Datasheet LTC1543 Datasheet (Linear Technology)

FEATURES

■

Software-Selectable Transceiver Supports:
RS232, RS449, EIA530, EIA530-A, V.35, V.36, X.21

■

TUV/Detecon Inc. Certified NET1 and NET2
Compliant (Test Report No. NET2/102201/97)

■

TBR2 Compliant (Test Report No. CTR2/022701/98)

■

Software-Selectable Cable Termination Using
the LTC1344A

■

Complete DTE or DCE Port with LTC1544, LTC1344A

■

Operates from Single 5V Supply

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APPLICATIO S

■

Data Networking

■

CSU and DSU

■

Data Routers

LTC1543

Software-Selectable

Multiprotocol Transceiver

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DESCRIPTIO

The LTC®1543 is a 3-driver/3-receiver multiprotocol trans­ceiver that operates from a single 5V supply. The LTC1543
and LTC1544 form the core of a complete software-select­able DTE or DCE interface port that supports the RS232,
RS449, EIA530, EIA530-A, V.35, V.36 or X.21 protocols.
Cable termination may be implemented using the LTC1344A
software-selectable cable termination chip or by using exist­ing discrete designs.

The LTC1543 runs from a single 5V supply using an internal
charge pump that requires only five space-saving surface
mounted capacitors. The part is available in a 28-lead SSOP
surface mount package.

, LTC and LT are registered trademarks of Linear Technology Corporation.

TYPICAL APPLICATIO

DTE or DCE Multiprotocol Serial Interface with DB-25 Connector

LL

LTC1544

D4

CTS B

LL A (141)

R3

CTS A (106)

R2 R1R4

DSR A (109)

DSR B

DCD B

U

D3

DCD A (107)

DTRDSR DCDCTS

D2 D1

DTR A (108)

DTR B

RTS

RTS B

RTS A (105)

SHIELD (101)

RXD B

SG (102)

RXCRXD

R2

RXC A (115)

RXC B

RXD A (104)

LTC1543

R1R3

D3

TXC A (114)

TXC B

D2

SCTE A (113)

SCTE B

TXDSCTETXC

D1

TXD A (103)

TXD B

LTC1344A

21424111512179314192062322513 81018 7 16

DB-25 CONNECTOR

1543 TA01

1

LTC1543

WW

W

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ABSOLUTE MAXIMUM RATINGS

(Note 1)

Supply Voltage ....................................................... 6.5V

Input Voltage

Transmitters ........................... –0.3V to (VCC + 0.3V)

Receivers............................................... –18V to 18V

Logic Pins .............................. –0.3V to (VCC + 0.3V)

Output Voltage

Transmitters ................. (VEE – 0.3V) to (VDD + 0.3V)

Receivers................................ –0.3V to (VCC + 0.3V)

Logic Pins .............................. –0.3V to (VCC + 0.3V)

VEE........................................................ –10V to 0.3V

VDD....................................................... –0.3V to 10V

Short-Circuit Duration

Transmitter Output ..................................... Indefinite

Receiver Output.......................................... Indefinite

VEE.................................................................. 30 sec

Operating Temperature Range

LTC1543C .............................................. 0°C to 70°C

LTC1543I........................................... –40°C to 85°C

Storage Temperature Range ................ –65°C to 150°C

Lead Temperature (Soldering, 10 sec)................. 300°C

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PACKAGE/ORDER INFORMATION

TOP VIEW

–

1

C1

+

2

C1

V

V

M0

M1

M2

DCE/DTE

3

DD

4

CC

5

D1

6

D2

7

D3

8

R1

9

R2

10

R3

11

12

13

14

CHARGE PUMP

D1

D2

D3

R1

R2

R3

G PACKAGE

28-LEAD PLASTIC SSOP

T

= 150°C, θJA = 65°C/W

JMAX

Consult factory for Military grade parts.

28

27

26

25

24

23

22

21

20

19

18

17

16

15

C2

C2

V

EE

GND

D1 A

D1 B

D2 A

D2 B

D3/R1 A

D3/R1 B

R2 A

R2 B

R3 A

R3 B

+

–

ORDER PART

NUMBER

LTC1543CG
LTC1543IG

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ELECTRICAL CHARACTERISTICS

VCC = 5V (Notes 2, 3)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Supplies

I

CC

VCC Supply Current (DCE Mode, RS530, RS530-A, X.21 Modes, No Load 13 mA
All Digital Pins = GND or V

) RS530, RS530-A, X.21 Modes, Full Load ● 100 130 mA

CC

V.35 Mode, No Load 20 mA
V.35 Mode, Full Load

● 126 170 mA

V.28 Mode, No Load 20 mA
V.28 Mode, Full Load
No-Cable Mode

P

D

Internal Power Dissipation (DCE Mode) RS530, RS530-A, X.21 Modes, Full Load 230 mW

● 40 75 mA

● 120 500 µA

V.35 Mode, Full Load 600 mW
V.28 Mode, Full Load 140 mW

+

V

Positive Charge Pump Output Voltage Any Mode, No Load ● 8.0 9.4 V

V.28 Mode, with Load

● 8.0 8.7 V

V.28 Mode, with Load, IDD = 10mA 6.5 V

–

V

Negative Charge Pump Output Voltage V.28, V.35 Modes, No Load –9.6 V

V.28 Mode, Full Load ● – 8.0 –8.5 V

● – 5.5 –6.7 V

● – 4.5 –5.7 V

f
t

OSC

r

V.35 Mode, Full Load

RS530, RS530-A, X.21 Modes, Full Load
Charge Pump Oscillator Frequency 150 kHz
Supply Rise Time No-Cable Mode or Power-Up to Turn On 2 ms

