Typical Operating Circuit
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim's website at www.maxim-ic.com.
General Description
The MXL1344A contains six software-selectable, multi-
protocol cable termination networks. Each network is
capable of terminating V.11 (RS-422, RS-530, RS-530A,
RS-449, V.36 and X.21) with a 100
differential load,
V.35 with a T-network load, or V.28 (RS-232) and V.10
(RS-423) with an open-circuit load for use with trans-
ceivers having on-chip termination. The termination pro-
tocol can be selected by the serial interface cable
wiring or by software control. The MXL1344A replaces
discrete resistor termination networks and expensive
relays required for multiprotocol termination, saving
space and cost.
The MXL1344A terminator is designed to form a com-
plete +5V cable- or software-selectable multiprotocol
DCE/DTE interface port when used with the MXL1543
and MXL1544/MAX3175 transceiver ICs. The MXL1344A
terminator can use the V
EE
power generated by the
MXL1543 charge pump, simplifying system design. The
MXL1344A, MXL1543, and MXL1544/MAX3175 are pin-
for-pin compatible with the LTC1344A, LTC1543, and
LTC1544, but for proper operation the entire Maxim
chipset must be used without substituting other manu-
facturer's parts on a chip-by-chip basis.
The MXL1344A is available in a 24-pin SSOP package
and is specified for the 0C to +70C commercial tem-
perature range.
Features
o Certified TBR-1 and TBR-2-Compliant Chipset
(NET1 and NET2)--Pending Completion of
Testing
o Supports V.10 (RS-423), V.11 (RS-422, RS-530,
RS-530A, RS-449, V.36, and X.21), V.28 (RS-232)
and V.35 Termination
o Cable- or Software-Selectable Termination
o Cable- or Software-Selectable DTE/DCE
o Replaces Discrete Resistor Termination Networks
and Expensive Relays
o Available in Small 24-Pin SSOP Package
Applications
Data Networking
PCI Cards
CSU and DSU
Telecommunication Equipment
Data Routers
Data Switches
MXL1344A
+5V Multiprotocol, Software-Selectable
Cable Terminator
________________________________________________________________ Maxim Integrated Products
1
19-1775; Rev 0; 2/01
Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
MXL1344ACAG
0
C to +70C
24 SSOP
D1
D2
D3
D4
R1
R2
R3
MXL1543
RXD
RXC
TXD
TXC
SCTE
D1
D2
D3
R1
R2
R3
MXL1544/
MAX3175
CTS
DSR
RTS
DTR
DCD
RXC B
RXD A (104)
RXD B
SG (102)
SHIELD (101)
RTS A (105)
RTS B
DTR A (108)
DTR B
DCD A (107)
DCD B
DSR A (109)
CTS A (106)
DSR B
CTS B
LL A (141)
TXD B
SCTE A (113)
SCTE B
TXC A (114)
TXC B
TXD A (103)
DB-25 CONNECTOR
13
R4
LL
RXC A (115)
18
5
10 8
22 6
23 20 19 4
1
7
16 3
9 17
12 15 11 24 14 2
MXL1344A
Pin Configuration appears at end of data sheet.
