LT1081CSW datasheet(4/12 Pages) LINER

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LT1080/LT1081

PI FU CTIO S (Pin numbers refer to LT1080)

TEMPERATURE (

°C)

–55

–25

100

125

1080/81 G01

–2

–4

–6

–8

–10

VCC = 5.5V

VCC = 4.5V

RL = 3k

OUTPUT HIGH

VCC = 5.5V

VCC = 4.5V

OUTPUT LOW

VCC = 5V

TIME (ms)

0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

1080/81 G03

–2

–4

–6

–8

–10

V+ SUPPLY

VCC = 5V

C1 TO C4 = 1

µF

RL = 4.7k; V

+ TO V–

V– SUPPLY

OUTPUT CURRENT (mA)

02468

10 12 14 16 18 20

1080/81 G02

–2

–4

–6

–8

–10

VCC = 5V

V+ OUTPUT VOLTAGE

LOADED TO V–

LOADED TO GROUND

LOADED TO V+

V– OUTPUT VOLTAGE

Driver Output Voltage

Supply Generator Outputs

Supply Generation from VCC

or Shutdown

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–

≈ –(2VCC – 2.5V). Requires an external capacitor

(

≥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

Ω.

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.

TYPICAL PERFOR A CE CHARACTERISTICS

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