MAXIM MXL1543 User Manual

General Description

The MXL1543 is a three-driver/three-receiver multipro­tocol transceiver that operates from a +5V single sup­ply. The MXL1543, along with the MXL1544/MAX3175
and the MXL1344A, form a complete software-selec­table data terminal equipment (DTE) or data communi­cation equipment (DCE) interface port that supports the
V.28 (RS-232), V.10/V.11 (RS-449/V.36, EIA-530, EIA­530A, X.21), and V.35 protocols. The MXL1543 trans­ceivers carry the high-speed clock and data signals
while the MXL1544/MAX3175 carry the control signals.
The MXL1543 can be terminated by the MXL1344A
software-selectable resistor termination network or by
discrete termination networks.

An internal charge pump and a proprietary low-dropout
transmitter output stage allow V.11- , V.28- , and V.35­compliant operation from a +5V single supply. A no­cable mode is entered when all mode pins (M0, M1,
and M2) are pulled high or left unconnected. In no­cable mode, supply current decreases to 0.5µA and all
transmitter and receiver outputs are disabled (high
impedance). Short-circuit current limiting and thermal
shutdown circuitry protect the drivers against excessive
power dissipation.

Applications

Features

♦ MXL1543, MXL1544/MAX3175, and MXL1344A

Chipset Is Pin Compatible with LTC1543,
LTC1544, and LTC1344A

♦ Supports RS-232, RS-449, EIA-530, EIA-530A,

V.35, V.36, and X.21

♦ Software-Selectable Cable Termination Using the

MXL1344A

♦ Complete DTE or DCE Port with MXL1544/

MAX3175, and MXL1344A

♦ +5V Single-Supply Operation

♦ 0.5µA No-Cable Mode

♦ TUV-Certified NET1/NET2 and TBR1/TBR2-

Compliant

MXL1543

+5V Multiprotocol, 3Tx/3Rx, Software-

Selectable Clock/Data Transceivers

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

19-1929; Rev 1; 9/01

Data Networking

CSU and DSU

Data Routers

PCI Cards

Telecommunications
Equipment

Typical Operating Circuit

Pin Configuration appears at end of data sheet.

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

PART TEMP. RANGE PIN-PACKAGE

MXL1543CAI 0° to +70°C 28 SSOP

CTS DSR RTSDTRDCD

LL

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)

R2R3

13

CTS A (106)

DSR B

CTS B

MAX3175

DSR A (109)

MXL1544

R1

D3

DCD A (107)

DCD B

DTR A (108)

DTR B

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

MXL1543

+5V Multiprotocol, 3Tx/3Rx, Software­Selectable Clock/Data Transceivers

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= +5.0V, C1 = C2 = C4 = 1µF, C3 = C5 = 4.7µF, (Figure 10), TA = T

MIN

to T

MAX

. Typical values are at TA = +25°C, unless oth-

erwise noted.)

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 Referenced to GND Unless Otherwise Noted.
Supply Voltages

V

CC

.......................................................................-0.3V to +6V

V

DD

....................................................................-0.3V to +7.3V

V

EE

.....................................................................+0.3V to -6.5V

V

DD

to V

EE

(Note 1)................................................................13V

Logic Input Voltages

M0, M1, M2, DCE/DTE, T_IN ................................-0.3V to +6V

Logic Output Voltages

R_OUT....................................................-0.3V to (V

CC

+ 0.3V)

Transmitter Outputs

T_OUT_, T3OUT_/R1IN_.....................................-15V to +15V

Short-Circuit Duration............................................Continuous

Receiver Input

R_IN_T3OUT_/R1IN_ ..........................................-15V to +15V

Continuous Power Dissipation (T

A

= +70°C)

28-Pin SSOP (derate 11.1mW/°C above +70°C) .........889mW

Operating Temperature Range

MXL1543CAI .......................................................0°C to 70°C

Junction Temperature .......................................................150°C

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

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

Note 1: VDDand VEEabsolute difference cannot exceed 13V.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DC CHARACTERISTICS

V

Operating Range V

CC

Supply Current
(DCE Mode)
(Digital Inputs = GND or

)

V

CC

(Transmitter Outputs Static)

Internal Power Dissipation
(DCE Mode)

Positive Charge-Pump
Output Voltage

Negative Charge-Pump
Output Voltage

Supply Rise Time t

LOGIC INPUTS (M0, M1, M2, DCE/DTE, T1IN, T2IN, T3IN)

Input High Voltage V

Input Low Voltage V

Logic Input Current I

CC

RS-530, RS-530A, X.21, no load 13

RS-530, RS-530A, X.21, full load 100 130

V.35 mode, no load 20

I

CC

P

V

DD

V

EE

IH

IL

IN

V.35 mode, full load 126 170

V.28 mode, no load 20

V.28 mode, full load 40 75

No-cable mode 0.5 10 µA

RS-530, RS-530A, X.21, full load 230

V.35 mode, full load 600

D

V.28 mode, full load 140

Any mode (except no-cable mode), no load 6.4 6.8

V.28 mode, with load 6.4 6.8

V.28, V.35 modes, with load, IDD = 10mA 6.4 6.8

V.28, V.35, no load -5.6

V.28 mode, full load -5.6 -5.4

V.35 mode, full load -5.6 -5.4

RS-530, RS-530A, X.21, full load -5.6 -5.4

No-cable mode or power-up to turn on 500 µs

r

T1IN, T2IN, T3IN ±10
M0, M1, M2, DCE/DTE = GND -100 -50 -30
M0, M1, M2, DCE/DTE = V

CC

4.75 5.25 V

2.0

0.8

±10

mA

mW

V

V

V

µA

MXL1543

+5V Multiprotocol, 3Tx/3Rx, Software-

Selectable Clock/Data Transceivers

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +5.0V, C1 = C2 = C4 = 1µF, C3 = C5 = 4.7µF, (Figure 10), TA= T

MIN

to T

MAX

. Typical values are at TA = +25°C, unless oth-

erwise noted.)

