LTC1347
5V Low Power RS232
3-Driver/5-Receiver Transceiver
with 5 Receivers Active
in Shutdown
FEATURES
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■
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■
■
■
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DESCRIPTIO
■
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Low Supply Current: 300µA
Five Receivers Kept Alive in Shutdown
ESD Protection Over
±10kV
Operates from a Single 5V Supply
Uses Small Capacitors: 0.1µF
Operates to 120kBaud
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
®
1347 is a 3-driver/5-receiver RS232 transceiver
with very low supply current. In the no load condition, the
supply current is only 300µA. The charge pump only
requires four 0.1µF capacitors.
In Shutdown mode, all five receivers are kept alive and the
supply current is 80µA. 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, 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
V
+
C1
0.1µF
C2
0.1µF
DRIVER 1 OUT
RX1 IN
DRIVER 2 OUT
RX2 IN
RX3 IN
RX4 IN
DRIVER 3 OUT
RX5 IN
ON/OFF
NC
V
CC
3-Drivers/5-Receivers with Shutdown
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LTC1347
28
27
26
25
24
23
22
21
20
19
18
17
16
15
C3
0.1µF
DRIVER 1 IN
RX1 OUT
DRIVER 2 IN
RX2 OUT
RX3 OUT
RX4 OUT
DRIVER 3 IN
RX5 OUT
GND
NC
NC
1347 TA01
Quiescent and Shutdown Supply Current
vs Temperature
1200
120
100
SHUTDOWN CURRENT (µA)
SHUTDOWN
CURRENT
80
60
QUIESCENT
CURRENT
40
20
V
–
C4
0.1µF
1000
QUIESCENT CURRENT (µA)
800
600
400
200
0
–40
0
0
80 100
20
60
40
TEMPERATURE (°C)
TEST CONDITION:
V
CC
= 5V, ALL DRIVER INPUTS TIED TO V
CC
.
–20
1347 TA02
U
1347fa
U
U
1
LTC1347
ABSOLUTE
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
+
1
V
CC
2
C1
+
3
28 V–
27 C2+
26 C2–
25 DR1 IN
24 RX1 OUT
23 DR2 IN
22 RX2 OUT
21 RX3 OUT
20 RX4 OUT
19 DR3 IN
18 RX5 OUT
17 GND
16 NC
15 NC
NW PACKAGE
28-LEAD PDIP
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
ORDER PART
NUMBER
LTC1347CG
LTC1347CNW
LTC1347CSW
C1– 4
DR1 OUT 5
RX1 IN 6
DR2 OUT 7
RX2 IN 8
RX3 IN 9
RX4 IN 10
DR3 OUT 11
RX5 IN 12
ON/OFF 13
NC 14
G PACKAGE
28-LEAD SSOP
SW PACKAGE
28-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 96°C/W (G)
T
JMAX
= 125°C,
θ
JA
= 56°C/W (NW)
T
JMAX
= 125°C,
θ
JA
= 85°C/W (SW)
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
Output Leakage Current
Any Receiver
Input Voltage Thresholds
Hysteresis
Input Resistance
Output Voltage
Output Short-Circuit Current
CONDITIONS
3k to GND
The
●
denotes specifications which apply over the full operating
temperature range. V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1µF, unless otherwise noted.
MIN
Positive
Negative
●
●
●
●
●
●
TYP
7.0
– 6.5
1.4
1.4
MAX
UNITS
V
V
V
V
µA
µA
mA
5.0
– 5.0
2.0
Input Low Level (V
OUT
= High)
Input High Level (V
OUT
= Low)
V
IN
= 5V
V
IN
= 0V
V
OUT
= 0V
Shutdown, V
OUT
=
±20V
(Note 3)
Input Low Threshold
Input High Threshold
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
0.8
5
–5
±9
±10
●
●
●
●
●
±12
±500
1.3
1.7
0.4
5
0.2
4.8
– 40
20
µA
V
V
V
kΩ
V
V
mA
mA
0.8
0.1
3
3.5
– 15
10
2.4
1.0
7
0.4
1347fa
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W
U
U
W W
W
LTC1347
DC ELECTRICAL CHARACTERISTICS
PARAMETER
Power Supply Generator
V
+
Output Voltage
V
–
Output Voltage
Supply Rise Time
Power Supply
V
CC
Supply Current
CONDITIONS
I
OUT
= 0mA
I
OUT
= 12mA
I
OUT
= 0mA
I
OUT
= – 12mA
Shutdown to Turn-On
The
●
denotes specifications which apply over the full operating
temperature range. V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1µF, unless otherwise noted.
