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19-1775; Rev 0; 2/01
+5V Multiprotocol, Software-Selectable Cable Terminator
General Description
The MXL1344A contains six software-selectable, multiprotocol 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 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 networks and expensive relays required for multiprotocol termination, saving space and cost. The MXL1344A terminator is designed to form a complete +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 VEE power generated by the MXL1543 charge pump, simplifying system design. The MXL1344A, MXL1543, and MXL1544/MAX3175 are pinfor-pin compatible with the LTC1344A, LTC1543, and LTC1544, but for proper operation the entire Maxim chipset must be used without substituting other manufacturer'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 temperature 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
MXL1344A
Applications
Data Networking CSU and DSU Data Routers PCI Cards Telecommunication Equipment Data Switches
Ordering Information
PART MXL1344ACAG TEMP. RANGE 0C to +70C PIN-PACKAGE 24 SSOP
Pin Configuration appears at end of data sheet.
Typical Operating Circuit
LL CTS DSR DCD DTR RTS RXD RXC TXC SCTE TXD
D4
R4
R3
R2
R1
MXL1544/ MAX3175
D3
D2
D1
MXL1543 R3 R2 R1
D3
D2
D1
MXL1344A
18 LL A (141)
13 5 10 8 CTS A (106) CTS B DSR A (109) DSR B
22 6 DCD A (107) DCD B
23 20 19 4 DTR A (108) DTR B RTS A (105) RTS B
1
7
16 3 RXD A (104) RXD B
9 17 RXC A (115) RXC B
12 15 11 24 14 2 TXC A (114) TXC B SCTE A (113) SCTE B TXD A (103) TXD B
DB-25 CONNECTOR
________________________________________________________________ Maxim Integrated Products
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.
SG (102) SHIELD (101)
1
+5V Multiprotocol, Software-Selectable Cable Terminator MXL1344A
ABSOLUTE MAXIMUM RATINGS
All Voltages to GND Unless Otherwise Noted Supply Voltages VCC ........................................................................-0.3V to +6V VEE.........................................................................+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 (TA = +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
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.
ELECTRICAL CHARACTERISTICS
(VCC = +5V 5%, VEE = -5V 5%, TA = 0C to 70C, unless otherwise noted. Typical values are at TA = +25C, VCC = +5V, VEE = -5V, unless otherwise noted.)
PARAMETER DC CHARACTERISTICS VCC Supply Current TERMINATOR PINS Differential-Mode Impedance V.35 Mode Common-Mode Impedance V.35 Mode Differential-Mode Impedance V.11 Mode High-Impedance Leakage Current Input High Voltage Input Low Voltage Logic Input Current IZ -2V VCM +2V, all loads, Figure 1 -2V VCM +2V, all loads, Figure 2 VCM = 0V, all loads -7V VCM +7V, all loads, TA = +25C -7V VCM +7V, all loads 90 135 100 100 -50 104 153 104 104 50 110 165 110 A ICC All logic inputs = GND or VCC 0.4 1.0 mA SYMBOL CONDITIONS MIN TYP MAX UNITS
LOGIC INPUTS (M0, M1, M2, LATCH, DCE/DTE) VIH VIL IIH, IIL VIN = VCC or GND 2.0 0.8 10 V V A
2
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+5V Multiprotocol, Software-Selectable Cable Terminator
Typical Operating Characteristics
(VCC = +5V, VEE = -5V, TA = +25C, unless otherwise noted.)
