1
LT1341
5V RS232 Transceiver with One
Receiver Active in Shutdown
S
FEATURE
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.
s
One Receiver Remains Active While in Shutdown
s
ESD Protection Over
10kV
s
Uses Small Capacitors: 0.1
F, 0.2
F
s
60
A Supply Current in Shutdown
s
Pin Compatible with LT1137A
s
120kBaud Operation for R
L
= 3k, C
L
= 2500pF
s
250kBaud Operation for R
L
= 3k, C
L
= 1000pF
s
CMOS Comparable Low Power: 60mW
s
Operates from a Single 5V Supply
s
Easy PC Layout: Flowthrough Architecture
s
Rugged Bipolar Design
s
Outputs Assume a High Impedance State When
Off or Powered Down
s
Absolutely No Latchup
s
Available in SSOP Package
D
U
ESCRIPTIO
, LTC and LT are registered trademarks of Linear Technology Corporation.
TransZorb is a registered trademark of General Instruments, GSI
Output Waveforms
R
LT1341 TA02
RECEIVER
OUTPUT
C
L
= 50pF
DRIVER
OUTPUT
R
L
= 3k
C
L
= 2500pF
INPUT
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
DRIVER 1 IN
RX1 OUT
DRIVER 2 IN
RX2 OUT
RX3 OUT
RX4 OUT
DRIVER 3 IN
V
+
0.1
F
2
0.1
F
2
0.1
F
0.1
F
GND
DRIVER DISABLE
TO LINE
TO LOGIC
V
LT1341 TA01
RX5 OUT (LOW-Q)
RING DETECT IN
CONTROLLER
OR
PROCESSOR
SHUTDOWN
CONTROL OUT
LT1341
NC
V
CC
DRIVER 1 OUT
RX1 IN
DRIVER 2 OUT
RX2 IN
RX3 IN
RX4 IN
DRIVER 3 OUT
RX5 IN (LOW-Q)
ON/OFF
NC
s
Notebook Computers
s
Palmtop Computers
U
S
A
O
PPLICATI
U
A
O
PPLICATI
TYPICAL
2
LT1341
(Note 1)
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
A
U
G
W
A
W
U
W
A
R
BSOLUTE
XI
TI
S
W
U
U
PACKAGE/ORDER I FOR ATIO
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Power Supply Generator
V
+
Output
8.6
V
V
Output
7
V
Supply Current (V
CC
)
(Note 3)
14
17
mA
Supply Current When OFF (V
CC
)
Shutdown (Note 4)
q
0.06
0.150
mA
Driver Disable
3
mA
Supply Rise Time
C1 = C2 = 0.2
F,
0.2
ms
Shutdown to Turn-On
C
+
= C
= 0.1
F
ON/OFF Pin Thresholds
Input Low Level (Device Shut Down)
q
1.4
0.8
V
Input High Level (Device Enabled)
q
2.4
1.4
V
ON/OFF Pin Current
0V
V
ON/OFF
5V
q
15
80
A
DRIVER DISABLE Pin Thresholds
Input Low Level (Drivers Enabled)
q
1.4
0.8
V
Input High Level (Drivers Disabled)
q
2.4
1.4
V
DRIVER DISABLE Pin Current
0V
V
DRIVER DISABLE
5V
q
10
500
A
Oscillator Frequency
130
kHz
ELECTRICAL C
C
HARA TERISTICS
(Note 2)
ORDER PART
NUMBER
Consult factory for Industrial and Military grade parts.
LT1341CG
LT1341CNW
LT1341CSW
1
2
3
4
5
6
7
8
9
10
11
12
13
14
V
+
5V V
CC
C1
+
C1
DRIVER 1 OUT
RX1 IN
DRIVER 2 OUT
RX2 IN
RX3 IN
RX4 IN
DRIVER 3 OUT
ON/OFF
NC
28
27
26
25
24
23
22
21
20
19
18
17
16
15
V
C2
C2
+
DRIVER 1 IN
RX1 OUT
DRIVER 2 IN
RX2 OUT
RX3 OUT
RX4 OUT
DRIVER 3 IN
GND
NC
NW PACKAGE
28-LEAD (WIDE) PDIP
TOP VIEW
SW PACKAGE
28-LEAD (WIDE) PLASTIC SO
G PACKAGE
28-LEAD PLASTIC SSOP
RX5 IN
(LOW-Q)
RX5 OUT
(LOW-Q)
DRIVER
DISABLE
T
JMAX
= 125
C,
JA
= 96
C/ W (G)
T
JMAX
= 125
C,
JA
= 56
C/ W (NW)
T
JMAX
= 125
C,
JA
= 85
C/ W (SW)
3
LT1341
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Any Driver
Output Voltage Swing
Load = 3k to GND
Positive
q
5
7.3
V
Negative
q
6.5
5
V
Logic Input Voltage Level
Input Low Level (V
OUT
= High)
q
1.4
0.8
V
Input High Level (V
OUT
= Low)
q
2
1.4
V
Logic Input Current
0.8V
V
IN
2V
q
5
20
A
Output Short-Circuit Current
V
OUT
= 0V
9
17
mA
Output Leakage Current
Shutdown V
OUT
=
30V (Note 4)
q
10
100
A
Data Rate (Note 7)
R
L
= 3k, C
L
= 2500pF
120
kBaud
R
L
= 3k, C
L
= 1000pF
250
kBaud
Slew Rate
R
L
= 3k, C
L
= 51pF
15
30
V/
s
R
L
= 3k, C
L
= 2500pF
4
6
V/
s
Propagation Delay
Output Transition t
HL
High to Low (Note 5)
0.6
1.3
s
Output Transition t
LH
Low to High
0.5
1.3
s
Any Receiver
Input Voltage Thresholds
Input Low Threshold (V
OUT
= High)
0.8
1.3
V
Input High Threshold (V
OUT
= Low)
1.7
2.4
V
Hysteresis
q
0.1
0.4
1.0
V
Input Resistance
3
5
7
k
Output Leakage Current
Shutdown (Note 4) 0
V
OUT
V
CC
q
1
10
A
Receivers 1 Through 4
Output Voltage
Output Low, I
OUT
= 1.6mA
q
0.2
0.4
V
Output High, I
OUT
= 160
A (V
CC
= 5V)
q
3.5
4.2
V
Output Short-Circuit Current
Sinking Current, V
OUT
= V
CC
20
10
mA
Sourcing Current, V
OUT
= 0V
10
20
mA
Propagation Delay
Output Transition t
HL
High to Low (Note 6)
250
600
ns
Output Transition t
LH
Low to High
350
600
ns
Receiver 5 (Low-I
Q
RX)
Output Voltage
Output Low, I
OUT
= 500
A
q
0.2
0.4
V
Output High, I
OUT
= 160
A (V
CC
= 5V)
q
3.5
4.2
V
Output Short-Circuit Current
Sinking Current, V
OUT
= V
CC
4
2
mA
Sourcing Current, V
OUT
= 0V
2
4
mA
Propagation Delay
Output Transition t
HL
High to Low (Note 6)
