LT1341
5V RS232 Transceiver with One
Receiver Active in Shutdown
FEATURES
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DESCRIPTIO
s
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One Receiver Remains Active While in Shutdown
ESD Protection Over
±10kV
Uses Small Capacitors: 0.1µF, 0.2µF
60µA Supply Current in Shutdown
Pin Compatible with LT1137A
120kBaud Operation for R
L
= 3k, C
L
= 2500pF
250kBaud Operation for R
L
= 3k, C
L
= 1000pF
CMOS Comparable Low Power: 60mW
Operates from a Single 5V Supply
Easy PC Layout: Flowthrough Architecture
Rugged Bipolar Design
Outputs Assume a High Impedance State When
Off or Powered Down
Absolutely No Latchup
Available in SSOP Package
The LT
®
1341 is an advanced low power three-driver, five-
receiver RS232 transceiver. Included on the chip is a
shutdown pin for reducing supply current to near zero.
During shutdown one receiver remains active to detect
incoming RS232 signals, for example, to wake up a
system. All other receivers and the drivers assume high
impedance states during shutdown.
The driver disable function provides additional control of
operating mode. When driver disable is high the charge
pump and drivers turn off. Receivers continue to operate
during driver disable.
New ESD structures on the chip allow the LT1341 to
survive multiple
±10kV
strikes, eliminating the need for
costly TransZorbs
®
on the RS232 line pins.
The LT1341 is fully compliant with all EIA RS232 specifi-
cations and operates in excess of 120kbaud even driving
heavy capacitive loads.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TransZorb is a registered trademark of General Instruments, GSI
APPLICATI
s
s
S
Notebook Computers
Palmtop Computers
TYPICAL APPLICATI
V
+
0.1µF
2
×
0.1µF
DRIVER 1 OUT
RX1 IN
DRIVER 2 OUT
TO LINE
RX2 IN
RX3 IN
RX4 IN
DRIVER 3 OUT
RX5 IN (LOW-Q)
ON/OFF
NC
V
CC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LT1341
28 V
–
27
26
25
24
23
22
21
20
19
DRIVER 1 IN
RX1 OUT
DRIVER 2 IN
RX2 OUT
RX3 OUT
RX4 OUT
TO LOGIC
2
×
0.1µF
0.1µF
RECEIVER
OUTPUT
C
L
= 50pF
DRIVER
R
OUTPUT
R
L
= 3k
C
L
= 2500pF
DRIVER 3 IN
18 RX5 OUT (LOW-Q)
17
GND
16
DRIVER DISABLE
15
NC
INPUT
RING DETECT IN
µCONTROLLER
OR
µPROCESSOR
SHUTDOWN
CONTROL OUT
LT1341 • TA01
U
Output Waveforms
LT1341 • TA02
UO
UO
1
LT1341
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
+
1
5V V
CC
2
C1
+
3
C1
–
4
DRIVER 1 OUT 5
RX1 IN 6
DRIVER 2 OUT 7
RX2 IN 8
RX3 IN 9
RX4 IN 10
DRIVER 3 OUT 11
RX5 IN
(LOW-Q) 12
ON/OFF 13
NC 14
28 V
–
27 C2
–
26 C2
+
25 DRIVER 1 IN
24 RX1 OUT
23 DRIVER 2 IN
22 RX2 OUT
21 RX3 OUT
20 RX4 OUT
19 DRIVER 3 IN
RX5 OUT
18 (LOW-Q)
17 GND
16 DRIVER
DISABLE
15 NC
Supply Voltage (V
CC
) ................................................ 6V
V
+
........................................................................ 13.2V
V
–
...................................................................... –13.2V
Input Voltage
Driver ........................................................... V
+
to V
–
Receiver ................................................ 30V to – 30V
Output Voltage
Driver .................................................... – 30V to 30V
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
LT1341C ................................................. 0°C to 70°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
ORDER PART
NUMBER
LT1341CG
LT1341CNW
LT1341CSW
G PACKAGE
NW PACKAGE
28-LEAD PLASTIC SSOP 28-LEAD (WIDE) PDIP
SW PACKAGE
28-LEAD (WIDE) 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 factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