V.11 OR V.35 DIFFERENTIAL-MODE IMPEDANCE vs. TEMPERATURE
MXL1344A toc01
MXL1344A
V.11 OR V.35 DIFFERENTIAL-MODE IMPEDANCE vs. COMMON MODE VOLTAGE
MXL1344A toc02
V.11 OR V.35 DIFFERENTIAL-MODE IMPEDANCE vs. SUPPLY VOLTAGE (VCC)
MXL1344A toc03
106.0 105.5 IMPEDANCE () 105.0 104.5 VCM = +7V 104.0 103.5 103.0 0 10 20 30 40 50 60
110
110
VCM = -7V VCM = 0
105 IMPEDANCE () IMPEDANCE () -7 -5 -3 -1 1 3 5 7
105
100
100
95
95
90 70 TEMPERATURE (C) VCM (V)
90 4.50 4.75 5.00 VCC (V) 5.25 5.50
V.11 OR V.35 DIFFERENTIAL-MODE IMPEDANCE vs. SUPPLY VOLTAGE (VEE)
MXL1344A toc04
V.35 COMMON-MODE IMPEDANCE vs. TEMPERATURE
MXL1344A toc05
V.35 COMMON-MODE IMPEDANCE vs. COMMON-MODE VOLTAGE (VCM)
MXL1344A toc06
110
165 160 IMPEDANCE () 155 150 145 140
165 160 IMPEDANCE () 155 150 145 140 135
105 IMPEDANCE ()
100
95
90 -5.50
135 -5.25 -5.00 VEE (V) -4.75 -4.50 0 10 20 30 40 50 60 70 TEMPERATURE (C)
-2
-1
0 VCM (V)
1
2
V.35 COMMON-MODE IMPEDANCE vs. SUPPLY VOLTAGE (VCC)
MXL1344A toc07
V.35 COMMON-MODE IMPEDANCE vs. SUPPLY VOLTAGE (VEE)
MXL1344A toc08
SUPPLY CURRENT vs. TEMPERATURE
450 SUPPLY CURRENT (A) 400 350 300 250 200 150 100 ICC IEE
MXL1344A toc09
165 160 IMPEDANCE () 155 150 145 140 135 4.5 4.7 4.9 5.1 5.3
165 160 IMPEDANCE () 155 150 145 140 135
500
5.5
-5.5
-5.3
-5.1
-4.9
-4.7
-4.5
0
10
20
VCC (V)
VEE (V)
30 50 40 TEMPERATURE (C)
60
70
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3
+5V Multiprotocol, Software-Selectable Cable Terminator MXL1344A
Pin Description
PIN 1 2 3 4 5 6 7 8 9 10 11 12, 13 14 15 16 17 18 19 20 21 22 23 24 NAME M0 VEE R1C R1B R1A R2A R2B R2C R3A R3B R3C GND VCC R4B R4A R5B R5A R6A R6B LATCH DCE/ DTE M2 M1 Mode-Select Pin (Table 1) Negative Supply Voltage (typically connected to VEE of MXL1543*). Bypass to GND with a 0.1F capacitor. Load 1, Center Tap Load 1, Node B Load 1, Node A Load 2, Node A Load 2, Node B Load 2, Center Tap Load 3, Node A Load 3, Node B Load 3, Center Tap Ground +5V Supply Voltage. Bypass to GND with a 0.1F capacitor. Load 4, Node B Load 4, Node A Load 5, Node B Load 5, Node A Load 6, Node A Load 6, Node B 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. Logic Level HIGH selects DCE interface, (Table 1) Mode-Select Pin (Table 1) Mode-Select Pin (Table 1) FUNCTION
*VEE is typically supplied by the charge pump of the MXL1543. The VEE input level varies with the mode of chipset operation as follows: V.35/V.28 Modes: -6.50V VEE -5.45V, in typical operation VEE = -5.80V V.10/V.11 Modes: -4.60V VEE -3.80V, in typical operation VEE = -4.20V
Detailed Description
The MXL1344A contains six software-selectable multiprotocol cable termination networks (Figure 3). Each network is capable of terminating V.11 (RS-422, RS530, 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 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 net4
works and expensive relays required for multiprotocol termination, saving space and cost. The MXL1344A terminator is designed to form a complete +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 VEE power generated by the MXL1543 charge pump, simplifying system design. The MXL1344A, MXL1543, and MXL1544/MAX3175 are pinfor-pin compatible with the LTC1344A, LTC1543, and LTC1544, but for proper operation, the entire Maxim
_______________________________________________________________________________________
+5V Multiprotocol, Software-Selectable Cable Terminator MXL1344A
A A
I
R1 = 52 R1 = 52
AMMETER
S1 ON R3 = 127 S2 OFF AMMETER S2 ON R2 = 52 I R2 = 52 VCM = 2V B VCM = 7V OR 2V V RDM = DM I RCM = VCM I B S1 ON R3 = 127
VDM = 2V
Figure 1. V.11 or V.35 Differential Impedance Measurement
Figure 2. V.35 Common-Mode Impedance Measurement
3 1 24 23 22 21 M0 M1 M2 DCE/DTE LATCH VCC VEE 14 2 54 1 MXL1344A
8
11 12
13
2
3
4
5
6
67
9 10 16 15 18 17 19 20
Figure 3. Block Diagram
chipset must be used without substituting other manufacturer'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 terminals A and B suitable for V.28 and V.10 modes.