LOGIC OUTPUTS (R1OUT, R2OUT, R3OUT)

Output High Voltage V

Output Low Voltage V

Output Short-Circuit Current I

Output Pullup Current I

V.11 TRANSMITTER

Open-Circuit Differential Output
Voltage

Loaded Differential Output
Voltage

Change in Magnitude of Output
Differential Voltage

Common-Mode Output Voltage V

Change in Magnitude of Output
Common-Mode Voltage

Short-Circuit Current I

Output Leakage Current I

Rise or Fall Time t

Transmitter Input to Output
Delay

Data Skew It

Output to Output Skew t

V.11 RECEIVER

Differential Threshold Voltage V

Input Hysteresis ∆V

Receiver Input Current I

Receiver Input Resistance R

Rise or Fall Time tr, t

Receiver Input to Output Delay t

Data Skew |t

V.35 TRANSMITTER

Differential Output Voltage V

Output High Current I

Output Low Current I

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

V

V

OH

OL

SC

L

ODO

ODL

I

SOURCE

I

SINK

0 ≤ V

V

Open circuit, R = 1.95kΩ (Figure 1) ±5V

R = 50Ω (Figure 1), TA = +25oC

= 4mA 3 4.5

= 4mA 0.3 0.8

≤ V

OUT

CC

= 0, no-cable mode 70 µA

OUT

R = 50Ω (Figure 1) ±2

∆V

OD

OC

∆V

OC

SC

Z

,

t

r

t

t

PHL

,

- t

PHL

SKEW

TH

TH

IN

IN

PHL,tPLH

- t

PHL

OD

OH

OL

R = 50Ω (Figure 1) 0.2 V

R = 50Ω (Figure 1) 3.0 V

R = 50Ω (Figure 1) 0.2 V

V

= GND 150 mA

OUT

-0.25V ≤ V

≤ +0.25V, power-off or

OUT

no-cable mode

(Figures 2, 6) 2 10 25 ns

f

(Figures 2, 6) 40 80 ns

PLH

I (Figures 2, 6) 3 12 ns

PLH

(Figures 2, 6) 3 ns

-7V ≤ VCM ≤ 7V -200 200 mV

-7V ≤ VCM ≤ 7V 15 40 mV

-10V ≤ V

-10V ≤ V

(Figures 2, 7) 15 ns

f

≤10V ±0.66 mA

A, B

≤ 10V 15 30 kΩ

A, B

(Figures 2, 7) 50 80 ns

| (Figures 2, 7) 4 16 ns

PLH

Open circuit (Figure 3) ±7

With load, -4V ≤ VCM ≤ 4V (Figure 3) ±0.44 ±0.55 ±0.66

V

= 0 -13 -11 -9 mA

A,B

V

= 0 9 11 13 mA

A,B

✕

0.5

V

ODO

±1 ±100 µA

±50 mA

✕

0.67
V

ODO

V

V

V

MXL1543

+5V Multiprotocol, 3Tx/3Rx, Software­Selectable Clock/Data Transceivers

4 _______________________________________________________________________________________

,

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +5.0V, C1 = C2 = C4 = 1µF, C3 = C5 = 4.7µF, (Figure 10), TA= T

MIN

to T

MAX

. Typical values are at TA = +25°C, unless oth-

erwise noted.)

