1349fa.pm7
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LTC1349
1349fa
5V Low Power RS232
3-Driver/5-Receiver Transceiver
with 2 Receivers Active
in Shutdown
Quiescent and Shutdown Supply Current
vs Temperature
Low Supply Current: 300A
Two Receivers Kept Alive in Shutdown
ESD Protection Over 10kV
Operates from a Single 5V Supply
Uses Small Capacitors: 0.1F
Operates to 120k Baud
Three-State Outputs Are High Impedance When Off
Output Overvoltage Does Not Force Current
Back into Supplies
RS232 I/O Lines Can Be Forced to 25V
Without Damage
Pin Compatible with LT1137A and LT1237
Flowthrough Architecture
The LTC
1349 is a 3-driver/ 5-receiver RS232 transceiver
with very low supply current. In the no load condition, the
supply current is only 300A. The charge pump only
requires four 0.1F capacitors.
In Shutdown mode, two receivers are kept alive and the
supply current is 35A. All RS232 outputs assume a high
impedance state in Shutdown and with the power off.
The LTC1349 is fully compliant with all data rate and
overvoltage RS232 specifications. The transceiver can
operate up to 120k baud with a 2500pF, 3k load. Both
driver outputs and receiver inputs can be forced to 25V
without damage, and can survive multiple 10kV ESD
strikes.
Notebook Computers
Palmtop Computers
TEMPERATURE (C)
QUIESCENT CURRENT (
A)
1200
1000
800
600
400
200
0
20
40
60
LTC1349 TA02
80
0
40
60
50
40
30
20
10
0
SHUTDOWN CURRENT (
A)
QUIESCENT
CURRENT
SHUTDOWN
CURRENT
TEST CONDITION:
V
CC
= 5V, ALL DRIVER INPUTS TIED TO V
CC
.
20
100
3-Drivers/5-Receivers with Shutdown
LTC1349 TA01
V
CC
C1
0.1F
LTC1349
1
2
3
4
5
6
7
8
9
10
11
12
13
14
DRIVER 1 OUT
RX1 IN
DRIVER 2 OUT
RX2 IN
RX3 IN
RX4 IN
DRIVER 3 OUT
RX5 IN
ON/OFF
NC
28
27
26
25
24
23
22
21
20
19
18
17
16
15
C3
0.1F
DRIVER 1 IN
RX1 OUT
DRIVER 2 IN
RX2 OUT
RX3 OUT
RX4 OUT
DRIVER 3 IN
RX5 OUT
GND
NC
NC
V
V
+
C2
0.1F
C4
0.1F
FEATURES
DESCRIPTIO
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APPLICATIO S
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TYPICAL APPLICATIO
U
, LTC and LT are registered trademarks of Linear Technology Corporation.
2
LTC1349
1349fa
LTC1349CG
LTC1349CNW
LTC1349CSW
LTC1349IG
LTC1349INW
LTC1349ISW
ORDER PART
NUMBER
Supply Voltage (V
CC
) ................................................ 6V
Input Voltage
Driver ....................................... 0.3V to V
CC
+ 0.3V
Receiver ............................................... 25V to 25V
On/Off Pin .................................. 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
Commercial (LTC1349C) ........................ 0C to 70C
Industrial (LTC1349I) ........................ 40C to 85C
Storage Temperature Range ................ 65C to 150C
Lead Temperature (Soldering, 10 sec)................. 300C
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
V
+
V
CC
C1
+
C1
DR1 OUT
RX1 IN
DR2 OUT
RX2 IN
RX3 IN
RX4 IN
DR3 OUT
RX5 IN
ON/OFF
NC
V
C2+
C2
DR1 IN
RX1 OUT
DR2 IN
RX2 OUT
RX3 OUT
RX4 OUT
DR3 IN
RX5 OUT
GND
NC
NC
NW PACKAGE
28-LEAD PDIP
TOP VIEW
SW PACKAGE
28-LEAD PLASTIC SO
G PACKAGE
28-LEAD SSOP
T
JMAX
= 125C,
JA
= 96C/W (G)
T
JMAX
= 125C,
JA
= 56C/W (NW)
T
JMAX
= 125C,
JA
= 85C/W (SW)
Consult LTC Marketing for parts specified with wider operating temperature
ranges.
