LTC1334IG [Linear]
Single 5V RS232/RS485 Multiprotocol Transceiver; 单5V RS232 / RS485多协议收发器
| 型号： | LTC1334IG |
| 厂家： | 
Linear |
| 描述： | Single 5V RS232/RS485 Multiprotocol Transceiver |
| 文件： | 总16页 (文件大小：273K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC1334
Single 5V RS232/RS485
Multiprotocol Transceiver
U
FEATURES
DESCRIPTIO
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 0.1µF capacitors to generate
boostedpositiveandnegativesupplies,allowingtheRS232
drivers to meet the RS232 ±5V output swing requirement
with only a single 5V supply. A shutdown mode reduces
the ICC supply current to 10µA.
■
Four RS232 Transceivers or Two RS485
Transceivers on One Chip
■
Operates from a Single 5V Supply
■
Withstands Repeated ±10kV ESD Pulses
■
Uses Small Charge Pump Capacitors: 0.1µF
■
Low Supply Current: 8mA Typical
■
10µA Supply Current in Shutdown
■
Self-Testing Capability in Loopback Mode
■
Power-Up/Down Glitch-Free Outputs
■
Driver Maintains High Impedance in Three-State,
Shutdown or with Power Off
Thermal Shutdown Protection
Receiver Inputs Can Withstand ±25V
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.
■
■
U
APPLICATIO S
■
Low Power RS485/RS422/RS232/EIA562 Interface
■
Software-Selectable Multiprotocol Interface Port
■
Cable Repeaters
Level Translators
■
, LTC and LT are registered trademarks of Linear Technology Corporation.
U
TYPICAL APPLICATIO
27
28
1
2
2
1
28
27
3
3
LTC1334
LTC1334
26
17
26
24
V
V
CC1
5V
CC2
13
12
4
5
5V
RS485 INTERFACE
RX OUT
RX OUT
23
22
18
19
120Ω
DR ENABLE
120Ω
DR ENABLE
DR IN
11
6
DR IN
10
9
7
4000-FT 24-GAUGE TWISTED PAIR
RS232 INTERFACE
21
20
24
25
22
23
15
21
20
19
18
17
16
15
8
5V
5V
5V
0V
5V
5V
5V
0V
8
9
4
5
11
10
13
12
RX OUT
RX OUT
DR IN
DR IN
DR IN
RX OUT
RX OUT
6
7
DR IN
14
14
ALL CAPACITORS: 0.1µF MONOLITHIC CERAMIC TYPE
LTC1334 • TA01
1
LTC1334
W
U
W W W
U
ABSOLUTE AXI U RATI GS
/O
PACKAGE RDER I FOR ATIO
(Note 1)
TOP VIEW
ORDER PART
NUMBER
Supply Voltage (VCC) ............................................. 6.5V
Input Voltage
Drivers ................................... –0.3V to (VCC + 0.3V)
Receivers ............................................. –25V to 25V
ON/OFF, LB, SEL1, SEL2 ........ –0.3V to (VCC + 0.3V)
Output Voltage
Drivers ................................................. –18V to 18V
Receivers ............................... –0.3V to (VCC + 0.3V)
Short-Circuit Duration
Output ........................................................ Indefinite
VDD, VEE, C1+, C1–, C2+, C2–.......................... 30 sec
Operating Temperature Range
+
–
+
–
C1
C1
1
2
3
4
5
6
7
8
9
28 C2
27 C2
V
26
25
24
23
22
V
DD
A1
CC
LTC1334CG
LTC1334CNW
LTC1334CSW
LTC1334IG
R
R
D
D
B1
A1
B1
Y1
Z1
/DE1
Z1
Y1
SEL1
SEL2
21 LB
LTC1334ISW
20 ON/OFF
Z2 10
Y2 11
19
18
17
16
15
D
D
R
R
Y2
/DE2
Z2
A2
B2
EE
B2 12
A2 13
GND 14
V
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
G PACKAGE
NW PACKAGE
28-LEAD PLASTIC SSOP 28-LEAD PDIP WIDE
SW PACKAGE
28-LEAD PLASTIC SO WIDE
TJMAX = 125°C, θJA = 90°C/W (G)
T
T
JMAX = 125°C, θJA = 56°C/W (NW)
JMAX = 125°C, θJA = 85°C/W (SW)
Consult factory for Military grade parts.
