MAXIM MXL1344A User Manual

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, 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 100Ω 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 VEEpower 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 0°C to +70°C commercial tem­perature range.

Features

♦ Certified TBR-1 and TBR-2-Compliant Chipset

(NET1 and NET2)—Pending Completion of
Testing

♦ 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

♦ Cable- or Software-Selectable Termination

♦ Cable- or Software-Selectable DTE/DCE

♦ Replaces Discrete Resistor Termination Networks

and Expensive Relays

♦ 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

Pin Configuration appears at end of data sheet.

PART TEMP. RANGE PIN-PACKAGE

MXL1344ACAG

0°C to +70°C

24 SSOP

LL

CTS DSR RTSDTRDCD

MXL1544/

MAX3175

D3

DCD B

R1

13

CTS A (106)

CTS B

R2R3

DSR A (109)

DSR B

R4

18 5 10 8 22 6 23 20 19 4 1 7 16 3 9 17 12 15 11 24 14 2

LL A (141)

DTR A (108)

DTR B

DCD A (107)

D1D2

RTS A (105)

RTS B

DB-25 CONNECTOR

RXD RXC TXDTXC SCTE

MXL1543

R1

R2R3

RXC B

RXD A (104)

RXD B

SG (102)

SHIELD (101)

RXC A (115)

D3D4

TXC A (114)

TXC B

SCTE A (113)

SCTE B

D1D2

TXD B

TXD A (103)

MXL1344A

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

= +70°C)

24-Pin SSOP (derate 8mW/°C above +70°C) ...............640mW

Operating Temperature Range...............................0°C to +70°C

Die Temperature ..............................................................+150°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

ELECTRICAL CHARACTERISTICS

(VCC= +5V ±5%, VEE= -5V ±5%, TA= 0°C to 70°C, unless otherwise noted. Typical values are at TA= +25°C, VCC= +5V, VEE= -5V,
unless otherwise noted.)

DC CHARACTERISTICS
V
TERMINATOR PINS

Differential-Mode Impedance

V.35 Mode

Common-Mode Impedance

V.35 Mode

Differential-Mode Impedance

V.11 Mode

High-Impedance Leakage

Current

LOGIC INPUTS (M0, M1, M2, LATCH, DCE/DTE)
Input High Voltage V
Input Low Voltage V
Logic Input Current I

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Supply Current I

CC

CC

-2V ≤ V

-2V ≤ V

I

IH

All logic inputs = GND or V

≤ +2V, all loads, Figure 1 90 104 110 Ω

CM

≤ +2V, all loads, Figure 2 135 153 165 Ω

CM

V

= 0V, all loads 100 104 110

CM

-7V ≤ VCM ≤ +7V, all loads, TA = +25°C 100 104

-7V ≤ V

Z

2.0 V

IH

0.8 V

IL

, I

V

IL

IN

≤+7V, all loads -50 50 µA

CM

= VCC or GND ±10 µA

CC

0.4 1.0 mA

Ω

MXL1344A

+5V Multiprotocol, Software-Selectable

Cable Terminator

_______________________________________________________________________________________ 3

Typical Operating Characteristics

(VCC= +5V, VEE= -5V, TA = +25°C, unless otherwise noted.)

V.11 OR V.35 DIFFERENTIAL-MODE

IMPEDANCE vs. TEMPERATURE

106.0

105.5

105.0

104.5

IMPEDANCE (Ω)

104.0

103.5

103.0
0304010 20 50 60 70

TEMPERATURE (°C)

VCM = -7V

VCM = 0

V.11 OR V.35 DIFFERENTIAL-MODE

IMPEDANCE vs. SUPPLY VOLTAGE (V

110

105

VCM = +7V

EE

MXL1344A toc01

)

MXL1344A toc04

V.11 OR V.35 DIFFERENTIAL-MODE

IMPEDANCE vs. COMMON MODE VOLTAGE

110

105

100

IMPEDANCE (Ω)

95

90

-7 -1 1-5 -3 3 5 7

V.35 COMMON-MODE IMPEDANCE

165

160

155

VCM (V)

vs. TEMPERATURE

MXL1344A toc02

MXL1344A toc05

V.11 OR V.35 DIFFERENTIAL-MODE

IMPEDANCE vs. SUPPLY VOLTAGE (V

110

105

100

IMPEDANCE (Ω)

95

90

4.50 5.004.75 5.25 5.50
VCC (V)

V.35 COMMON-MODE IMPEDANCE

vs. COMMON-MODE VOLTAGE (V

165

160

155

CM

CC

)

)

MXL1344A toc03

MXL1344A toc06

100

IMPEDANCE (Ω)

95

90

-5.50 -5.00-5.25 -4.75 -4.50
VEE (V)

V.35 COMMON-MODE IMPEDANCE

vs. SUPPLY VOLTAGE (V

165

160

155

150

IMPEDANCE (Ω)

145

140

135

4.5 4.94.7 5.1 5.3 5.5
VCC (V)

CC

150

IMPEDANCE (Ω)

145

140

135

0304010 20 50 60 70

TEMPERATURE (°C)

150

IMPEDANCE (Ω)

145

140

135

-2 0-1 1 2
VCM (V)

V.35 COMMON-MODE IMPEDANCE

)

165

160

MXL1344A toc07

155

150

IMPEDANCE (Ω)

145

140

135

vs. SUPPLY VOLTAGE (V

-5.5 -5.1-5.3 -4.9 -4.7 -4.5
VEE (V)

)

EE

MXL1344A toc08

SUPPLY CURRENT vs. TEMPERATURE

500

450

400

350

300

250

SUPPLY CURRENT (µA)

200

150

100

0203010

40

TEMPERATURE (°C)

I

EE

I

CC

50 60 70

MXL1344A toc09

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 100Ω 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 net-

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 VEEpower 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

MXL1344A

+5V Multiprotocol, Software-Selectable
Cable Terminator

4 _______________________________________________________________________________________

Pin Description

*V

EE

is typically supplied by the charge pump of the MXL1543. The VEEinput level varies with the mode of chipset operation

as follows:

V.35/V.28 Modes: -6.50V ≤ V

EE

≤ -5.45V, in typical operation VEE= -5.80V

V.10/V.11 Modes: -4.60V ≤ V

EE

≤ -3.80V, in typical operation VEE= -4.20V

PIN NAME FUNCTION

1 M0 Mode-Select Pin (Table 1)

2V

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

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

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)

EE

CC

Negative Supply Voltage (typically connected to VEE of MXL1543*). Bypass to GND with a 0.1µF
capacitor.

+5V Supply Voltage. Bypass to GND with a 0.1µF capacitor.

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.