LTC1348CG-PBF Ver la hoja de datos (PDF) - Linear Technology
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LTC1348CG-PBF Datasheet PDF : 8 Pages
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LTC1348
APPLICATIONS INFORMATION
High Data Rates
The LTC1348 maintains true RS232 ±5V minimum driver
output even at high data rates. Figure 5 shows a test circuit
with 2m wires connecting the two test chips. Both chips
are run from 3.3V supplies. Figure 6 shows the typical line
waveforms with all three drivers, loaded with 1000pF and
3kΩ, toggling simultaneously at 120kbaud. Figure 7 shows
the same circuit with a single 1000pF/3kΩ loaded driver
driven at 250kbaud, and the other two drivers loaded but
not toggling. This closely approximates the actual behav-
ior of an RS232 serial port, with only one driver (TX) driven
at high speed and the other two drivers (RTS and DTR)
driven at a relatively low data rate or at DC. Under the same
conditions, the LTC1348 can go as fast as 350kbaud and
still meet EIA562 (±3.7V) minimum driver output levels.
0.1µF
V+
1
C2+ 2
0.1µF
3
C2– 4
VCC
C1+ 5
0.1µF
6
DR1 OUT C1– 7
8
RX1 IN
DR2 OUT 9
RX2 IN 10
11
RX3 IN
12
RX4 IN
DR3 OUT 13
14
1000pF RX5 IN
LTC1348
28
V–
27 C3+
26
0.1µF
25 C3–
DR1 IN
24
RX1 OUT
23 DR2 IN
22 RX2 OUT
21
RX3 OUT
20
RX4 OUT
19 DR3 IN
18
RX5 OUT
17
DREN
16
RXEN
15 GND
0.1µF
0.1µF
V+
1
C2+ 2
0.1µF
3
C2–
VCCC1+
4
5
0.1µF
6
DR1
C1–
OUT
7
RX1 IN 8
DR2 OUT 9
RX2 IN 10
1000pF RX3 IN 11
RX4 IN 12
DR3 OUT 13
RX5 IN 14
1000pF
LTC1348
28
V–
27 C3+
26
0.1µF
25 C3–
DRIVER 1 IN
24 RX1 OUT
23
DRIVER 2 IN
22
RX2 OUT
21
RX3 OUT
20
RX4 OUT
19
DRIVER 3 IN
18
RX5 OUT
17
DREN
16 RXEN
15 GND
LT1348 • F05
Figure 5. Data Rate Evaluation Circuit
0.1µF
DRIVER OUTPUT
RECEIVER OUTPUT
DRIVER INPUT
LTC1348 G06
Figure 6. Driver Test Result at 120kbps
DRIVER OUTPUT
RECEIVER OUTPUT
DRIVER INPUT
LTC1348 G07
Figure 7. Driver Test Results at 250kbps
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
7
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