LTC1344A
Software-Selectable
Cable Terminator
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DESCRIPTION
FEATURES
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The LTC ®1344A features six software-selectable
multiprotocol cable terminators. Each terminator can be
configured as an RS422 (V.11) 100Ω minimum differential load, V.35 T-network load or an open circuit for use
with RS232 (V.28) or RS423 (V.10) transceivers that
provide their own termination. When combined with the
LTC1543 and LTC1544, the LTC1344A forms a complete
software-selectable multiprotocol serial port. A data bus
latch feature allows sharing of the select lines between
multiple interface ports.
Software-Selectable Cable Termination for:
RS232 (V.28)
RS423 (V.10)
RS422 (V.11)
RS485
RS449
EIA530
EIA530-A
V.35
V.36
X.21
Outputs Won’t Load the Line with Power Off
The LTC1344A is similar to the LTC1344 except for a
difference in the Mode Selection table.
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APPLICATIONS
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■
Data Networking
CSU and DSU
Data Routers
, LTC and LT are registered trademarks of Linear Technology Corporation.
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The LTC1344A is available in a 24-lead SSOP.
TYPICAL APPLICATION
DTE or DCE Multiprotocol Serial Interface with DB-25 Connector
LL
CTS
DSR
DCD
DTR
RTS
RXD
TXC
RXC
Daisy-Chained Control Outputs
D3
R4
R3
R2
D2
TXD
D2
D1
LTC1543
LTC1544
D4
SCTE
D3
D1
R3
R1
R1
R2
LTC1344A
18
13 5
10 8
22 6
23 20 19 4
1
7
16 3
17
12 15 11 24 14
2
TXD A (103)
TXD B
SCTE A (113)
TXC A (114)
SCTE B
TXC B
RXC A (115)
RXC B
RXD A (104)
RXD B
SG (102)
SHIELD (101)
RTS A (105)
RTS B
DTR A (108)
DCD A (107)
DTR B
DCD B
DSR A (109)
CTS A (106)
DSR B
CTS B
LL A (141)
DB-25 CONNECTOR
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1344A TA01
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LTC1344A
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ABSOLUTE MAXIMUM RATINGS
PACKAGE/ORDER I FOR ATIO
(Note 1)
Positive Supply Voltage (VCC) ................................... 7V
Negative Supply Voltage (VEE) ........................... – 13.2V
Input Voltage
(Logic Inputs) .................... (VEE – 0.3V) to (VCC + 0.3V)
Input Voltage (Load Inputs) .................................. ±18V
Power Dissipation .............................................. 600mW
Operating Temperature Range
LTC1344AC ............................................ 0°C to 70°C
LTC1344AI ......................................... – 40°C to 85°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
TOP VIEW
M0
1
24 M1
VEE
2
23 M2
R1C
3
22 DCE/DTE
R1B
4
21 LATCH
R1A
5
20 R6B
R2A
6
19 R6A
R2B
7
18 R5A
R2C
8
17 R5B
R3A
9
16 R4A
R3B 10
15 R4B
R3C 11
14 VCC
GND 12
13 GND
ORDER PART
NUMBER
LTC1344ACG
LTC1344AIG
G PACKAGE
24-LEAD PLASTIC SSOP
TJMAX = 150°C, θJA = 100°C/W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
VCC = 5V ±5%, VEE = – 5V ±5%, TA = TMIN to TMAX (Notes 2, 3) unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Current
All Digital Pins = GND or VCC
●
0.4
1.0
mA
All Loads (Figure 1), – 2V ≤ VCM ≤ 2V (Commercial)
All Loads (Figure 2), – 2V ≤ VCM ≤ 2V (Commercial)
●
●
90
135
104
153
110
165
Ω
Ω
All Loads (Figure 1), – 2V ≤ VCM ≤ 2V (Industrial)
All Loads (Figure 2), – 2V ≤ VCM ≤ 2V (Industrial)
●
●
90
130
104
153
115
170
Ω
Ω
All Loads (Figure 1), VCM = 0V (Commercial)
All Loads (Figure 1), – 7V ≤ VCM ≤ 7V (Commercial)
●
100
100
104
104
110
Ω
Ω
All Loads (Figure 1), VCM = 0V (Industrial)
All Loads (Figure 1), – 7V ≤ VCM ≤ 7V (Industrial)
●
95
100
104
104
115
Ω
Ω
All Loads, – 7V ≤ VCM ≤ 7V
●
±1
±50
µA
Supplies
ICC
Terminator Pins
RV.35
RV.11
ILEAK
Differential Mode Impedance
Common Mode Impedance
Differential Mode Impedance
High Impedance Leakage Current
Logic Inputs
VIH
Input High Voltage
All Logic Input Pins
●
VIL
Input Low Voltage
All Logic Input Pins
●
0.8
V
IIN
Input Current
All Logic Input Pins
●
±10
µA
The ● denotes specifications which apply over the full operating
temperature range.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
2
2
V
Note 2: All currents into device pins are positive; all currents out of device
pins are negative. All voltages are reference to ground unless otherwise
specified.