DC ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, C1 = C2 = C3 = C4 = 0.1µF (Notes 2, 3)
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
RS485 Driver (SEL1 = SEL2 = High)
V
V
Differential Driver Output Voltage (Unloaded)
Differential Driver Output Voltage (With Load)
I = 0
●
6
V
OD1
OD2
O
Figure 1, R = 50Ω (RS422)
Figure 1, R = 27Ω (RS485)
●
●
2.0
1.5
6
6
V
V
∆V
OD
Change in Magnitude of Driver Differential
Output Voltage for Complementary Output States
Figure 1, R = 27Ω or R = 50Ω
●
0.2
V
V
Driver Common Mode Output Voltage
Figure 1, R = 27Ω or R = 50Ω
Figure 1, R = 27Ω or R = 50Ω
●
●
3
V
V
OC
∆ V
Change in Magnitude of Driver Common Mode
Output Voltage for Complementary Output States
0.2
OC
I
I
Driver Short-Circuit Current
–7V ≤ V ≤ 12V, V = High
●
●
35
10
250
250
mA
mA
OSD
O
O
–7V ≤ V ≤ 12V, V = Low (Note 4)
O
O
Three-State Output Current (Y,Z)
–7V ≤ V ≤ 12V
●
±5
±500
µA
OZD
O
RS232 Driver (SEL1 = SEL2 = Low)
V
Output Voltage Swing
Figure 4, R = 3k, Positive
●
●
5
–5
6.5
–6.5
V
V
O
L
Figure 4, R = 3k, Negative
L
I
Output Short-Circuit Current
V = 0V
O
●
±60
mA
OSD
Driver Inputs and Control Inputs
V
V
Input High Voltage
Input Low Voltage
Input Current
D, DE, ON/OFF, SEL1, SEL2, LB
D, DE, ON/OFF, SEL1, SEL2, LB
●
●
2
V
V
IH
IL
0.8
I
D, SEL1, SEL2
DE, ON/OFF, LB
●
●
±10
–15
µA
µA
IN
–4
2
LTC1334
DC ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, C1 = C2 = C3 = C4 = 0.1µF (Notes 2, 3)
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
RS485 Receiver (SEL1 = SEL2 = High)
V
Differential Input Threshold Voltage
–7V ≤ V ≤ 12V, LTC1334C
●
●
–0.2
–0.3
0.2
0.3
V
V
TH
CM
–7V ≤ V ≤ 7V, LTC1334I
CM
∆V
Input Hysteresis
V
= 0V
CM
70
24
mV
TH
I
Input Current (A, B)
V
V
= –7V
= 12V
●
●
–0.8
1.0
mA
mA
IN
IN
IN
R
IN
Input Resistance
–7V ≤ V ≤ 12V
●
12
kΩ
IN
RS232 Receiver (SEL1 = SEL2 = Low)
V
Receiver Input Threshold Voltage
Input Low Threshold
Input High Threshold
●
●
0.8
V
V
TH
2.4
7
∆V
Receiver Input Hysteresis
Receiver Input Resistance
0.6
5
V
TH
R
V
= ±10V
IN
3
3.5
7
kΩ
IN
Receiver Output
V
V
Receiver Output High Voltage
Receiver Output Low Voltage
Short-Circuit Current
I = –3mA, V = 0V, SEL1 = SEL2 = Low
●
●
●
●
4.6
0.2
V
V
OH
OL
O
IN
I = 3mA, V = 3V, SEL1 = SEL2 = Low
0.4
85
O
IN
I
I
0V ≤ V ≤ V
CC
mA
µA
kΩ
OSR
OZR
O
Three-State Output Current
ON/OFF = Low
±10
R
Inactive “B” Output Pull-Up Resistance (Note 5)
ON/OFF = High, SEL1 = SEL2 = High
50
OB
Power Supply Generator
V
V
Output Voltage
No Load, ON/OFF = High
8.5