MIN
TYP
8.0
7.5
– 8.0
– 7.0
0.2
MAX
UNITS
V
V
V
V
ms
No Load (All Drivers V
IN
= 5V)(Note 2)
No Load (All Drivers V
IN
= 0V) (Note 2)
Shutdown (Note 3)
●
●
●
●
●
On/Off Threshold Low
On/Off Threshold High
2.0
0.6
0.8
80.0
1.4
1.4
1.1
1.3
120.0
0.8
mA
mA
µA
V
V
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.
V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1µF, unless otherwise 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
0.2
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.
Note 3:
Supply current and leakage current measurements in Shutdown
are performed with V
ON/OFF
= 0V.
TYPICAL PERFOR A CE CHARACTERISTICS
Driver Output Voltage
10
8
R
L
= 3k
OUTPUT HIGH
V
CC
= 5V
DRIVER OUTPUT VOLTAGE (V)
THRESHOLD VOLTAGE (V)
SUPPLY CURRENT (mA)
6
4
2
0
–2
–4
–6
V
CC
= 4.5V
OUTPUT LOW
V
CC
= 4.5V
V
CC
= 5V
–8
–40
–20
20
0
40
60
TEMPERATURE (°C)
U W
80
1347 G01
Receiver Input Thresholds
2.2
2.0
1.8
V
TH
1.6
V
TL
1.4
1.2
1.0
–40 –20
Supply Current vs Data Rate
45
40
35
30
25
20
15
10
5
0
V
CC
= 5V
R
L
= 3k
C
L
= 2500pF
3 DRIVERS ACTIVE
100
40
20
60
0
TEMPERATURE (˚C)
80
100
0
25
75 100 125
50
DATA RATE (kBAUD)
150
175
1347 G02
1347 G03
1347fa
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LTC1347
TYPICAL PERFOR A CE CHARACTERISTICS
V
CC
Supply Current
20
16
3 DRIVERS LOADED
R
L
= 3k
LEAKAGE CURRENT (µA)
SUPPLY CURRENT (mA)
14
12
10
8
6
4
2
0
0
10
30
20
40
50
TEMPERATURE (°C)
60
70
1 DRIVER LOADED
R
L
= 3k
35
30
25
20
15
10
5
0
0
10
30
20
40
50
TEMPERATURE (°C)
60
70
V
OUT
= 20V
V
OUT
= –20V
SHORT-CIRCUIT CURRENT (mA)
Receiver Short-Circuit Current
60
SHORT-CIRCUIT CURRENT (mA)
50
40
I
SC–
30
I
SC
20
+
1347 G08
1347 G09
10
–40 –20
40
20
0
60
TEMPERATURE (°C)
PI FU CTIO S
V
CC
:
5V Input Supply Pin. Supply current is typically 80µA
in the Shutdown mode. This pin should be decoupled with
a 0.1µF 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 80µA. 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
= 0.1µF 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 = 0.1µF 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
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1347 G04
Driver Leakage in Shutdown
45
40
20
18
16
14
12
10
8
6
4
Driver Short-Circuit Current
I
SC–
I
SC+
0
–40
–20
20
0
40
60
TEMPERATURE (°C)
80
100
1347 G05
1347 G06
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
80
100
1347 G07
U
U
U
LTC1347
PI FU CTIO S
charge pump efficiency, the capacitor’s effective series
resistance should be less than 2Ω.
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.
SWITCHI G TI E WAVEFOR S
DRIVER
INPUT
DRIVER
OUTPUT
t
LHD
V
CC
1.4V
1.4V
0V
V
+
0V
t
HLD
1347 F01
Figure 1. Driver Propagation Delay Timing
RX
INPUT
RX
OUTPUT
t
LHR
1.7V
Figure 2. Receiver Propagation Delay Timing
W
W
U
U
U
U
0V
V
–
V
CC
1.3V
0V
2.4V
0.8V
t
HLR
V
CC
0V
1347 F02
1347fa
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