Linear Technology LT1081IN, LT1081CSW, LT1081CN, LT1081CJ, LT1081 Datasheet

FEATURES

LT1080/LT1081

Advanced Low Power

5V RS232 Dual Driver/Receiver

U

DESCRIPTIO

■

Superior to CMOS

– Improved Speed: Operates over 120kBaud
– Improved Protection: Outputs Can Be Forced

to ±30V without Damage

– Three-State Outputs Are High

Impedance When Off

– Only Needs 1µF Capacitors

■

Absolutely No Latchup

■

CMOS Comparable Low Power: 60mW

■

Can Power Additional RS232 Drivers: 10mA

■

Supply Current in Shutdown: 1µA

■

Available in SO Package

■

Available with or without Shutdown

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APPLICATIO S

■

Portable Computers

■

Battery-Powered RS232 Systems

■

Power Supply Generator

■

Terminals

■

Modems

The LT®1080/LT1081 are the only dual RS232 driver/
receiver with charge pump to guarantee absolutely no
latchup. These interface optimized devices provide a real­istic balance between CMOS levels of power dissipation
and real world requirements for ruggedness. The driver
outputs are fully protected against overload and can be

shorted to ±30V. Unlike CMOS, the advanced architecture

of the LT1080/LT1081 does not load the signal line when
“shut down” or when power is off. Both the receiver and
RS232 outputs are put into a high impedance state. An
advanced output stage allows driving higher capacitive
loads at higher speeds with exceptional ruggedness
against ESD.

For applications requiring up to five drivers and five
receivers with charge pump in one package see the LT1130A
Series data sheet. A version of the LT1080/LT1081, the

LT1180A and LT1181A that use only 0.1µF capacitors, is

also available. All of Linear Technology’s RS232 ICs are
available in standard surface mount packages.

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

TYPICAL APPLICATIO

LOGIC

INPUTS

LOGIC

OUTPUTS

ON/OFF

1µF

1µF

2

4

LT1080

5

6

12

11

13

10

18

17

3

7

15

8

14

5k

9

5k

16

U

1µF

1µF

5V INPUT

9V OUTPUT

–9V OUTPUT

RS232 OUTPUT

RS232 OUTPUT

RS232 INPUT

RS232 INPUT

1080/81 • TA01

Supply Generator Outputs

10

8

RL TO V

6

4

2

VCC = 5V

0

–2

–4

OUTPUT VOLTAGE (V)

–6

RL TO V

–8

–10

02468101214161820

V+ OUTPUT

–

+

V– OUTPUT

OUTPUT CURRENT (mA)

RL TO GND

RL TO GND

1080/81 TA01a

1

LT1080/LT1081

A

W

O

LUTEXI TIS

S

A

WUW

U

ARB

G

Supply Voltage (VCC) ................................................. 6V

+

V

...........................................................................................

–

V

.......................................................................................

12V

–12V

Input Voltage

Driver ........................................................... V– to V

Receiver ................................................. –30V to 30V

ON/OFF Pin .............................................. GND to 12V

Output Voltage

Driver ................................. (V– + 30V) to (V+ – 30V)

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

WU

/

TOP VIEW

1

2

3

4

5

6

7

8

9

SW PACKAGE

O

RDER I FOR ATIO

ORDER PART

ON/OFF

18

V

17

CC

GND

16

TR1 OUT

LT1080

15

REC1 IN

14

REC1 OUT

13

TR1 IN

12

TR2 IN

11

REC2 OUT

10

N PACKAGE

18-LEAD PDIP

NUMBER

LT1080CJ
LT1080CN
LT1080CSW
LT1080IN
LT1080ISW
LT1080MJ

PACKAGE

NC

+

C1

+

V

–

C1

+

C2

–

C2

–

V

TR2 OUT

REC2 IN

J PACKAGE

18-LEAD CERDIP

18-LEAD PLASTIC SO WIDE

T

= 150°C, θJA = 100°C/W, θJC = 40°C/W (J)

JMAX

T

= 150°C, θJA = 120°C/W, θJC = 50°C/W (N)

JMAX

= 150°C, θJA = 90°C/W, θJC = 26°C/W (SW)

T

JMAX

(Note 1)

Short-Circuit Duration

+

V

......................................................................................

–

V

......................................................................................