7.6
V
V
DD
DD
I
= –10mA, ON/OFF = High
DD
V
V
Output Voltage
No Load, ON/OFF = High
= 10mA, ON/OFF = High
–7.7
–6.9
V
V
EE
EE
I
EE
Power Supply
I
V
Supply Current
CC
No Load, SEL1 = SEL2 = High
No Load Shutdown, ON/OFF = 0V
●
●
8
10
25
100
mA
µA
CC
AC ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, C1 = C2 = C3 = C4 = 0.1µF (Notes 2, 3)
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
RS232 Mode (SEL1 = SEL2 = Low)
SR
Slew Rate
Figure 4, R = 3k, C = 15pF
●
●
30
V/µs
V/µs
L
L
Figure 4, R = 3k, C = 1000pF
4
L
L
t
t
t
t
t
Transition Time
Figure 4, R = 3k, C = 2500pF
●
●
●
●
●
0.22
1.9
0.6
0.6
0.3
0.4
3.1
4
µs
µs
µs
µs
µs
T
L
L
Driver Input to Output
Driver Input to Output
Receiver Input to Output
Receiver Input to Output
Figures 4, 9, R = 3k, C = 15pF
L L
PLH
PHL
PLH
PHL
Figures 4, 9, R = 3k, C = 15pF
4
L
L
Figures 5, 10
Figures 5, 10
6
6
RS485 Mode (SEL1 = SEL2 = High)
t
t
t
Driver Input to Output
Driver Input to Output
Driver Output to Output
Driver Rise and Fall Time
Figures 2, 6, R = 54Ω, C = 100pF
●
●
●
●
20
20
40
40
5
70
70
15
40
ns
ns
ns
ns
PLH
L
L
Figures 2, 6, R = 54Ω, C = 100pF
PHL
L
L
Figures 2, 6, R = 54Ω, C = 100pF
SKEW
L
L
t , t
Figures 2, 6, R = 54Ω, C = 100pF
3
15
r
f
L
L
3
LTC1334
AC ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, C1 = C2 = C3 = C4 = 0.1µF (Notes 2, 3)
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
RS485 Mode (SEL1 = SEL2 = High)
t
t
t
t
t
t
t
Driver Enable to Output Low
Driver Enable to Output High
Driver Disable from Low
Driver Disable from High
Receiver Input to Output
Receiver Input to Output
Differential Receiver Skew, t
Figures 3, 7, C = 100pF, S1 Closed
●
●
●
●
●
●
50
50
50
60
60
70
10
90
90
ns
ns
ns
ns
ns
ns
ns
ZL
L
Figures 3, 7, C = 100pF, S2 Closed
ZH
L
Figures 3, 7, C = 15pF, S1 Closed
90
LZ
L
Figures 3, 7, C = 15pF, S2 Closed
90
HZ
L
Figures 2, 8, R = 54Ω, C = 100pF
20
20
140
140
PLH
PHL
SKEW
L
L
Figures 2, 8, R = 54Ω, C = 100pF
L
L
– t
Figures 2, 8, R = 54Ω, C = 100pF
L L
PLH
PHL
Note 1: Absolute Maximum Ratings are those values beyond which the
safety of the device cannot be guaranteed.
Note 4: Short-circuit current for RS485 driver output low state folds back
above V . Peak current occurs around V = 3V.
CC
O
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 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 . See Applications Information
CC
section for more details.
Note 3: All typicals are given at V = 5V, C1 = C2 = C3 = C4 = 0.1µF
CC
and T = 25°C.
