HD26LS31P Renesas, HD26LS31P Datasheet - Page 10

• Manufacturer Part Number: HD26LS31P
• Description: Quadruple Differential Line Receivers With 3 State Outputs
• Manufacturer: Renesas

HD26LS32
This is because, since the termination resistance is normally matched to the transmission line characteristic impedance,
the value falls to several tens of hundreds of ohms, and the differential input pins are shorted by this termination
resistance. That is, the differential input voltage V
and the output becomes undetermined.
To prevent this, resistance R
of the termination resistance. Resistance R
and R
Inserting resistances R
but the following points must be noted.
Figure 7 shows experimental differential input voltages for variations in R
Rev.2.00, Jul.16.2004, page 10 of 14
Smallest possible R
If this value is large, the receiver input sensitivity will fall.
Largest possible R
If this value is small, the load on the driver will be large.
1
, enabling the value of R
V
ID
: –0.2 V < V
0.6
0.5
0.4
0.3
0.2
0.1
0
2
1
1
value
and R
value
IA
Figure 5 Examples of Transmission Line Disconnection
– V
1
is inserted in series with the transmission line as shown in figure 6, minimizing the effect
2
Figure 6 Method of Enhancing Fail-Safe Function
1
in this way provides for the differential input voltage V
IB
to be kept small.
Figure 7 R
< 0.2 V
5
Driver
R
T
R1 (k )
2
is added to increase the current flowing between the termination resistance
1
, R
Undetermined
ID
2
comes within the range
vs. Differential Input Voltage
10
V
Ta = 25°C
CC
R
= 5 V
T
R
R
R
1
1
T
15
R
R
1
V
2
2
and R
CC
100
Receiver
2
.
"H"
ID
R
R
to become 200 mV or higher,
1
1
V
R
R
ID
2
2
V
CC