PARAMETER
Power Supply Generator
V
+
Output
V
–
Output
Supply Current (V
CC
)
Supply Current When OFF (V
CC
)
Supply Rise Time
Shutdown to Turn-On
ON/OFF Pin Thresholds
ON/OFF Pin Current
DRIVER DISABLE Pin Thresholds
DRIVER DISABLE Pin Current
Oscillator Frequency
CONDITIONS
(Note 2)
MIN
TYP
8.6
–7
14
0.06
3
0.2
1.4
1.4
1.4
1.4
130
MAX
UNITS
V
V
mA
mA
mA
ms
V
V
µA
V
V
µA
kHz
(Note 3)
Shutdown (Note 4)
Driver Disable
C1 = C2 = 0.2µF,
C
+
= C
–
= 0.1µF
Input Low Level (Device Shut Down)
Input High Level (Device Enabled)
0V
≤
V
ON/OFF
≤
5V
Input Low Level (Drivers Enabled)
Input High Level (Drivers Disabled)
0V
≤
V
DRIVER DISABLE
≤
5V
q
17
0.150
q
q
q
q
q
q
0.8
80
0.8
500
2.4
–15
2.4
–10
2
U
W
U
U
W W
W
LT1341
ELECTRICAL CHARACTERISTICS
PARAMETER
Any Driver
Output Voltage Swing
Logic Input Voltage Level
Logic Input Current
Output Short-Circuit Current
Output Leakage Current
Data Rate (Note 7)
Slew Rate
Propagation Delay
Any Receiver
Input Voltage Thresholds
Hysteresis
Input Resistance
Output Leakage Current
Receivers 1 Through 4
Output Voltage
Output Short-Circuit Current
Propagation Delay
Receiver 5 (Low-I
Q
RX)
Output Voltage
Output Short-Circuit Current
Propagation Delay
CONDITIONS
Load = 3k to GND
(Note 2)
MIN
Positive
Negative
q
q
q
q
q
TYP
7.3
– 6.5
1.4
1.4
5
±17
10
MAX
UNITS
V
V
V
V
µA
mA
µA
kBaud
kBaud
V/µs
V/µs
µs
µs
V
V
V
kΩ
µA
V
V
mA
mA
ns
ns
V
V
mA
mA
µs
µs
5
Input Low Level (V
OUT
= High)
Input High Level (V
OUT
= Low)
0.8V
≤
V
IN
≤
2V
V
OUT
= 0V
Shutdown V
OUT
=
±30V
(Note 4)
R
L
= 3k, C
L
= 2500pF
R
L
= 3k, C
L
= 1000pF
R
L
= 3k, C
L
= 51pF
R
L
= 3k, C
L
= 2500pF
Output Transition t
HL
High to Low (Note 5)
Output Transition t
LH
Low to High
Input Low Threshold (V
OUT
= High)
Input High Threshold (V
OUT
= Low)
–5
0.8
20
100
2
±9
q
120
250
4
15
6
0.6
0.5
1.3
1.7
0.4
5
1
0.2
4.2
– 20
20
250
350
0.2
4.2
–4
4
1
1
30
1.3
1.3
0.8
q
0.1
3
Shutdown (Note 4) 0
≤
V
OUT
≤
V
CC
Output Low, I
OUT
= – 1.6mA
Output High, I
OUT
= 160µA (V
CC
= 5V)
Sinking Current, V
OUT
= V
CC
Sourcing Current, V
OUT
= 0V
Output Transition t
HL
High to Low (Note 6)
Output Transition t
LH
Low to High
Output Low, I
OUT
= – 500µA
Output High, I
OUT
= 160µA (V
CC
= 5V)
Sinking Current, V
OUT
= V
CC
Sourcing Current, V
OUT
= 0V
Output Transition t
HL
High to Low (Note 6)
Output Transition t
LH
Low to High
q
q
q
2.4
1.0
7
10
0.4
– 10
600
600
0.4
–2
3
3
3.5
10
q
q
3.5
2
The
q
denotes specifications which apply over the full 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.
Note 2:
Testing done at V
CC
= 5V and V
ON/OFF
= 3V.
Note 3:
Supply current is measured as the average over several charge
pump cycles. C
+
= C
–
= 0.1µF, C1 = C2 = 0.2µF. All outputs are open with
all driver inputs tied high.
Note 4:
Supply current and leakage measurements in shutdown are
performed with V
ON/OFF
≤
0.1V. Supply current measurements using driver
disable are performed with V
DRIVER DISABLE
≥
3V.
Note 5:
For driver delay measurements, R
L
= 3k and C
L
= 51pF. Trigger
points are set between the driver’s input logic threshold and the output
transition to the zero crossing (t
HL
= 1.4V to 0V and t
LH
= 1.4V to 0V).
Note 6:
For receiver delay measurements, C
L
= 51pF. Trigger points are
set between the receiver’s input logic threshold and the output transition
to standard TTL/CMOS logic threshold (t
HL
= 1.3V to 2.4V and t
LH
= 1.7V
to 0.8V).
Note 7:
Data rate operation guaranteed by slew rate, short-circuit current
and propagation delay tests.
