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1
LTC1347
5V Low Power RS232
3-Driver/5-Receiver Transceiver
with 5 Receivers Active
in Shutdown
S
FEATURE
D
U
ESCRIPTIO
s
Low Supply Current: 300
µ
A
s
Five Receivers Kept Alive in Shutdown
s
ESD Protection Over
±
10kV
s
Operates from a Single 5V Supply
s
Uses Small Capacitors: 0.1
µ
F
s
Operates to 120kBaud
s
Three-State Outputs Are High Impedance When Off
s
Output Overvoltage Does Not Force Current Back
into Supplies
s
RS232 I/O Lines Can Be Forced to
±
25V
Without Damage
s
Pin Compatible with LT1137 and LT1237
s
Flowthrough Architecture
The LTC1347 is a 3-driver/ 5-receiver RS232 transceiver
with very low supply current. In the no load condition, the
supply current is only 300
µ
A. The charge pump only
requires four 0.1
µ
F capacitors.
In Shutdown mode, all five receivers are kept alive and the
supply current is 80
µ
A. All RS232 outputs assume a high
impedance state in Shutdown and with the power off.
The LTC1347 is fully compliant with all data rate and
overvoltage RS232 specifications. The transceiver can
operate up to 120kbaud 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.
U
S
A
O
PPLICATI
s
Notebook Computers
s
Palmtop Computers
3-Drivers/5-Receivers with SHUTDOWN
U
A
O
PPLICATI
TYPICAL
Quiescent and Shutdown Supply Current vs
Temperature
1347 TA01
V
CC
C1
0.1
µ
F
LTC1347
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
0.1
µ
F
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
0.1
µ
F
C4
0.1
µ
F
TEMPERATURE (°C)
QUIESCENT CURRENT (
µ
A)
1200
1000
800
600
400
200
0
20
40
60
1347 TA02
80
0
40
120
100
80
60
40
20
0
SHUTDOWN CURRENT (
µ
A)
QUIESCENT
CURRENT
SHUTDOWN
CURRENT
TEST CONDITION:
V
CC
= 5V, ALL DRIVER INPUTS TIED TO V
CC
.
20
100
2
LTC1347
A
U
G
W
A
W
U
W
A
R
BSOLUTE
XI
TI
S
W
U
U
PACKAGE/ORDER I FOR ATIO
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 .................... 0
°
C to 70
°
C
Storage Temperature Range ................ 65
°
C to 150
°
C
Lead Temperature (Soldering, 10 sec) ................. 300
°
C
1
2
3
4
5
6
7
8
9
10
11
12
13
14
V
+
V
CC
C1
+
C1
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
V
C2
+
C2
DRIVER 1 IN
RX1 OUT
DRIVER 2 IN
RX2 OUT
RX3 OUT
RX4 OUT
DRIVER 3 IN
RX5 OUT
GND
NC
NC
N PACKAGE
28-LEAD PLASTIC DIP
TOP VIEW
S PACKAGE
28-LEAD PLASTIC SOL
G PACKAGE
28-LEAD SSOP
ORDER PART
NUMBER
LTC1347CG
LTC1347CN
LTC1347CS
T
JMAX
= 125
°
C,
JA
= 96
°
C/W (G)
T
JMAX
= 125
°
C,
JA
= 56
°
C/W (N)
T
JMAX
= 125
°
C,
JA
= 85
°
C/W (S)
Consult factory for Industrial and Military grade parts.
ELECTRICAL C
C
HARA TERISTICS
C
D
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Any Driver
Output Voltage Swing
3k to GND
Positive
q
5.0
7.0
V
Negative
q
5.0
6.5
V
Logic Input Voltage Level
Input Low Level (V
OUT
= High)
q
1.4
0.8
V
Input High Level (V
OUT
= Low)
q
2.0
1.4
V
Logic Input Current
V
IN
= 5V
q
5
µ
A
V
IN
= 0V
q
5
µ
A
Output Short-Circuit Current
V
OUT
= 0V
±
12
mA
Output Leakage Current
Shutdown, V
OUT
=
±
20V (Note 3)
±
10
±
500
µ
A
Any Receiver
Input Voltage Thresholds
Input Low Threshold
q
0.8
1.3
V
Input High Threshold
q
1.7
2.4
V
Hysteresis
q
0.1
0.4
1.0
V
Input Resistance
V
IN
=
±
10V
3
5
7
k
Output Voltage
Output Low, I
OUT
= 1.6mA (V
CC
= 5V)
q
0.2
0.4
V
Output High, I
OUT
= 160
µ
A (V
CC
= 5V)
q
3.5
4.8
V
Output Short-Circuit Current
Sinking Current, V
OUT
= V
CC
15
40
mA
Sourcing Current, V
OUT
= 0V
10
20
mA
V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1
µ
F, unless otherwise noted.
3
LTC1347
Note 2: Supply current is measured with driver and receiver outputs
unloaded.
Note 3: Supply current and leakage current measurements in Shutdown
are performed with V
ON/OFF
= 0V.
The
q
denotes specifications which apply over the operating temperature
range (0
°
C
T
A
70
°
C for commercial grade.
