Linear Technology LTC1334 Datasheet

FEATURES

LTC1334

Single 5V RS232/RS485

Multiprotocol Transceiver

U

DESCRIPTIO

■

Four RS232 Transceivers or Two RS485
Transceivers on One Chip

■

Operates from a Single 5V Supply

■

Withstands Repeated ±10kV ESD Pulses

■

Uses Small Charge Pump Capacitors: 0.1µF

■

Low Supply Current: 8mA Typical

■

10µA Supply Current in Shutdown

■

Self-Testing Capability in Loopback Mode

■

Power-Up/Down Glitch-Free Outputs

■

Driver Maintains High Impedance in Three-State,
Shutdown or with Power Off

■

Thermal Shutdown Protection

■

Receiver Inputs Can Withstand ±25V

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APPLICATIO S

■

Low Power RS485/RS422/RS232/EIA562 Interface

■

Software-Selectable Multiprotocol Interface Port

■

Cable Repeaters

■

Level Translators

The LTC®1334 is a low power CMOS
ceiver featuring two

reconfigurable interface ports. It can

bidirectional trans-

be configured as two RS485 differential ports, as two dual
RS232 single-ended ports or as one RS485 differential
port and one dual RS232 single-ended port. An onboard
charge pump requires four 0.1µF capacitors to generate
boosted positive and negative supplies, allowing the RS232
drivers to meet the RS232 ±5V output swing requirement
with only a single 5V supply. A shutdown mode reduces
the ICC supply current to 10µA.

The RS232 transceivers are in full compliance with RS232
specifications. The RS485 transceivers are in full compli­ance with RS485 and RS422 specifications. All interface
drivers feature short-circuit and thermal shutdown pro­tection. An enable pin allows RS485 driver outputs to be
forced into high impedance, which is maintained even
when the outputs are forced beyond supply rails or power
is off. Both driver outputs and receiver inputs feature
±10kV ESD protection. A loopback mode allows the driver
outputs to be connected back to the receiver inputs for
diagnostic self-test.

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

TYPICAL APPLICATIO

12

3

LTC1334

DR IN

DR IN
DR IN

26
24

23

22

21

5V

20

5V

19
18
17
16
15

V

CC1

5V

RX OUT

DR ENABLE

RX OUT
RX OUT

U

2728

LTC1334

4
5

6
7
8
9
11
10
13
12

14

120Ω

5V
0V

ALL CAPACITORS: 0.1µF MONOLITHIC CERAMIC TYPE

RS485 INTERFACE

4000-FT 24-GAUGE TWISTED PAIR

RS232 INTERFACE

120Ω

13
12

11
10

9

5V

8

0V

4
5
6
7

14

212827

3

26
17

18

19

21
20
24
25
22
23
15

RX OUT

DR ENABLE

DR IN

5V
5V
RX OUT
RX OUT
DR IN
DR IN

V

CC2

5V

LTC1334 • TA01

1

LTC1334

A

S

(Note 1)

W

O

LUTEXI TIS

A

WUW

U

ARB

G

Supply Voltage (VCC) ............................................. 6.5V

Input Voltage

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

Receivers ............................................. – 25V to 25V

ON/OFF, LB, SEL1, SEL2 ........ –0.3V to (VCC + 0.3V)

Output Voltage

Drivers ................................................. – 18V to 18V

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

Short-Circuit Duration

Output ........................................................ Indefinite

VDD, VEE, C1+, C1–, C2+, C2–.......................... 30 sec

Operating Temperature Range

Commercial........................................... 0°C to 70°C

Industrial............................................ –40°C to 85°C

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

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

PACKAGE

+

1

C1

–

2

C1

3

V

DD

4

A1

5

B1

6

Y1

7

Z1

8

SEL1

9

SEL2

10

Z2

11

Y2

12

B2

13

A2

14

GND

G PACKAGE

28-LEAD PLASTIC SSOP

28-LEAD PLASTIC SO WIDE

T

= 125°C, θJA = 90°C/W (G)

JMAX

T

= 125°C, θJA = 56°C/W (NW)

