HD26LS31 Renesas, HD26LS31 Datasheet - Page 10

• Manufacturer Part Number: HD26LS31
• Manufacturer: Renesas

HD26LS31
HD26LS31 Line Driver Applications
The HD26LS31 is a line driver that meets the EIA RS-422A conditions, and has been designed to supply a
high current for differential signals to a bus line. Its features are listed below.
A block diagram is shown in figure 1. The enable function is common to all four drivers, and either active-
high or active-low can be selected.
The output section consists of two output stages (the Y side and Z side), each of which has the same sink
current and source current capacity.
Input is TTL compatible, and an output current limiter circuit is built into the output stage as shown in
figure 2.
The output current limiter circuit consists of transistor Q
drop on both sides of R
When a current greater than this flows, Q
flow of an excessively large output current is prevented.
However, since this type of current limiter circuit has the characteristics shown in figure 3, the output stage
power dissipation is large.
Therefore, when the output is shorted, this should be limited to a maximum of one second for one pin only.
The I
8
Operates on a single 5 V power supply.
High output impedance when power is off
Three-state output
On-chip current limiter circuit
Sink current and source current both 40 mA
OL
vs. V
i = 0.7 (V) / 9 ( )
OL
characteristic for low-level output is shown in figure 4.
1
reaches approximately 0.7 V. At this time the current, i, is as follows:
78 (mA)
Figure 1 HD26LS31 Block Diagram
Enable G
Enable G
1
is turned on, the Q
4A
1A
2A
3A
1
and resistance R
2
base current flows to the output side, and the
1Y
1Z
2Y
2Z
3Y
3Z
4Y
4Z
1
, and operates when the voltage