Output Leakage Current I

Rise or Fall Time tr, t

Transmitter Input to Output
Delay

Data Skew |t

Output-to-Output Skew t

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Z

f

t

t

PHL

PLH

PHL–tPLH

SKEW

-0.25V ≤ V
cable mode

(Figures 3, 6) 5 ns

(Figures 3, 6) 35 80 ns

| (Figures 3, 6) 4 16 ns

(Figures 3, 6) 4 ns

≤ +0.25V, power-off or no-

OUT

V.35 RECEIVER

Differential Input Voltage V

Input Hysteresis ∆V

Receiver Input Current I

Receiver Input Resistance R

Rise or Fall Time tr, t

Receiver Input to Output Delay t

Data Skew |t

PHL

PHL–tPLH

TH

TH

IN

IN

, t

-2V ≤ VCM ≤ 2V (Figure 3) -200 200 mV

-2V ≤ VCM ≤ 2V (Figure 3) 15 40 mV

-10V ≤ VA,B ≤ 10V ±0.66 mA

-10V ≤ VA,B ≤ 10V 15 30 kΩ

(Figures 3, 7) 15 ns

f

(Figures 3, 7) 50 80 ns

PLH

| (Figures 3, 7) 4 16 ns

V.28 TRANSMITTER

Output Voltage Swing (Figure 4) V

Short-Circuit Current I

Output Leakage Current I

O

SC

Z

Open circuit ±7

RL = 3kΩ±5 ±6

-0.25V ≤ V

≤ +0.25V, power-off or no-

OUT

cable mode

Output Slew Rate SR RL = 3kΩ, CL = 2500pF (Figures 4, 8) 4 30 V/µs

Transmitter Input to Output
Delay

Transmitter Input to Output
Delay

t

PHL

t

PLH

RL = 3kΩ, CL = 2500pF (Figures 4, 8) 1.5 2.5 µs

RL = 3kΩ, CL = 2500pF (Figures 4, 8) 1.5 3 µs

V.28 RECEIVER

Input Threshold Low V

Input Threshold High V

Input Hysteresis V

Input Resistance R

Rise or Fall Time tr, t

Receiver Input to Output Delay t

Receiver Input to Output Delay t

IL

IH

HYST

IN

PHL

PLH

-15V ≤ VIN ≤ +15V 3 5 7 kΩ

(Figures 5, 9) 15 ns

f

(Figures 5, 9) 60 100 ns

(Figures 5, 9) 160 250 ns

±1 ±100 µA

±1 ±100 µA

0.8 1.2 V

1.2 2.0 V

0.05 0.3 V

±150 mA

V

MXL1543

+5V Multiprotocol, 3Tx/3Rx, Software-

Selectable Clock/Data Transceivers

_______________________________________________________________________________________ 5

Typical Operating Characteristics

(VCC= +5.0V, C1 = C2 = C4 =1µF, C3 = C5 = 4.7µF, (Figure 10), TA= T

MIN

to T

MAX

, TA = +25°C, unless otherwise noted.)

V.11 SUPPLY CURRENT

vs. DATA RATE

160

140

120

100

80

60

SUPPLY CURRENT (mA)

40

DCE MODE, R = 50Ω, ALL TRANSMITTERS

20

OPERATING AT THE SPECIFIED DATA RATE

0

0.1 100 1000

101 10,000

DATA RATE (kbps)

V.11 DRIVER DIFFERENTIAL OUTPUT

VOLTAGE vs. TEMPERATURE

5

DCE MODE, R = 50Ω

4

3

2

1

0

-1

-2

-3

-4

DRIVER DIFFERENTIAL OUTPUT VOLTAGE (V)

-5
0 10203040506070

TEMPERATURE (°C)

100

MXL1543 toc01

80

60

40

SUPPLY CURRENT (mA)

20

0

10

V

OUT+

V

OUT-

MXL1543 toc04

-2

OUTPUT VOLTAGE (V)

-4

-6

-8

-10

8

6

4

2

0

V.28 SUPPLY CURRENT

vs. DATA RATE

DCE MODE ALL TRANSMITTERS
OPERATING AT THE SPECIFIED DATA RATE

= 3kΩ, CL = 2500pF

R

L

0 10050 150 200 250

DATA RATE (kbps)

V.28 OUTPUT VOLTAGE

vs. TEMPERATURE

DCE MODE, RL = 3kΩ

0304010 20 50 60 70

TEMPERATURE (°C)

V

OUT+

V

OUT-

V.35 SUPPLY CURRENT

vs. DATA RATE

200

180

MXL1543 toc02

160

140

120

100

80

60

SUPPLY CURRENT (mA)

40

DCE MODE, FULL LOAD, ALL TRANSMITTERS

20

OPERATING AT THE SPECIFIED DATA RATE

0

0.1 100 1000

100.1 10,000

DATA RATE (kbps)

V.35 OUTPUT VOLTAGE

vs. TEMPERATURE

0.66

DCE MODE, VCM = 0

0.44

MXL1543 toc05

FULL LOAD

0.22

0

-0.22

OUTPUT VOLTAGE (V)

-0.44

-0.66
0304010 20 50 60 70

TEMPERATURE (°C)

MXL1543 toc03

V

OH

V

OL

MXL1543 toc06

V.35 DIFFERENTIAL OUTPUT VOLTAGE

vs. COMMON-MODE VOLTAGE

600

590

580

570

560

550

540

DIFFERENTIAL OUTPUT VOLTAGE (mV)

530

520

-4 -2 -1-3 01234

|VOD|

COMMON-MODE VOLTAGE (V)

MXL1543 toc07

V.11/V.35 RECEIVER INPUT CURRENT

vs. INPUT VOLTAGE

300

DCE MODE

200

100

0

-100

RECEIVER INPUT CURRENT (µA)

-200

-300

-10 -2-4-8-6 0246810
INPUT VOLTAGE (V)

V.28 RECEIVER INPUT CURRENT

2.5

DCE MODE

2.0

MXL1543 toc08

1.5

1.0

0.5

0

-0.5

-1.0

-1.5

RECEIVER INPUT CURRENT (mA)

-2.0

-2.5

-10 -2-4-8-6 0246810

vs. INPUT VOLTAGE

MXL1543 toc09

INPUT VOLTAGE (V)

MXL1543

+5V Multiprotocol, 3Tx/3Rx, Software­Selectable Clock/Data Transceivers

6 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VCC= +5.0V, C1= C2 = C4 =1µF, C3 = C5 = 4.7µF (Figure 10), TA = +25°C, unless otherwise noted.)