MXL1344A
+5V Multiprotocol, Software-Selectable
Cable Terminator
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
All Voltages to GND Unless Otherwise Noted
Supply Voltages
V
CC
........................................................................-0.3V to +6V
V
EE
.........................................................................+0.3V to -7V
Logic Input Voltages
M0, M1, M2, DCE/DTE, LATCH.............................-0.3V to +6V
Termination Network Inputs
R_A, R_B ..............................................................-15V to +15V
R_A to R_B........................................................................15V
Continuous Power Dissipation (T
A
= +70C)
24-Pin SSOP (derate 8mW/C above +70C) ...............640mW
Operating Temperature Range...............................0C to +70C
Die Temperature ..............................................................+150C
Storage Temperature Range .............................-65C to +150C
Lead Temperature (soldering, 10s) .................................+300C
ELECTRICAL CHARACTERISTICS
(V
CC
= +5V 5%, V
EE
= -5V 5%, T
A
= 0C to 70C, unless otherwise noted. Typical values are at T
A
= +25C, V
CC
= +5V, V
EE
= -5V,
unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DC CHARACTERISTICS
V
CC
Supply Current
I
CC
All logic inputs = GND or V
CC
0.4
1.0
mA
TERMINATOR PINS
Differential-Mode Impedance
V.35 Mode
-2V
V
CM
+2V, all loads, Figure 1
90
104
110
Common-Mode Impedance
V.35 Mode
-2V
V
CM
+2V, all loads, Figure 2
135
153
165
V
CM
= 0V, all loads
100
104
110
Differential-Mode Impedance
V.11 Mode
-7V
V
CM
+7V, all loads, T
A
= +25
C
100
104
High-Impedance Leakage
Current
I
Z
-7V
V
CM
+7V, all loads
-50
50
A
LOGIC INPUTS (M0, M1, M2, LATCH, DCE/DTE)
Input High Voltage
V
IH
2.0
V
Input Low Voltage
V
IL
0.8
V
Logic Input Current
I
IH
, I
IL
V
IN
= V
CC
or GND
10
A
MXL1344A
+5V Multiprotocol, Software-Selectable
Cable Terminator
_______________________________________________________________________________________
3
103.0
104.0
103.5
105.0
104.5
105.5
106.0
0
30
40
10
20
50
60
70
V.11 OR V.35 DIFFERENTIAL-MODE
IMPEDANCE vs. TEMPERATURE
MXL1344A toc01
TEMPERATURE (
C)
IMPEDANCE (
)
V
CM
= +7V
V
CM
= -7V
V
CM
= 0
90
95
100
105
110
V.11 OR V.35 DIFFERENTIAL-MODE
IMPEDANCE vs. COMMON MODE VOLTAGE
MXL1344A toc02
V
CM
(V)
IMPEDANCE (
)
-7
-1
1
-5
-3
3
5
7
90
95
100
105
110
V.11 OR V.35 DIFFERENTIAL-MODE
IMPEDANCE vs. SUPPLY VOLTAGE (V
CC
)
MXL1344A toc03
V
CC
(V)
IMPEDANCE (
)
4.50
5.00
4.75
5.25
5.50
90
95
100
105
110
V.11 OR V.35 DIFFERENTIAL-MODE
IMPEDANCE vs. SUPPLY VOLTAGE (V
EE
)
MXL1344A toc04
V
EE
(V)
IMPEDANCE (
)
-5.50
-5.00
-5.25
-4.75
-4.50
135
145
140
155
150
160
165
0
30
40
10
20
50
60
70
V.35 COMMON-MODE IMPEDANCE
vs. TEMPERATURE
MXL1344A toc05
TEMPERATURE (
C)
IMPEDANCE (
)
135
145
140
155
150
160
165
-2
0
-1
1
2
V.35 COMMON-MODE IMPEDANCE
vs. COMMON-MODE VOLTAGE (V
CM
)
MXL1344A toc06
V
CM
(V)
IMPEDANCE (
)
135
145
140
155
150
160
165
4.5
4.9
4.7
5.1
5.3
5.5
V.35 COMMON-MODE IMPEDANCE
vs. SUPPLY VOLTAGE (V
CC
)
MXL1344A toc07
V
CC
(V)
IMPEDANCE (
)
135
145
140
155
150
160
165
-5.5
-5.1
-5.3
-4.9
-4.7
-4.5
V.35 COMMON-MODE IMPEDANCE
vs. SUPPLY VOLTAGE (V
EE
)
MXL1344A toc08
V
EE
(V)
IMPEDANCE (
)
SUPPLY CURRENT vs. TEMPERATURE
MXL1344A toc09
100
150
250
200
400
450
350
300
500
SUPPLY CURRENT (
A)
0
20
30
10
40
50
60
70
I
EE
I
CC
TEMPERATURE (
C)
Typical Operating Characteristics
(V
CC
= +5V, V
EE
= -5V, T
A
= +25C, unless otherwise noted.)
Detailed Description
The MXL1344A contains six software-selectable multi-
protocol cable termination networks (Figure 3). Each
network is capable of terminating V.11 (RS-422, RS-
530, RS-530A, RS-449, V.36 and X.21) with a 100
dif-
ferential load, V.35 with a T-network load, or V.28
(RS-232) and V.10 (RS-423) with an open-circuit load
for use with transceivers having on-chip termination.
