1
LTC1334
Single 5V RS232/RS485
Multiprotocol Transceiver
The LTC
®
1334 is a low power CMOS bidirectional trans-
ceiver featuring two reconfigurable interface ports. It can
be configured as two RS485 differential ports, as two dual
RS232 single-ended ports or as one RS485 differential
port and one dual RS232 single-ended port. An onboard
charge pump requires four 0.1
µ
F capacitors to generate
boosted positive and negative supplies, allowing the RS232
drivers to meet the RS232
±
5V output swing requirement
with only a single 5V supply. A shutdown mode reduces
the I
CC
supply current to 10
µ
A.
The RS232 transceivers are in full compliance with RS232
specifications. The RS485 transceivers are in full compli-
ance with RS485 and RS422 specifications. All interface
drivers feature short-circuit and thermal shutdown pro-
tection. An enable pin allows RS485 driver outputs to be
forced into high impedance, which is maintained even
when the outputs are forced beyond supply rails or power
is off. Both driver outputs and receiver inputs feature
±
10kV ESD protection. A loopback mode allows the driver
outputs to be connected back to the receiver inputs for
diagnostic self-test.
s
Four RS232 Transceivers or Two RS485
Transceivers on One Chip
s
Operates from a Single 5V Supply
s
Withstands Repeated
±
10kV ESD Pulses
s
Uses Small Charge Pump Capacitors: 0.1
µ
F
s
Low Supply Current: 8mA Typical
s
10
µ
A Supply Current in Shutdown
s
Self-Testing Capability in Loopback Mode
s
Power-Up/Down Glitch-Free Outputs
s
Driver Maintains High Impedance in Three-State,
Shutdown or with Power Off
s
Thermal Shutdown Protection
s
Receiver Inputs Can Withstand
±
25V
s
Low Power RS485/RS422/RS232/EIA562 Interface
s
Software-Selectable Multiprotocol Interface Port
s
Cable Repeaters
s
Level Translators
, LTC and LT are registered trademarks of Linear Technology Corporation.
21
5V
8
5V
9
5V
20
0V
26
3
26
3
27
28
V
CC1
5V
120
4
LTC1334
LTC1334 · TA01
RX OUT
23
RS485 INTERFACE
DR ENABLE
5
6
7
14
24
DR IN
22
15
13
21
LTC1334
RX OUT
18
5V
DR ENABLE
12
11
10
9
8
14
17
DR IN
19
5V
20
15
120
4000-FT 24-GAUGE TWISTED PAIR
5V
0V
11
DR IN
19
4
24
RX OUT
12
16
RX OUT
7
DR IN
23
RS232 INTERFACE
ALL CAPACITORS: 0.1
µ
F MONOLITHIC CERAMIC TYPE
10
DR IN
18
5
25
RX OUT
13
17
RX OUT
6
DR IN
22
1
2
2
1
28
27
V
CC2
5V
DESCRIPTIO
U
FEATURES
APPLICATIO S
U
TYPICAL APPLICATIO
U
2
LTC1334
A
U
G
W
A
W
U
W
A
R
BSOLUTE
XI
TI
S
ORDER PART
NUMBER
LTC1334CG
LTC1334CNW
LTC1334CSW
LTC1334IG
LTC1334ISW
(Note 1)
Supply Voltage (V
CC
) ............................................. 6.5V
Input Voltage
Drivers ................................... 0.3V to (V
CC
+ 0.3V)
Receivers ............................................. 25V to 25V
ON/OFF, LB, SEL1, SEL2 ........ 0.3V to (V
CC
+ 0.3V)
Output Voltage
Drivers ................................................. 18V to 18V
Receivers ............................... 0.3V to (V
CC
+ 0.3V)
Short-Circuit Duration
Output ........................................................ Indefinite
V
DD
, V
EE
, C1
+
, C1
, C2
+
, C2
.......................... 30 sec
Operating Temperature Range
Commercial ........................................... 0
°
C to 70
°
C
Industrial ............................................ 40
°
C to 85
°
C
Storage Temperature Range ................ 65
°
C to 150
°
C
Lead Temperature (Soldering, 10 sec)................ 300
°
C
W
U
U
PACKAGE/ORDER I FOR ATIO
T
JMAX
= 125
°
C,
JA
= 90
°
C/W (G)
T
JMAX
= 125
°
C,
JA
= 56
°
C/W (NW)
T
JMAX
= 125
°
C,
JA
= 85
°
C/W (SW)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
TOP VIEW
28
27
26
25
24
23
22
21
20
19
18
17
16
15
C2
+
C2
V
CC
R
B1
R
A1
D
Z1
/DE1
D
Y1
LB
ON/OFF
D
Y2
D
Z2
/DE2
R
A2
R
B2
V
EE
C1
+
C1
V
DD
A1
B1
Y1
Z1
SEL1
SEL2
Z2
Y2
B2
A2
GND
SW PACKAGE
28-LEAD PLASTIC SO WIDE
G PACKAGE
28-LEAD PLASTIC SSOP
NW PACKAGE
28-LEAD PDIP WIDE
Consult factory for Military grade parts.