Note 3: All typicals are given at VCC = 5V, VEE = – 5V, TA = 25°C.
LTC1344A
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TYPICAL PERFORMANCE CHARACTERISTICS
V.11 or V.35 Differential Mode
Impedance vs Supply Voltage
(VCC)
V.11 or V.35 Differential Mode
Impedance vs Common Mode
Voltage
V.11 or V.35 Differential Mode
Impedance vs Temperature
105
VCM = –2V
110
VCM = 0V
105
VCM = 7V
100
–40 –20
0
20
40
60
80
108
106
104
102
100
100
TA = 25°C
–6
– 4 –2
0
2
4
6
COMMON MODE VOLTAGE (V)
1344 G01
104
4.6
8
V.35 Common Mode Impedance
vs Common Mode Voltage
165
158
TA = 25°C
104
– 5.2
– 5.0
– 4.8
VEE VOLTAGE (V)
160
VCM = –2V
155
VCM = 0V
150
VCM = 2V
145
– 40 –20
103
– 4.6
COMMON MODE IMPEDANCE (Ω)
COMMON MODE IMPEDANCE (Ω)
TA = 25°C
60
40
20
TEMPERATURE (°C)
0
1344 G04
80
156
154
152
150
–2
100
0
–1
1
COMMON MODE VOLTAGE (V)
1344 G05
Supply Current vs Temperature
500
154
153
2
1344 G06
V.35 Common Mode Inpedance
vs Negative Supply Voltage (VEE)
V.35 Common Mode Impedance
vs Supply Voltage (VCC)
TA = 25°C
152
151
4.8
5.0
5.2
VCC VOLTAGE (V)
5.4
1344 G07
153
SUPPLY CURRENT (µA)
COMMON MODE IMPEDANCE (Ω)
TA = 25°C
4.6
5.4
1344 G03
V.35 Common Mode Impedance
vs Temperature
105
– 5.4
4.8
5.0
5.2
VCC VOLTAGE (V)
1344 G02
V.11 or V.35 Differential Mode
Impedance vs Negative Supply
Voltage (VEE)
DIFFERENTIAL MODE IMPEDANCE (Ω)
TA = 25°C
103
–8
TEMPERATURE (°C)
COMMON MODE IMPEDANCE (Ω)
DIFFERENTIAL MODE IMPEDANCE (Ω)
VCM = –7V
115
DIFFERENTIAL MODE IMPEDANCE (Ω)
DIFFERENTIAL MODE IMPEDANCE (Ω)
120
152
151
150
– 5.4
– 5.2
– 4.8
– 5.0
VEE VOLTAGE (V)
– 4.6
1344 G08
420
340
260
180
–40 –20
0
40
60
20
TEMPERATURE (°C)
80
100
1344 G09
3
LTC1344A
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PIN FUNCTIONS
M0 (Pin 1): TTL Level Mode Select Input. The data on M0
is latched when LATCH is high.