1
3
s
Output Transition t
LH
Low to High
1
3
s
ELECTRICAL C
C
HARA TERISTICS
(Note 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
= 0.1
F, C1 = C2 = 0.2
F. 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.
4
LT1341
C
C
HARA TERISTICS
U
W
A
TYPICAL PERFOR
CE
Driver Output Voltage
Supply Current vs Data Rate
TEMPERATURE (C)
55
10
DRIVER OUTPUT VOLTAGE (V)
8
4
2
0
10
4
0
50
75
LT1341 TPC01
6
6
8
2
25
25
100
125
OUTPUT HIGH
OUTPUT LOW
R
L
= 3k
V
CC
= 5V
V
CC
= 4.5V
V
CC
= 5.5V
V
CC
= 4.5V
V
CC
= 5V
V
CC
= 5.5V
TEMPERATURE (C)
55
0.50
THRESHOLD VOLTAGE (V)
0.75
1.25
1.50
1.75
3.00
2.25
0
50
75
LT1341 TPC02
1.00
2.50
2.75
2.00
25
25
100
125
INPUT HIGH
INPUT LOW
Receiver Input Thresholds
DATA RATE (kBAUD)
0
0
SUPPLY CURRENT (mA)
20
30
40
60
25
50
125
150
LT1341 TPC03
70
80
50
10
75
100
3DRIVERS ACTIVE
R
L
= 3k
C
L
= 2500pF
DRIVER DISABLE Threshold
Supply Current in Shutdown
ON/OFF Thresholds
TEMPERATURE (C)
55
0
SUPPLY CURRENT (mA)
2
5
0
50
75
LT1341 TPC05
1
4
3
25
25
100
125
TEMPERATURE (C)
55
THRESHOLD VOLTAGE (V)
2.0
2.5
3.0
25
75
LT1341 TPC06
1.5
1.0
25
0
50
100
125
0.5
0
TEMPERATURE (C)
55
THRESHOLD VOLTAGE (V)
2.0
2.5
3.0
25
75
LT1341 TPC07
1.5
1.0
25
0
50
100
125
0.5
0
ON THRESHOLD
OFF THRESHOLD
Supply Current
TEMPERATURE (C)
55
SUPPLY CURRENT (
A)
100
125
150
25
75
LT1341 TPC04
75
50
25
0
50
100
125
25
0
Driver Leakage in Shutdown
TEMPERATURE (C)
0.1
LEAKAGE CURRENT(
A)
10
100
LT1341 TPC09
1
55
0
50
75
25
25
100
125
V
OUT
= 30V
V
OUT
= 30V
TEMPERATURE (C)
0
SUPPLY CURRENT (mA)
10
15
20
30
LT1341 TPC08
35
40
25
5
55
0
50
75
25
25
100
125
NO LOAD
1DRIVER LOADED R
L
= 3k
2DRIVERS LOADED R
L
= 3k
3DRIVERS LOADED R
L
= 3k
Supply Current in Driver Disable
5
LT1341
C
C
HARA TERISTICS
U
W
A
TYPICAL PERFOR
CE
Receiver Output Waveforms
Receiver Short-Circuit Current
Driver Output Waveforms
LT1341 TPC12
DRIVER OUTPUT
R
L
= 3k
C
L
= 2500pF
INPUT
DRIVER OUTPUT
R
L
= 3k
PI FU CTIO S
U
U
U
V
CC
: 5V Input Supply Pin. This pin should be decoupled
with a 0.1
F 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 60
A 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
LT1341 TPC13
Driver Short-Circuit Current
TEMPERATURE (
C)
55
SHORT-CIRCUIT CURRENT (mA)
20
25
30
25
75
LT1341 TPC10
15
10
25
0
50
100
125
5
0
I
SC
+
I
SC
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
0.1
F, 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.
RX5 OUTPUT
C
L
= 50pF
RX1 TO RX4
OUTPUT
C
L
= 50pF
INPUT
TEMPERATURE (
C)
55
0
SHORT-CIRCUIT CURRENT (mA)
20
50
0
50
75
LT1341 TPC11
10
40
30
25
25
100
125
RX5 I
SC
+
RX5 I
SC
RX1 TO RX4 I
SC
+
RX1 TO RX4 I
SC
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