JMAX

T

= 125°C, θJA = 85°C/W (SW)

JMAX

/

O

RDER I FOR ATIO

TOP VIEW

28-LEAD PDIP WIDE

SW PACKAGE

28

C2

27

C2

26

V

CC

25

R

B1

24

R

A1

23

DZ1/DE1

22

D

Y1

21

LB

20

ON/OFF

19

D

Y2

18

DZ2/DE2

17

R

A2

16

R

B2

15

V

EE

NW PACKAGE

+
–

ORDER PART

LTC1334CG
LTC1334CNW
LTC1334CSW
LTC1334IG
LTC1334ISW

WU

U

NUMBER

Consult factory for Military grade parts.

DC ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, C1 = C2 = C3 = C4 = 0.1µF (Notes 2, 3)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
RS485 Driver (SEL1 = SEL2 = High)

V

OD1

V

OD2

∆V

OD

V

OC

∆VOC Change in Magnitude of Driver Common Mode Figure 1, R = 27Ω or R = 50Ω ● 0.2 V

I

OSD

I

OZD

RS232 Driver (SEL1 = SEL2 = Low)

V

O

I

OSD

Driver Inputs and Control Inputs

V

IH

V

IL

I

IN

Differential Driver Output Voltage (Unloaded) IO = 0 ● 6V
Differential Driver Output Voltage (With Load) Figure 1, R = 50Ω (RS422) ● 2.0 6 V

Figure 1, R = 27Ω (RS485) ● 1.5 6 V

Change in Magnitude of Driver Differential Figure 1, R = 27Ω or R = 50Ω ● 0.2 V
Output Voltage for Complementary Output States

Driver Common Mode Output Voltage Figure 1, R = 27Ω or R = 50Ω ● 3V

Output Voltage for Complementary Output States
Driver Short-Circuit Current –7V ≤ VO ≤ 12V, VO = High ● 35 250 mA

–7V ≤ V

Three-State Output Current (Y, Z) –7V ≤ VO ≤ 12V ● ±5 ±500 µA

Output Voltage Swing Figure 4, RL = 3k, Positive ● 5 6.5 V

Figure 4, R

Output Short-Circuit Current VO = 0V ● ±60 mA

Input High Voltage D, DE, ON/OFF, SEL1, SEL2, LB ● 2V
Input Low Voltage D, DE, ON/OFF, SEL1, SEL2, LB ● 0.8 V
Input Current D, SEL1, SEL2 ● ±10 µA

DE, ON/OFF, LB

≤ 12V, VO = Low (Note 4) ● 10 250 mA

O

= 3k, Negative ● –5 –6.5 V

L

● –4 –15 µA

2

LTC1334

DC ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, C1 = C2 = C3 = C4 = 0.1µF (Notes 2, 3)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
RS485 Receiver (SEL1 = SEL2 = High)

V

TH

∆V

TH

I

IN

R

IN

RS232 Receiver (SEL1 = SEL2 = Low)

V

TH

∆V

TH

R

IN

Receiver Output

V

OH

V

OL

I

OSR

I

OZR

R

OB

Power Supply Generator

V

DD

V

EE

Power Supply

I

CC

Differential Input Threshold Voltage –7V ≤ VCM ≤ 12V, LTC1334C ● –0.2 0.2 V

–7V ≤ V

≤ 7V, LTC1334I ● –0.3 0.3 V

CM

Input Hysteresis VCM = 0V 70 mV
Input Current (A, B) VIN = –7V ● – 0.8 mA

= 12V ● 1.0 mA

V

IN

Input Resistance –7V ≤ VIN ≤ 12V ● 12 24 kΩ

Receiver Input Threshold Voltage Input Low Threshold ● 0.8 V

Input High Threshold

● 2.4 V

Receiver Input Hysteresis 0.6 V
Receiver Input Resistance VIN = ±10V 3 5 7 kΩ

Receiver Output High Voltage IO = –3mA, VIN = 0V, SEL1 = SEL2 = Low ● 3.5 4.6 V
Receiver Output Low Voltage IO = 3mA, VIN = 3V, SEL1 = SEL2 = Low ● 0.2 0.4 V
Short-Circuit Current 0V ≤ VO ≤ V