R4B (Pin 15): Load 4 Node B.
VEE (Pin 2): Negative Supply Voltage Input. Can connect
directly to the LTC1543 VEE pin. Connect a 1µF capacitor
to ground.
R5B (Pin 17): Load 5 Node B.
R1C (Pin 3): Load 1 Center Tap.
R6A (Pin 19): Load 6 Node A.
R1B (Pin 4): Load 1 Node B.
R6B (Pin 20): Load 6 Node B.
R1A (Pin 5): Load 1 Node A.
LATCH (Pin 21): TTL Level Logic Signal Latch Input. When
LATCH is low the input buffers on M0, M1, M2 and DCE/
DTE are transparent. When LATCH is high the logic pins
are latched into their respective input buffers. The data
latch allows the select lines to be shared between multiple
I/O ports.
R2A (Pin 6): Load 2 Node A.
R2B (Pin 7): Load 2 Node B.
R2C (Pin 8): Load 2 Center Tap.
R3A (Pin 9): Load 3 Node A.
R4A (Pin 16): Load 4 Node A.
R5A (Pin 18): Load 5 Node A.
DCE/DTE (Pin 22): TTL Level Mode Select Input. DCE
mode is selected when high and DTE mode when low. The
data on DCE/DTE is latched when LATCH is high.
R2B (Pin 10): Load 2 Node B.
R3C (Pin 11): Load 3 Center Tap.
GND (Pin 12): Ground Connection for Load 1 to Load 3.
GND (Pin 13): Ground Connection for Load 4 to Load 6.
VCC (Pin 14): Positive Supply Input. 4.75V ≤ VCC ≤ 5.25V.
M2 (Pin 23): TTL Level Mode Select Input 1. The data on
M2 is latched when LATCH is high.
M1 (Pin 24): TTL Level Mode Select Input 2. The data on
M1 is latched when LATCH is high.
TEST CIRCUITS
C
C
LTC1344A
A
LTC1344A
R1
51.5Ω
Ω
S1
ON
S2
OFF
R1
51.5Ω
S1
ON
R3
124Ω
S2
ON
R3
124Ω
A, B
R2
51.5Ω
R2
51.5Ω
Ω
B
V
±7V OR ±2V
1344 F01
Figure 1. Differential V.11 or V.35 Impedance Measurement
4
V
±2V
1344 F02
Figure 2. V.35 Common Mode Impedance Measurement
LTC1344A
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ODE SELECTIO
LTC1344A
MODE NAME
DCE/DTE
M2
M1
M0
R1
R2
R3
R4
R5
R6
V.10/RS423
X
0
0
0
Z
Z
Z
Z
Z
Z
RS530A
0
1
0
0
0
0
1
1
Z
Z
Z
Z
Z
Z
V.11
Z
V.11
V.11
V.11
V.11
RS530
0
1
0
0
1
1
0
0
Z
Z
Z
Z
Z
Z
V.11
Z
V.11
V.11
V.11
V.11
X.21
0
1
0
0
1
1
1
1
Z
Z
Z
Z
Z
Z
V.11
Z
V.11
V.11
V.11
V.11
V.35
0
1
1
1
0
0
0
0
V.35
V.35
V.35
V.35
Z
V.35
V.35
Z
V.35
V.35
V.35
V.35
RS449/V.36
0
1
1
1
0
0
1
1
Z
Z
Z
Z
Z
Z
V.11
Z
V.11
V.11
V.11
V.11
V.28/RS232
X
1
1
0
Z
Z
Z
Z
Z
Z
No Cable
X
1
1
1
V.11
V.11
V.11
V.11
V.11
V.11
X = don’t care, 0 = logic low, 1 = logic high
C
A
R1
51.5Ω
S1
ON
S2
OFF
C
LTC1344A
A
R1
51.5Ω
S1
ON
R3
124Ω
R2
51.5Ω
B
S2
ON
C
LTC1344A
R1
51.5Ω
S1
OFF
R3
124Ω
R2
51.5Ω
B
V.11 Mode
A
S2
OFF
LTC1344A
R3
124Ω
R2
51.5Ω
B
V.35 Mode
High-Z Mode
1344 F03
Figure 3. LTC1344A Modes
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LTC1344A
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APPLICATIONS INFORMATION
Multiprotocol Cable Termination
GENERATOR
One of the most difficult problems facing the designer of
a multiprotocol serial interface is how to allow the transmitters and receivers for different electrical standards to
share connector pins. In some cases the transmitters and
receivers for each interface standard can be simply tied
together and the appropriate circuitry enabled. But the
biggest problem still remains: how to switch the various
cable termination required by the different standards.