The termination protocol can be selected by the serial
interface cable wiring or by software control. The
MXL1344A replaces discrete resistor termination net-
works and expensive relays required for multiprotocol
termination, saving space and cost.
The MXL1344A terminator is designed to form a com-
plete +5V cable- or software-selectable multiprotocol
DTE/DCE interface port when used with the MXL1543
and MXL1544/MAX3175 transceivers. The MXL1344A
terminator can use the V
EE
power generated by the
MXL1543 charge pump, simplifying system design. The
MXL1344A, MXL1543, and MXL1544/MAX3175 are pin-
for-pin compatible with the LTC1344A, LTC1543, and
LTC1544, but for proper operation, the entire Maxim
MXL1344A
+5V Multiprotocol, Software-Selectable
Cable Terminator
4
_______________________________________________________________________________________
Pin Description
PIN
NAME
FUNCTION
1
M0
Mode-Select Pin (Table 1)
2
V
EE
Negative Supply Voltage (typically connected to V
EE
of MXL1543*). Bypass to GND with a 0.1
F
capacitor.
3
R1C
Load 1, Center Tap
4
R1B
Load 1, Node B
5
R1A
Load 1, Node A
6
R2A
Load 2, Node A
7
R2B
Load 2, Node B
8
R2C
Load 2, Center Tap
9
R3A
Load 3, Node A
10
R3B
Load 3, Node B
11
R3C
Load 3, Center Tap
12, 13
GND
Ground
14
V
CC
+5V Supply Voltage. Bypass to GND with a 0.1
F capacitor.
15
R4B
Load 4, Node B
16
R4A
Load 4, Node A
17
R5B
Load 5, Node B
18
R5A
Load 5, Node A
19
R6A
Load 6, Node A
20
R6B
Load 6, Node B
21
LATCH
Latch Signal Input. When LATCH is LOW, the input latches are transparent. When LATCH is high, the
data at the mode-select inputs are latched.
22
DCE/ DTE
Logic Level HIGH selects DCE interface, (Table 1)
23
M2
Mode-Select Pin (Table 1)
24
M1
Mode-Select Pin (Table 1)
*V
EE
is typically supplied by the charge pump of the MXL1543. The V
EE
input level varies with the mode of chipset operation
as follows:
V.35/V.28 Modes: -6.50V
V
EE
-5.45V, in typical operation V
EE
= -5.80V
V.10/V.11 Modes: -4.60V
V
EE
-3.80V, in typical operation V
EE
= -4.20V
MXL1344A
+5V Multiprotocol, Software-Selectable
Cable Terminator
_______________________________________________________________________________________
5
V
CM
=
7V OR 2V
V
DM
=
2V
R
DM
=
V
DM
R2 = 52
R3 = 127
R1 = 52
S1 ON
A
I
I
B
S2 OFF
AMMETER
V
CM
=
2V
R2 = 52
R3 = 127
R1 = 52
S1 ON
A
B
S2 ON
AMMETER
R
CM
=
V
CM
I
I
Figure 1. V.11 or V.35 Differential Impedance Measurement
Figure 3. Block Diagram
Figure 2. V.35 Common-Mode Impedance Measurement
M2
1
2
3
4
5
6
5
2
1
24
23
22
21
4
6 7
9 10 16 15 18 17
14
19 20
3
8
11 12
13
V
CC
V
EE
M1
M0
DCE/DTE
LATCH
MXL1344A
chipset must be used without substituting other manu-
facturer's parts on a chip-by-chip basis.
Termination Modes
The termination networks in the MXL1344A can be set
to one of three modes, V.11, V.35, or high impedance
(high-Z). As shown in Figure 4, in V.11 mode, switch S1
is closed and switch S2 is open, presenting 104
across terminals A and B. In V.35 mode, switches S1
and S2 are both closed, presenting a T-network with
104
differential impedance and 153 common-mode
impedance. In high-Z mode, switches S1 and S2 are
both open, presenting a high impedance across termi-
nals A and B suitable for V.28 and V.10 modes.
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