Note 1: Absolute maximum ratings are those values beyond which the life
of the device may be impaired.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Slew Rate
R
L
= 3k, C
L
= 51pF
8
30
V/
µ
s
R
L
= 3k, C
L
= 2500pF
3
5
V/
µ
s
Driver Propagation Delay
t
HLD
(Figure 1)
q
2
3.5
µ
s
(TTL to RS232)
t
LHD
(Figure 1)
q
2
3.5
µ
s
Receiver Propagation Delay
t
HLR
(Figure 2)
q
0.3
0.8
µ
s
(RS232 to TTL)
t
LHR
(Figure 2)
q
0.2
0.8
µ
s
C
C
HARA TERISTICS
AC
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
Driver Output Voltage
TEMPERATURE (°C)
40
8
DRIVER OUTPUT VOLTAGE (V)
6
2
0
2
40
10
1347 G01
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 (kBAUD)
0
SUPPLY CURRENT (mA)
150
45
40
35
30
25
20
15
10
5
0
1347 G03
50
175
25
75
100
125
V
CC
= 5V
R
L
= 3k
C
L
= 2500pF
3 DRIVERS ACTIVE
Supply Current vs Data Rate
TEMPERATURE (°C)
40
THRESHOLD VOLTAGE (V)
1.8
2.0
2.2
20
60
1347 G02
1.6
1.4
20
0
40
80
100
1.2
1.0
V
TH
V
TL
Receiver Input Thresholds
V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1
µ
F, unless otherwise noted.
ELECTRICAL C
C
HARA TERISTICS
C
D
V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1
µ
F, unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
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
Power Supply
V
CC
Supply Current
No Load (All Drivers V
IN
= 5V)(Note 2)
q
0.6
1.1
mA
No Load (All Drivers V
IN
= 0V) (Note 2)
q
0.8
1.3
mA
Shutdown (Note 3)
q
80.0
120.0
µ
A
On/Off Threshold Low
q
1.4
0.8
V
On/Off Threshold High
q
2.0
1.4
V
4
LTC1347
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
TEMPERATURE (°C)
0
SUPPLY CURRENT (mA)
60
20
16
14
12
10
8
6
4
2
0
1347 G04
20
70
10
30
40
50
3 DRIVERS LOADED
R
L
= 3k
1 DRIVER LOADED
R
L
= 3k
V
CC
Supply Current
TEMPERATURE (°C)
40
0
SHORT-CIRCUIT CURRENT (mA)
4
8
10
12
40
20
1347 G06
6
0
80
14
16
18
20
60
20
100
I
SC
+
I
SC
Driver Short-Circuit Current
TEMPERATURE (°C)
0
LEAKAGE CURRENT (
µ
A)
60
45
40
35
30
25
20
15
10
5
0
1347 G05
20
70
10
30
40
50
V
OUT
= 20V
V
OUT
= 20V
Driver Leakage in Shutdown
Receiver Short-Circuit Current
TEMPERATURE (°C)
40
10
SHORT-CIRCUIT CURRENT (mA)
30
60
0
40
60
1347 G07
20
50
40
20
20
80
100
I
SC
I
SC
+
Driver Output Waveforms
Receiver Output Waveforms
DRIVER
OUTPUT
R
L
= 3k
C
L
= 2500pF
1347 G08
1347 G09
RECEIVER
OUTPUT
C
L
= 51pF
INPUT
DRIVER
OUTPUT
R
L
= 3k
INPUT
PI FU CTIO S
U
U
U
V
CC
: 5V Input Supply Pin. Supply current is typically 80
µ
A
in the Shutdown mode. This pin should be decoupled with
a 0.1
µ
F ceramic capacitor.
GND: Ground Pin.
ON/OFF: TTL/CMOS Compatible Shutdown Pin. A logic
low puts the device in the shutdown mode with all receiv-
ers kept alive, and the supply current is 80
µ
A. All driver
outputs are in high impedance state. This pin cannot float.
V
+
: Positive Supply Output (RS232 Drivers).
V
+
2V
CC
1V. This pin requires an external capacitor C
= 0.1
µ
F for charge storage. The capacitor may be tied to
ground or V
CC
. With multiple devices, the V
+
and V
pins
may be paralleled into common capacitors. For large
numbers of devices, 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 = 0.1
µ
F for charge storage.
5
LTC1347
PI FU CTIO S
U
U
U
C1
+
, C1
, C2
+
, C2
: Commutating Capacitor Inputs. These
pins require two external capacitors C = 0.1
µ
F: 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 2
.
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. All receivers are kept alive in shutdown.
0.8V
V
CC
0V
2.4V
RX
INPUT
RX
OUTPUT
1.3V
t
HLR
1.7V
t
LHR
1347 F02
V
CC
0V
SWITCHI G TI E WAVEFOR S
W
W
U
Figure 1. Driver Propagation Delay Timing
1.4V
0V
V
CC
0V
V
+
V
0V
DRIVER
INPUT
DRIVER
OUTPUT
1.4V
t
HLD
t
LHD
1347 F01
Figure 2. Receiver Propagation Delay Timing
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