Driver Output ............................................... Indefinite

+

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

Operating Temperature Range

LT1080C/LT1081C ................................. 0°C to 70°C

LT1080I/LT1081I................................ –40°C to 85°C

LT1080M/LT1081M.......................... –55°C to 125°C

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

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

U

TOP VIEW

+

1

C1

+

2

V

–

3

C1

+

C2

–

C2

–

V

TR2 OUT

REC2 IN

J PACKAGE

16-LEAD CERDIP

T

= 150°C, θJA = 100°C/W, θJC = 40°C/W (J)

JMAX

T

= 150°C, θJA = 120°C/W, θJC = 50°C/W (N)

JMAX

= 150°C, θJA = 95°C/W, θJC = 27°C/W (SW)

T

JMAX

LT1081

4

5

6

7

8

SW PACKAGE

16-LEAD PLASTIC SO WIDE

16

15

14

13

12

11

10

9

N PACKAGE

16-LEAD PDIP

V

CC

GND

TR1 OUT

REC1 IN

REC1 OUT

TR1 IN

TR2 IN

REC2 OUT

ORDER PART

NUMBER

LT1081CJ
LT1081CN
LT1081CSW
LT1081IN
LT1081ISW
LT1081MJ

30 sec
30 sec

2

LT1080/LT1081

LECTRICAL C CHARA TERIST

E

ICS

temperature range, otherwise specifications are at T

The ● denotes the specifications which apply over the full operating

= 25°C. (Note 2)

A

PARAMETER CONDITIONS MIN TYP MAX UNITS

Driver

Output Voltage Swing Load = 3k to GND Both Outputs Positive ● 5 7.3 V

● –5 –6.5 V

Logic Input Voltage Level Input Low Level (V

Input High Level (V

Logic Input Current V

≥ 2V ● 520 µA

IN

V

≤ 0.8V ● 520 µA

IN

Output Short-Circuit Current Sourcing Current, V

Sinking Current, V

= High) ● 1.4 0.8 V

OUT

= Low) ● 2 1.4 V

OUT

OUT

= 0V –9 –12 mA

OUT

Output Leakage Current SHUTDOWN (Note 3), V

Negative

= 0V 9 12 mA

= ±30V ● 10 100 µA

OUT

Data Rate (Note 6) RL = 3k, CL = 2500pF 120 kBd

= 3k, CL = 1000pF 250 kBd

R

L

Slew Rate RL = 3k, C

= 51pF 4 15 30 V/µs

L

Receiver

Input Voltage Thresholds Input Low Threshold Commercial ● 0.8 1.3 V

Industrial and Military

● 0.2 1.3 V

Input High Threshold Commercial ● 1.7 2.4 V

Industrial and Military

● 1.7 3.0 V

Hysteresis ● 0.1 0.4 1 V

Input Resistance V

Output Voltage Output Low, I

Output Short-Circuit Current Sinking Current, V

Output Leakage Current SHUTDOWN (Note 3), 0V ≤ V

= ±10V 3 5 7 kΩ

IN

= –1.6mA ● 0.2 0.4 V

Output High, I

Sourcing Current, V

OUT

= 160µA (VCC = 5V) ● 3.5 4.8 V

OUT

= V

OUT

CC

= 0V 0.6 1 mA

OUT

≤ V

OUT

CC

–10 –20 mA

● 110 µA

Power Supply Generator (Note 4)

V+ Output Voltage I

V– Output Voltage I

= 0mA 8.0 9.0 V

OUT

= 10mA 7.0 8.0 V

I

OUT

= 15mA 6.5 7.5 V

I

OUT

= 0mA –7.5 –8.5 V

OUT

I

= –10mA –5.5 –6.5 V

OUT

= –15mA –5.0 –6.0 V

I

OUT

Supply Current ● 12 22 mA

Supply Leakage Current (V

ON/OFF Pin Current 0V ≤ V

) SHUTDOWN (Note 3), LT1080 Only ● 1 100 µA

CC

≤ 5V, LT1080 Only ● –15 80 µA

ON/OFF

Supply Rise Time (Note 5), LT1080 Only 1 ms

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

Note 2: These parameters apply for 4.5V ≤ V

≤ 5.5V and V

CC

ON/OFF

= 3V,

unless otherwise specified.
Note 3: V

50°C ≤ T

= 0.4V for –55°C ≤ TA ≤ 50°C, and V

ON/OFF

≤ 125°C. (LT1080 only)

A

ON/OFF

= 0.2V for

Note 4: Unless otherwise specified, V

–

V

equals zero and the driver outputs are low (inputs high).