DC ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
RS485 Driver (SEL1 = SEL2 = High)
V
OD1
Differential Driver Output Voltage (Unloaded)
I
O
= 0
q
6
V
V
OD2
Differential Driver Output Voltage (With Load)
Figure 1, R = 50
(RS422)
q
2.0
6
V
Figure 1, R = 27
(RS485)
q
1.5
6
V
V
OD
Change in Magnitude of Driver Differential
Figure 1, R = 27
or R = 50
q
0.2
V
Output Voltage for Complementary Output States
V
OC
Driver Common Mode Output Voltage
Figure 1, R = 27
or R = 50
q
3
V
V
OC
Change in Magnitude of Driver Common Mode
Figure 1, R = 27
or R = 50
q
0.2
V
Output Voltage for Complementary Output States
I
OSD
Driver Short-Circuit Current
7V
V
O
12V, V
O
= High
q
35
250
mA
7V
V
O
12V, V
O
= Low (Note 4)
q
10
250
mA
I
OZD
Three-State Output Current (Y, Z)
7V
V
O
12V
q
±
5
±
500
µ
A
RS232 Driver (SEL1 = SEL2 = Low)
V
O
Output Voltage Swing
Figure 4, R
L
= 3k, Positive
q
5
6.5
V
Figure 4, R
L
= 3k, Negative
q
5
6.5
V
I
OSD
Output Short-Circuit Current
V
O
= 0V
q
±
60
mA
Driver Inputs and Control Inputs
V
IH
Input High Voltage
D, DE, ON/OFF, SEL1, SEL2, LB
q
2
V
V
IL
Input Low Voltage
D, DE, ON/OFF, SEL1, SEL2, LB
q
0.8
V
I
IN
Input Current
D, SEL1, SEL2
q
±
10
µ
A
DE, ON/OFF, LB
q
4
15
µ
A
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
°
C. V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1
µ
F (Notes 2, 3)
3
LTC1334
AC ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
RS485 Receiver (SEL1 = SEL2 = High)
V
TH
Differential Input Threshold Voltage
7V
V
CM
12V, LTC1334C
q
0.2
0.2
V
7V
V
CM
7V, LTC1334I
q
0.3
0.3
V
V
TH
Input Hysteresis
V
CM
= 0V
70
mV
I
IN
Input Current (A, B)
V
IN
= 7V
q
0.8
mA
V
IN
= 12V
q
1.0
mA
R
IN
Input Resistance
7V
V
IN
12V
q
12
24
k
RS232 Receiver (SEL1 = SEL2 = Low)
V
TH
Receiver Input Threshold Voltage
Input Low Threshold
q
0.8
V
Input High Threshold
q
2.4
V
V
TH
Receiver Input Hysteresis
0.6
V
R
IN
Receiver Input Resistance
V
IN
=
±
10V
3
5
7
k
Receiver Output
V
OH
Receiver Output High Voltage
I
O
= 3mA, V
IN
= 0V, SEL1 = SEL2 = Low
q
3.5
4.6
V
V
OL
Receiver Output Low Voltage
I
O
= 3mA, V
IN
= 3V, SEL1 = SEL2 = Low
q
0.2
0.4
V
I
OSR
Short-Circuit Current
0V
V
O
V
CC
q
7
85
mA
I
OZR
Three-State Output Current
ON/OFF = Low
q
±
10
µ
A
R
OB
Inactive "B" Output Pull-Up Resistance (Note 5)