Logic Inputs and Outputs

V

IH

V

IL

Logic Input High Voltage ● 2V
Logic Input Low Voltage ● 0.8 V

2

LTC1543

ELECTRICAL CHARACTERISTICS

VCC = 5V (Notes 2, 3)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

I

IN

Logic Input Current D1, D2, D3 ● ±10 µA

M0, M1, M2, DCE = GND (LTC1543C) ● –100 –50 – 30 µA

● –120 –50 – 30 µA

● ±10 µA

● –50 50 mA

±1 µA

V
V
I

OSR

I

OZR

OH

OL

M0, M1, M2, DCE = GND (LTC1543I)
M0, M1, M2, DCE = V

CC

Output High Voltage IO = –4mA ● 3 4.5 V
Output Low Voltage IO = 4mA ● 0.3 0.8 V
Output Short-Circuit Current 0V ≤ VO ≤ V
Three-State Output Current M0 = M1 = M2 = VCC, 0V ≤ VO ≤ V

CC

CC

V.11 Driver

V
V

ODO

ODL

Open Circuit Differential Output Voltage RL = 1.95k (Figure 1) ● ±5V
Loaded Differential Output Voltage RL = 50Ω (Figure 1) 0.5V

ODO

0.67V

ODO

RL = 50Ω (Figure 1) ● ±2V

∆V

OD

Change in Magnitude of Differential RL = 50Ω (Figure 1) ● 0.2 V
Output Voltage

V
∆V

OC

OC

Common Mode Output Voltage RL = 50Ω (Figure 1) ● 3V
Change in Magnitude of Common Mode RL = 50Ω (Figure 1) ● 0.2 V

Output Voltage

I

SS

I

OZ

Short-Circuit Current V

= GND 150 mA

OUT

Output Leakage Current –0.25V ≤ VO ≤ 0.25V, Power Off or ● ± 1 ±100 µA

No-Cable Mode or Driver Disabled

tr, t

f

Rise or Fall Time (Figures 2, 6) (LTC1543C) ● 21525 ns

(Figures 2, 6) (LTC1543I) ● 21535 ns

t

PLH

t

PHL

∆t Input to Output Difference, t

t

SKEW

Input to Output (Figures 2, 6) (LTC1543C) ● 20 40 65 ns

(Figures 2, 6) (LTC1543I)

● 20 40 75 ns

Input to Output (Figures 2, 6) (LTC1543C) ● 20 40 65 ns

● 20 40 75 ns

● 0317 ns

PLH

(Figures 2, 6) (LTC1543I)

– t

 (Figures 2, 6) (LTC1543C) ● 0312 ns

PHL

(Figures 2, 6) (LTC1543I)

Output to Output Skew (Figures 2, 6) 3 ns

V.11 Receiver

V

TH

∆V

TH

I

IN

R

IN

tr, t

f

t

PLH

t

PHL

∆t Input to Output Difference, t

Input Threshold Voltage –7V ≤ VCM ≤ 7V ● –0.2 0.2 V
Input Hysteresis –7V ≤ VCM ≤ 7V ● 15 40 mV
Input Current (A, B) –10V ≤ V
Input Impedance –10V ≤ V

≤ 10V ● ±0.66 mA

A,B

≤ 10V ● 15 30 kΩ

A,B

Rise or Fall Time (Figures 2, 7) 15 ns
Input to Output (Figures 2, 7) (LTC1543C) ● 50 80 ns

(Figures 2, 7) (LTC1543I)

● 50 90 ns

Input to Output (Figures 2, 7) (LTC1543C) ● 50 80 ns

● 50 90 ns

● 0421 ns

PLH

(Figures 2, 7) (LTC1543I)

– t

 (Figures 2, 7) (LTC1543C) ● 0416 ns

PHL

(Figures 2, 7) (LTC1543I)

V.35 Driver

V

OD

Differential Output Voltage Open Circuit ● ±10.00 V

With Load, –4V ≤ VCM ≤ 4V (Figure 3) ● ±0.44 ±0.55 ±0.66 V

I

OH

I

OL

I

OZ

Transmitter Output High Current V
Transmitter Output Low Current V

= 0V ● – 13 –11 – 9.0 mA

A, B

= 0V ● 9.0 11 13 mA

A, B

Transmitter Output Leakage Current –0.25V ≤ V

≤ 0.25V ● ±1 ±100 µA

A, B

V

3

LTC1543

ELECTRICAL CHARACTERISTICS

VCC = 5V (Notes 2, 3)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

tr, t

f

t

PLH

t

PHL

∆t Input to Output Difference, t

t

SKEW

Rise or Fall Time (Figures 3, 6) 5 ns
Input to Output (Figures 3, 6) (LTC1543C) ● 20 35 65 ns

(Figures 3, 6) (LTC1543I)

● 20 35 75 ns

Input to Output (Figures 3, 6) (LTC1543C) ● 20 35 65 ns

● 20 35 75 ns

● 0421 ns

PLH

(Figures 3, 6) (LTC1543I)

– t

 (Figures 3, 6) (LTC1543C) ● 0416 ns

PHL

(Figures 3, 6) (LTC1543I)

Output to Output Skew (Figures 3, 6) 4 ns

V.35 Receiver

V
∆V
I

IN

R
tr, t
t

PLH

t

PHL

TH

TH

IN

f

Differential Receiver Input Threshold Voltage –2V ≤ (VA + VB)/2 ≤ 2V (Figure 3) ● – 0.2 0.2 V
Receiver Input Hysteresis –2V ≤ (VA + VB)/2 ≤ 2V (Figure 3) ● 15 40 mV
Receiver Input Current (A, B) – 10V ≤ V
Receiver Input Impedance –10V ≤ V

