LTC1337
5V Low Power RS232
3-Driver/5-Receiver Transceiver
FEATURES
s
s
s
s
s
s
s
s
DESCRIPTIO
s
s
s
Low Supply Current: 300µA
1µA Supply Current in SHUTDOWN
ESD Protection: Over
±10kV
Operates from a Single 5V Supply
Uses Small Capacitors: 0.1µF
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 LTC1337 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 and can supply up to 12mA
of extra current to power external circuitry.
In SHUTDOWN mode, the supply current is further re-
duced to 1µA. All RS232 outputs assume a high imped-
ance state in SHUTDOWN and with the power off.
The LTC1337 is fully compliant with all data rate and
overvoltage RS232 specifications. The transceiver can
operate up to 120k baud with a 1000pF// 3kΩ load. Both
driver outputs and receiver inputs can be forced to
±25V
without damage, and can survive multiple
±10kV
ESD
strikes.
APPLICATI
s
s
S
Notebook Computers
Palmtop Computers
TYPICAL APPLICATI
3-Drivers/5-Receivers with SHUTDOWN
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
V
CC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LTC1337
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1337 TA01
C3
0.1µF
DRIVER 1 IN
RX1 OUT
DRIVER 2 IN
RX2 OUT
RX3 OUT
RX4 OUT
DRIVER 3 IN
RX5 OUT
GND
C4
0.1µF
QUIESCENT CURRENT OPERATING (µA)
V
–
600
500
400
300
200
100
0
SHUTDOWN
CURRENT
–20
TEST CONDITION:
V
CC
= 5V, ALL DRIVER INPUTS TIED TO V
CC
1337 TA02
U
Supply Current
1.2
1.0
SHUTDOWN CURRENT (µA)
UO
UO
QUIESCENT
CURRENT
0.8
0.6
0.4
0.2
0
0
20
40
60
TEMPERATURE (°C)
80
1
LTC1337
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
+
1
V
CC
2
C1
+
3
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
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
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 (LTC1337C) ........................ 0°C to 70°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
ORDER PART
NUMBER
LTC1337CG
LTC1337CN
LTC1337CS
G PACKAGE
N PACKAGE
28-LEAD SSOP
28-LEAD PLASTIC DIP
S PACKAGE
28-LEAD PLASTIC SOL
T
JMAX
= 125°C,
θ
JA
= 96°C/W (G)
T
JMAX
= 125°C,
θ
JA
= 56°C/W (N)
T
JMAX
= 125°C,
θ
JA
= 85°C/W (S)
Consult factory for Industrial and Military grade parts.
DC ELECTRICAL CHARACTERISTICS
V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1µF, unless otherwise noted.
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
Output Leakage Current
CONDITIONS
R
L
= 3k to GND
R
L
= 3k to GND
Input Low Level (V
OUT
= High)
Input High Level (V
OUT
= Low)
V
IN
= 5V
V
IN
= 0
V
OUT
= 0V
SHUTDOWN, V
OUT
=
±20V
(Note 3)
Input Low Threshold
Input High Threshold
Positive
Negative
q
q
q
q
q
q
q
q
q
q
MIN
5.0
– 5.0
2.0
TYP
7.0
– 6.5
1.4
1.4
MAX
UNITS
V
V
V
V
µA
µA
mA
µA
V
V
V
kΩ
V
V
mA
mA
µA
0.8
5
–5
±10
10
0.8
0.1
3
3.5
15
– 15
1.3
1.7
0.4
5
0.2
4.8
20
– 40
1
200
Output Low, I
OUT
= – 1.6mA (V
CC
= 5V)
Output High, I
OUT
= 160µA (V
CC
= 5V)
Sourcing Current, V
OUT
= 0
Sinking Current, V
OUT
= V
CC
SHUTDOWN, 0
≤
V
OUT
≤
V
CC
(Note 3)
q
q
2.4
1
7
0.4
q
10
2
U
W
U
U
W W
W
LTC1337
DC ELECTRICAL CHARACTERISTICS
V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1µF, unless otherwise noted.
PARAMETER
Power Supply Generator
V
+
Output Voltage
V
–
Output Voltage
Supply Rise Time
Power Supply
V
CC
Supply Current
Supply Leakage Current (V
CC
)
On/Off Threshold Low
On/Off Threshold High
CONDITIONS
I
OUT
= 0mA
I
OUT
= 12mA
I
OUT
= 0mA
I
OUT
= 12mA
SHUTDOWN to Turn-On
No Load (Note 2)
SHUTDOWN (Note 3)
q
q
q
q
MIN
TYP
8.0
7.5
– 8.0
– 6.5
0.2
0.3
1
1.4
1.4
MAX
UNITS
V
V
V
V
ms
0.5
10
0.8
2.0
mA
µA
V
V
AC CHARACTERISTICS
PARAMETER
Slew Rate
Driver Propagation Delay
(TTL to RS232)
Receiver Propagation Delay
(RS232 to TTL)
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
2
q
q
q
q
TYP
8
4
2
2
0.3
0.2
MAX
30
3
3
0.6
0.6
UNITS
V/µs
V/µs
µs
µs
µs
µs
The
q
denotes specifications which apply over the operating temperature
range (0°C
≤
T
A
≤
70°C).