V.11 LOOPBACK OPERATION

R = 50Ω

T

IN

T

OUT/RIN

R

OUT

200ns/div

V.28 SLEW RATE vs. C

24
22

20
18
16
14
12
10

SLEW RATE (V/µs)

8
6

RL = 3kΩ

4

1 TRANSMITTER SWITCHING AT 250kbps.

2

OTHER TRANSMITTERS SWITCHING AT 15kbps

0

0 1000 2000 3000 4000 5000

+SLEW

C

LOAD

(pF)

-SLEW

LOAD

MXL1543 toc10

5V/div

5V/div

5V/div

MXL1543 toc13

V.28 LOOPBACK OPERATION

CL = 2500pF
RL = 3kΩ

T

IN

T

OUT/RIN

R

OUT

1µs/div

V.11 TRANSMITTER PROPAGATION DELAY

vs. TEMPERATURE

80

70

60

0203010

t

PLH

t

PHL

TEMPERATURE (°C)

40

50

40

30

PROPAGATION DELAY (ns)

20

10

0

MXL1543 toc11

50 60 70

5V/div

5V/div

5V/div

MXL1543 toc14

V.35 LOOPBACK OPERATION

FULL LOAD

T

IN

T

OUT/RIN

R

OUT

200ns/div

V.11 RECEIVER PROPAGATION DELAY

vs. TEMPERATURE

80

70

0203010

t

PHL

t

PLH

TEMPERATURE (°C)

60

50

40

30

PROPAGATION DELAY (ns)

20

10

0

40

MXL1543 toc12

5V/div

1V/div

5V/div

MXL1543 toc15

50 60 70

V.35 TRANSMITTER PROPAGATION DELAY

vs. TEMPERATURE

80

70

60

50

40

30

PROPAGATION DELAY (ns)

20

10

0

0203010

t

PLH

t

PHL

40

TEMPERATURE (°C)

50 60 70

MXL1543 toc16

V.35 RECEIVER PROPAGATION DELAY

vs. TEMPERATURE

100

90

80

70

60

50

40

30

PROPAGATION DELAY (ns)

20

10

0

0203010

t

PHL

t

PLH

40

TEMPERATURE (°C)

50 60 70

MXL1543 toc17

MXL1543

+5V Multiprotocol, 3Tx/3Rx, Software-

Selectable Clock/Data Transceivers

_______________________________________________________________________________________ 7

Figure 1. V.11 DC Test Circuit

Figure 4. V.28 Driver Test Circuit

Figure 5. V.28 Receiver Test Circuit

Figure 2. V.11 AC Test Circuit

Figure 3. V.35 Transmitter/Receiver Test Circuit

Test Circuits

V

OD

100pF

B

R

V

R

OC

D

A

100Ω

100pF

50Ω

V

B

D

V

OD

A

125Ω

50Ω

CM

125Ω

50Ω

50Ω

B

R

A

15pF

R

B

A

15pF

A

D

C

V

L

O

A

D

R

L

R

15pF

MXL1543

+5V Multiprotocol, 3Tx/3Rx, Software­Selectable Clock/Data Transceivers

8 _______________________________________________________________________________________

Figure 6. V.11, V.35 Driver Propagation Delays

Figure 7. V.11, V.35 Receiver Propagation Delays

Figure 8. V.28 Driver Propagation Delays

Figure 9. V.28 Receiver Propagation Delays

Timing Diagrams

5V

D

0

V

0

B — A

-V

0

A

B

V

1.5V

t

PLH

50%

0

V

0

B — A

-V

0

V

0H

R

V

0L

0

t

PLH

3V

D

0

V

0

A

-V

0

1.5V

t

PHL

3V

f = 1MHz: tr ≤10ns: tf ≤ 10ns

90%
10%

t

r

t

SKEW

1.5V

0

-3V

t

r

V

= V(A) - V(B)

DIFF

1/2 V

0

f = 1MHz: tr ≤10ns: tf ≤ 10ns

INPUT

OUTPUT

1.5V

-3V

1.5V

t

PHL

90%

0

t

PHL

t

PLH

0

50%

10%

t

f

t

SKEW

1.5V

3V

t

r

V

IH

A

V

IL

V

0H

R

V

0L

1.3V

t

PHL

0.8V

1.7V

t

PLH

2.4V

Detailed Description

The MXL1543 is a three-driver/three-receiver, multipro­tocol transceiver that operates from a single +5V sup­ply. The MXL1543, along with the MXL1544/MAX3175
and MXL1344A, form a complete software-selectable
DTE or DCE interface port that supports the V.28 (RS-

232), V.10/V.11 (RS-449/V.36, EIA-530, EIA-530A,
X.21), and V.35 protocols. The MXL1543 transceivers
carry the high-speed clock and data signals, while the
MXL1544/MAX3175 transceivers carry serial interface
control signaling. The MXL1543 can be terminated by
the MXL1344A software-selectable resistor termination
network or by a discrete termination network. The
MXL1543 features a 0.5µA no-cable mode, true fail-

safe operation, and thermal shutdown circuitry. Thermal
shutdown protects the drivers against excessive power
dissipation. When activated, the thermal shutdown cir­cuitry places the driver outputs into a high-impedance
state.