≤ 10V ● ±0.66 mA

A,B

≤ 10V ● 15 30 kΩ

A,B

Rise or Fall Time (Figures 3, 7) 15 ns
Input to Output (Figures 3, 7) (LTC1543C) ● 50 80 ns

(Figures 3, 7) (LTC1543I)

● 50 90 ns

Input to Output (Figures 3, 7) (LTC1543C) ● 50 80 ns

(Figures 3, 7) (LTC1543I) ● 50 90 ns

∆t Input to Output Difference, t

PLH

– t

 (Figures 3, 7) (LTC1543C) ● 0416 ns

PHL

(Figures 3, 7) (LTC1543I) ● 0421 ns

V.28 Driver

V

O

I

SS

I

OZ

Output Voltage Open Circuit ● ±10 V

= 3k (Figure 4) ● ±5 ±8.5 V

R

L

Short-Circuit Current V

= GND ● ±150 mA

OUT

Output Leakage Current –0.25V ≤ VO ≤ 0.25V, Power Off or ● ±1 ±100 µA

No-Cable Mode or Driver Disabled
SR Slew Rate RL = 3k, CL = 2500pF (Figures 4, 8) ● 430V/µs
t
t

PLH

PHL

Input to Output RL = 3k, CL = 2500pF (Figures 4, 8) ● 1.5 2.5 µs
Input to Output RL = 3k, CL = 2500pF (Figures 4, 8) ● 1.5 3 µs

V.28 Receiver
V

THL

V

TLH

∆V

TH

R

IN

tr, t

f

t

PLH

t

PHL

The ● denotes specifications which apply over the full operating
temperature range.

Note 1: Absolute Maximum Ratings are those beyond which the safety of a
device may be impaired.

Input Low Threshold Voltage ● 1.2 0.8 V
Input High Threshold Voltage ● 2 1.2 V
Receiver Input Hysteresis ● 0 0.05 0.3 V
Receiver Input Impedance –15V ≤ VA ≤ 15V ● 357 kΩ
Rise or Fall Time (Figures 5, 9) 15 ns
Input to Output (Figures 5, 9) ● 60 100 ns
Input to Output (Figures 5, 9) ● 160 250 ns

Note 2: All currents into device pins are positive; all currents out of device
are negative. All voltages are referenced to device ground unless otherwise
specified.

Note 3: All typicals are given for V

= C

C

VDD

= 3.3µF tantalum capacitors and TA = 25°C.

VEE

= 5V, C1 = C2 = C

CC

VCC

= 1µF,

4

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PIN FUNCTIONS

LTC1543

C1–␣ (Pin 1): Capacitor C1 Negative Terminal. Connect a
1µF capacitor between C1+ and C1–.

C1+ (Pin 2): Capacitor C1 Positive Terminal. Connect a
1µF capacitor between C1+ and C1–.

VDD (Pin 3): Generated Positive Supply Voltage for
V.28. Connect a 1µF capacitor to ground.

VCC (Pin 4): Positive Supply Voltage Input. 4.75V ≤ V

CC

≤ 5.25V. Bypass with a 1µF capacitor to ground.

D1 (Pin 5): TTL Level Driver 1 Input.
D2 (Pin 6): TTL Level Driver 2 Input.
D3 (Pin 7): TTL Level Driver 3 Input.
R1 (Pin 8): CMOS Level Receiver 1 Output.
R2 (Pin 9): CMOS Level Receiver 2 Output.
R3 (Pin 10): CMOS Level Receiver 3 Output.
M0 (Pin 11): TTL Level Mode Select Input 0 with Pull-Up

to VCC.
M1 (Pin 12): TTL Level Mode Select Input 1 with Pull-Up

to VCC.
M2 (Pin 13): TTL Level Mode Select Input 2 with Pull-Up

to VCC.
DCE/DTE (Pin 14): TTL Level Mode Select Input with Pull-

Up to VCC.

R3 B (Pin 15): Receiver 3 Noninverting Input with Pull-Up
to VCC.

R3 A (Pin 16): Receiver 3 Inverting Input.
R2 B (Pin 17): Receiver 2 Noninverting Input.
R2 A (Pin 18): Receiver 2 Inverting Input.
D3/R1 B (Pin 19): Receiver 1 Noninverting Input and

Driver 3 Noninverting Output.
D3/R1 A (Pin 20): Receiver 1 Inverting Input and Driver 3

Inverting Output.

D2 B (Pin 21): Driver 2 Noninverting Output.
D2 A (Pin 22): Driver 2 Inverting Output.
D1 B (Pin 23): Driver 1 Noninverting Output.
D1 A (Pin 24): Driver 1 Inverting Output.
GND (Pin 25): Ground.
VEE (Pin 26): Negative Supply Voltage. Connect a 3.3µF

capacitor to GND.
C2– (Pin 27): Capacitor C2 Negative Terminal. Connect a

1µF capacitor between C2+ and C2–.
C2+ (Pin 28): Capacitor C2 Positive Terminal. Connect a

1µF capacitor between C2+ and C2–.