CC

● 785mA

Three-State Output Current ON/OFF = Low ● ±10 µA
Inactive “B” Output Pull-Up Resistance (Note 5) ON/OFF = High, SEL1 = SEL2 = High 50 kΩ

VDD Output Voltage No Load, ON/OFF = High 8.5 V

= –10mA, ON/OFF = High 7.6 V

I

DD

VEE Output Voltage No Load, ON/OFF = High – 7.7 V

= 10mA, ON/OFF = High –6.9 V

I

EE

VCC Supply Current No Load, SEL1 = SEL2 = High ● 825 mA

No Load Shutdown, ON/OFF = 0V

● 10 100 µA

AC ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, C1 = C2 = C3 = C4 = 0.1µF (Notes 2, 3)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
RS232 Mode (SEL1 = SEL2 = Low)

SR Slew Rate Figure 4, RL = 3k, CL = 15pF ● 30 V/µs

t
t
t
t
t

T

PLH

PHL

PLH

PHL

Figure 4, R
Transition Time Figure 4, RL = 3k, CL = 2500pF ● 0.22 1.9 3.1 µs
Driver Input to Output Figures 4, 9, RL = 3k, CL = 15pF ● 0.6 4 µs
Driver Input to Output Figures 4, 9, RL = 3k, CL = 15pF ● 0.6 4 µs
Receiver Input to Output Figures 5, 10 ● 0.3 6 µs
Receiver Input to Output Figures 5, 10 ● 0.4 6 µs

= 3k, CL = 1000pF ● 4V/µs

L

RS485 Mode (SEL1 = SEL2 = High)

t

PLH

t

PHL

t

SKEW

tr, t

f

Driver Input to Output Figures 2, 6, RL = 54Ω, CL = 100pF ● 20 40 70 ns
Driver Input to Output Figures 2, 6, RL = 54Ω, CL = 100pF ● 20 40 70 ns
Driver Output to Output Figures 2, 6, RL = 54Ω, CL = 100pF ● 515 ns
Driver Rise and Fall Time Figures 2, 6, RL = 54Ω, CL = 100pF ● 31540 ns

3

LTC1334

AC ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, C1 = C2 = C3 = C4 = 0.1µF (Notes 2, 3)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
RS485 Mode (SEL1 = SEL2 = High)

t

ZL

t

ZH

t

LZ

t

HZ

t

PLH

t

PHL

t

SKEW

Note 1: Absolute Maximum Ratings are those values beyond which the
safety of the device cannot be guaranteed.

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

Note 3: All typicals are given at VCC = 5V, C1 = C2 = C3 = C4 = 0.1µF
and T

Driver Enable to Output Low Figures 3, 7, CL = 100pF, S1 Closed ● 50 90 ns
Driver Enable to Output High Figures 3, 7, CL = 100pF, S2 Closed ● 50 90 ns
Driver Disable from Low Figures 3, 7, CL = 15pF, S1 Closed ● 50 90 ns
Driver Disable from High Figures 3, 7, CL = 15pF, S2 Closed ● 60 90 ns
Receiver Input to Output Figures 2, 8, RL = 54Ω, CL = 100pF ● 20 60 140 ns
Receiver Input to Output Figures 2, 8, RL = 54Ω, CL = 100pF ● 20 70 140 ns
Differential Receiver Skew, t

PLH

– t

 Figures 2, 8, R

PHL

= 54Ω, CL = 100pF 10 ns

L

Note 4: Short-circuit current for RS485 driver output low state folds back
above VCC. Peak current occurs around VO = 3V.

Note 5: The “B” RS232 receiver output is disabled in RS485 mode
(SEL1 = SEL2 = high). The unused output driver goes into a high
impedance mode and has a resistor to VCC. See Applications Information
section for more details.

= 25°C.

