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LT1781CN#PBF

P1-P3P4-P6P7-P9P10-P12
1
LT1780/LT1781
Low Power 5V RS232
Dual Driver/Receiver with
±15kV ESD Protection
TransZorb is a registered trademark of General Instruments, GSI.
R
Output Waveforms
1780/81 • TA02
DRIVER
OUTPUT
R
L
= 3k
C
L
= 2500pF
RECEIVER
OUTPUT
C
L
= 50pF
INPUT
0.1µF
0.1µF
0.1µF
0.1µF
LOGIC
INPUTS
LOGIC
OUTPUTS
ON/OFF
18
10
13
11
12
6
5
4
2
16
9
14
8
15
7
3
17
5V INPUT
V
+
OUT
V
–
OUT
RS232 OUTPUT
RS232 OUTPUT
RS232 INPUT
RS232 INPUT
1780/81 • TA01
5k
5k
LT1780
U
A
O
PP
L
IC
AT
ITY
P
I
CA
L
S
F
EA
T
U
RE
D
U
ESCRIPTIO
The LT
®
1780/LT1781 are dual RS232 driver/receiver pairs
with integral charge pump to generate RS232 voltage
levels from a single 5V supply. Using only 0.1µF external
capacitors, these circuits consume only 40mW of power,
and can operate to 120kbaud even while driving heavy
capacitive loads. New ESD structures on the chip allow the
LT1780/LT1781 to survive ±15kV air gap and ±8kV con-
tact ESD tests per IEC 1000-4-2, eliminating the need for
costly TransZorbs
®
on the RS232 line pins. The LT1780/
LT1781 are fully compliant with EIA RS232 standards.
Driver outputs are protected from overload, and can be
shorted to ground or up to ±30V without damage. During
SHUTDOWN or power-off conditions, driver and receiver
outputs are in a high impedance state, allowing line
sharing.
The LT1780/LT1781 are direct upgrades to the LT1180A/
LT1181A, LT1280A/LT1281A and LT1381 for applications
which require the utmost ESD protection.
The LT1781 is available in 16-pin DIP,SO and SW pack-
ages. The LT1780 is supplied in 18-pin DIP and SW
packages for applications which require SHUTDOWN.
■
10mA Max Supply Current
■
ESD Protection to IEC 1000-4-2 Level 4
±
15kV Air Gap,
±
8kV Contact
■
Uses Small Capacitors: 0.1
µ
F
■
120kBaud Operation for R
L
= 3k, C
L
= 2500pF
■
250kBaud Operation for R
L
= 3k, C
L
= 1000pF
■
Outputs Withstand ±30V Without Damage
■
CMOS Comparable Low Power: 40mW
■
Operates from a Single 5V Supply
■
Rugged Bipolar Design
■
Outputs Assume a High Impedance State When Off
or Powered Down
■
Meets All RS232 Specifications
■
Available With or Without Shutdown
■
Absolutely No Latch-up
■
Portable Computers
■
Battery-Powered Systems
■
Power Supply Generator
■
Terminals
■
Modems
U
S
A
O
PP
L
IC
AT
I
, LTC and LT are registered trademarks of Linear Technology Corporation.
2
LT1780/LT1781
A
U
G
W
A
W
U
W
ARB
S
O
LU
T
EXI T
I
S
Supply Voltage (V
CC
) ................................................ 6V
V
+
........................................................................ 13.2V
V
–
...................................................................... –13.2V
Input Voltage
Driver ........................................................... V
–
to V
+
Receiver ............................................... – 30V to 30V
ON/OFF ................................................. –0.3V to 12V
Output Voltage
Driver ...................................... V
+
– 30V to V
–
+ 30V
Receiver .................................... – 0.3V to V
CC
+ 0.3V
Short-Circuit Duration
V
+
................................................................... 30 sec
V
–
................................................................... 30 sec
Driver Output.............................................. Indefinite
Receiver Output.......................................... Indefinite
Operating Temperature Range ..................... 0°C to 70°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
WU
U
PACKAGE
/
O
RDER I FOR ATIO
ORDER
PART
NUMBER
ORDER
PART
NUMBER
LT1780CN
LT1780CSW
LT1781CN
LT1781CS
LT1781CSW
(Note 2)
E
LECTR
IC
AL C CHARA TERIST
ICS
PARAMETER CONDITIONS MIN TYP MAX UNITS
Power Supply Generator