TEST CIRCUITS

A

B

Figure 1. V.11 Driver Test Circuit Figure 2. V.11 Driver/Receiver AC Test Circuit

R

L

50Ω

V

OD

R

V

OC

L

50Ω

1543 F01

B

R

L

100Ω

A

C

L

100pF

C

L

100pF

B

R

A

15pF

1543 F02

5

LTC1543

TEST CIRCUITS

Figure 4. V.10/V.28 Driver Test Circuit

W

ODE SELECTIO

B

D

V

A

50Ω

125Ω

OD

50Ω

V

CM

125Ω

50Ω

50Ω

B

R

A

15pF

1543 F03

Figure 3. V.35 Driver/Receiver Test Circuit

D

A

R

C

L

L

1543 F04

D

A

A

R

15pF

1543 F04

Figure 5. V.10/V.28 Receiver Test Circuit

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LTC1543 MODE NAME M2 M1 M0 DCE/DTE D1 D2 D3 R1 R2 R3

Not Used (Default V.11) 0000V.11 V.11 Z V.11 V.11 V.11
RS530A 0010V.11 V.11 Z V.11 V.11 V.11
RS530 0100V.11 V.11 Z V.11 V.11 V.11
X.21 0110V.11 V.11 Z V.11 V.11 V.11
V.35 1000V.35 V.35 Z V.35 V.35 V.35
RS449/V.36 1010V.11 V.11 Z V.11 V.11 V.11
V.28/RS232 1100V.28 V.28 Z V.28 V.28 V.28
No Cable 1110ZZZZZZ
Not Used (Default V.11) 0001V.11 V.11 V.11 Z V.11 V.11
RS530A 0011V.11 V.11 V.11 Z V.11 V.11
RS530 0101V.11 V.11 V.11 Z V.11 V.11
X.21 0111V.11 V.11 V.11 Z V.11 V.11
V.35 1001V.35 V.35 V.35 Z V.35 V.35
RS449/V.36 1011V.11 V.11 V.11 Z V.11 V.11
V.28/RS232 1101V.28 V.28 V.28 Z V.28 V.28
No Cable 1111ZZZZZZ

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SWITCHI G TI E WAVEFOR S

LTC1543

B – A

B – A

–V

5V

D

0V

V

O

–V

O

A

B

V

1.5V 1.5V

t

PLH

50%

O

90%

10%

t

r

t

SKEW

f = 1MHz : tr ≤ 10ns : tf ≤ 10ns

= V(A) – V(B)

V

DIFF

1/2 V

O

t

PHL

90%

50%

10%

t

f

t

SKEW

1543 F06

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

V

OD2

OD2

V

OH

R

V

OL

0V

t

PLH

1.5V

f = 1MHz : tr ≤ 10ns : tf ≤ 10ns

INPUT

OUTPUT

0V

t

PHL

1.5V

1543 F07

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

3V

D

0V

V

O

A

–V

O

1.5V

t

PHL

3V

0V

–3V

t

f

1.5V

–3V

t

PLH

0V

3V

t

r

1543 F08

Figure 8. V.10, V.28 Driver Propagation Delays

V

IH

A

V

IL

V

OH

R

V

OL

1.3V

t

PHL

0.8V

1.7V

t

PLH

2.4V

1543 F09

Figure 9. V.10, V.28 Receiver Propagation Delays

7

LTC1543

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APPLICATIONS INFORMATION

Overview

The LTC1543/LTC1544 form the core of a complete soft­ware-selectable DTE or DCE interface port that supports
the RS232, RS449, EIA530, EIA530-A, V.35, V.36 or X.21
protocols. Cable termination may be implemented using
the LTC1344A software-selectable cable termination chip
or by using existing discrete designs.

A complete DCE-to-DTE interface operating in EIA530
mode is shown in Figure 10. The LTC1543 of each port is
used to generate the clock and data signals. The LTC1544
is used to generate the control signals along with LL (Local
Loopback).The LTC1344A cable termination chip is used
only for the clock and data signals because they must
support V.35 cable termination. The control signals do not
need any external resistors.

Mode Selection

The interface protocol is selected using the mode select
pins M0, M1 and M2 (see the Mode Selection table).

For example, if the port is configured as a V.35 interface,
the mode selection pins should be M2 = 1, M1 = 0, M0 = 0.
For the control signals, the drivers and receivers will
operate in V.28 (RS232) electrical mode. For the clock and
data signals, the drivers and receivers will operate in V.35
electrical mode. The DCE/DTE pin will configure the port
for DCE mode when high, and DTE when low.

The interface protocol may be selected simply by plugging
the appropriate interface cable into the connector. The
mode pins are routed to the connector and are left uncon­nected (1) or wired to ground (0) in the cable as shown in
Figure 11.

The internal pull-up current sources will ensure a binary 1
when a pin is left unconnected and that the LTC1543/
LTC1544 and the LTC1344A enter the no-cable mode
when the cable is removed. In the no-cable mode the
LTC1543/LTC1544 supply current drops to less than
200µA and all LTC1543/LTC1544 driver outputs and

LTC1344A resistive terminations are forced into a high
impedance state.

The mode selection may also be accomplished by using
jumpers to connect the mode pins to ground or VCC.

Cable Termination

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 or separate termina­tions are built on the board and a custom cable routes the
signals to the appropriate termination. Switching the
terminations with 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.

Using the LTC1344A along with the LTC1543/LTC1544
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.

V.10 (RS423) Interface

A typical V.10 unbalanced interface is shown in Figure 12.
A V.10 single-ended generator output A with ground C is
connected to a differential receiver with inputs 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 13.

The V.10 receiver configuration in the LTC1544 is shown
in Figure 14. In V.10 mode switch S3 inside the LTC1544
is turned off.The noninverting input is disconnected inside
the LTC1544 receiver and connected to ground. The cable
termination is then the 30k input impedance to ground of
the LTC1544 V.10 receiver.

