LT1180A/LT1181A
Low Power 5V RS232
Dual Driver/Receiver with
0.1µF Capacitors
FEATURES
s
s
s
s
s
s
s
s
s
DESCRIPTIO
s
s
s
s
ESD Protection over
±10kV
Uses Small Capacitors: 0.1µF
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
Available in SO Package
APPLICATI
s
s
s
s
s
S
Portable Computers
Battery-Powered Systems
Power Supply Generator
Terminals
Modems
The LT
®
1180A/LT1181A are dual RS232 driver/receiver
pairs with integral charge pump to generate RS232 volt-
age levels from a single 5V supply. These circuits feature
rugged bipolar design to provide operating fault tolerance
and ESD protection unmatched by competing CMOS
designs. Using only 0.1µF external capacitors, these cir-
cuits consume only 40mW of power, and can operate to
120k baud even while driving heavy capacitive loads. New
ESD structures on the chip allow the LT1180A/LT1181A to
survive multiple
±10kV
strikes, eliminating the need for
costly TransZorbs
®
on the RS232 line pins. The LT1180A/
LT1181A 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 LT1181A is available in 16-pin DIP and SO packages.
The LT1180A is supplied in 18-pin DIP and SO packages
for applications which require shutdown.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TransZorb is a registered trademark of General Instruments, GSI
TYPICAL APPLICATI
+
0.1µF
2
4
LT1180A
3
17
5V INPUT
+
0.1µF
7
0.1µF
15
8
14
5k
10
18
5k
9
16
V
+
OUT
DRIVER
OUTPUT
R
L
= 3k
C
L
= 2500pF
+
0.1µF
5
6
12
V
–
OUT
RS232 OUTPUT
RS232 OUTPUT
RS232 INPUT
LOGIC
INPUTS
11
13
RECEIVER
OUTPUT
R
C
L
= 50pF
INPUT
LOGIC
OUTPUTS
RS232 INPUT
ON/OFF
LT1180A • TA01
U
Output Waveforms
LT1180A • TA02
UO
+
UO
1
LT1180A/LT1181A
ABSOLUTE
AXI U
RATI GS
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
PACKAGE/ORDER I FOR ATIO
TOP VIEW
NC
C1
+
V
+
C1
–
C2
+
C2
–
V
–
TR2 OUT
REC2 IN
1
2
3
4
5
6
7
8
9
18 ON/OFF
17 V
CC
16 GND
15 TR1 OUT
14 REC1 IN
13 REC1 OUT
12 TR1 IN
11 TR2 IN
10 REC2 OUT
ORDER PART
NUMBER
LT1180ACN
LT1180ACSW
LT1180AIN
LT1180AISW
LT1180AMJ
N PACKAGE
J PACKAGE
SW PACKAGE
18-LEAD CERDIP 18-LEAD PDIP 18-LEAD PLASTIC SO (WIDE)
T
JMAX
= 150°C,
θ
JA
=100°C/ W,
θ
JC
= 40°C/W (J)
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)
ELECTRICAL CHARACTERISTICS
PARAMETER
Power Supply Generator
V
+
Output
V
–
Output
Supply Current (V
CC
)
Supply Current When OFF (V
CC
)
Supply Rise Time
Shutdown to Turn-On
ON/OFF Pin Thresholds
ON/OFF Pin Current
Oscillator Frequency
(Note 3), T
A
= 25°C
CONDITIONS
(Note 2)
MIN
TYP
7.9
– 7.0
9
q
q
Shutdown (Note 4) LT1180A Only
C1 = C2 = C3 = C4 = 0.1µF
LT1180A Only
Input Low Level (Device Shutdown)
Input High Level (Device Enabled)
0V
≤
V
ON/OFF
≤
5V
2
U
U
W
W W
U
W
(Note 1)
Short-Circuit Duration
V
+
................................................................... 30 sec