5
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+5V Multiprotocol, Software-Selectable Cable Terminator MXL1344A
A MXL1344A R1 52 R1 52 A MXL1344A R1 52 A MXL1344A
S1 CLOSED C
S1 CLOSED C
S1 OPEN C
S2 OPEN R2 52
R3 127
S2 CLOSED R2 52
R3 127
S2 OPEN R2 52
R3 127
B
B
B
(a) V.11
Figure 4. Termination Modes
(b) V.35
(c) Z
Table 1. Termination Mode Select Table
PROTOCOL V.10/RS-423 RS-530A RS-530 X.21 V.35 RS-449/V.36 V.28/RS-232 No Cable V.10/RS-423 RS-530A RS-530 X.21 V.35 RS-449/V.36 V.28/RS-232 No Cable DCE/ DTE 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 M2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 M1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 M0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 R1 Z Z Z Z V.35 Z Z V.11 Z Z Z Z V.35 Z Z V.11 R2 Z Z Z Z V.35 Z Z V.11 Z Z Z Z V.35 Z Z V.11 R3 Z Z Z Z Z Z Z V.11 Z Z Z Z V.35 Z Z V.11 R4 Z V.11 V.11 V.11 V.35 V.11 Z V.11 Z Z Z Z Z Z Z V.11 R5 Z V.11 V.11 V.11 V.35 V.11 Z V.11 Z V.11 V.11 V.11 V.35 V.11 Z V.11 R6 Z V.11 V.11 V.11 V.35 V.11 Z V.11 Z V.11 V.11 V.11 V.35 V.11 Z V.11
Note: Z Indicates high impedance, 1 = high and 0 = low. Z, V.11, and V.35 refer to termination modes (Figure 4.)
The state of the MXL1344A's mode-select pins, M0, M1, M2, and DCE/DTE determines the mode of each of the six termination networks. Table 1 shows a cross-reference of termination mode and select pin state for
each of the six termination networks within the MXL1344A.
6
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+5V Multiprotocol, Software-Selectable Cable Terminator MXL1344A
100pF 100pF 100pF
3 VCC 5V 14 3 4.7F 1 1F 1F DTE_TXD/DCE_RXD DTE_SCTE/DCE_RXC 5 6 7 DTE_TXC/DCE_TXC DTE_RXC/DCE_SCTE DTE_RXD/DCE_TXD 8 9 10 D1 D2 D3 R1 R2 R3 20 19 18 17 16 15 24 23 22 21 2 CHARGE PUMP 28 27 26 25 4.7F 0.1F 54 0.1F 1F 2
8
11
12 13 MXL1344A
LATCH
21
DCE/DTE M2 M1
67
9 10 16 15 18 17 19 20 22 23 24 1
M0
SYSTEM PROPRIETARY CONNECTOR INTERCONNECT CABLE
DB-25 CONNECTOR
DTE 2 TXD A 14 TXD B 24 SCTE A 11 SCTE B 15 12 17 9 3 16 7 1
DCE RXD A RXD B RXC A RXC B
TXC A TXC B
TXC A TXC B
S GND 11 M0 MXL1543 12 M1 13 M2 14 DCE/DTE
RXC A SCTE A RXC B SCTE B RXD A TXD A RXD B TXD B SIGNAL GND SHIELD
0.1F
VCC 1 28 VCC VDD VEE 0.1F 2 GND 27
M0 M1 M2 DCE/DTE
1F DTE_RTS/DCE_CTS DTE_DTR/DCE_DSR 3 4 5 DTE_DCD/DCE_DCD DTE_DSR/DCE_DTR DTE_CTS/DCE_RTS LOCAL_LOOP_BACK 6 7 8 10 9 11 D1 D2 D3 R1 R2 R3 R4 D4 22 21 20 19 18 17 16 8 DCD A 10 DCD B 6 DSR A 22 DSR B 5 CTS A 13 CTS B 18 LL DCD A DCD B DTR A DTR B RTS A RTS B 26 25 24 23 4 19 20 23 RTS A RTS B DTR A DTR B CTS A CTS B DSR A DSR B
M0 MXL1544/ MAX3175 12 M1 13 M2 15 14 DCE/DTE INVERT
Figure 5. Cable-Selectable Multiprotocol DCE/DTE Serial Interface (Configured in RS-530A DTE Mode)
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7
+5V Multiprotocol, Software-Selectable Cable Terminator MXL1344A
No-Cable Mode
The MXL1344A enters no-cable mode when the mode select inputs, M0, M1, and M2 are connected HIGH or left unconnected. In no-cable mode, all six termination networks are placed in V.11 mode, with S1 closed and S2 open (Figure 4). the correct termination. The MXL1344A provides a simple solution to this termination problem. All required termination configurations are easily cable- or softwareselectable using the four mode-control input pins M0, M1, M2, and DCE/DTE.
