LT1080, LT1081
ADVANCED LOW-POWER
5-V DUAL EIA-232 DRIVER/RECEIVERS
SLLS050A – D3121, SEPTEMBER 1989 – REVISED FEBRUARY 1991
logic symbols
†
LT1080
VCC
17
C1 +
C1 –
C2 +
C2 –
ON/OFF
T1IN
T2IN
R1OUT
R2OUT
2
4
5
6
18
12
11
13
10
0V
16
GND
† These symbols are in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.
CX1 +
CX1 –
CX2 +
CX2 –
EN
15
8
14
9
T1OUT
T2OUT
R1IN
R2IN
VCC
1.8 VCC
– 1.7 VCC
3
7
VS +
VS –
C1 +
C1 –
C2 +
C2 –
T1IN
T2IN
R1OUT
R2OUT
1
3
4
5
11
10
12
9
0V
15
GND
CX1 +
CX1–
CX2 +
CX2 –
LT1081
VCC
16
VCC
1.8 VCC
– 1.7 VCC
2
6
14
7
13
8
VS +
VS –
T1OUT
T2OUT
R1IN
R2IN
Terminal Functions
PIN
NAME
C1 +
C1 –
C2 +
C2 –
GND
ON/OFF
NO.†
2 [1]
4 [3]
5 [4]
6 [5]
16 [15]
18
I
I/O
External capacitor C1
External capacitor C2
Ground pin
Controls the operation mode and is TTL/CMOS compatible. A low logic level places the device in the shutdown
mode, which reduces input supply current to near zero and places both driver and receiver outputs in a
high-impedance state. This input is not available on the LT1081.
Receiver input. Accepts EIA-232 voltage levels (± 30 V) and has hysteresis to provide noise immunity.
Same as R1IN
Receiver output with TTL/CMOS voltage levels. Output is in a high-impedance state when in the shutdown
mode or when VCC = 0 to allow bus operation. Fully short-circuit protected to GND or VCC with power on, power
off, or in the shutdown mode.
Same as R1OUT
EIA-232 driver input pin. Input is TTL/CMOS compatible. Unused inputs should be tied to VCC.
Same as T1IN
Driver output with EIA-232 voltage levels. Outputs are in a high-impedance state when in the shutdown mode
or when VCC = 0 to allow bus operation. Fully short-circuit protected to GND or VCC with power on, power off,
or in the shutdown mode.
Same as T1OUT
Positive supply for EIA-232 drivers. Requires an external capacitor (1-µF) for charge storage.
Negative supply for EIA-232 drivers. Requires an external capacitor (1-µF) for charge storage.
Input supply pin. Supply current drops to near zero in the shutdown mode. Driver and receiver outputs are
in a high-impedance state when VCC = 0.
DESCRIPTION
R1IN
R2IN
R1OUT
14 [13]
9 [8]
13 [12]
I
I
O
R2OUT
T1IN
T2IN
T1OUT
10 [9]
12 [11]
11 [10]
15 [14]
O
I
I
O
T2OUT
VS+
VS–
VCC
8 [7]
3 [2]
7 [6]
17 [16]
O
† Pin numbers in brackets are for the LT1081.
2–2
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DALLAS, TEXAS 75265
TI [ TEXAS INSTRUMENTS ]
