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LTC1546CG#PBF

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7
LTC1546
Figure 1. V.11 Driver DC Test Circuit
Figure 2. V.11 Driver AC Test Circuit
Figure 4. V.11, V.35 Receiver AC Test Circuit
Figure 3. Input Impedance Test Circuit
1546 F01
V
OD
V
OC
R
L
R
L
A
B
D
A
B
D
1546 F02
R
L
100Ω
C
L
100pF
C
L
100pF
R
1546 F03
V
CM
= ±7V
B
I
B
A
+
–
I
A
2(V
B
– V
A
)
I
B
– I
A
R
IN
=
A
B
1546 F04
R
C
L
Figure 5. V.35 Driver Open-Circuit Test
1546 F05
V
OD
V
OC
R
L
50Ω
V
OB
V
OA
125Ω
50Ω
R
L
1546 F06
50Ω
V
OB
V
OA
125Ω 125Ω
50Ω
50Ω
50Ω
V
CM
Figure 6. V.35 Driver Test Circuit
1546 F07
50Ω
125Ω
50Ω
V
CM
= ±2V
+
–
1546 F08
50Ω50Ω
125Ω
125Ω
50Ω
50Ω
1546 F09
V
TH
V
CM
+
–
+
–
R
Figure 7. V.35 Driver Common Mode
Impedance Test Circuit
Figure 8. V.35 Driver AC Test Circuit Figure 9. V.35 Receiver DC Test Circuit
1546 F10
51.5Ω
125Ω
51.5Ω
V
CM
= ±2V
+
–
Figure 10. Receiver Common Mode
Impedance Test Circuit
A
D
1546 F11
R
L
C
L
R
A
1546 F12
C
L
V
A
Figure 11. V.28 Driver Test Circuit Figure 12. V.28 Receiver Test Circuit
TEST CIRCUITS
8
LTC1546
SWITCHI G TI E WAVEFOR S
UWW
Figure 14. V.11, V.35 Receiver Propagation Delays
Figure 13. V.11, V.35 Driver Propagation Delays
V
OD2
–V
OD2
0V
1.5V
0V
1.5V
t
PLH
V
OH
V
OL
B – A
R
t
PHL
1546 F14
f = 1MHz : t
r
≤ 10ns : t
f
≤ 10ns
INPUT
OUTPUT
5V
1.5V 1.5V
50%
10%
90%
t
PLH
t
r
0V
V
O
V
O
–V
O
D
B – A
A
B
t
PHL
t
SKEW
t
SKEW
1546 F13
1/2 V
O
f = 1MHz : t
r
≤ 10ns : t
f
≤ 10ns
50%
10%
90%
t
f
ODE SELECTIO
W
U
LTC1546 MODE NAME M2 M1 M0 DCE/DTE D1 D2 D3 R1 R2 R3
Not Used (Default V.11) 0000V.11 V.11 Z V.11 V.11 V.11
RS530A 0010V.11 V.11 Z V.11 V.11 V.11
RS530 0100V.11 V.11 Z V.11 V.11 V.11
X.21 0110V.11 V.11 Z V.11 V.11 V.11
V.35 1000V.35 V.35 Z V.35 V.35 V.35
RS449/V.36 1010V.11 V.11 Z V.11 V.11 V.11
V.28/RS232 1100V.28 V.28 Z V.28 V.28 V.28
No Cable 1110ZZZZZZ
Not Used (Default V.11) 0001V.11 V.11 V.11 Z V.11 V.11
RS530A 0011V.11 V.11 V.11 Z V.11 V.11
RS530 0101V.11 V.11 V.11 Z V.11 V.11
X.21 0111V.11 V.11 V.11 Z V.11 V.11
V.35 1001V.35 V.35 V.35 Z V.35 V.35
RS449/V.36 1011V.11 V.11 V.11 Z V.11 V.11
V.28/RS232 1101V.28 V.28 V.28 Z V.28 V.28
No Cable 1111ZZZZZZ
Table 1
9
LTC1546
Figure 15. V.28 Driver Propagation Delays
Figure 16. V.28 Receiver Propagation Delays
V
IH
V
IL
1.3V
0.8V
1.7V
2.4V
t
PHL
V
OH
V
OL
A
R
t
PLH
1546 F16
3V
0V
1.5V
0V
–3V
3V
1.5V
0V
3V
–3V
t
PHL
t
f
V
O
–V
O
D
A
t
PLH
t
r
1546 F15
SR =
6V
t
f
SR =
6V
t
r
SWITCHI G TI E WAVEFOR S
UWW
Overview
The LTC1546 and LTC1544 form a complete software-
selectable DTE or DCE interface port that supports the
RS232, RS449, EIA530, EIA530-A, V.35, V.36 and X.21
protocols. Cable termination is provided on-chip, elimi-
nating the need for discrete termination designs.
A complete DCE-to-DTE interface operating in EIA530
mode is shown in Figure 17. The LTC1546 half of each port
is used to generate and appropriately terminate the clock
and data signals. The LTC1544 is used to generate the
control signals along with LL (Local Loopback).
Mode Selection
The interface protocol is selected using the mode select
pins M0, M1 and M2 (see Table 1).
For example, if the port is configured as a V.35 interface,
the mode selection pins should be M2 = 1, M1 = 0, M0 = 0.
For the control signals, the drivers and receivers will
operate in V.28 (RS232) electrical mode. For the clock and
data signals, the drivers and receivers will operate in V.35
electrical mode. The DCE/DTE pin will configure the port
for DCE mode when high, and DTE when low.
The interface protocol may be selected simply by plugging
the appropriate interface cable into the connector. The
mode pins are routed to the connector and are left uncon-
nected (1) or wired to ground (0) in the cable as shown in
Figure 18. The internal pull-up current sources will ensure
a binary 1 when a pin is left unconnected.
The mode selection may also be accomplished by using
jumpers to connect the mode pins to ground or V
CC
.
When the cable is removed, leaving all mode pins uncon-
nected, the LTC1546/LTC1544 will enter no-cable mode.
In this mode the LTC1546/LTC1544 supply current drops
to less than 500µA and the LTC1546/LTC1544 driver
outputs are forced into a high impedance state. At the
same time, the R2 and R3 receivers of the LTC1546 are
differentially terminated with 103Ω and the other receiv-
ers on the LTC1546 and LTC1544 are terminated with
30kΩ to ground.
APPLICATIO S I FOR ATIO
WUUU
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LTC1546CG#PBF

Mfr. #:
Buy LTC1546CG#PBF
Manufacturer:
Analog Devices Inc.
Description:
RS-232 Interface IC Multiprotocol (LTCK011, 012)
Lifecycle:
New from this manufacturer.
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