Applications Information
Older multiprotocol interface termination circuits have been constructed using expensive relays with discrete resistors, custom cables with built-in termination, or complex circuit-board configurations to route signals to
Using the MXL1344A in a Multiprotocol Serial Interface
The MXL1344A terminator is designed to form a complete +5V cable- or software-selectable multiprotocol DCE/DTE interface port when used with the MXL1543 and MXL1544/MAX3175 differential driver/receivers. The MXL1344A terminator is designed to use the VEE power generated by the MXL1543's charge pump and will meet all data sheet specifications when connected as illustrated in Figure 5. The mode-selection tables of all three devices are identical, allowing the M0, M1, M2, and DCE/DTE pins of each device to be connected to a single 4-wire control bus. The MXL1543 and MXL1544/ MAX3175 provide internal pullups for the four lines, forcing them to the logic high state if they are not grounded. This allows interface-mode configuration by simply strapping the appropriate pins to ground in the interconnect cable. In Figure 5, M1, M2 and DCE/DTE are shorted to the cable ground, forcing logic LOW on these control lines. Input M0 is left floating and will be pulled HIGH by internal pullups on the MXL1543 and MXL1544/
GENERATOR
BALANCED INTERCONNECTING CABLE
LOAD CABLE RECEIVER TERMINATION A 100 MIN
A
B C
B C
Figure 6. Typical V.11 Interface
A
A R5 30k R1 52
MXL1543
MXL1344A
R8 5k
R6 10k
RECEIVER
S1 S2
S3 R3 127
R2 52 B B R4 30k
R7 10k
C GND
Figure 7. V.11 Termination and Internal Resistance Networks 8 _______________________________________________________________________________________
+5V Multiprotocol, Software-Selectable Cable Terminator MXL1344A
GENERATOR BALANCED INTERCONNECTING CABLE A 50 A CABLE TERMINATION 50 LOAD RECEIVER
125
125
50 B C B C
50
Figure 8. Typical V.35 Interface
A
A R5 30k R1 52
MXL1543
MXL1344A
R8 5k
R6 10k
RECEIVER
S1
S3 R3 127 S2 R2 52 R7 10k B R4 30k
B
C GND
Figure 9. V.35 Termination and Internal Resistance Networks
MAX3175. With this cable wiring, the multiprotocol serial port is set in RS-530A DTE mode (Table 1).
V.11 Termination
A standard V.11 interface is shown in Figure 6. For high-speed data transmission, the V.11 specification recommends terminating the cable at the receiver with a 100 (min) resistor. The resistor, although not required, prevents reflections from corrupting transmitted data. In Figure 7, the MXL1344A is used to terminate the V.11 receiver on the MXL1543. Internal to the MXL1344A, S1 is closed and S2 is open to present a 104 typical differential resistance and high-Z common-mode impedance. The MXL1543's internal V.28 termination is disabled by opening S3.
The V.11 specification allows for signals with commonmode variations of 7V and differential signal amplitudes from 2V to 6V with data rates as high as 10Mbps. The MXL1344A maintains termination impedance between 100 and 110 over these conditions.