A
W
U
TYPICAL PERFORMANCE CHARACTERISTICS
Receiver Output High Voltage
vs Temperature
Receiver Output Low Voltage
vs Temperature
RS485 Receiver Skew
tPLH – tPHL vs Temperature
5.0
4.9
4.8
4.7
4.6
4.5
4.4
4.3
4.2
4.1
4.0
0.5
0.4
0.3
0.2
0.1
0
20
18
16
14
12
10
8
I
= 3mA
= 5V
I
= 3mA
= 5V
V
= 5V
OUT
CC
OUT
CC
CC
V
V
6
4
2
0
–50
0
25
50
75 100 125
–50
0
25
50
75 100 125
–50
–25
0
25
50
75 100 125
–25
–25
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
LTC1334 • TPC01
LTC1334 • TPC02
LTC1334 • TPC03
4
LTC1334
W
U
TYPICAL PERFORMANCE CHARACTERISTICS
Receiver Output Current
vs Output High Voltage
Receiver Output Current
vs Output Low Voltage
RS232 Receiver Input Threshold
Voltage vs Temperature
40
35
30
25
20
15
10
5
20
18
16
14
12
10
8
2.0
1.8
1.6
1.4
1.2
1.0
0.8
T
= 25°C
CC
T
= 25°C
CC
A
V
CC
= 5V
A
V
= 5V
V
= 5V
INPUT HIGH
INPUT LOW
6
4
2
0
0
2.5
0
0.5
1.0
1.5
2.0
3.0
2.0
2.5
3.5
4.0
4.5
5.0
–50 –25
0
25
50
75
100 125
3.0
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
TEMPERATURE (°C)
LTC1334 • TPC05
LTC1334 • TPC04
LTC1334 • TPC06
Charge Pump Output Voltage
vs Temperature
Supply Current
Supply Current
vs Temperature (RS485)
vs Temperature (RS232)
10
8
25
20
15
10
5
10
9
8
7
6
5
4
3
2
1
0
V
= 5V
V
= 5V
CC
CC
NO LOAD
NO LOAD
V
DD
(–10mA LOAD)
SEL 1 = SEL 2 = HIGH
6
SEL 1 = SEL 2 = HIGH
V
DD
(NO LOAD)
4
2
V
CC
= 5V
0
–2
–4
–6
–8
–10
V
EE
(10mA LOAD)
V
EE
(NO LOAD)
0
–50
0
25
50
75 100 125
–50
0
25
50
75 100 125
–50
–25
0
25
50
75 100 125
–25
–25
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
LTC1334 • TPC07
LTC1334 • TPC08
LTC1334 • TPC09
RS485 Driver Differential Output
Voltage vs Temperature
RS485 Driver Differential Output
Current vs Output Voltage
RS485 Driver Skew
vs Temperature
2.6
2.5
2.4
2.3
2.2
2.1
2.0
1.9
1.8
1.7
1.6
15
12
9
70
60
50
40
30
20
10
0
V = 5V
CC
R
V
= 54Ω
CC
T
= 25°C
CC
L
A
= 5V
V
= 5V
6
3
0
–50
0
25
50
75 100 125
–50
0
25
50
75 100 125
–25
–25
1
2
5
0
3
4
TEMPERATURE (°C)
TEMPERATURE (°C)
DIFFERENTIAL OUTPUT VOLTAGE (V)
LTC1334 • TPC10
LTC1334 • TPC12
LTC1334 • TPC11
5
LTC1334
TYPICAL PERFORMANCE CHARACTERISTICS
W
U
RS485 Driver Output Low Voltage
vs Output Current
RS485 Driver Output High Voltage
vs Output Current
RS485 Driver Output Short-Circuit
Current vs Temperature
120
100
80
60
40
20
0
160
140
120
100
80
–80
–70
–60
–50
–40
–30
–20
–10
0
T
= 25°C
CC
T
= 25°C
CC
A
V
CC
= 5V
A
V
= 5V
V
= 5V
SINK
OUT
(V
= 5V)
SOURCE
OUT
(V
= 0V)
60
40
0
1
2
3
4
5
1
2
4
