LTC1337
5V Low Power RS232
3-Driver/5-Receiver Transceiver
FEATURES
■
■
■
■
■
■
■
■
DESCRIPTIO
■
■
■
Low Supply Current: 300µA
ESD Protection: Over
±10kV
1µA Supply Current in Shutdown
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 LT
®
1137A and LT1237
Flowthrough Architecture
The LTC
®
1337 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 reduced
to 1µA. All RS232 outputs assume a high impedance 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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
■
■
Notebook Computers
Palmtop Computers
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
V
CC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LTC1337
3-Drivers/5-Receivers with Shutdown
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)
28
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)
0.8
0.6
0.4
0.2
0
QUIESCENT
CURRENT
0
20
40
60
TEMPERATURE (°C)
80
1337fa
U
U
1
LTC1337
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
+
C1
+
1
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
V
CC
2
3
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
LTC1337CNW
LTC1337CSW
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
NW PACKAGE
28-LEAD PLASTIC SSOP
28-LEAD PDIP
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
Output Leakage Current
CONDITIONS
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
µA
V
V
V
kΩ
V
V
mA
mA
µA
1337fa
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
– 10V
≤
V
IN
≤
10V
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)
5.0
– 5.0
2.0
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
500
●
●
2.4
1
7
0.4
●
10
2
U
W
U
U
W W
W
LTC1337
DC ELECTRICAL CHARACTERISTICS
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)
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
– 6.5
0.2
●
●
●
●
MAX
UNITS
V
V
V
V
ms
2.0
0.3
1
1.4
1.4
0.5
10
0.8
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
2
●
●
●
●
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
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)
6
4
2
0
–2
–4
–6
–8
0
10
V
CC
= 5V
30
20
40
50
TEMPERATURE (°C)
60
70
OUTPUT LOW
V
CC
= 4.5V
R
L
= 3k
OUTPUT HIGH
V
CC
= 5V
THRESHOLD VOLTAGE (V)
V
CC
= 4.5V
2.0
1.9
1.7
1.6
1.5
1.4
1.3
1.2
1.1
0
10
30
20
40
50
TEMPERATURE (°C)
60
70
INPUT LOW
SUPPLY CURRENT (mA)
U W
1337 G01
Receiver Input Thresholds
45
40
INPUT HIGH
35
30
25
20
15
10
5
0
0
Supply Current vs Data Rate
V
CC
= 5V
R
L
= 3k
C
L
= 2500pF
3 DRIVERS ACTIVE
1.8
25
75 100 125
50
DATA RATE (k BAUD)
150
175
1337 G02
1337 G03
1337fa
3
LTC1337
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
45
40
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
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. 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 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.
1337fa
4
U W
1337 G04
1337 G07
Driver Leakage in Shutdown
20
18
16
14
12
10
8
6
4
2
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
Receiver Output Waveforms
RX
OUTPUT
C
L
= 50pF
INPUT
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 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 Levels.
Outputs are in a high impedance state when in Shutdown
mode to allow data line sharing.
SWITCHI G TI E WAVEFOR S
DRIVER
INPUT
DRIVER
OUTPUT
t
LHD
V
CC
1.4V
1.4V
0V
V
+
0V
t
HLD
1337 F01
Figure 1. Driver Propagation Delay Timing
TEST CIRCUITS
DRIVER
OUTPUT
DRIVER
51pF
3k
C1
0.1µF
1337 F03
DRIVER
INPUT
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
RX IN
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
1337fa
5
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