BALANCED
INTERCONNECTING
CABLE
LOAD
CABLE
TERMINATION
A
A'
C
C'
1344 F04
Figure 4. Typical V.10 Interface
A
Traditional implementations have included switching resistors with expensive relays or requiring the user to
change termination modules every time the interface
standard has changed. Custom cables have been used
with the termination in the cable head. Another method
uses separate termination built on the board, and a custom
cable which routes the signals to the appropriate termination. Switching the termination using FETs is difficult
because the FETs must remain off even though the signal
voltage is beyond the supply voltage for the FET drivers or
the power is off.
51.5Ω
S1
OFF
S2
OFF
V.10
RECEIVER
LTC1344A
Z
124Ω
Z
51.5Ω
B
C
IZ
3.25mA
–10V
–3V
Z
The LTC1344A solves the cable termination switching
problem via software control. The LTC1344A provides
termination for the V.10 (RS423), V.11 (RS422), V.28
(RS232) and V.35 electrical protocols.
RECEIVER
3V
– 3.25mA
VZ
10V
1344 F05
Figure 5. V.10 Interface Using the LTC1344A
V.10 (RS423) Termination
V.11 (RS422) Termination
A typical V.10 unbalanced interface is shown in Figure 4.
A V.10 single-ended generator output A with ground C is
connected to a differential receiver with input A' connected to A and input C' connected to the signal return
ground C. Usually no cable termination is required for V.10
interfaces but the receiver inputs must be compliant with
the impedance curve shown in Figure 5.
A typical V.11 balanced interface is shown in Figure 6. A
V.11 differential generator with outputs A and B with
ground C is connected to a differential receiver with
ground C', inputs A' connected to A, B' connected to B. The
V.11 interface requires a differential termination at the
receiver end that has a minimum value of 100Ω. The
receiver inputs must also be compliant with the impedance curve shown in Figure 7.
In V.10 mode, both switches S1 and S2 are turned off so
the only cable termination is the input impedance of the
V.10 receiver.
6
In V.11 mode, switch S1 is turned on and S2 is turned off
so the cable is terminated with a 103Ω impedance.
LTC1344A
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APPLICATIONS INFORMATION
BALANCED
INTERCONNECTING
CABLE
GENERATOR
LOAD
GENERATOR
BALANCED
INTERCONNECTING
CABLE
CABLE
TERMINATION RECEIVER
A
A'
B
B'
C
C'
LOAD
CABLE
TERMINATION RECEIVER
100Ω
MIN
A
A'
C
C'
1344 F08
1344 F06
Figure 8. Typical V.28 Interface
Figure 6. Typical V.11 Interface
A
A
51.5Ω
S1
ON
S2
OFF
V.11
RECEIVER
LTC1344A
51.5Ω
S1
OFF
Z
124Ω
S2
OFF
V.28
RECEIVER
LTC1344A
124Ω
5k
Z
51.5Ω
51.5Ω
B
B
C
C
IZ
3.25mA
–10V
1344 F09
Figure 9. V.28 Interface Using the LTC1344A
–3V
Z
3V
– 3.25mA
VZ
10V
1344 F07
Figure 7. V.11 Interface Using the LTC1344A
V.28 (RS232) Termination
A typical V.28 unbalanced interface is shown in Figure 8.