ON/OFF = High, SEL1 = SEL2 = High
50
k
Power Supply Generator
V
DD
V
DD
Output Voltage
No Load, ON/OFF = High
8.5
V
I
DD
= 10mA, ON/OFF = High
7.6
V
V
EE
V
EE
Output Voltage
No Load, ON/OFF = High
7.7
V
I
EE
= 10mA, ON/OFF = High
6.9
V
Power Supply
I
CC
V
CC
Supply Current
No Load, SEL1 = SEL2 = High
q
8
25
mA
No Load Shutdown, ON/OFF = 0V
q
10
100
µ
A
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
RS232 Mode (SEL1 = SEL2 = Low)
SR
Slew Rate
Figure 4, R
L
= 3k, C
L
= 15pF
q
30
V/
µ
s
Figure 4, R
L
= 3k, C
L
= 1000pF
q
4
V/
µ
s
t
T
Transition Time
Figure 4, R
L
= 3k, C
L
= 2500pF
q
0.22
1.9
3.1
µ
s
t
PLH
Driver Input to Output
Figures 4, 9, R
L
= 3k, C
L
= 15pF
q
0.6
4
µ
s
t
PHL
Driver Input to Output
Figures 4, 9, R
L
= 3k, C
L
= 15pF
q
0.6
4
µ
s
t
PLH
Receiver Input to Output
Figures 5, 10
q
0.3
6
µ
s
t
PHL
Receiver Input to Output
Figures 5, 10
q
0.4
6
µ
s
RS485 Mode (SEL1 = SEL2 = High)
t
PLH
Driver Input to Output
Figures 2, 6, R
L
= 54
, C
L
= 100pF
q
20
40
70
ns
t
PHL
Driver Input to Output
Figures 2, 6, R
L
= 54
, C
L
= 100pF
q
20
40
70
ns
t
SKEW
Driver Output to Output
Figures 2, 6, R
L
= 54
, C
L
= 100pF
q
5
15
ns
t
r
, t
f
Driver Rise and Fall Time
Figures 2, 6, R
L
= 54
, C
L
= 100pF
q
3
15
40
ns
DC ELECTRICAL CHARACTERISTICS
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
°
C. V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1
µ
F (Notes 2, 3)
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
°
C. V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1
µ
F (Notes 2, 3)
4
LTC1334
AC ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those values beyond which the
safety of the device cannot be guaranteed.
Note 2: All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to device ground unless
otherwise specified.
Note 3: All typicals are given at V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1
µ
F
and T
A
= 25
°
C.
Note 4: Short-circuit current for RS485 driver output low state folds back
above V
CC
. Peak current occurs around V
O
= 3V.
Note 5: The "B" RS232 receiver output is disabled in RS485 mode
(SEL1 = SEL2 = high). The unused output driver goes into a high
impedance mode and has a resistor to V
CC
. See Applications Information
section for more details.