–50 –25
0
25
50
75
100 125
0
5
3
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
TEMPERATURE (°C)
LTC1334 • TPC14
LTC1334 • TPC13
LTC1334 • TPC15
RS232 Driver Short-Circuit
Current vs Temperature
RS232 Driver Output Voltage
vs Temperature
Driver Output Leakage Current
(Disable/Shutdown) vs Temperature
10
8
500
450
400
350
300
250
200
150
100
50
30
25
20
15
10
5
V
CC
= 5V
V
V
= 0V
OUT
CC
= 5V
OUTPUT HIGH
6
4
SOURCE
SINK
50
2
V
= 5V
CC
L
0
R
= 3k
–2
–4
–6
–8
–10
OUTPUT LOW
0
0
–50
0
25
50
75 100 125
–50
0
25
50
75 100 125
–25
–25
100 125
–50 –25
0
25
75
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
LTC1334 • TPC16
LTC1334 • TPC18
LTC1334 • TPC17
U
U
U
PIN FUNCTIONS
C1+(Pin1):CommutatingCapacitorC1PositiveTerminal.
Requires 0.1µF external capacitor between Pins 1 and 2.
C1– (Pin 2): Commutating Capacitor C1 Negative Terminal.
SEL1 (Pin 8): Interface Mode Select Input.
SEL2 (Pin 9): Interface Mode Select Input.
Z2 (Pin 10): Driver Output.
VDD (Pin 3): Positive Supply Output for RS232 Drivers.
Requires an external 0.1µF capacitor to ground.
Y2 (Pin 11): Driver Output.
B2 (Pin 12): Receiver Input.
A1 (Pin 4): Receiver Input.
B1 (Pin 5): Receiver Input.
Y1 (Pin 6): Driver Output.
Z1 (Pin 7): Driver Output.
A2 (Pin 13): Receiver Input.
GND (Pin 14): Ground.
VEE (Pin 15): Negative Supply Output. Requires an exter-
nal 0.1µF capacitor to ground.
6
LTC1334
U
U
U
PI FU CTIO S
RB2 (Pin 16): Receiver Output.
C2– (Pin27):CommutatingCapacitorC2NegativeTermi-
nal. Requires 0.1µF external capacitor between Pins 27
and 28.
C2+ (Pin 28): Commutating Capacitor C2 Positive Terminal.
RA2 (Pin 17): Receiver Output.
DZ2/DE2 (Pin 18): RS232 Driver Input in RS232 Mode.
RS485DriverEnablewithinternalpull-upinRS485mode.
D
Y2 (Pin 19): Driver Input.
1
2
28
27
26
25
24
23
22
21
20
19
18
17
16
15
+
–
+
–
C1
C1
V
C2
C2
ON/OFF (Pin 20): A high logic input enables the transceiv-
ers. A low puts the device into shutdown mode and
reduces ICC to 10µA. This pin has an internal pull-up.
3
V
DD
A1
B1
Y1
CC
4
R
B1
A1
LB (Pin 21): Loopback Control Input. A low logic level
enables internal loopback connections. This pin has an
internal pull-up.
5
R
D
D
6
/DE1
Z1
7
Z1
SEL1
SEL2
Y1
DY1 (Pin 22): Driver Input.
8
LB
DZ1/DE1 (Pin 23): RS232 Driver Input in RS232 Mode.
RS485DriverEnablewithinternalpull-upinRS485mode.
9
ON/OFF
10
11
12
13
14
D
Z2
Y2
B2
Y2
RA1 (Pin 24): Receiver Output.
D
R
R
/DE2
Z2
RB1 (Pin 25): Receiver Output.