Mode Selection

The state of the mode-select pins M0, M1, and M2
determines which serial interface protocol is selected
(Table 1). The state of the DCE/DTE input determines
whether the transceiver will be configured as a DTE or
DCE serial port. When the DCE/DTE input is logic
HIGH, driver T3 is activated and receiver R1 is dis­abled. When the DCE/DTE input is logic LOW, driver T3

MXL1543

+5V Multiprotocol, 3Tx/3Rx, Software-

Selectable Clock/Data Transceivers

_______________________________________________________________________________________ 9

Pin Description

PIN NAME FUNCTION

1 C1- Capacitor C1 Negative Terminal. Connect a 1µF ceramic capacitor between C1+ and C1-.

2 C1+ Capacitor C1 Positive Terminal. Connect a 1µF ceramic capacitor between C1+ and C1-.

3VDDGenerated Positive Supply. Connect a 4.7µF ceramic capacitor to ground.

4VCC+5V Supply Voltage (±5%). Decouple with a 1µF capacitor to ground.

5 T1IN Transmitter 1 TTL-Compatible Input

6 T2IN Transmitter 2 TTL-Compatible Input

7 T3IN Transmitter 3 TTL-Compatible Input

8 R1OUT Receiver 1 CMOS Output

9 R2OUT Receiver 2 CMOS Output

10 R3OUT Receiver 3 CMOS Output

11 M0 Mode-Select Pin with Internal Pullup to V

CC

12 M1 Mode-Select Pin with Internal Pullup to V

CC

13 M2 Mode-Select Pin with Internal Pullup to V

CC

14 DCE/DTE DCE/DTE Mode-Select Pin with Internal Pullup to V

CC

15 R3INB Noninverting Receiver Input

16 R3INA Inverting Receiver Input

17 R2INB Noninverting Receiver Input

18 R2INA Inverting Receiver Input

19

Noninverting Transmitter Output/Noninverting Receiver Input

20

Inverting Transmitter Output/Inverting Receiver Input

21 T2OUTB Noninverting Transmitter Output

22 T2OUTA Inverting Transmitter Output

23 T1OUTB Noninverting Transmitter Output

24 T1OUTA Inverting Transmitter Output

25 GND Ground

26 V

EE

Generated Negative Supply. Connect a 4.7µF ceramic capacitor to ground.

27 C2- Capacitor C2 Negative Terminal. Connect a 1µF ceramic capacitor between C2+ and C2-.

28 C2+ Capacitor C2 Positive Terminal. Connect a 1µF ceramic capacitor between C2+ and C2-.

T3OUTB/R1INB

T3OUTA/R1INA

MXL1543

is disabled and receiver R1 is activated. M0, M1, M2,
and DCE/DTE are internally pulled up to V

CC

to ensure

a logic HIGH if left unconnected.

No-Cable Mode

The MXL1543 will enter no-cable mode when the
mode-select pins are left unconnected or connected
high (M0 = M1 = M2 = 1). In this mode, the multiproto­col drivers and receivers are disabled and the supply
current drops to 0.5µA. The receivers’ outputs enter a
high-impedance state in no-cable mode, which allow
these output lines to be shared with other receivers’
outputs (the receivers’ outputs have internal pullup
resistors to pull the outputs HIGH if not driven). Also, in
no-cable mode, the transmitter outputs enter a high­impedance state so that these output lines can be
shared with other devices.

Dual Charge-Pump Voltage Converter

The MXL1543’s internal power supply consists of a reg­ulated dual charge pump that provides positive and
negative output voltages from a +5V supply. The
charge pump operates in discontinuous mode. If the
output voltage is less than the regulated voltage, the
charge pump is enabled. If the output voltage exceeds
the regulated voltage, the charge pump is disabled.

Each charge pump requires a flying capacitor (C1, C2)
and a reservoir capacitor (C3, C5) to generate the V

DD

and VEEsupplies. Figure 10 shows charge-pump con­nections.

Fail-Safe Receivers

The MXL1543 guarantees a logic-high receiver output
when the receiver inputs are shorted or open, or when
they are connected to a terminated transmission line
with all the drivers disabled. This is done by setting the
receivers’ threshold between -25mV and -200mV in the

+5V Multiprotocol, 3Tx/3Rx, Software­Selectable Clock/Data Transceivers

10 ______________________________________________________________________________________

)

)