V
+
Output 7.9 V
V
–
Output –7 V
Supply Current (V
CC
) (Note 3), T
A
= 25°C 8 10 mA
● 14 mA
Supply Current When OFF (V
CC
) SHUTDOWN (Note 4) LT1780 Only ● 110 µA
Supply Rise Time C1 = C2 = C3 = C4 = 0.1µF 0.2 ms
SHUTDOWN to Turn-On LT1780 Only 0.2 ms
ON/OFF Pin Thresholds Input Low Level (Device SHUTDOWN)
● 0.8 1.2 V
Input High Level (Device Enabled) ● 1.6 2.4 V
ON/OFF Pin Current 0V ≤ V
ON/OFF
≤ 5V ● –15 80 µA
Oscillator Frequency 130 kHz
Driver
Output Voltage Swing Load = 3k to GND Positive ● 5.0 7.5 V
Negative
● –6.3 – 5 V
Logic Input Voltage Level Input Low Level (V
OUT
= High) ● 1.4 0.8 V
Input High Level (V
OUT
= Low) ● 2.0 1.4 V
1
2
3
4
5
6
7
8
9
TOP VIEW
18
17
16
15
14
13
12
11
10
NC
C1
+
V
+
C1
–
C2
+
C2
–
V
–
TR2 OUT
REC2 IN
N PACKAGE
18-LEAD PLASTIC DIP
ON/OFF
V
CC
GND
TR1 OUT
REC1 IN
REC1 OUT
TR1 IN
TR2 IN
REC2 OUT
SW PACKAGE
18-LEAD PLASTIC SO
T
JMAX
= 125°C, θ
JA
= 80°C/W, θ
JC
= 36°C/W (N)
T
JMAX
= 125°C, θ
JA
= 90°C/W, θ
JC
= 26°C/W (SW)
1
2
3
4
5
6
7
8
TOP VIEW
16
15
14
13
12
11
10
9
C1
+
V
+
C1
–
C2
+
C2
–
V
–
TR2 OUT
REC2 IN
V
CC
GND
TR1 OUT
REC1 IN
REC1 OUT
TR1 IN
TR2 IN
REC2 OUT
N PACKAGE
16-LEAD PLASTIC DIP
S PACKAGE
16-LEAD PLASTIC SO
SW PACKAGE
16-LEAD PLASTIC SO
T
JMAX
= 125°C, θ
JA
= 90°C/W, θ
JC
= 46°C/W (N)
T
JMAX
= 125°C, θ
JA
= 95°C/W, θ
JC
= 34°C/W (S)
T
JMAX
= 125°C, θ
JA
= 95°C/W, θ
JC
= 27°C/W (SW)
Consult factory for Industrial and Military grade parts.
(Note 1)
3
LT1780/LT1781
E
LECTR
IC
AL C CHARA TERIST
ICS
(Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Logic Input Current 0.8V ≤ V
IN
≤ 2.0V ● 520 µA
Output Short-Circuit Current V
OUT
= 0V ±717 mA
Output Leakage Current SHUTDOWN V
OUT
= ±30V (Note 4) ● 10 100 µA
Data Rate R
L
= 3k, C
L
= 2500pF 120 kBaud
R
L
= 3k, C
L
= 1000pF 250 kBaud
Slew Rate R
L
= 3k, C
L
= 51pF 15 30 V/µs
R
L
= 3k, C
L
= 2500pF 4 7 V/µs
Propagation Delay Output Transition t
HL
High-to-Low (Note 5) 0.6 1.3 µs
Output Transition t
LH
Low-to-High 0.5 1.3 µs
Receiver
Input Voltage Thresholds Input Low Threshold (V
OUT
= High) 0.8 1.3 V
Input High Threshold (V
OUT
= Low) 1.7 2.4 V
Hysteresis ● 0.1 0.4 1 V
Input Resistance V
IN
= ±10V 357 kΩ
Output Leakage Current SHUTDOWN (Note 4) 0 ≤ V
OUT
≤ V
CC
● 110 µA
Output Voltage Output Low, I
OUT
= –1.6mA ● 0.2 0.4 V
Output High, I
OUT
= 160µA (V
CC
= 5V) ● 3.5 4.2 V
Output Short-Circuit Current Sinking Current, V
OUT
= V
CC
–10 mA
Sourcing Current, V
OUT
= 0V 10 20 mA
Propagation Delay Output Transition t
HL
High-to-Low (Note 6) 250 600 ns
Output Transition t
LH
Low-to-High 350 600 ns
Note 4: Supply current measurements in SHUTDOWN are performed with
V
ON/OFF
≤ 0.1V.
Note 5: For driver delay measurements, R
L
= 3k and C
L
= 51pF. Trigger
points are set between the driver’s input logic threshold and the output
transition to the zero crossing (t
HL
= 1.4V to 0V and t
LH
= 1.4V to 0V).
Note 6: For receiver delay measurements, C
L
= 51pF. Trigger points are
set between the receiver’s input logic threshold and the output transition
to standard TTL/CMOS logic threshold (t
HL
= 1.3V to 2.4V and t
LH
= 1.7V
to 0.8V).
The ● denotes specifications which apply over the operating temperature
range.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2: Testing done at V
CC
= 5V and V
ON/OFF
= 3V, unless otherwise
specified.
Note 3: Supply current is measured as the average over several charge
pump cycles. C
+
= C
–
= C1 = C2 = 0.1µF. All outputs are open, with all
driver inputs tied high.
–20
P1-P3P4-P6P7-P9P10-P12

LT1781CN#PBF

Mfr. #:
Buy LT1781CN#PBF
Manufacturer:
Analog Devices Inc.
Description:
RS-232 Interface IC L Pwr 5V RS232 2x Drvr/Rcv w/ 15kV E
Lifecycle:
New from this manufacturer.
Delivery:
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