A V.28 single-ended generator output A with ground C is
connected to a single-ended receiver with input A' connected to A, ground C' connected via the signal return
ground to C. The V.28 standard requires a 5k terminating
resistor to ground which is included in almost all compliant receivers as shown in Figure 9. Because the termination is included in the receiver, both switches S1 and S2 in
the LTC1344A are turned off.
V.35 Termination
A typical V.35 balanced interface is shown in Figure 10. A
V.35 differential generator with outputs A and B with
ground C is connected to a differential receiver with
ground C', inputs A' connected to A, B' connected to B. The
V.35 interface requires a T-network termination at the
receiver end and the generator end. In V.35 mode both
switches S1 and S2 in the LTC1344A are turned on as
shown in Figure 11.
The differential impedance measured at the connector
must be 100Ω ±10Ω and the impedance between shorted
terminals A' and B' to ground C' must be 150Ω ±15Ω. The
input impedance of the V.35 receiver is connected in
parallel with the T-network inside the LTC1344A, which
could cause the overall impedance to fail the specification
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LTC1344A
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APPLICATIONS INFORMATION
A
BALANCED
INTERCONNECTING
CABLE
GENERATOR
LOAD
V.35
DRIVER
CABLE
TERMINATION RECEIVER
A'
A
50Ω
125Ω
125Ω
50Ω
LTC1344A
51.5Ω
124Ω
S2
ON
S1
ON
51.5Ω
B
50Ω
B
B'
C
C'
50Ω
C1
100pF
Figure 12. V.35 Driver Using the LTC1344A
Figure 10. Typical V.35 Interface
A
51.5Ω
S1
ON
S2
ON
The generator differential impedance must be 50Ω to
150Ω and the impedance between shorted terminals A
and B to ground C must be 150Ω ±15Ω. For the generator
termination, switches S1 and S2 are both on and the top
side of the center resistor is brought out to a pin so it can
be bypassed with an external capacitor to reduce common
mode noise as shown in Figure 12.
V.35
RECEIVER
LTC1344A
Z
124Ω
Z
51.5Ω
B
C
IZ
1mA
–7V
–3V
Z
3V
–0.8mA
VZ
12V
1344 F11
Figure 11. V.35 Receiver Using the LTC1344A
if the receiver input impedance is on the low side. All of
Linear Technology’s V.35 receivers meet the RS485 input
impedance specification as shown in Figure 11, which
insures compliance with the V.35 specification when used
with the LTC1344A.
8
C
1344 F12
1344 F10
Any mismatch in the driver rise and fall times or skew in
the driver propagation delays will force current through
the center termination resistor to ground causing a high
frequency common mode spike on the A and B terminals.
The common mode spike can cause EMI problems that are
reduced by capacitor C1 which shunts much of the common mode energy to ground rather than down the cable.
The LATCH Pin
The LATCH pin (21) allows the select lines (M0, M1, M2
and DCE/DTE) to be shared with multiple LTC1344As,
each with its own LATCH signal. When the LATCH pin is
held low the select line input buffers are transparent. When
the LATCH pin is pulled high, the select line input buffers
latch the state of the Select pins so that changes on the
select lines are ignored until LATCH is pulled low again. If
the latch feature is not used, the LATCH pin should be tied
to ground.