The
denotes specifications which apply over the full operating
temperature range. V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1F, unless noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Any Driver
Output Voltage Swing
3k to GND
Positive
5.0
7.0
V
Negative
5.0
6.5
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
Logic Input Current
V
IN
= 5V
5
A
V
IN
= 0V
5
A
Output Short-Circuit Current
V
OUT
= 0V
9
12
mA
Output Leakage Current
Shutdown, V
OUT
= 20V (Note 3)
10
500
A
Any Receiver
Input Voltage Thresholds
Input Low Threshold
0.8
1.3
V
Input High Threshold
1.7
2.4
V
Hysteresis
0.1
0.4
1.0
V
Input Resistance
10V V
IN
10V
3
5
7
k
Output Voltage
Output Low, I
OUT
= 1.6mA (V
CC
= 5V)
0.2
0.4
V
Output High, I
OUT
= 160A (V
CC
= 5V)
3.5
4.8
V
Output Short-Circuit Current
Sinking Current, V
OUT
= V
CC
15
40
mA
Output Leakage Current
Shutdown, 0 V
OUT
V
CC
(Note 3)
1
10
A
Power Supply Generator
V
+
Output Voltage
I
OUT
= 0mA
8.0
V
I
OUT
= 12mA
7.5
V
V
Output Voltage
I
OUT
= 0mA
8.0
V
I
OUT
= 12mA
7.0
V
Supply Rise Time
Shutdown to Turn-On
0.2
ms
ABSOLUTE AXI U RATI GS
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PACKAGE/ORDER I FOR ATIO
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DC ELECTRICAL CHARACTERISTICS
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LTC1349
1349fa
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.
The
denotes specifications which apply over the full operating
temperature range. V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1F, unless noted.
The
denotes specifications which apply over the full operating temperature range.
V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1F, unless noted.
TYPICAL PERFOR A CE CHARACTERISTICS
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AC CHARACTERISTICS
DC ELECTRICAL CHARACTERISTICS
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Power Supply
V
CC
Supply Current
No Load (All Drivers V
IN
= V
CC
)(Note 2), 0C T
A
70C
0.3
0.8
mA
No Load (All Drivers V
IN
= 0V)(Note 2), 0C T
A
70C
0.5
1.0
mA
No Load (All Drivers V
IN
= V
CC
)(Note 2), 0C T
A
85C
0.3
1.0
mA
No Load (All Drivers V
IN
= V
CC
)(Note 2), 40C T
A
0C
0.3
1.5
mA
No Load (All Drivers V
IN
= 0V)(Note 2), 40C T
A
85C
0.5
1.5
mA
Supply Leakage Current (V
CC
)
Shutdown (Note 3)
35
50
A
On/Off Threshold Low
1.4
0.8
V
On/Off Threshold High
2.0
1.4
V
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Slew Rate
R
L
= 3k, C
L
= 51pF
8
30
V/s
R
L
= 3k, C
L
= 2500pF
3
5
V/s
Driver Propagation Delay
t
HLD
(Figure 1)
2
3.5
s
(TTL to RS232)
t
LHD
(Figure 1)
2
3.5
s
Receiver Propagation Delay
t
HLR
(Figure 2)
0.3
0.8
s
(RS232 to TTL)
t
LHR
(Figure 2)
0.2
0.8
s
Note 3: Supply current and leakage current measurements in Shutdown
are performed with V
ON/OFF
= 0V.
Driver Output Voltage
Supply Current vs Data Rate
Receiver Input Thresholds
TEMPERATURE (C)
40
8
DRIVER OUTPUT VOLTAGE (V)
6
2
0
2
40
10
LTC1349 TPC01
4
0
100
4
6
8
20
20
60
80
R
L
= 3k
OUTPUT HIGH
V
CC
= 5V
V
CC
= 4.5V
OUTPUT LOW
V
CC
= 4.5V
V
CC
= 5V
DATA RATE (k BAUD)
0
SUPPLY CURRENT (mA)
150
45
40
35
30
25
20
15
10
5
0
LTC1349 TPC03
50
175
25
75
100
125
V
CC
= 5V
R
L
= 3k
C
L
= 2500pF
3 DRIVERS ACTIVE
TEMPERATURE (C)
40
THRESHOLD VOLTAGE (V)
1.8
2.0
2.2
20
60
LTC1349 TPC02
1.6
1.4
20
0
40
80
100
1.2
1.0
V
TH
V
TL
4
LTC1349
1349fa
TYPICAL PERFOR A CE CHARACTERISTICS
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PI FU CTIO S
With multiple devices, the V
+
and V
pins may be paral-
leled into common capacitors. For large numbers of de-
vices, increasing the size of the shared common storage
capacitors is recommended to reduce ripple.