Note 5: Time from either SHUTDOWN high or power on until V

–

V

≤ –6V. All external capacitors are 1µF.

= 5V, external loading of V+ and

CC

+

≥ 6V and

Note 6: Data rate operation guaranteed by slew rate, short-circuit current
and propagation delay tests.

3

LT1080/LT1081

UUU

PI FU CTIO S

(Pin numbers refer to LT1080)

C1+; C1–; C2+; C2– (Pins 2, 4, 5, 6): Requires an external

capacitor (≥1µF) from C1

+

to C1– and another from C2

+

to C2–. Pin 2 can be used for connecting a second positive
supply. When a separate positive supply is used, C1 can be
deleted.

V+ (Pin 3): Positive Supply for RS232 Drivers.

+

V

≈ 2VCC – 1.5V. Requires an exterenal capacitor (≥1µF)

for charge storage. May be loaded (up to 15mA) for
external system use. Loading does reduce V+ voltage (see
graphs). Capacitor may be tied to ground or +5V input
supply. With multiple transceivers, the V+ and V– pins may
be paralleled into common capacitors.

V– (Pin 7): Negative Supply for RS232 Drivers.

–

V

≈ –(2V

– 2.5V). Requires an external capacitor

CC

(≥1µF) for charge stroage. May be loaded (up to –15mA)

for external system use. Loading does reduce V– voltage
(see graphs). With multiple transceivers, the V+ and V

–

pins may be paralleled into common capacitors.

TR2 OUT; TR1 OUT (Pins 8, 15): Driver Outputs with
RS232 Voltage Levels. Outputs are in a high impedance
state when in the SHUTDOWN mode or when power is off
(VCC = 0V) to allow data line sharing. Outputs are fully
short-circuit protected from (V– + 30V) to (V+ – 30V) with
power on, off or in the SHUTDOWN mode. Typical output

breakdowns are greater than ±45V and higher applied

voltages will not damage the device if moderately current
limited. Shorting one output will affect output from the
other.

REC2 IN; REC1 IN (Pins 9, 14): Receiver Inputs. Accepts

RS232 voltage levels (±30V) and has 0.4V of hysteresis to

provide noise immunity. Input impedance is nominally

5kΩ.

REC2 OUT; REC1 OUT (Pins 10, 13): Receiver Outputs
with TTL/CMOS Voltage Levels. Outputs are in a high
impedance state when in the SHUTDOWN mode to allow
data line sharing. Outputs are fully short-circuit protected
to ground or VCC with power on, off or in the SHUTDOWN
mode.

TR2 IN; TR1 IN (Pins 11, 12): RS232 Driver Input Pins.
Inputs are TTL/CMOS compatible. Inputs should not be
allowed to float. Tie unused inputs to VCC.

GND (Pin 16): Ground Pin.

VCC (Pin 17): Input Supply Pin. Supply current drops to

zero in the SHUTDOWN mode.

ON/OFF (Pin 18): Contols the operation mode of the
LT1080 and is TTL/CMOS compatible. A logic low puts the
device in the SHUTDOWN mode which reduces input
supply current to zero and places both driver and receiver
outputs in a high impedance state. A logic high fully
enables the device.

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TYPICAL PERFOR A CE CHARACTERISTICS

Driver Output Voltage Supply Generator Outputs

10

VCC = 5.5V

8

6

VCC = 4.5V

4

2

RL = 3k

0

–2

–4

VCC = 4.5V

–6

DRIVER OUTPUT VOLTAGE (V)

–8

VCC = 5.5V

–10

–55 –25 0 25 50 75 100 125

OUTPUT HIGH

VCC = 5V

VCC = 5V

OUTPUT LOW

TEMPERATURE (°C)

1080/81 G01

10

8

LOADED TO V

6

4

2

VCC = 5V

0

–2

–4

OUTPUT VOLTAGE (V)

–6

LOADED TO V

–8

–10

02468101214161820

V+ OUTPUT VOLTAGE

–

LOADED TO GROUND

LOADED TO GROUND

+

V– OUTPUT VOLTAGE

OUTPUT CURRENT (mA)

4

1080/81 G02

Supply Generation from V
or Shutdown

10

8

6

4

2

0

–2

–4

SUPPLY VOLTAGE (V)

–6

–8

–10

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

V+ SUPPLY

V– SUPPLY

TIME (ms)

VCC = 5V
C1 TO C4 = 1µF

= 4.7k; V+ TO V

R

L

CC

–

1080/81 G03