LTC1344A
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TYPICAL APPLICATIONS N
Controller Selectable Multiprotocol DTE/DCE Port with DB-25 Connector
C6
C7
C8
100pF 100pF 100pF
3
8
11
12
13
LTC1344A
VCC
5V
14
44
C5
1µF
41
LTC1343
D1
6
DTE_TXD/DCE_RXD
D2
7
DTE_SCTE/DCE_RXC
VEE
C12
1µF
8
5
DTE_LL/DCE_TM
2
C4
3.3µF
D3
5 4 6 7
9 10
M0
CHARGE
PUMP
4
3
21
C2
1µF
43
42
M1
C1
1µF
LATCH
VCC
M2
2
+
C3
1µF
C13
1µF
DCE/DTE
1
16 15 18 17 19 20 22 23 24 1
39
18
38
2
37
14
36
24
35
11
DTE
DCE
LL A
TM A
TXD A
RXD A
TXD B
RXD B
SCTE A
RXC A
SCTE B
RXC B
TXC A
TXC A
34
9
DTE_TXC/DCE_TXC
R1
14
DTE_RXC/DCE_SCTE
R2
15
DTE_RXD/DCE_TXD
R3
16
DTE_TM/DCE_LL
20
22
11
25
R1
100k
33
D4
10
12
13
R4
CTRL
DCE
LATCH
M2
INVERT
M1
423SET
M0
GND
EC
C10
1µF
VCC
LB
1
VCC
2
VDD
3
VEE
GND
4
D2
DTE_CTS/DCE_RTS
DTE_RL/DCE_RL
6
R1
7
R2
8
R3
10
R4
9
11
12
13
14
DCE/DTE
M2
M1
M0
17
29
9
28
3
27
16
26
25
21
7
19
1
18
TXC B
RXC A
SCTE A
RXC B
SCTE B
RXD A
TXD A
RXD B
TXD B
TM A
LL A
SG
SHIELD
17
24
28
C11
1µF
27
26
4
25
19
24
20
23
23
RTS A
CTS A
RTS B
CTS B
DTR A
DSR A
DTR B
DSR B
DCD A
DCD A
D3
LTC1544
DTE_DSR/DCE_DTR
30
TXC B
DB-25
CONNECTOR
D1
5
DTE_DCD/DCE_DCD
12
23
C9, 1µF
DTE_DTR/DCE_DSR
15
31
VCC
40
LB
DTE_RTS/DCE_CTS
32
22
8
21
10
20
6
19
22
18
5
17
13
16
21
DCD B
DCD B
DSR A
DTR A
DSR B
DTR B
CTS A
RTS A
CTS B
RTS B
RL A
RL A
D4
M0
INVERT
15
NC
M1
M2
DCE/DTE
1344A TA04
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LTC1344A
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TYPICAL APPLICATIONS N
Cable Selectable Multiprotocol DTE/DCE Port with DB-25 Connector
C6
C7
C8
100pF 100pF 100pF
3
8
11
12
13
LTC1344A
VCC
5V
14
4
D2
7
R1
9
DTE_RXC/DCE_SCTE
R2
10
DTE_RXD/DCE_TXD
11
12
NC
13
14
5 4 6 7
9 10
16 15 18 17 19 20 22 23 24 1
VCC
2
23
14
22
24
21
11
DTE
DCE
TXD A
RXD A
TXD B
RXD B
SCTE A
RXC A
SCTE B
RXC B
TXC A
TXC A
TXC B
TXC B
RXC A
SCTE A
RXC B
SCTE B
RXD A
TXD A
RXD B
TXD B
D3
8
DTE_TXC/DCE_TXC
VEE
24
D1
6
C4
3.3µF
C12
1µF
LTC1543
5
DTE_SCTE/DCE_RXC
2
25
C5
1µF
DTE_TXD/DCE_RXD
C2
1µF
26
CHARGE
PUMP
2
21
M0
27
M1
1
M2
28
LATCH
VCC
DCE/DTE
C1
1µF
3
+
C3
1µF
C13
1µF
R3
20
15
19
12
18
17
17
9
16
3
15
16
M0
7
M1
M2
1
DCE/DTE
SG
SHIELD
DB-25
CONNECTOR
VCC
C9, 1µF
1
VCC
2
VDD
C10
1µF
VEE
GND
25
DCE/DTE
21
M1
18
M0
4
RTS A
19
RTS B
20
DTR A
23
DTR B
28
C11
1µF
27
26
3
DTE_RTS/DCE_CTS
D1
24
4
DTE_DTR/DCE_DSR
D2
5
6
R1
7
DTE_DSR/DCE_DTR
R2
8
DTE_CTS/DCE_RTS
R3
10
R4
9
11
12
NC
13
14
23
22
8
21
10
CTS B
DSR A
DSR B
20
6
19
22
18
5
17
13
CABLE WIRING FOR MODE SELECTION
MODE
V.35
RS449, V.36
RS232
M0
M1
DCE/DTE INVERT
DCD A
DCD B
DCD B
DSR A
DTR A
DSR B
DTR B
CTS A
RTS A
CTS B
RTS B
16
D4
M2
DCD A
15
PIN 18
PIN 7
NC
PIN 7
PIN 21
PIN 7
PIN 7
NC
CABLE WIRING FOR
DTE/DCE SELECTION
MODE
PIN 25
DTE
PIN 7
DCE
NC
NC
1344A TA05
10
CTS A
D3
LTC1544
DTE_DCD/DCE_DCD
25
LTC1344A
U
PACKAGE DESCRIPTION
Dimensions in inches (millimeters) unless otherwise noted.