8

LTC1543

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APPLICATIONS INFORMATION

SERIAL

CONTROLLER

TXD

SCTE

TXC

RXC

RXD

LTC1543

D1

D2

D3

R1

R2

R3

LTC1344A

103Ω

103Ω

103Ω

TXD

SCTE

TXC

RXC

RXD

LTC1344A

103Ω

103Ω

DCEDTE

LTC1543

R3

R2

R1

SERIAL

CONTROLLER

TXD

SCTE

D3

D2

D1

TXC

RXC

RXD

RTS

DTR

DCD

DSR

CTS

LTC1544

D1

D2

D3

R1

R2

R3

LL

D4 R4

R4

RTS

DTR

DCD

DSR

CTS

LL

LTC1544

R3

R2

R1

D3

D2

D1

D4

RTS

DTR

DCD

DSR

CTS

LL

1543 F10

Figure 10. Complete Multiprotocol Interface in EIA530 Mode

9

LTC1543

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APPLICATIONS INFORMATION

LTC1344A

DCE/

M2 M1

DTE

22

23 24 1

(DATA)

11

M0

LTC1543

DCE/DTE

LTC1544

DCE/DTE

M1

M2

M2

M1

M0

(DATA)

12

13

14

14

13

12

11

LATCH

M0 (DATA)

21

CONNECTOR

NC

NC

CABLE

1543 F11

Figure 11: Single Port DCE V.35 Mode Selection in the Cable

BALANCED

GENERATOR

INTERCONNECTING

CABLE

TERMINATION

AA

CC

'

'

LOAD

CABLE

RECEIVER

1543 F12

Figure 12. Typical V.10 Interface

10

LTC1543

AA

'

B

C

B

'

C

'

GENERATOR

BALANCED

INTERCONNECTING

CABLE

LOAD

CABLE

TERMINATION

RECEIVER

100Ω
MIN

1543 F15

R3

124Ω

R5

20k

LTC1344A

LTC1543
LTC1544

RECEIVER

1543 F16

A

B

A

'

B

'

C

'

R1

51.5Ω

R8
6k

S2

S3

R2

51.5Ω

R6
10k

R7
10k

GND

R4

20k

S1

U

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APPLICATIONS INFORMATION

I

Z

–10V

–3.25mA

Figure 13. V.10 Receiver Input Impedance

–3V

3V 10V

1543 F13

3.25mA

V

Z

A

'

A

R5

R8

20k

6k

S3

R4

B

C

B

'

'

20k

GND

R6
10k

R7
10k

LTC1544

RECEIVER

Figure 14. V.10 Receiver Configuration

1543 F14

V.11 (RS422) Interface

A typical V.11 balanced interface is shown in Figure 15. 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 has a differential termination at the receiver
end that has a minimum value of 100Ω. The termination
resistor is optional in the V.11 specification, but for the
high speed clock and data lines, the termination is required
to prevent reflections from corrupting the data. The
receiver inputs must also be compliant with the imped­ance curve shown in Figure 13.

In V.11 mode, all switches are off except S1 inside the
LTC1344A which connects a 103Ω differential termina­tion impedance to the cable as shown in Figure 16.

Figure 15. Typical V.11 Interface

Figure 16. V.11 Receiver Configuration

11

LTC1543

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APPLICATIONS INFORMATION

V.28 (RS232) Interface

A typical V.28 unbalanced interface is shown in Figure 17.
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 C.

In V.28 mode all switches are off except S3 inside the
LTC1543/LTC1544 which connects a 6k (R8) impedance
to ground in parallel with 20k (R5) plus 10k (R6) for a
combined impedance of 5k as shown in Figure 18. The
noninverting input is disconnected inside the LTC1543/
LTC1544 receiver and connected to a TTL level reference
voltage for a 1.4V receiver trip point.

BALANCED

GENERATOR

INTERCONNECTING

CABLE

TERMINATION

AA

'

LOAD

CABLE

RECEIVER

V.35 Interface

A typical V.35 balanced interface is shown in Figure 19. 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 or delta network termination at
the receiver end and the generator end. The receiver
differential impedance measured at the connector must be
100Ω␣ ±10Ω, and the impedance between shorted termi­nals (A' and B') and ground C' must be 150Ω ±15Ω.

In V.35 mode, both switches S1 and S2 inside the LTC1344A
are on, connecting the T network impedance as shown in
Figure 20. The switch in the LTC1543 is off. The 30k input

BALANCED

INTERCONNECTING

GENERATOR

50Ω

125Ω

CABLE

TERMINATION

'

A

A

CABLE

125Ω

LOAD

RECEIVER

50Ω

CC

'

Figure 17. Typical V.28 Interface

1543 F17

50Ω

B

B

C

'

C

'

50Ω

1543 F19

Figure 19. Typical V.35 Interface

A

'

A

LTC1344A

R1

51.5Ω

S1

R3

S2

124Ω

R2

51.5Ω

B

'

C

'

B

R8
6k

S3

GND

R5

20k

R4

20k

R6
10k

R7
10k

LTC1543
LTC1544

RECEIVER

1543 F18

'

A

A

LTC1344A

R1

51.5Ω

S1

R3

S2

124Ω

R2

51.5Ω

B

'

C

'

B

R8
6k

S3

GND

R5

20k

R4

20k

R6
10k

R7
10k

LTC1543

RECEIVER

1543 F20

Figure 18. V.28 Receiver Configuration

Figure 20. V.35 Receiver Configuration

12

LTC1543

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APPLICATIONS INFORMATION

impedance of the receiver is placed in parallel with the T
network termination, but does not affect the overall input
impedance significantly.

