LTC1349
5V Low Power RS232
3-Driver/5-Receiver Transceiver
with 2 Receivers Active
in Shutdown
FEATURES
■
■
■
■
■
■
■
■
DESCRIPTIO
■
■
■
Low Supply Current: 300µA
Two Receivers Kept Alive 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 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 300µA. The charge pump only
requires four 0.1µF capacitors.
In Shutdown mode, two receivers are kept alive and the
supply current is 35µA. 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, 3kΩ load. Both
driver outputs and receiver inputs can be forced to
±25V
without damage, and can survive multiple
±10kV
ESD
strikes.
APPLICATIO S
■
■
Notebook Computers
Palmtop Computers
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
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
NC
V
CC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LTC1349
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
LTC1349 • TA01
Quiescent and Shutdown Supply Current
vs Temperature
1200
C4
0.1µF
V
–
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
LTC1349 • TA02
U
60
50
SHUTDOWN CURRENT (µA)
U
U
SHUTDOWN
CURRENT
40
30
QUIESCENT
CURRENT
20
10
1349fa
1
LTC1349
ABSOLUTE
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
NW PACKAGE
28-LEAD PDIP
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 (LTC1349C) ........................ 0°C to 70°C
Industrial (LTC1349I) ........................ – 40°C to 85°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
ORDER PART
NUMBER
LTC1349CG
LTC1349CNW
LTC1349CSW
LTC1349IG
LTC1349INW
LTC1349ISW
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
Output Leakage Current
Power Supply Generator
V
+
Output Voltage
V
–
Output Voltage
Supply Rise Time
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 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
µA
V
V
V
V
ms
1349fa
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
– 10V
≤
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
Shutdown, 0
≤
V
OUT
≤
V
CC
(Note 3)
I
OUT
= 0mA
I
OUT
= 12mA
I
OUT
= 0mA
I
OUT
= – 12mA
Shutdown to Turn-On
0.8
5
–5
±9
●
●
●
●
●
●
●
±12
±10
±500
0.8
0.1
3
3.5
– 15
1.3
1.7
0.4
5
0.2
4.8
– 40
1
8.0
7.5
– 8.0
– 7.0
0.2
2.4
1.0
7
0.4
10
2
U
W
U
U
W W
W
LTC1349
DC ELECTRICAL CHARACTERISTICS
PARAMETER
Power Supply
V
CC
Supply Current
CONDITIONS
The
●
denotes specifications which apply over the full operating
temperature range. V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1µF, unless noted.
MIN
●
●
●
●
●
●
●
●
TYP
0.3
0.5
0.3
0.3
0.5
35
1.4
1.4
MAX
0.8
1.0
1.0
1.5
1.5
50
0.8
UNITS
mA
mA
mA
mA
mA
µA
V
V
Supply Leakage Current (V
CC
)
On/Off Threshold Low
On/Off Threshold High
No Load (All Drivers V
IN
= V
CC
)(Note 2), 0°C
≤
T
A
≤
70°C
No Load (All Drivers V
IN
= 0V)(Note 2), 0°C
≤
T
A
≤
70°C
No Load (All Drivers V
IN
= V
CC
)(Note 2), 0°C
≤
T
A
≤
85°C
No Load (All Drivers V
IN
= V
CC
)(Note 2), – 40°C
≤
T
A
≤
0°C
No Load (All Drivers V
IN
= 0V)(Note 2), – 40°C
≤
T
A
≤
85°C
Shutdown (Note 3)
2.0
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 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)
4
2
0
–2
–4
–6
V
CC
= 5V
–8
–40
–20
20
0
40
60
TEMPERATURE (°C)
80
100
OUTPUT LOW
V
CC
= 4.5V
1.8
V
TH
1.6
V
TL
1.4
1.2
SUPPLY CURRENT (mA)
6
V
CC
= 4.5V
LTC1349 • TPC01
U W
Receiver Input Thresholds
2.2
2.0
35
30
25
20
15
10
5
45
40
Supply Current vs Data Rate
V
CC
= 5V
R
L
= 3k
C
L
= 2500pF
3 DRIVERS ACTIVE
1.0
–40 –20
40
20
60
0
TEMPERATURE (˚C)
80
100
0
0
25
75 100 125
50
DATA RATE (k BAUD)
150
175
LTC1349 • TPC02
LTC1349 • TPC03
1349fa
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LTC1349
TYPICAL PERFOR A CE CHARACTERISTICS
V
CC
Supply Current
20
16
3 DRIVERS LOADED
R
L
= 3k
LEAKAGE CURRENT (µA)
SUPPLY CURRENT (mA)
45
40
35
30
25
20
15
10
5
0
V
OUT
= 20V
V
OUT
= –20V
14
12
10
8
6
4
2
0
0
10
SHORT-CIRCUIT CURRENT (mA)
1 DRIVER LOADED
R
L
= 3k
30
20
40
50
TEMPERATURE (°C)
LTC1349 • TPC04
Receiver Short-Circuit Current
60
SHORT-CIRCUIT CURRENT (mA)
DRIVER
OUTPUT
R
L
= 3k
C
L
= 2500pF
50
40
I
SC
30
–
I
SC
20
+
LTC1349 • TPC08
LTC1349 • TPC09
10
–40 –20
40
20
0
60
TEMPERATURE (°C)
PI FU CTIO S
V
CC
:
5V Input Supply Pin. Supply current is typically 35µA
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 Shutdown mode, with receivers 4
and 5 kept alive and the supply current equal to 35µA. 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 = 0.1µF 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 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 = 0.1µF 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 20Ω.
1349fa
4
U W
60
80
LTC1349 • TPC07
Driver Leakage in Shutdown
20
18
16
14
12
10
8
6
4
60
70
Driver Short-Circuit Current
I
SC–
I
SC+
70
0
10
30
20
40
50
TEMPERATURE (°C)
0
–40
–20
20
0
40
60
TEMPERATURE (°C)
80
100
LTC1349 • TPC05
LTC1349 • TPC06
Driver Output Waveforms
Receiver Output Waveforms
DRIVER
OUTPUT
R
L
= 3k
INPUT
RECEIVER
OUTPUT
C
L
= 2500pF
INPUT
100
U
U
U
LTC1349
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
DRIVER
INPUT
DRIVER
OUTPUT
t
LHD
V
CC
1.4V
1.4V
0V
V
+
0V
t
HLD
LTC1349 • F01
Figure 1. Driver Propagation Delay Timing
RX
INPUT
RX
OUTPUT
t
LHR
1.7V
Figure 2. Receiver Propagation Delay Timing
TEST CIRCUITS
Driver Timing Test Load
DRIVER
OUTPUT
DRIVER
51pF
3k
DRIVER
INPUT
LTC1349 • TA03
W
W
U
U
U
U
0V
V
–
V
CC
1.3V
0V
2.4V
0.8V
t
HLR
V
CC
0V
LTC1349 • F02
Receiver Timing Test Load
RX
OUTPUT
RX INPUT
RX
51pF
LTC1349 • TA04
1349fa
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