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 and driver inputs tied high.
Note 3:
Supply current and leakage measurements in SHUTDOWN are
performed with V
ON
= 0V.
TYPICAL PERFOR A CE CHARACTERISTICS
Driver Output Voltage
10
8
DRIVER OUTPUT VOLTAGE (V)
2.0
R
L
= 3k
OUTPUT HIGH
V
CC
= 5V
THRESHOLD VOLTAGE (V)
4
2
0
–2
–4
–6
–8
0
10
V
CC
= 4.5V
SUPPLY CURRENT (mA)
6
OUTPUT LOW
V
CC
= 4.5V
V
CC
= 5V
30
20
40
50
TEMPERATURE (°C)
60
70
U W
1337 G01
Receiver Input Thresholds
45
40
INPUT HIGH
35
30
25
20
15
10
5
0
0
10
30
20
40
50
TEMPERATURE (°C)
60
70
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
INPUT LOW
Supply Current vs Data Rate
V
CC
= 5V
R
L
= 3k
C
L
= 2500pF
3 DRIVERS ACTIVE
0
25
75 100 125
50
DATA RATE (k BAUD)
150
175
1337 G02
1337 G03
3
LTC1337
TYPICAL PERFOR A CE CHARACTERISTICS
V
CC
Supply Current
20
16
3 DRIVERS LOADED
R
L
= 3k
45
40
LEAKAGE CURRENT (µA)
SUPPLY CURRENT (mA)
14
12
10
8
6
4
2
0
0
10
35
30
25
20
15
10
5
0
V
OUT
= 20V
V
OUT
= –20V
SHORT-CIRCUIT CURRENT (mA)
1 DRIVER LOADED
R
L
= 3k
30
20
40
50
TEMPERATURE (°C)
Receiver Short-Circuit Current
55
50
SHORT-CIRCUIT CURRENT (mA)
45
40
35
30
25
20
15
10
0
10
30
20
40
50
TEMPERATURE (°C)
60
70
I
SC+
I
SC–
PI FU CTIO S
V
CC
:
5V Input Supply Pin. Supply current less than 1µA 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 which
reduces input supply current to less than 1µA and places
all drivers and receivers in high impedance state.
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 5V.
With multiple devices, the V
+
and V
–
pins may be paral-
leled 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
charge pump efficiency, the capacitor’s effective series
resistance should be less than 50Ω.
4
U W
60
70
1337 G04
1337 G07
Driver Leakage in SHUTDOWN
20
18
16
14
12
10
8
6
4
2
0
10
30
20
40
50
TEMPERATURE (°C)
60
70
Driver Short-Circuit Current
I
SC–
I
SC+
0
10
30
20
40
50
TEMPERATURE (°C)
60
70
1337 G05
1337 G06
Driver Output Waveforms
DRIVER
OUTPUT
R
L
= 3k
C
L
= 2500pF
DRIVER
OUTPUT
R
L
= 3k
INPUT
INPUT
Receiver Output Waveforms
RX
OUTPUT
C
L
= 50pF
U
U
U
LTC1337
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 SHUT-
DOWN 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. Outputs are in a high impedance state when in SHUT-
DOWN mode to allow data line sharing.
SWITCHI G TI E WAVEFOR S
DRIVER
INPUT
DRIVER
OUTPUT
t
LHD
V
CC
1.4V
1.4V
RX IN
0V
V
+
0V
t
HLD
1337 F01
Figure 1. Driver Propagation Delay Timing
TEST CIRCUITS
DRIVER
INPUT
DRIVER
OUTPUT
DRIVER
51pF
3k
C1
0.1µF
1337 F03
Figure 3. Driver Timing Test Load
RS232
LINE PINS
PROTECTED
TO ±10kV
RX
OUTPUT
RX IN
RX
51pF
1337 F04
Figure 4. Receiver Timing Test Load
W
W
U
U
U
U
1.7V
V
CC
1.3V
0V
V
CC
0.8V
0V
t
HLR
0V
1337 F02
0V
V
–
RX
OUTPUT
t
LHR
Figure 2. Receiver Propagation Delay Timing
ESD Test Circuit
V
+
V
CC
C2
0.1µF
DRIVER 1 OUT
RX1 IN
DRIVER 2 OUT
RX2 IN
RX3 IN
RX4 IN
DRIVER 3 OUT
RX5 IN
ON/OFF
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LTC1337
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1337 TC01
V
–
C3
0.1µF
DRIVER 1 IN
RX1 OUT
DRIVER 2 IN
RX2 OUT
RX3 OUT
RX4 OUT
DRIVER 3 IN
RX5 OUT
GND
C4
0.1µF
5
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