The generator differential impedance must be 50Ω to
150Ω and the impedance between shorted terminals (A
and B) and 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 21.

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.

No-Cable Mode

The no-cable mode (M0 = M1 = M2 = 1) is intended for the
case when the cable is disconnected from the connector.
The charge pump, bias circuitry, drivers and receivers are
turned off, the driver outputs are forced into a high
impedance state, and the supply current drops to less than
200µA.

Charge Pump

The LTC1543 uses an internal capacitive charge pump to
generate VDD and VEE as shown in Figure 22. A voltage
doubler generates about 8V on VDD and a voltage inverter
generates about – 7.5V for VEE. Four 1µF surface mounted
tantalum or ceramic capacitors are required for C1, C2, C3
and C4. The VEE capacitor C5 should be a minimum of

3.3µF. All capacitors are 16V and should be placed as close
as possible to the LTC1543 to reduce EMI.

LTC1344A

V.35 DRIVER

124Ω

C1
100pF

ON

51.5Ω

S1

S2

ON

51.5Ω

Figure 21. V.35 Driver Using the LTC1344A

A

B

C

1543 F21

Receiver Fail-Safe

All LTC1543/LTC1544 receivers feature fail-safe opera­tion in all modes. If the receiver inputs are left floating or
shorted together by a termination resistor, the receiver
output will always be forced to a logic high.

3

V

C1
1µF

C4
1µF

DD

2

+

C1

LTC1543

1

–

C1

4

V

CC

C3
1µF

5V

Figure 22. Charge Pump

C2

C2

V

GND

28

+

C2

27

–

26

EE

25

1µF

C5

+

3.3µF

1543 F22

13

LTC1543

U

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APPLICATIONS INFORMATION

DTE vs DCE Operation

The DCE/DTE pin acts as an enable for Driver 3/Receiver
1 in the LTC1543, and Driver 3/Receiver 1 and Driver 4/
Receiver 4 in the LTC1544. The INVERT pin in the LTC1544
allows the Driver 4/Receiver 4 enable to be high or low true
polarity.

The LTC1543/LTC1544 can be configured for either DTE
or DCE operation in one of two ways: a dedicated DTE or
DCE port with a connector of appropriate gender or a port
with one connector that can be configured for DTE or DCE
operation by rerouting the signals to the LTC1543/LTC1544
using a dedicated DTE cable or dedicated DCE cable.

A dedicated DTE port using a DB-25 male connector is
shown in Figure 23. The interface mode is selected by logic
outputs from the controller or from jumpers to either V
or GND on the mode select pins. A dedicated DCE port
using a DB-25 female connector is shown in Figure 24.

A port with one DB-25 connector, but can be configured
for either DTE or DCE operation is shown in Figure 25. The
configuration requires separate cables for proper signal
routing in DTE or DCE operation. For example, in DTE
mode, the TXD signal is routed to Pins 2 and 14 via Driver
1 in the LTC1543. In DCE mode, Driver 1 now routes the
RXD signal to Pins 2 and 14.

CC

LTC1343. The LTC1343 has an additional single-ended
driver/receiver pair that can handle two more optional
control signals such as TM and LL.

Cable-Selectable Multiprotocol Interface

A cable-selectable multiprotocol DTE/DCE interface is
shown in Figure 27. The select lines M0, M1 and DCE/DTE
are brought out to the connector. The mode is selected by
the cable by wiring M0 (connector Pin 18) and M1 (con­nector Pin 21) and DCE/DTE (connector Pin 25) to ground
(connector Pin 7) or letting them float. If M0, M1 or DCE/
DTE is floating, internal pull-up current sources will pull
the signals to VCC. The select bit M2 is hard wired to VCC.
When the cable is pulled out, the interface will go into the
no-cable mode.

Compliance Testing

A European standard EN 45001 test report is available for
the LTC1543/LTC1544/LTC1344A chipset. A copy of the
test report is available from LTC or TUV Telecom Services
Inc. (formerly Detecon Inc.)

The title of the report is:
Test Report No. NET2/102201/97.
The address of TUV Telecom Services Inc. is:

Multiprotocol Interface with RL, LL, TM and a DB-25
Connector

If the RL, LL and TM signals are implemented, there are not
enough drivers and receivers available in the LTC1543/
LTC1544. In Figure 26, the required control signals are
handled by the LTC1544 but the clock/data signals use the

14

TUV Telecom Services Inc.
Type Approval Division
1775 Old Highway 8, Ste 107
St. Paul, MN 55112 USA
Tel. [phone]
Fax. [phone]

U

TYPICAL APPLICATIONS

V

CC

5V

3

TXD

SCTE

C3
1µF

1µF

1

C1

C5
1µF

CHARGE

2

PUMP

4

LTC1543

5

D1

6

D2

7

D3

LTC1543

C6

100pFC7100pF

3 8 11 12 13

V

CC

28

C2
1µF

27
26

C4

+

3.3µF

25

24
23

22
21

C13
1µF

C12
1µF

2

V

EE

5

C8

100pF

16109764

15 18 17 19 20 22

LTC1344A

LATCH

DCE/DTEM2M1

23 24141

21

M0

2

TXD A (103)

14

TXD B

24

SCTE A (113)