Table 1. Mode Selection

Figure 10. Charge Pump

MXL1543

MODE NAME

Not Used (Default V.11

RS-530A 0 0 1 0 V.11 V.11 Z V.11 V.11 V.11

RS-530 0 1 0 0 V.11 V.11 Z V.11 V.11 V.11

X.21 0 1 1 0 V.11 V.11 Z V.11 V.11 V.11

V.35 1 0 0 0 V.35 V.35 Z V.35 V.35 V.35

RS-449/V.36 1 0 1 0 V.11 V.11 Z V.11 V.11 V.11

V.28/RS-232 1 1 0 0 V.28 V.28 Z V.28 V.28 V.28

No Cable 1 1 1 0 Z Z Z Z Z Z

Not Used (Default V.11

RS-530A 0 0 1 1 V.11 V.11 V.11 Z V.11 V.11

RS-530 0 1 0 1 V.11 V.11 V.11 Z V.11 V.11

X.21 0 1 1 1 V.11 V.11 V.11 Z V.11 V.11

V.35 1 0 0 1 V.35 V.35 V.35 Z V.35 V.35

RS-449/V.36 1 0 1 1 V.11 V.11 V.11 Z V.11 V.11

V.28/RS-232 1 1 0 1 V.28 V.28 V.28 Z V.28 V.28

No Cable 1 1 1 1 Z Z Z Z Z Z

M2 M1 M0

0 0 0 0 V.11 V.11 Z V.11 V.11 V.11

0 0 0 1 V.11 V.11 V.11 Z V.11 V.11

DCE/

DTE

T1 T2 T3 R1 R2 R3

5V

4.7µF

1µF

C3

C1

1µF

C4

V

C1+

C1-

V

DD

CC

MXL1543

C2+

C2-

GND

V

EE

C2
1µF

C5

4.7µF

MXL1543

+5V Multiprotocol, 3Tx/3Rx, Software-

Selectable Clock/Data Transceivers

______________________________________________________________________________________ 11

Figure 11. Cable-Selectable Multiprotocol DTE/DCE Port

DTE_TXD/DCE_RXD

DTE_SCTE/DCE_RXC

DTE_TXC/DCE_TXC

DTE_RXC/DCE_SCTE

DTE_RXD/DCE_TXD

C10
1µF

DTE_RTS/DCE_CTS

DTE_DTR/DCE_DSR

DTE_DCD/DCE_DCD

DTE_DSR/DCE_DTR

DTE_CTS/DCE_RTS

C3

4.7µF

C6

100pFC7100pFC8100pF

3

8111213

V

5V

1µF

CC

14

V

C11
1µF

C12
1µF

CC

2

V

EE

4 6 7 9 10 16 15 18 17 19 20 22 23 24 15

C13

C2
1µF

C5

4.7µF

1µF

PUMP

D1

D2

D3

R1

R2

R3

D1

D2

D3

R1

R2

R3

R4

D4

GND

28

27
26

25

24
23
22
21

20
19

18
17
16
15

28

V

EE

27

26
25
24
23

22
21

20
19
18
17

16

15

3

1

C1

1µF

C4
1µF

NC

C9

V

NC

10

11

12
13
14

CC

10

11

12
13
14

CHARGE

2
4

5

6

7

8

9

MXL1543

M0
M1
M2
DCE/DTE

1

V

CC

2

V

DD

3

4

5

6

7

8

9

MXL1544

M0

MAX3175

M1
M2

DCE/DTE INVERT

MXL1344A

DCE/DTE

M2

V

CC

LATCH

M1

21

M0

DCE

DTE

2

RXD A

TXD A

14
24
11

15
12

17

16

25

21
18

19
20
23

10

22

13

TXD B
SCTE A
SCTE B

TXC A
TXC B

RXC A

9

RXC B

3

RXD A
RXD B

7

SG

1

SHIELD

CONNECTOR

DCE/DTE
M1
M0

4

RTS A
RTS B

DTR A
DTR B

8

DCD A
DCD B

6

DSR A
DSR B

5

CTS A
CTS B

DB-25

RXD B
RXC A
RXC B

TXC A
TXC B

SCTE A
SCTE B

TXD A
TXD B

CTS A
CTS B

DSR A
DSR B

DCD A
DCD B

DTR A
DTR B

RTS A
RTS B

MXL1543

+5V Multiprotocol, 3Tx/3Rx, Software­Selectable Clock/Data Transceivers

12 ______________________________________________________________________________________

V.11 and V.35 modes. If the differential receiver input
voltage (B - A) is ≥ -25mV, R_OUT is logic HIGH. If (B ­A) is ≤ -200mV, R_OUT is logic LOW. In the case of a
terminated bus with all transmitters disabled, the
receiver’s differential input voltage is pulled to zero by
the termination. With the receiver thresholds of the
MXL1543, this results in a logic HIGH with a 25mV mini­mum noise margin.

Applications Information

Capacitor Selection

The capacitors used for the charge pumps, as well as
for supply bypassing, should have a low equivalent
series resistance (ESR) and low temperature coeffi­cient. Multilayer ceramic capacitors with an X7R dielec­tric offer the best combination of performance, size,
and cost. The flying capacitors (C1, C2) and the
bypass capacitor (C4) should have a value of 1µF,
while the reservoir capacitors (C3, C5) should have a
minimum value of 4.7µF (Figure 10). To reduce the rip­ple present on the transmitter outputs, capacitors C3,
C4, and C5 can be increased. The values of C1 and C2
should not be increased.

Cable Termination

The MXL1344A software-selectable resistor network is
designed to be used with the MXL1543. The MXL1344A
multiprotocol termination network provides V.11- and
V.35-compliant termination, while V.28 receiver termina­tion is internal to the MXL1543. These cable termination
networks provide compatibility with V.11, V.28, and
V.35 protocols. Using the MXL1344A termination net­works provide the advantage of not having to build
expensive termination networks out of resistors and
relays, manually changing termination modules, or
building custom termination networks

Cable-Selectable Mode

A cable-selectable multiprotocol interface is shown in
Figure 11. The mode control lines M0, M1, and
DCE/DTE are wired to the DB-25 connector. To select
the serial interface mode, the appropriate combination
of M0, M1, and DCE/DTE are grounded within the cable
wiring. The control lines that are not grounded are
pulled high by the internal pullups on the MXL1543.
The serial interface protocol of the MXL1543,
MXL1544/MAX3175, and MXL1344A is selected based
on the cable that is connected to the DB-25 interface.