V.35 Termination
Figure 8 shows a standard V.35 interface. The generator and the load must both present a 100 10 differential impedance and a 150 15 common-mode impedance. The V.35 driver generates a current output (11mA typ) that develops an output voltage between 440mV and 660mV across the load termination networks. In Figure 9, the MXL1344A is used to implement the resistive T-network that is needed to properly terminate
9
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+5V Multiprotocol, Software-Selectable Cable Terminator MXL1344A
the V.35 receiver. Internal to the MXL1344A, S1 and S2 are closed to connect the T-network resistors to the circuit. The V.35 specification allows for 4V of ground difference between the V.35 generator and V.35 load, with data rates as high as 10Mbps. The MXL1344A maintains correct termination impedance over these conditions.
Compliance Testing
A European Standard EN 45001 test report for the MXL1543, MXL1544/MAX3175, and MXL1344A chipset will be available from Maxim upon completion of testing. Contact Maxim Quality Assurance for a copy of the report.
V.35 EMI reduction
For applications where EMI reduction is especially important, the MXL1344A termination networks provide a pin for shunting common-mode driver currents to GND. Mismatches between the driver A and B output propagation delays can create a common-mode disturbance on the cable. This common-mode energy can be shunted to GND by placing a 100pF capacitor to GND from the center tap of the T-network termination (R1C, R2C and R3C as shown in Figure 5).
Chip Information
TRANSISTOR COUNT: 1,054 PROCESS TECHNOLOGY: BiCMOS
Pin Configuration
TOP VIEW
M0 1 VEE 2 R1C 3 R1B 4 R1A 5 R2A 6 R2B 7 R2C 8 R3A 9 R3B 10 R3C 11 GND 12 24 M1 23 M2 22 DCE/DTE 21 LATCH
V.28 Termination
Most industry-standard V.28 receivers (including the MXL1543) do not require external termination because the receiver includes an internal 5k termination resistor. When the MXL1344A is placed in V.28 mode, all six of the termination networks are placed in a high-Z mode. In high-Z mode, the MXL1344A termination networks will not interfere with the MXL1543's internal 5k termination. In Figure 10, the MXL1344A and MXL1543 are placed in V.28 mode. Switches S1 and S2 are opened on the MXL1344A to place the network in high-Z mode. Switch S3 is closed on the MXL1543 to enable the 5k terminating resistor.
MAX1344A
20 R6B 19 R6A 18 R5A 17 R5B 16 R4A 15 R4B 14 VCC 13 GND
A Complete X.21 Interface
A complete DTE-to-DCE interface operating in X.21 mode is shown in Figure 11. The MXL1344A terminates the V.11 clock and data signals. The MXL1543 carries the clock and data signals, and the MXL1544/MAX3175 carries the control signals. The control signals generally do not require external termination.
24 SSOP
10
______________________________________________________________________________________
+5V Multiprotocol, Software-Selectable Cable Terminator MXL1344A
A A R5 30k R1 52
MXL1543
MXL1344A
R8 5k
R6 10k
RECEIVER
S1 S2
S3 R3 127
R2 52 B B R4 30k
R7 10k
C GND
Figure 10. V.28 Termination and Internal Resistance Networks
DTE SERIAL CONTROLLER TXD
MXL1543 MXL1344A MXL1344A
DCE
MXL1543
SERIAL CONTROLLER TXD
D1
TXD
104
R3
SCTE
D2 D3
SCTE
104
R2 R1
SCTE
TXC RXC
R1 R2
104 104
TXC RXC RXD
D3 D2
TXC RXC
RXD
R3
104
D1
RXD
MXL1544/MAX3175
MXL1544/MAX3175
RTS DTR
D1 D2 D3
RTS DTR
R3 R2 R1
RTS DTR
DCD DSR CTS LL
R1 R2 R3 D4 R4
DCD DSR CTS LL
D3 D2 D1 R4 D4
DCD DSR CTS LL
Figure 11. DTE-to-DCE X.21 Interface ______________________________________________________________________________________ 11
+5V Multiprotocol, Software-Selectable Cable Terminator MXL1344A
Package Information
SSOP.EPS
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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