V
–
................................................................... 30 sec
Driver Output .............................................. Indefinite
Receiver Output .......................................... Indefinite
Operating Temperature Range
LT1180AI/LT1181AI .......................... – 40°C to 85°C
LT1180AC/LT1181AC ............................. 0°C to 70°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
TOP VIEW
C1
+
V
+
C1
–
C2
+
C2
–
V
–
TR2 OUT
REC2 IN
1
2
3
4
5
6
7
8
16 V
CC
15 GND
14 TR1 OUT
13 REC1 IN
12 REC1 OUT
11 TR1 IN
10 TR2 IN
9
REC2 OUT
ORDER PART
NUMBER
LT1181ACN
LT1181ACSW
LT1181AIN
LT1181AISW
LT1181AMJ
SW PACKAGE
J PACKAGE
N PACKAGE
16-LEAD CERDIP 16-LEAD PDIP 16-LEAD PLASTIC SO (WIDE)
T
JMAX
= 150°C,
θ
JA
= 100°C/ W,
θ
JC
= 40°C/W (J)
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
= 27°C/W (SW)
MAX
UNITS
V
V
13
16
10
mA
mA
µA
ms
ms
1
0.2
0.2
q
q
q
0.8
– 15
1.2
1.6
130
2.4
80
V
V
µA
kHz
LT1180A/LT1181A
ELECTRICAL CHARACTERISTICS
PARAMETER
Driver
Output Voltage Swing
Logic Input Voltage Level
Logic Input Current
Output Short-Circuit Current
Output Leakage Current
Date Rate (Note 7)
Slew Rate
Propagation Delay
Receiver
Input Voltage Thresholds
Load = 3k to GND
CONDITIONS
(Note 2)
MIN
Positive
Negative
5.0
q
q
q
q
TYP
7.5
– 6.3
1.4
1.4
5
17
10
MAX
UNITS
V
V
V
V
µA
mA
µA
kBaud
kBaud
– 5.0
0.8
20
100
Input Low Level (V
OUT
= High)
Input High Level (V
OUT
= Low)
0.8V
≤
V
IN
≤
2.0V
V
OUT
= 0V
Shutdown V
OUT
=
±30V
(Note 4)
R
L
= 3k, C
L
= 2500pF
R
L
= 3k, C
L
= 1000pF
R
L
= 3k, C
L
= 51pF
R
L
= 3k, C
L
= 2500pF
Output Transition t
HL
High-to-Low (Note 5)
Output Transition t
LH
Low-to-High
Input Low Threshold (V
OUT
= High)
Input High Threshold (V
OUT
= Low)
Input Low
Input High
C Grade
C Grade
I, M Grade
I, M Grade
2.0
±9
q
120
250
4
15
7
0.6
0.5
q
q
q
q
q
30
1.3
1.3
V/µs
V/µs
µs
µs
V
V
V
V
V
kΩ
µA
V
V
mA
mA
ns
ns
0.8
0.2
0.1
3
1.3
1.7
1.3
1.7
0.4
5
1
0.2
4.2
–20
20
250
350
2.4
3.0
1.0
7
10
0.4
– 10
600
600
Hysteresis
Input Resistance
Output Leakage Current
Output Voltage
Output Short-Circuit Current
Propagation Delay
V
IN
=
±10V
Shutdown (Note 4) 0
≤
V
OUT
≤
V
CC
Output Low, I
OUT
= – 1.6mA
Output High, I
OUT
= 160µA (V
CC
= 5V)
Sinking Current, V
OUT
= V
CC
Sourcing Current, V
OUT
= 0V
Output Transition t
HL
High-to-Low (Note 6)
Output Transition t
LH
Low-to-High
q
q
q
3.5
10
The
q
denotes specifications which apply over the operating temperature
range (0°C
≤
T
A
≤
70°C for commercial grade, and – 40°C
≤
T
A
≤
85°C for
industrial grade.
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.
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).
Note 7:
Data rate operation guaranteed by slew rate, short-circuit current
and propagation delay tests.