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
Receiver Output High Voltage
vs Temperature
TEMPERATURE (
°
C)
50
OUTPUT VOLTAGE (V)
5.0
4.9
4.8
4.7
4.6
4.5
4.4
4.3
4.2
4.1
4.0
0
50
75
LTC1334 · TPC01
25
25
100
125
I
OUT
= 3mA
V
CC
= 5V
TEMPERATURE (
°
C)
50
TIME (ns)
20
18
16
14
12
10
8
6
4
2
0
0
50
75
LTC1334 · TPC03
25
25
100
125
V
CC
= 5V
RS485 Receiver Skew
t
PLH
t
PHL
vs Temperature
TEMPERATURE (
°
C)
50
OUTPUT VOLTAGE (V)
0.5
0.4
0.3
0.2
0.1
0
0
50
75
LTC1334 · TPC02
25
25
100
125
I
OUT
= 3mA
V
CC
= 5V
Receiver Output Low Voltage
vs Temperature
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
°
C. V
CC
= 5V, C1 = C2 = C3 = C4 = 0.1
µ
F (Notes 2, 3)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
RS485 Mode (SEL1 = SEL2 = High)
t
ZL
Driver Enable to Output Low
Figures 3, 7, C
L
= 100pF, S1 Closed
q
50
90
ns
t
ZH
Driver Enable to Output High
Figures 3, 7, C
L
= 100pF, S2 Closed
q
50
90
ns
t
LZ
Driver Disable from Low
Figures 3, 7, C
L
= 15pF, S1 Closed
q
50
90
ns
t
HZ
Driver Disable from High
Figures 3, 7, C
L
= 15pF, S2 Closed
q
60
90
ns
t
PLH
Receiver Input to Output
Figures 2, 8, R
L
= 54
, C
L
= 100pF
q
20
60
140
ns
t
PHL
Receiver Input to Output
Figures 2, 8, R
L
= 54
, C
L
= 100pF
q
20
70
140
ns
t
SKEW
Differential Receiver Skew,
t
PLH
t
PHL
Figures 2, 8, R
L
= 54
, C
L
= 100pF
10
ns
5
LTC1334
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
Receiver Output Current
vs Output High Voltage
RS232 Receiver Input Threshold
Voltage vs Temperature
Receiver Output Current
vs Output Low Voltage
OUTPUT VOLTAGE (V)
2.0
OUTPUT CURRENT (mA)
2.5
3.0
3.5
4.0
LTC1334 · TPC04
4.5
20
18
16
14
12
10
8
6
4
2
0
5.0
T
A
= 25
°
C
V
CC
= 5V
OUTPUT VOLTAGE (V)
0
0.5
OUTPUT CURRENT (mA)
1.0
2.0
1.5
2.5
3.0
LTC1334 · TPC05
40
35
30
25
20
15
10
5
0
T
A
= 25
°
C
V
CC
= 5V
TEMPERATURE (
°
C)
50
INPUT THRESHOLD VOLTAGE (V)
2.0
1.8
1.6
1.4
1.2
1.0
0.8
25
75
LTC1334 · TPC06
25
0
50
100
125
INPUT HIGH
INPUT LOW
V
CC
= 5V
Charge Pump Output Voltage
vs Temperature
Supply Current
vs Temperature (RS232)
Supply Current
vs Temperature (RS485)
TEMPERATURE (
°
C)
50
OUTPUT VOLTAGE (V)
10
8
6
4
2
0
2
4
6
8
10
0
50
75
LTC1334 · TPC07
25
25
100
125
V
DD
(NO LOAD)
V
DD
(10mA LOAD)
V
EE
(10mA LOAD)
V
EE
(NO LOAD)
V
CC
= 5V
TEMPERATURE (
°
C)
50
0
SUPPLY CURRENT (mA)
10
25
0
50
75
LTC1334 · TPC08
5
20
15
25
25
100
125
V
CC
= 5V
NO LOAD
SEL 1 = SEL 2 = HIGH
TEMPERATURE (
°
C)
50
SUPPLY CURRENT (mA)
10
9
8
7
6
5
4
3
2
1
0
0
50
75
LTC1334 · TPC09
25
25
100
125
V
CC
= 5V
NO LOAD
SEL 1 = SEL 2 = HIGH
RS485 Driver Differential Output
Voltage vs Temperature
RS485 Driver Skew
vs Temperature
RS485 Driver Differential Output
Current vs Output Voltage
TEMPERATURE (
°
C)
50
DIFFERENTIAL OUTPUT VOLTAGE (V)
2.6
2.5
2.4
2.3
2.2
2.1
2.0
1.9
1.8
1.7
1.6
0
50
75
LTC1334 · TPC10
25
25
100
125
R
L
= 54
V
CC
= 5V
DIFFERENTIAL OUTPUT VOLTAGE (V)
0
70
60
50
40
30
20
10
0
3
4
LTC1334 · TPC11
1
2
5
DIFFERENTIAL OUTPUT CURRENT (mA)
T
A
= 25
°
C
V
CC
= 5V
TEMPERATURE (
°
C)
50
TIME (
µ
s)
15
12
9
6
3
0
0
50
75
LTC1334 · TPC12
25
25
100
125
V
CC
= 5V
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