V
: Negative Supply Output (RS232 Drivers). V
2V
CC
1.5V. This pin requires an external capacitor C = 0.1F for
charge storage.
C1
+
, C1
, C2
+
, C2
: Commutating Capacitor Inputs. These
pins require two external capacitors C = 0.1F: one from
C1
+
to C1
, and another from C2
+
to C2
. To maintain
charge pump efficiency, the capacitor's effective series
resistance should be less than 20.
DRIVER
OUTPUT
R
L
= 3k
DRIVER
OUTPUT
R
L
= 3k
C
L
= 2500pF
INPUT
RECEIVER
OUTPUT
C
L
= 2500pF
INPUT
LTC1349 TPC08
LTC1349 TPC09
V
CC
Supply Current
Driver Short-Circuit Current
Driver Leakage in Shutdown
TEMPERATURE (C)
0
SUPPLY CURRENT (mA)
60
20
16
14
12
10
8
6
4
2
0
LTC1349 TPC04
20
70
10
30
40
50
3 DRIVERS LOADED
R
L
= 3k
1 DRIVER LOADED
R
L
= 3k
TEMPERATURE (C)
0
LEAKAGE CURRENT (
A)
60
45
40
35
30
25
20
15
10
5
0
LTC1349 TPC05
20
70
10
30
40
50
V
OUT
= 20V
V
OUT
= 20V
TEMPERATURE (C)
40
0
SHORT-CIRCUIT CURRENT (mA)
4
8
10
12
40
20
LTC1349 TPC06
6
0
80
14
16
18
20
60
20
100
I
SC
+
I
SC
Receiver Short-Circuit Current
Receiver Output Waveforms
Driver Output Waveforms
TEMPERATURE (C)
40
10
SHORT-CIRCUIT CURRENT (mA)
30
60
0
40
60
LTC1349 TPC07
20
50
40
20
20
80
100
I
SC
I
SC
+
V
CC
: 5V Input Supply Pin. Supply current is typically 35A
in the Shutdown mode. This pin should be decoupled with
a 0.1F ceramic capacitor.
GND: Ground Pin.
ON/OFF: TTL/CMOS Compatible Shutdown Pin. A logic
low puts the device in Shutdown mode, with receivers 4
and 5 kept alive and the supply current equal to 35A. All
driver outputs and other receiver outputs are in high
impedance state. This pin can not float.
V
+
: Positive Supply Output (RS232 Drivers). V
+
2V
CC
1V. This pin requires an external capacitor C = 0.1F for
charge storage. The capacitor may be tied to ground or 5V.
5
LTC1349
1349fa
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PI FU CTIO S
DRIVER IN: RS232 Driver Input Pins. Inputs are TTL/
CMOS compatible. Inputs should not be allowed to float.
Tie unused inputs to V
CC
.
DRIVER OUT: Driver Outputs at RS232 Voltage Levels.
Outputs are in a high impedance state when in Shutdown
mode or V
CC
= 0V. 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 Lev-
els. Receiver 1, 2 and 3 outputs are in a high impedance
state when in Shutdown mode to allow data line sharing.
Receivers 4 and 5 are kept alive in Shutdown.
SWITCHI G TI E WAVEFOR S
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Figure 1. Driver Propagation Delay Timing
Figure 2. Receiver Propagation Delay Timing
1.4V
0V
V
CC
0V
V
+
V
0V
DRIVER
INPUT
DRIVER
OUTPUT
1.4V
t
HLD
t
LHD
LTC1349 F01
0.8V
V
CC
0V
2.4V
RX
INPUT
RX
OUTPUT
1.3V
t
HLR
1.7V
t
LHR
LTC1349 F02
V
CC
0V
TEST CIRCUITS
Driver Timing Test Load
Receiver Timing Test Load
DRIVER
DRIVER
INPUT
3k
51pF
DRIVER
OUTPUT
LTC1349 TA03
RX
RX INPUT
51pF
RX
OUTPUT
LTC1349 TA04
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