11

SCTE B

C10

1µF

TXC

RXC

RXD

RTS

DTR

DCD

DSR

CTS

GND

INVERT

20
19
18
17
16
15

28

V

EE

27

26
25

24
23

22
21
20
19

18
17

16

15

NC

C11
1µF

8

R1

9

R2

10

R3

11

M0

12

M1

13

M2

14

DCE/DTE

V

CC

C9

1

1µF

LL

10

11
12
13
14

2

3

4

5

6

7

8

9

V

CC

V

DD

D1

D2

D3

LTC1544

D4

M0
M1
M2
DCE/DTE

R1

R2

R3

R4

15
12
17

9
3

16

7

1

4

19
20

23

8

10

6

22

5

13

18

TXC A (114)
TXC B
RXC A (115)
RXC B
RXD A (104)
RXD B

SG

SHIELD

DB-25 MALE
CONNECTOR

RTS A (105)
RTS B
DTR A (108)
DTR B

DCD A (109)
DCD B
DSR A (107)
DSR B
CTS A (106)
CTS B

LL A (141)

M2
M1
M0

1543 F23

Figure 23. Controller-Selectable Multiprotocol DTE Port with DB-25 Connector

15

LTC1543

TYPICAL APPLICATIONS

V

CC

5V

3

RXD

RXC

C3
1µF

1µF

1

C1

C5
1µF

CHARGE

2

PUMP

4

LTC1543

5

D1

6

D2

7

D3

U

C6

100pFC7100pF

3 8 11 12 13

V

CC

28

C2
1µF

27
26

C4

+

3.3µF

25

24
23

22
21

C13
1µF

C12
1µF

2

V

EE

5

C8

100pF

16109764

15 18 17 19 20 22

LTC1344A

DCE/DTEM2M1

V

CC

LATCH

23 24141

21

M0

3

RXD A (104)

16

RXD B

17

RXC A (115)

9

RXC B

C10

1µF

TXC

SCTE

TXD

CTS

DSR

DCD

DTR

RTS

R1

R2

R1

R2

R3

R4

V

GND

INVERT

20
19
18
17
16
15

28

EE

27

26
25

24
23

22
21
20
19

18
17

16

15

NC

C11
1µF

8

9

10

R3

11

M0

12

M1

13

M2

14

DCE/DTE

NC

V

CC

C9

1

1µF

LL

V

CC

2

V

DD

3

D1

4

D2

5

D3

LTC1544

6

7

8

10

9

D4

11

M0

12

M1

13

M2

14

NC

DCE/DTE

15
12
24

SCTE A (113)

11

SCTE B

2

TXD A (103)

14

TXD B

7

SGND (102)

1

SHIELD (101)

5

CTS A (106)

13

CTS B

6

DSR A (107)

22

DSR B

8

DCD A (109)

10

DCD B

20

DTR A (108)

23

DTR B

4

RTS A (105)

19

RTS B

18

LL A (141)

