LTC1383
5V Low Power
RS232 Transceiver
FEATURES
■
■
■
■
■
■
■
DESCRIPTIO
■
■
Operates from a Single 5V Supply
Low Supply Current: I
CC
= 220µA
ESD Protection Over
±10kV
Available in 16-Pin SOIC Narrow Package
Uses Small Capacitors: 0.1µF
Operates to 120kBaud
Output Overvoltage Does Not Force Current
Back into Supplies
RS232 I/O Lines Can Be Forced to
±25V
Without Damage
Pin Compatible with LT1181A and MAX232A
The LTC
®
1383 is an ultra-low power 2-driver/2-receiver
RS232 transceiver that operates from a single 5V
supply. The charge pump requires only four space-
saving 0.1µF capacitors. The supply current (I
CC
) of the
transceiver is only 220µA with driver outputs unloaded.
The LTC1383 is fully compliant with all data rate and
overvoltage RS232 specifications. The transceiver can
operate up to 120kbaud with a 2500pF, 3kΩ load. Both
driver outputs and receiver inputs can be forced to
±25V
without damage and can survive multiple
±10kV
ESD strikes.
APPLICATIO S
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■
Notebook Computers
Palmtop Computers
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
Quiescent Supply Current vs Temperature
1
0.1µF
3
4
0.1µF
5
11
V
CC
300k
LOGIC INPUT
LOGIC OUTPUT
10
12
5k
9
5k
8
15
7
13
232 OUTPUT
232 INPUT
LTC1383
V
CC
300k
14
16
2
6
0.1µF
0.1µF
600
V
CC
= 5V
TEST CONDITION: V
CC
= 5V
500
QUIESCENT CURRENT (µA)
400
300
200
100
0
–20
QUIESCENT
CURRENT
LOGIC INPUT
232 OUTPUT
0
LOGIC OUTPUT
232 INPUT
LTC1383 • TA01
U
20
40
TEMPERATURE (°C)
60
80
LTC1383 • TA02
U
U
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1
LTC1383
ABSOLUTE
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
C1
+
V
+
C1
–
C2
+
C2
–
V
–
TR2 OUT
RX2 IN
1
2
3
4
5
6
7
8
16 V
CC
15 GND
14 TR1 OUT
13 RX1 IN
12 RX1 OUT
11 TR1 IN
10 TR2 IN
9
RX2 OUT
Supply Voltage (V
CC
) ................................................ 6V
Input Voltage
Driver ....................................... – 0.3V to V
CC
+ 0.3V
Receiver ............................................... – 25V to 25V
Digital Input ............................... – 0.3V to V
CC
+ 0.3V
Output Voltage
Driver .................................................... – 25V to 25V
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
LTC1383C ............................................... 0°C to 70°C
LTC1383I ............................................ – 40°C to 85°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
ORDER PART
NUMBER
LTC1383CN
LTC1383CS
LTC1383IN
LTC1383IS
N PACKAGE
16-LEAD PDIP
S PACKAGE
16-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 70°C/W (N)
T
JMAX
= 125°C,
θ
JA
= 90°C/W (S)
Consult LTC Marketing for parts specified with wider operating
temperature ranges.
DC ELECTRICAL CHARACTERISTICS
PARAMETER
Any Driver
Output Voltage Swing
Logic Input Voltage Level
Logic Input Current
Output Short-Circuit Current
Any Receiver
Input Voltage Thresholds
Hysteresis
Input Resistance
Output Voltage
Output Short-Circuit Current
Power Supply Generator
V
+
Output Voltage
V
–
Output Voltage
CONDITIONS
3k to GND
The
●
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1µF, unless noted.
MIN
Positive
Negative
●
●
●
●
●
●
TYP
7.0
– 6.5
1.4
1.4
– 20
±12
1.3
1.7
0.4
5
0.2
3.2
– 40
20
8.0
7.5
– 8.0
– 7.0
MAX
UNITS
V
V
V
V
µA
µA
mA
V
V
V
kΩ
V
V
mA
mA
V
V
V
V
5.0
– 5.0
2.0
Input Low Level (V
OUT
= High)
Input High Level (V
OUT
= Low)
V
IN
= V
CC
V
IN
= 0V
V
OUT
= 0V
Input Low Threshold
Input High Threshold
– 10V
≤
V
IN
≤
10V
Output Low, I
OUT
= – 1.6mA (V
CC
= 5V)
Output High, I
OUT
= 160µA (V
CC
= 5V)
Sinking Current, V
OUT
= V
CC
Sourcing Current V
OUT
= 0V
I
OUT
= 0mA
I
OUT
= 8mA
I
OUT
= 0mA
I
OUT
= – 8mA
0.8
5
– 40
±9
●
●
●
●
●
0.8
0.1
3
3.0
– 15
10
2.4
1
7
0.4
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2
U
W
U
U
W W
W
LTC1383
DC ELECTRICAL CHARACTERISTICS
PARAMETER
Power Supply
V
CC
Supply Current
Digital Input Threshold Low
Digital Input Threshold High
CONDITIONS
The
●
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1µF, unless noted.
MIN
●
●
●
●
TYP
0.22
0.35
1.4
1.4
MAX
0.5
1.0
0.8
UNITS
mA
mA
V
V
No Load (Note 2), 0°C to 70°C
No Load (Note 2), – 40°C to 85°C
2.0
AC CHARACTERISTICS
PARAMETER
Slew Rate
Driver Propagation Delay
(TTL to RS232)
Receiver Propagation Delay
(RS232 to TTL)
The
●
denotes specifications which apply over the full operating temperature range,
otherwise specifications are at T
A
= 25°C. V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1µF, unless noted.
