Datasheet

7
LTC488/LTC489
U
S
A
O
PP
L
IC
AT
I
WU
U
I FOR ATIO
Figure 5. Typical Connection
120Ω
120Ω
3
RX
2
1
488/9 F05
DX
1
3
SHIELD
RX
EN
DX
1/4 LTC486
12
SHIELD
4
12
3
2
DX
DX
1/4 LTC486
1
EN
1/4 LTC488 OR
1/4 LTC489
RX
3
1
2
4
RX
1/4 LTC488 OR
1/4 LTC489
EN
EN
FREQUENCY (MHz)
0.1
0.1
LOSS PER 100 FT (dB)
1
10
1 10 100
488/9 F06
Figure 7. Cable Length vs Data Rate
DATA RATE (bps)
10k
10
CABLE LENGTH (FT)
100
1k
10k
100k 1M 10M
488/9 F07
2.5M
Figure 6. Attenuation vs Frequency for Belden 9841
When using low loss cables, Figure 7 can be used as a
guideline for choosing the maximum line length for a given
data rate. With lower quality PVC cables, the dielectric loss
factor can be 1000 times worse. PVC twisted-pairs have
terrible losses at high data rates (> 100kbps), and greatly
reduce the maximum cable length. At low data rates
however, they are acceptable and much more economical.
Cable Termination
The proper termination of the cable is very important. If the
cable is not terminated with its characteristic impedance,
distorted waveforms will result. In severe cases, distorted
(false) data and nulls will occur. A quick look at the output
of the driver will tell how well the cable is terminated. It is