3
LT1341
TYPICAL PERFOR A CE CHARACTERISTICS
Driver Output Voltage
10
8
DRIVER OUTPUT VOLTAGE (V)
R
L
= 3k
OUTPUT HIGH
THRESHOLD VOLTAGE (V)
6
4
2
0
–2
–4
–6
–8
–10
–55 –25
2.25
2.00
1.75
1.50
1.25
1.00
0.75
INPUT LOW
INPUT HIGH
SUPPLY CURRENT (mA)
V
CC
= 5.5V
V
CC
= 5V
V
CC
= 4.5V
V
CC
= 4.5V
V
CC
= 5V
V
CC
= 5.5V
OUTPUT LOW
50
25
0
75
TEMPERATURE (°C)
100
125
Supply Current in Shutdown
150
125
THRESHOLD VOLTAGE (V)
SUPPLY CURRENT (µA)
SUPPLY CURRENT (mA)
100
75
50
25
0
–55 –25
50
25
75
0
TEMPERATURE (°C)
ON/OFF Thresholds
3.0
2.5
THRESHOLD VOLTAGE (V)
LEAKAGE CURRENT(
µA)
SUPPLY CURRENT (mA)
2.0
1.5
1.0
ON THRESHOLD
OFF THRESHOLD
0.5
0
–55 –25
50
25
75
0
TEMPERATURE (°C)
4
U W
LT1341 • TPC01
Receiver Input Thresholds
3.00
2.75
2.50
Supply Current vs Data Rate
80
70
60
50
40
30
20
10
3DRIVERS ACTIVE
R
L
= 3k
C
L
= 2500pF
0.50
–55 –25
50
25
0
75
TEMPERATURE (°C)
100
125
0
0
25
75
50
100
DATA RATE (kBAUD)
125
150
LT1341 • TPC02
LT1341 • TPC03
Supply Current in Driver Disable
5
DRIVER DISABLE Threshold
3.0
2.5
2.0
1.5
1.0
0.5
0
–55 –25
4
3
2
1
100
125
0
–55 –25
50
25
0
75
TEMPERATURE (°C)
100
125
50
25
75
0
TEMPERATURE (°C)
100
125
LT1341 • TPC04
LT1341 • TPC05
LT1341 • TPC06
Supply Current
40
35
30
25
20
15
10
5
100
125
Driver Leakage in Shutdown
100
3DRIVERS LOADED R
L
= 3k
2DRIVERS LOADED R
L
= 3k
1DRIVER LOADED R
L
= 3k
NO LOAD
10
1
V
OUT
= 30V
V
OUT
= –30V
0
–55 –25
50
25
0
75
TEMPERATURE (°C)
100
125
0.1
–55 –25
50
25
0
75
TEMPERATURE (°C)
100
125
LT1341 • TPC07
LT1341 • TPC08
LT1341 • TPC09
LT1341
TYPICAL PERFOR A CE CHARACTERISTICS
Driver Short-Circuit Current
30
SHORT-CIRCUIT CURRENT (mA)
25
20
15
SHORT-CIRCUIT CURRENT (mA)
10
5
0
–55 –25
50
25
75
0
TEMPERATURE (°C)
Receiver Output Waveforms
DRIVER OUTPUT
R
L
= 3k
RX5 OUTPUT
C
L
= 50pF
RX1 TO RX4
OUTPUT
C
L
= 50pF
INPUT
PI FU CTIO S
V
CC
:
5V Input Supply Pin. This pin should be decoupled
with a 0.1µF ceramic capacitor close to the package pin.
Insufficient supply bypassing can lead to low output drive
levels and erratic charge pump operation.
GND:
Ground Pin.
ON/OFF:
A TTL/CMOS logic low puts the device in the low
power shutdown mode. All of the drivers and four receiv-
ers go to a high impedance state. Receiver RX5 remains
active while the transceiver is in shutdown. The trans-
ceiver consumes only 60µA of supply current while in
shutdown. A logic high fully enables the transceiver.
DRIVER DISABLE:
This pin provides an alternate control
for the charge pump and RS232 drivers. A logic high on
this pin shuts down the charge pump and places all drivers
in a high impedance state. All receivers remain active
under these conditions. Floating the driver disable pin or
driving it to a logic low level fully enables the transceiver.
Supply current drops to 3mA when in driver disable mode.
A logic low on the ON/OFF pin supersedes the state of the
DRIVER DISABLE pin.
V
+
:
Positive Supply Output (RS232 Drivers). V
+
≈
2V
CC
–
1.5V. This pin requires an external charge storage capaci-
tor C
≥
0.1µF, tied to ground or V
CC
. Larger value
capacitors may be used to reduce supply ripple. With
multiple transceivers, the V
+
and V
–
pins may be paral-
leled into common capacitors. For large numbers of
transceivers, increasing the size of the storage capaci-
tors is recommended to reduce ripple.
U W
Receiver Short-Circuit Current
50
I
SC+
40
RX1 TO RX4 I
SC–
30
RX1 TO RX4 I
SC+
RX5 I
SC–
I
SC–
20
10
RX5 I
SC+
100
125
0
–55 –25
50
25
0
75
TEMPERATURE (°C)
100
125
LT1341 • TPC10
LT1341 • TPC11
Driver Output Waveforms
DRIVER OUTPUT
R
L
= 3k
C
L
= 2500pF
INPUT
LT1341 • TPC12
LT1341 • TPC13
U
U
U
5
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