CONDITIONS
R
L
= 3k, C
L
= 51pF
R
L
= 3k, C
L
= 2500pF
t
HLD
(Figure 1)
t
LHD
(Figure 1)
t
HLR
(Figure 2)
t
LHR
(Figure 2)
MIN
3
●
●
●
●
TYP
8
5
2
2
0.3
0.3
MAX
30
3.5
3.5
0.8
0.8
UNITS
V/µs
V/µs
µs
µs
µs
µs
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2:
Supply current is measured with driver and receiver outputs
unloaded.
TYPICAL PERFOR A CE CHARACTERISTICS
Driver Output Voltage
vs Temperature
10
8
R
L
= 3k
OUTPUT HIGH
V
CC
= 5V
DRIVER OUTPUT VOLTAGE (V)
THRESHOLD VOLTAGE (V)
4
2
0
–2
–4
–6
–8
0
10
20
30
40
50
TEMPERATURE (°C)
60
70
OUTPUT LOW
V
CC
= 4.5V
V
CC
= 5V
SUPPLY CURRENT (mA)
6
V
CC
= 4.5V
LTC1383 • TPC01
U W
Receiver Input Thresholds
vs Temperature
2.2
2.0
V
TH
1.8
1.6
1.4
1.2
5
35
30
25
20
15
10
45
40
Supply Current vs Data Rate
V
CC
= 5V
R
L
= 3k
C
L
= 2500pF
2 DRIVERS ACTIVE
V
TL
1.0
0
10
40
30
50
20
TEMPERATURE (˚C)
60
70
0
0
25
50
75
100 125
DATA RATE (kBAUD)
150
175
LTC1383 • TPC02
LTC1383 • TPC03
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LTC1383
TYPICAL PERFOR A CE CHARACTERISTICS
V
CC
Supply Current
vs Temperature
18
16
SUPPLY CURRENT (mA)
14
12
10
8
6
4
1 DRIVER LOADED
R
L
= 3k
2 DRIVERS LOADED
R
L
= 3k
2
0
0
10
20
30
40
50
TEMPERATURE (°C)
60
70
LTC1383 • TPC04
PI FU CTIO S
V
CC
:
5V Input Supply Pin. This pin should be decoupled
with a 0.1µF ceramic capacitor.
GND:
Ground Pin.
V
+
:
Positive Supply Output (RS232 Drivers). V
+
≅
2V
CC
–
2V. This pin requires an external capacitor C = 0.1µF for
charge storage. The capacitor may be tied to ground or
V
CC
. With multiple devices, the V
+
and V
–
pins may share
a common capacitor. For large numbers of devices, in-
creasing the size of the shared common storage capaci-
tors is recommended to reduce ripple.
V
–
:
Negative Supply Output (RS232 Drivers). V
–
≅
– (2V
CC
– 2V). This pin requires an external capacitor C = 0.1µF for
charge storage.
C1
+
, C1
–
, C2
+
, C2
–
:
Commutating Capacitor Inputs. These
pins require two external capacitors C = 0.1µF: one from
C1
+
to C1
–
and another from C2
+
to C2
–
. To maintain
4
U W
Driver Output Waveforms
DRIVER
OUTPUT
R
L
= 3k
C
L
= 2500pF
DRIVER
OUTPUT
R
L
= 3k
INPUT
Receiver Output Waveforms
RECEIVER
OUTPUT
C
L
= 51pF
INPUT
LTC1383 • TPC05
LTC1383 • TPC06
5µs/DIV
5µs/DIV
U
U
U
charge pump efficiency, the capacitor’s effective series
resistance should be less than 2Ω.
TR IN:
RS232 Driver Input Pins. Inputs are TTL/CMOS
compatible. The inputs of unused drivers can be left
unconnected since 300k input pull-up resistors to V
CC
are
included on chip.
TR OUT:
Driver Outputs at RS232 Voltage Levels. The
driver outputs are protected against ESD to
±10kV
for
human body model discharges.
RX IN:
Receiver Inputs. These pins can be forced to
±25V
without damage. The receiver inputs are protected against
ESD to
±10kV
for human body model discharges. Each
receiver provides 0.4V of hysteresis for noise immunity.
RX OUT:
Receiver Outputs with TTL/CMOS Voltage
Levels.
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LTC1383
SWITCHI G TI E WAVEFOR S
DRIVER
INPUT
DRIVER
OUTPUT
t
LHD
V
CC
1.4V
1.4V
0V
V
+
0V
t
HLD
LTC1383 • F01
Figure 1. Driver Propagation Delay Timing
TEST CIRCUITS
Driver Timing Test Load
DRIVER
OUTPUT
DRIVER
51pF
3k
DRIVER
INPUT
LTC1383 • TA03
0.1µF
0.1µF
LOGIC INPUT
LOGIC INPUT
LOGIC OUTPUT
LOGIC OUTPUT
W
W
U
RX
INPUT
RX
OUTPUT
t
LHR
1.7V
V
CC
1.3V
0V
2.4V
0.8V
t
HLR
V
CC
0V
LTC1383 • F02
0V
V
–
Figure 2. Receiver Propagation Delay Timing
Receiver Timing Test Load
RX
OUTPUT
RX INPUT
RX
51pF
LTC1383 • TA04
ESD Test Circuit
1
3
4
5
11
V
CC
300k
10
12
5k
9
5k
8
15
7
13
232 OUTPUT
232 INPUT
RS232
LINE PINS
PROTECTED
TO
±10kV
LTC1383
V
CC
300k
14
16
2
6
0.1µF
0.1µF
V
CC
232 OUTPUT
232 INPUT
LTC1383 • TA05
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PCB Design
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