G Package
24-Lead Plastic SSOP (0.209)
(LTC DWG # 05-08-1640)
0.318 – 0.328*
(8.07 – 8.33)
24 23 22 21 20 19 18 17 16 15 14 13
0.301 – 0.311
(7.65 – 7.90)
1 2 3 4 5 6 7 8 9 10 11 12
0.205 – 0.212**
(5.20 – 5.38)
0.068 – 0.078
(1.73 – 1.99)
0° – 8°
0.005 – 0.009
(0.13 – 0.22)
0.022 – 0.037
(0.55 – 0.95)
*DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
0.0256
(0.65)
BSC
0.010 – 0.015
(0.25 – 0.38)
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
0.002 – 0.008
(0.05 – 0.21)
G24 SSOP 0595
11
LTC1344A
U
TYPICAL APPLICATIO
Figure 13 shows a typical application for the LTC1344A
using the LTC1543 mixed mode transceiver chip to generate the clock and data signals for a serial interface. The
LTC1344A VEE supply is generated from the LTC1543
charge pump and the select lines M0, M1, M2 and
DCE/DTE are shared by both chips. Each driver output and
receiver input is connected to one of the LTC1344A
termination ports. Each electrical protocol can then be
chosen using the digital select lines.
100pF
100pF
100pF
3
M0
M1
M2
DCE/DTE
1
8
11
12
9
10
13
M0
24
M1
23
M2
22
LTC1344A
DCE/DTE
21
LATCH
VCC
VEE
14
C1
1µF
4
5
2
4
6
7
16
15
18
17
19
20
C2
3.3µF
26
LTC1543
11
M0
12
M1
13
M2
14
DCE/DTE
24
DTE
TXD+
DCE
RXD+
23
TXD–
RXD–
SCTE +
RXC+
21
SCTE –
RXC –
20
TXC +
TXC +
19
18
TXC –
RXC +
TXC –
SCTE+
RXC –
RXD+
SCTE–
TXD+
RXD–
TXD–
5
22
6
7
8
9
17
16
10
15
1344 F13
Figure 13. Typical Application Using the LTC1344A
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC1334
Single Supply RS232/RS485 Transceiver
2 RS485 Dr/Rx or 4 RS232 Dr/Rx Pairs
LTC1343
Multiprotocol Serial Transceiver
Software Selectable Mulitprotocol Interface
LTC1345
Single Supply V.35 Transceiver
3 Dr/3 Rx for Data and CLK Signals
LTC1346A
Dual Supply V.35 Transceiver
3 Dr/3 Rx for Data and CLK Signals
LTC1543
Multiprotocol Serial Transceiver
Software-Selectable Transceiver for Data and CLK Signals
LTC1544
Multiprotocol Serial Transceiver
Software-Selectable Transceiver for Control Signals
12
Linear Technology Corporation
1344af, sn1344a LT/TP 0898 4K • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com
 LINEAR TECHNOLOGY CORPORATION 1998