V.11 Interface

As shown in Figure 12, the V.11 protocol is a fully bal­anced differential interface. The V.11 driver generates a
minimum of ±2V between nodes A and B when a 100Ω
(min) resistance is presented at the load. The V.11
receiver is sensitive to ±200mV differential signals at
receiver inputs A’ and B’. The V.11 receiver rejects
common-mode signals developed across the cable
(referenced from C to C’) of up to ±7V, allowing for
error-free reception in noisy environments. The receiver
inputs must comply with the impedance curve shown in
Figure 13.

For high-speed data transmission, the V.11 specifica­tion recommends terminating the cable at the receiver
with a 100Ω resistor. This resistor, although not
required, prevents reflections from corrupting transmit­ted data. In Figure 14, the MXL1344A is used to termi­nate the V.11 receiver. Internal to the MXL1344A, S1 is
closed and S2 is open to present a 100Ω minimum dif­ferential resistance. The MXL1543’s internal V.28 termi­nation is disabled by opening S3.

V.35 Interface

Figure 15 shows a fully-balanced, differential standard
V.35 interface. The generator and the load must both
present a 100Ω ±10Ω differential impedance and a
150Ω ±15Ω common-mode impedance as shown by
the resistive T networks in Figure 15. The V.35 driver
generates a current output (±11mA, typ) that develops
an output voltage of ±550mV across the generator and

Figure 12. Typical V.11 Interface

Figure 13. Receiver Input Impedance

BALANCED

INTERCONNECTING

GENERATOR

A

B

C

GND GND

CABLE

TERMINATION

A′

B′

C′

CABLE

100Ω

MIN

LOAD

RECEIVER

I

Z

-10V

-3.25mA

-3V

+3V

3.25mA

+10V

V

Z

MXL1543

+5V Multiprotocol, 3Tx/3Rx, Software-

Selectable Clock/Data Transceivers

______________________________________________________________________________________ 13

Figure 16. V.35 Termination and Internal Resistance Networks

Figure 14. V.11 Termination and Internal Resistance Networks

Figure 15. Typical V.35 Interface

A′

R1

MXL1344A

52Ω

S1

R3

S2

124Ω

R2
52Ω

B′

C′

GENERATOR

A

50Ω

125Ω

50Ω

B

C

GND GND

A

B

GND

BALANCED

INTERCONNECTING

CABLE

R8
5kΩ

125Ω

MXL1543

RECEIVER

LOAD

RECEIVER

50Ω

50Ω

R5

30kΩ

R6

10kΩ

S3

R7

10kΩ

R4

30kΩ

CABLE

TERMINATION

A′

B′

C′

A′

R1

MXL1344A

52Ω

S1

R2
52Ω

B′

C′

R3

124Ω

S2

A

R5

30kΩ
R8
5kΩ

B

GND

R6

10kΩ

S3

R7

10kΩ

R4

30kΩ

MXL1543

RECEIVER

MXL1543

+5V Multiprotocol, 3Tx/3Rx, Software­Selectable Clock/Data Transceivers

14 ______________________________________________________________________________________

Figure 17. Typical V.28 Interface

Figure 18. V.28 Termination and Internal Resistance Networks

load termination networks. The V.35 receiver is sensi­tive to ±200mV differential signals at receiver inputs A’
and B’. The V.35 receiver rejects common-mode sig­nals developed across the cable (referenced from C to
C’) of up to ±4V, allowing for error-free reception in
noisy environments.

In Figure 16, the MXL1344A is used to implement the
resistive T network that is needed to properly terminate
the V.35 driver and receiver. Internal to the MXL1344A,
S1 and S2 are closed to connect the T-network resis­tors to the circuit. The V.28 termination resistor (internal
to the MXL1543) is disabled by opening S3 to avoid
interference with the T-network impedance.

V.28 Interface

The V.28 interface is an unbalanced single-ended inter­face (Figure 17). The V.28 driver generates a minimum
of ±5V across a 3kΩ load impedance between A’ and
C’. The V.28 receiver has a single-ended input. To aid

in rejecting system noise, the MXL1543’s V.28 receiver
has a typical hysteresis of 0.05V.

Figure 18 shows the MXL1344A’s termination network
disabled by opening S1 and S2. The MXL1543’s inter­nal 5kΩ V.28 termination is enabled by closing S3.

DTE vs. DCE Operation

Figure 19 shows a DCE or DTE controller-selectable
interface. DCE/DTE (pin 14) switches the port’s mode
of operation. See Table 1.

This application requires only one DB-25 connector,
but separate cables for DCE or DTE signal routing. See
Figure 19 for complete signal routing in DCE and DTE
modes.