3
LT1180A/LT1181A
TYPICAL PERFOR A CE CHARACTERISTICS
Driver Maximum Output Voltage
vs Load Capacitance
8.0
7.5
PEAK OUTPUT VOLTAGE (V)
DRIVER OUTPUT VOLTAGE (V)
PEAK OUTPUT VOLTAGE (V)
7.0
20kBAUD
6.5
60kBAUD
6.0
5.5
5.0
0
1
2
3 4 5 6 7 8
LOAD CAPACITANCE (nF)
9
10
120kBAUD
Receiver Input Thresholds
3.00
2.75
THRESHOLD VOLTAGE (V)
2.25
2.00
1.75
1.50
1.25
1.00
0.75
0.50
–55 –25
50
25
0
75
TEMPERATURE (°C)
100
125
INPUT LOW
INPUT HIGH
THRESHOLD VOLTAGE (V)
2.50
SUPPLY CURRENT (mA)
Supply Current
25
100
SHORT-CIRCUIT CURRENT (mA)
20
SUPPLY CURRENT (mA)
LEAKAGE CURRENT (
µA)
2 DRIVERS LOADED R
L
= 3k
15
1 DRIVER LOADED R
L
= 3k
10
NO LOAD
5
0
–55 –25
50
25
0
75
TEMPERATURE (°C)
4
U W
LT1180A • TPC01
Driver Minimum Output Voltage
vs Load Capacitance
–4.0
–4.5
120kBAUD
–5.0
60kBAUD
–5.5
–6.0
–6.5
–7.0
0
1
2
3 4 5 6 7 8
LOAD CAPACITANCE (nF)
9
10
20kBAUD
10
8
6
4
2
0
–2
–4
–6
–8
Driver Output Voltage
R
L
= 3k
V
CC
= 5.5V
V
CC
= 5V
V
CC
= 4.5V
OUTPUT HIGH
OUTPUT LOW
V
CC
= 4.5V
V
CC
= 5V
V
CC
= 5.5V
–10
–55 –25
50
25
0
75
TEMPERATURE (°C)
100
125
LT1180A • TPC02
LT1180A • TPC03
Supply Current vs Data Rate
50
2 DRIVERS ACTIVE
R
L
= 3k
C
L
= 2500pF
ON/OFF Thresholds
3.0
2.5
2.0
1.5
1.0
OFF THRESHOLD
0.5
0
–55 –25
40
30
ON THRESHOLD
20
10
0
0
25
50
75
100
DATA RATE (kBAUD)
125
150
50
25
75
0
TEMPERATURE (°C)
100
125
LT1180A • TPC04
LT1180A • TPC05
LT1180A • TPC06
Driver Leakage in Shutdown
30
25
Driver Short-Circuit Current
I
SC+
20
15
I
SC–
10
5
0
–55 –25
10
1
V
OUT
= 30V
V
OUT
= –30V
100
125
0.1
–55 –25
50
25
0
75
TEMPERATURE (°C)
100
125
50
25
75
0
TEMPERATURE (°C)
100
125
LT1180A • TPC07
LT1180A • TPC08
LT1180A • TPC09
LT1180A/LT1181A
TYPICAL PERFOR A CE CHARACTERISTICS
Receiver Short-Circuit Current
50
SHORT-CIRCUIT CURRENT (mA)
40
SLEW RATE (V/µs)
30
RX I
SC
20
10
0
–55 –25
50
25
75
0
TEMPERATURE (°C)
Shutdown to Driver Outputs
10V
DRIVER 1
OUTPUT
5V
GND
GND
DRIVER 2
OUTPUT
– 5V
– 10V
DRIVER OUTPUT
R
L
= 3k
DRIVER OUTPUT
R
L
= 3k
C
L
= 2500pF
ON/OFF PIN
INPUT
LT1180A • TPC12
LT1180A • TPC13
PI FU CTIO S
V
CC
:
5V Input Supply Pin. This pin should be decoupled
with a 0.1µF ceramic capacitor close to the package pin.
Insufficient supply bypassing can result in low output
drive levels and erratic charge pump operation.
GND:
Ground Pin.
ON/OFF:
A TTL/CMOS Compatible Operating Mode Con-
trol. A logic low puts the LT1180A in shutdown mode.
Supply current drops to zero and both driver and receiver
outputs assume a high impedance state. A logic high fully
enables the device.
V
+
:
Positive Supply Output (RS232 Drivers). V
+
≈
2V
CC
–
1.5V. This pin requires an external charge storage capaci-
tor C
≥
0.1µF, tied to ground or V
CC
. Larger value capaci-
tors may be used to reduce supply ripple. With multiple
transceivers, the V
+
and V
–
pins may be paralleled into
common capacitors.
V
–
:
Negative Supply Output (RS232 Drivers). V
–
≈
–(2V
CC
– 2.5V). This pin requires an external charge storage
capacitor C
≥
0.1µF. Larger value capacitors may be used
to reduce supply ripple. With multiple transceivers, the V
+
and V
–
pins may be paralleled into common capacitors.
U W
RX I
SC–
+
Slew Rate vs Load Capacitance
16
14
12
10
8
+SLEW
6
–SLEW
4
2
100
125
0
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
LOAD CAPACITANCE (nF)
LT1180A • TPC11
LT1180A • TPC10
Driver Output Waveforms
U
U
U
5
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