the cable.
TABLE 1. Functional Table
MODE SELECTED DE RE
DRIVER MODE H H
RECEIVER MODE L L
TRI-STATE MODE L H
FULL DUPLEX MODE H L
TABLE 2. Transmitter Mode
INPUTS OUTPUTS
DE DI DO+ DO−
HL L H
HH H L
H2
>
&
>
0.8 X X
LX Z Z
X = High or Low logic state
Z = High impedance state
L = Low state
H = High state
TABLE 3. Receiver Mode
INPUTS OUTPUT
RE
(RI+) − (RI−)
LL(
<
−100 mV) L
LH(
>
+100 mV) H
L 100 mV
>
&
>
−100 mV X
HXZ
X = High or Low logic state
Z = High impedance state
L = Low state
H = High state
TABLE 4. Device Pin Description
Pin Name Pin # Input/Output Description
D
IN
2 I TTL Driver Input
DO
±
11, 12 O LVDS Driver Outputs
RI
±
9, 10 I LVDS Receiver Inputs
R
OUT
4 O TTL Receiver Output
RE
8 I Receiver Enable TTL Input (Active Low)
DE 1 I Driver Enable TTL Input (Active High)
GND 7 NA Ground
V
CC
14 NA Power Supply (3.3V
±
0.3V or 5.0V
±
0.5V)
DS90LV019
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