TXC A (114)
TXC B

DB-25 FEMALE

CONNECTOR

16

M2
M1
M0

1543 F24

Figure 24. Controller-Selectable DCE Port with DB-25 Connector

U

TYPICAL APPLICATIONS

V

CC

5V

3

DTE_TXD/DCE_RXD

DTE_SCTE/DCE_RXC

C3
1µF

1µF

1

C1

C5
1µF

CHARGE

2

PUMP

4

LTC1543

5

D1

6

D2

7

D3

LTC1543

C6

100pFC7100pF

3 8 11 12 13

V

CC

28

C2
1µF

27
26

C4

+

3.3µF

25

24
23

22
21

C13
1µF

C12
1µF

2

V

EE

5

C8

100pF

16109764

15 18 17 19 20 22

LTC1344A

LATCH

DCE/DTEM2M1

23 24141

M0

21

14
24
11

DTE DCE

2

TXD A
TXD B
SCTE A
SCTE B

RXD A
RXD B
RXC A
RXC B

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

C9
1µF

20

8

9

10
11

M0

12

M1

13

M2

14

DCE/DTE

V

CC

1

V

CC

2

V

DD

3

4

5

LTC1544

6

7

8

10

9

11

M0

12

M1

13

M2

14

DCE/DTE

S

R1

R2

R3

D1

D2

D3

R1

R2

R3

R4

D4

GND

INVERT

19

S

18
17
16
15

28

V

EE

27

26

25
24
23

22
21
20
19

18
17

16

15

NC

C11
1µF

15
12
17

9
3

16

7

1

4

19
20

23

8

10

6

22

5

13

18

TXC A

TXC B
RXC A
RXC B
RXD A
RXD B

SG

SHIELD

DB-25

CONNECTOR

RTS A
RTS B
DTR A
DTR B

DCD A
DCD B
DSR A
DSR B
CTS A
CTS B

LL A

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

LL A

DCE/DTE

M2
M1
M0

1543 F25

Figure 25. Controller-Selectable Multiprotocol DTE/DCE Port with DB-25 Connector

17

LTC1543

U

TYPICAL APPLICATIONS

V

CC

5V

1

DTE_LL/DCE_TM

DTE_TXD/DCE_RXD

DTE_SCTE/DCE_RXC

DTE_TXC/DCE_TXC

DTE_RXC/DCE_SCTE

DTE_RXD/DCE_TXD

DTE_TM/DCE_LL

C10
1µF

DTE_RTS/DCE_CTS

DTE_DTR/DCE_DSR

DTE_DCD/DCE_DCD

DTE_DSR/DCE_DTR

DTE_CTS/DCE_RTS

DTE_RL/DCE_RL

DCE/DTE

C3
1µF

LB

C9
1µF

M2
M1
M0

1µF

2

C1

C5
1µF

R1

100k

CHARGE

4
3

8

LTC1343

5

D1

6

D2

7

D3

9

D4
10
12
13

14

15

16

20

CTRL

22

LATCH

11

INVERT

25

423SET

40

GND

V

CC

1

V

CC

2

V

DD

3

4

D2

5

LTC1544

6

7

8

10

9

11

M0

12

M1

13

M2

14

DCE/DTE

PUMP

D1

D3

D4

R1

R2

R3

R4

LB

R1

R2

R3

R4

DCE

23

GND

INVERT

C6

100pFC7100pF

V

CC

C11
1µF

C13
1µF

C12
1µF

2

V

EE

44

C2
1µF

43
42

C4

+

3.3µF

41

39

38
37
36
35
34
33

32
31
30
29
28
27

26

21
19

M2

18

M1

17

M0

V

CC

24

EC

28

V

EE

27

26
25
24
23

22
21
20
19

18
17

16

15

NC

C8

100pF

3 8 11 12 13

5

16109764

15 18 17 19 20 22

LTC1344A

LATCH

DCE/DTEM2M1

23 24141

M0

21

18

2

14
24
11

15
12
17

9
3

16

25

7

1

4

19
20
23

8

10

6

22

5

13

21

DTE DCE

LL A

TXD A
TXD B
SCTE A
SCTE B

TXC A
TXC B
RXC A
RXC B
RXD A
RXD B

TM A LL A

SG

SHIELD

DB-25

CONNECTOR

RTS A
RTS B
DTR A
DTR B

DCD A
DCD B
DSR A
DSR B
CTS A
CTS B

RL A

1543 F26

TM A

RXD A
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

RL A

18

Figure 26. Controller-Selectable Multiprotocol DTE/DCE Port with RL, LL, TM and DB-25 Connector

U

TYPICAL APPLICATIONS

LTC1543

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
1µF

C6

100pFC7100pF

3 8 11 12 13

V

CC

5V

V

CC

C13
1µF

2

V

EE

C12
1µF

C11
1µF

V.35 PIN 7 PIN 7

RS232 PIN 7 NC

5

1µF

C1

C9
1µF

C5
1µF

3

1

CHARGE

2

PUMP

4

LTC1543

5

D1

6

D2

7

D3

8

R1

9

R2

10

R3

11

M0

12

M1

13

M2

NC

14

DCE/DTE

V

CC

1

V

CC

2

V

DD

3

D1

4

D2

5

D3

LTC1544

6

R1

7

R2

8

R3

10

R4

9

D4

11

M0

12

M1

13

NC

M2

14

DCE/DTE

GND

INVERT

28

C2
1µF

27
26

C4

+

3.3µF

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

CABLE WIRING FOR MODE SELECTION

MODE PIN 18 PIN 21

RS449, V.36 NC PIN 7

15

NC

C8

100pF

16109764

CABLE WIRING FOR
DTE/DCE SELECTION

MODE PIN 25

DTE PIN 7
DCE NC

15 18 17 19 20 22

LTC1344A

LATCH

DCE/DTEM2M1

23 24141

V

CC

21

M0

DTE

TXD A
TXD B
SCTE A
SCTE B

TXC A
TXC B
RXC A
RXC B
RXD A
RXD B
SG

SHIELD

DB-25

CONNECTOR

DCE/DTE
M1
M0

RTS A
RTS B
DTR A
DTR B

DCD A
DCD B
DSR A
DSR B
CTS A
CTS B

DCE

RXD A
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

2

14
24

11

15

12

17

9

3

16

7

1

25
21
18

4

19

20

23

8

10

6

22

5

13

Figure 27. Cable-Selectable Multiprotocol DTE/DCE Port with DB-25 Connector

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.

1543/44 F27

19

LTC1543

PACKAGE DESCRIPTION

0.205 – 0.212**
(5.20 – 5.38)

U

Dimensions in inches (millimeters) unless otherwise noted.

G Package

28-Lead Plastic SSOP (0.209)

(LTC DWG # 05-08-1640)

0.397 – 0.407*
(10.07 – 10.33)

2526 22 21 20 19 181716 1523242728

12345678 9 10 11 12 1413

0.301 – 0.311
(7.65 – 7.90)

0.068 – 0.078
(1.73 – 1.99)

° – 8°

0

0.005 – 0.009
(0.13 – 0.22)

*

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

0.022 – 0.037
(0.55 – 0.95)

0.0256
(0.65)

BSC

0.010 – 0.015
(0.25 – 0.38)

0.002 – 0.008
(0.05 – 0.21)

G28 SSOP 0694

RELATED PARTS

PART NUMBER DESCRIPTION COMMENTS

LTC1321 Dual RS232/RS485 Transceiver Two RS232 Driver/Receiver Pairs or Two RS485 Driver/Receiver Pairs
LTC1334 Single 5V RS232/RS485 Multiprotocol Transceiver Two RS232 Driver/Receiver or Four RS232 Driver/Receiver Pairs
LTC1343 Software-Selectable Multiprotocol Transceiver 4-Driver/4-Receiver for Data and Clock Signals
LTC1344A Software-Selectable Cable Terminator Perfect for Terminating the LTC1543
LTC1345 Single Supply V.35 Transceiver 3-Driver/3-Receiver for Data and Clock Signals
LTC1346A Dual Supply V.35 Transceiver 3-Driver/3-Receiver for Data and Clock Signals
LTC1544 Software-Selectable Multiprotocol Transceiver Companion to LTC1543 for Control Signals

20

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

[phone] ● FAX: [phone]

●

www.linear-tech.com

1543fs, sn1543x LT/TP 0898 4K • PRINTED IN

USA

 LINEAR TECHNOLOGY CORPORATION 1998