Complete Multiprotocol X.21 Interface

A complete DTE-to-DCE interface operating in X.21
mode is shown in Figure 20. The MXL1543 is used to
generate the clock and data signals, and the

A′

B′

GENERATOR

UNBALANCED

INTERCONNECTING

CABLE

A

C

GND GND

A

R1

MXL1344A

52Ω

S1

R2
52Ω

R3

S2

124Ω

S3

B

R8
5kΩ

30kΩ

30kΩ

A′

C′

R5

R6

10kΩ

R7

10kΩ

R4

CABLE

TERMINATION

MXL1543

RECEIVER

LOAD

RECEIVER

C′

GND

MXL1543

+5V Multiprotocol, 3Tx/3Rx, Software-

Selectable Clock/Data Transceivers

______________________________________________________________________________________ 15

Figure 19. Multiprotocol DCE/DTE Port

DTE_TXD/DCE_RXD

DTE_SCTE/DCE_RXC

DTE_TXC/DCE_TXC

DTE_RXC/DCE_SCTE

DTE_RXD/DCE_TXD

C10
1µF

DTE_RTS/DCE_CTS

DTE_DTR/DCE_DSR

DTE_DCD/DCE_DCD

DTE_DSR/DCE_DTR

DTE_CTS/DCE_RTS

DTE_LL/DCE_LL

C3

4.7µF

C6

100pFC7100pFC8100pF

3

8111213

V

5V

1µF

CC

14

V

C11
1µF

C12
1µF

CC

2

V

EE

4 6 7 9 10 16 15 18 17 19 20 22 23 24 15

C13

C2
1µF

C5

4.7µF

1µF

CHARGE

PUMP

D1

D2

D3

R1

R2

R3

MXL1543

D1

D2

D3

R1

R2

R3

R4

D4

GND

28

27
26

25

24
23
22
21

20
19

18
17
16
15

28

V

EE

27

26
25
24
23

22
21

20
19
18
17

16

3

1

C1

1µF

2
4

C4
1µF

5

6

7

8

9

10

11

M0

12

M1

13

M2

14

DCE/DTE

C9

V

CC

1

V

CC

2

V

DD

3

4

5

6

7

8

10

9

MXL1344A

DCE/DTE

M2

LATCH

M1

21

M0

DCE

DTE

2

RXD A

TXD A

14

RXD B

TXD B

24

RXC A

SCTE A

11

RXC B

SCTE B

15

TXC A

TXC A

12

TXC B

TXC B

17

SCTE A

RXC A

9

SCTE B

RXC B

3

TXD A

RXD A

16

TXD B

RXD B

7

SG

1

SHIELD

DB-25

CONNECTOR

4

CTS A

RTS A

19

RTS B

CTS B

20

DSR A

DTR A

23

DTR B

DSR B

8

DCD A

DCD A

10

DCD B

DCD B

6

DTR A

DSR A

22

DTR B

DSR B

5

RTS A

CTS A

13

RTS B

CTS B

18

LLA

LLA

DCE/DTE

M2
M1
M0

11

12
13
14

MXL1544

M0

MAX3175

M1
M2
DCE/DTE

INVERT

15

MXL1543

+5V Multiprotocol, 3Tx/3Rx, Software­Selectable Clock/Data Transceivers

16 ______________________________________________________________________________________

Figure 20. DCE-to-DTE X.21 Interface

MXL1544/MAX3175 generate the control signals and
local loopback (LL). The MXL1344A is used to termi­nate the clock and data signals to support the V.11 pro­tocol for cable termination. The control signals do not
need external termination.

Compliance Testing

A European Standard EN 45001 test report is pending
for the MXL1543/MXL1544/MXL1344A chipset. A copy
of the test report will be available from Maxim upon
completion.

SERIAL

CONTROLLER

TXD

SCTE

TXC

RXC

RXD

RTS

DTR

DCD

DTE

D1

D2

D3

R3

R2

R1

MXL1544
MAX3175

D1

D2

D3

R1

MXL1344AMXL1543

104Ω

104Ω

104Ω

TXD

SCTE

TXC

RXC

RXD

RTS

DTR

DCD

104Ω

104Ω

DCE

MXL1543MXL1344A

MXL1544
MAX3175

SERIAL

CONTROLLER

R3

R2

R1

D1

D2

D3

R3

R2

R1

D3

TXD

SCTE

TXC

RXC

RXD

RTS

DTR

DCD

DSR

CTS

R2

R3

LL

D4

R4

DSR

CTS

LL

D2

D1

R4

D4

DSR

CTS

LL

MXL1543

+5V Multiprotocol, 3Tx/3Rx, Software-

Selectable Clock/Data Transceivers

______________________________________________________________________________________ 17

Pin ConfigurationChip Information

TRANSISTOR COUNT: 2619
PROCESS: BiCMOS

TOP VIEW

C1-

C1+

V

V

T1IN

T2IN

T3IN

R1OUT

R2OUT

R3OUT

M0

M1

M2

DCE/DTE

1

2

3

DD

4

CC

5

MXL1543

6

7

8

9

10

11

12

13

14

28

C2+

27

C2-

26

V

EE

25

GND

24

T1OUTA

23

T1OUTB

22

T2OUTA

21

T2OUTB

20

T3OUTA/R1INA

19

T3OUTB/R1INB

18

R2INA

17

R2INB

16

R3INA

15

R3INB

SSOP

MXL1543

+5V Multiprotocol, 3Tx/3Rx, Software­Selectable Clock/Data Transceivers

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.

18 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

© 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

Package Information

SSOP.EPS