A

W

U

TYPICAL PERFORMANCE CHARACTERISTICS

Receiver Output High Voltage
vs Temperature

5.0
I

= 3mA

OUT

4.9

4.8

4.7

4.6

4.5

4.4

4.3

OUTPUT VOLTAGE (V)

4.2

4.1

4.0

–50

= 5V

V

CC

–25

0

TEMPERATURE (°C)

50

25

75

100

LTC1334 • TPC01

125

Receiver Output Low Voltage
vs Temperature

0.5
I

= 3mA

OUT

V

= 5V

CC

0.4

0.3

0.2

OUTPUT VOLTAGE (V)

0.1

0

–50

0

–25

TEMPERATURE (°C)

50

25

75

100

LTC1334 • TPC02

125

RS485 Receiver Skew
t

– t

PLH

VCC = 5V

–25

PHL

0

TEMPERATURE (°C)

20
18
16
14
12
10

TIME (ns)

8
6
4
2
0

–50

 vs Temperature

50

25

75

100

LTC1334 • TPC03

125

4

W

TEMPERATURE (°C)

–50

INPUT THRESHOLD VOLTAGE (V)

2.0

1.8

1.6

1.4

1.2

1.0

0.8
25 75

LTC1334 • TPC06

–25 0

50 100 125

INPUT HIGH

INPUT LOW

VCC = 5V

TEMPERATURE (°C)

–50

SUPPLY CURRENT (mA)

10

9
8
7
6
5
4
3
2
1
0

0

50

75

LTC1334 • TPC09

–25

25

100

125

VCC = 5V
NO LOAD
SEL 1 = SEL 2 = HIGH

U

TYPICAL PERFORMANCE CHARACTERISTICS

LTC1334

Receiver Output Current
vs Output High Voltage

20
18
16
14
12
10

8
6

OUTPUT CURRENT (mA)

4
2
0

2.0

2.5

3.5 4.0

3.0

OUTPUT VOLTAGE (V)

Charge Pump Output Voltage
vs Temperature

10

8

VDD (–10mA LOAD)

6
4
2

VCC = 5V

0
–2
–4

OUTPUT VOLTAGE (V)

–6
–8

–10

–50

–25

VDD (NO LOAD)

VEE (10mA LOAD)

VEE (NO LOAD)

0

TEMPERATURE (°C)

50

25

TA = 25°C
V

CC

75

= 5V

4.5

LTC1334 • TPC04

100

LTC1334 • TPC07

125

5.0

Receiver Output Current
vs Output Low Voltage

40

TA = 25°C

= 5V

V

35

CC

30

25

20

15

OUTPUT CURRENT (mA)

10

5

0

0 0.5

1.0 2.01.5

OUTPUT VOLTAGE (V)

Supply Current
vs Temperature (RS485)

25

VCC = 5V
NO LOAD

20

SEL 1 = SEL 2 = HIGH

15

10

SUPPLY CURRENT (mA)

5

0

–50

–25

25

0

TEMPERATURE (°C)

RS232 Receiver Input Threshold
Voltage vs Temperature

2.5

3.0

LTC1334 • TPC05

Supply Current
vs Temperature (RS232)

50

75

100

LTC1334 • TPC08

125

RS485 Driver Differential Output
Voltage vs Temperature

2.6
RL = 54Ω

2.5

2.4

2.3

2.2

2.1

2.0

1.9

1.8

DIFFERENTIAL OUTPUT VOLTAGE (V)

1.7

1.6

= 5V

V

CC

–50

–25

25

50

0

TEMPERATURE (°C)

75

100

LTC1334 • TPC10

125

RS485 Driver Differential Output
Current vs Output Voltage

70

60

50

40

30

20

10

DIFFERENTIAL OUTPUT CURRENT (mA)

0

12 5

0

DIFFERENTIAL OUTPUT VOLTAGE (V)

34

TA = 25°C

= 5V

V

CC

LTC1334 • TPC11

RS485 Driver Skew
vs Temperature

15

VCC = 5V

12

9

TIME (µs)

6

3

0

–50

–25

0

TEMPERATURE (°C)

50

25

75

100

LTC1334 • TPC12

5

125