A2
B2
EE
VCC (Pin 26): Positive Supply; 4.75V ≤ VCC ≤ 5.25V
A2
GND
V
U
U
FU CTIO TABLES
RS485 Driver Mode
INPUTS
RS232 Driver Mode
INPUTS
OUTPUTS
OUTPUTS
Y, Z
ON/OFF
SEL
DE
D
0
1
X
X
X
CONDITIONS
No Fault
No Fault
Thermal Fault
X
Z
Y
1
0
Z
Z
Z
ON/OFF
SEL
D
0
1
X
X
CONDITIONS
No Fault
No Fault
Thermal Fault
X
1
1
1
1
0
1
1
0
1
Z
Z
Z
1
1
1
0
0
1
0
Z
Z
1
1
0
1
1
0
1
0
0
1
X
X
RS485 Receiver Mode
INPUTS
RS232 Receiver Mode
INPUTS
OUTPUTS
OUTPUTS
ON/OFF
SEL
B – A
< –0.2V
> 0.2V
R
R *
ON/OFF
SEL
A, B
R , R
A
B
A
B
1
1
1
0
1
0
1
1
Z
1
1
1
Z
1
1
1
0
0
0
1
0
1
Z
0
1
Inputs Open
X
1
0
1
Inputs Open
X
0
1
*See Note 5 of Electrical Characteristics table.
7
LTC1334
W
BLOCK DIAGRA SM
Interface Configuration with Loopback Disabled
PORT 1 = RS232 MODE
PORT 2 = RS232 MODE
PORT 1 = RS485 MODE
PORT 2 = RS232 MODE
PORT 1 = RS232 MODE
PORT 2 = RS485 MODE
PORT 1 = RS485 MODE
PORT 2 = RS485 MODE
1
28
1
28
1
28
1
28
C1
C2 C1
C2 C1
C2 C1
C2
2
3
27
26
2
3
27
26
2
3
27
26
2
3
27
26
V
V
CC
V
DD
V
CC
V
V
CC
V
DD
V
CC
DD
DD
4
5
25
24
4
5
4
5
25
24
4
5
25
24
25
24
A1
B1
Y1
Z1
R
R
D
D
A1
A1
B1
Y1
Z1
R
R
D
D
A1
B1
Y1
Z1
R
R
B1
A1
Z1
Y1
B1
A1
Z1
Y1
B1
R
R
B1
B1
Y1
Z1
A1
A1
6
23
22
6
23
22
6
23
22
6
23
22
DE1
DE1
7
8
7
8
7
8
7
8
D
Y1
D
Y1
SEL1 = 0V
SEL1 = 5V
SEL1 = 0V
SEL1 = 5V
21
21
21
21
LB
LB
LB
LB
20
19
20
19
20
19
20
19
9
9
9
9
ON
ON
ON
ON
SEL2 = 0V
Z2
SEL2 = 0V
Z2
SEL2 = 5V
Z2
SEL2 = 5V
Z2
10
10
10
10
D
Y2
D
Z2
R
A2
R
B2
D
Y2
D
Z2
R
A2
R
B2
D
D
Y2
DE2
Y2
DE2
11
12
18
17
11
12
18
17
11
12
18
17
11
12
18
17
Y2
B2
Y2
B2
Y2
B2
Y2
B2
R
R
R
R
A2
A2
13
14
16
15
13
14
16
15
13
14
16
15
13
14
16
15
A2
A2
A2
A2
B2
B2
GND
GND
GND
GND
V
V
EE
V
V
EE
EE
EE
LTC1334 • BD01
Interface Configuration with Loopback Enabled
PORT 1 = RS232 MODE
PORT 2 = RS232 MODE
28
PORT 1 = RS485 MODE
PORT 2 = RS232 MODE
PORT 1 = RS232 MODE
PORT 2 = RS485 MODE
PORT 1 = RS485 MODE
PORT 2 = RS485 MODE
1
1
28
1
28
1
28
C1
C2 C1
C2 C1
V
C2 C1
C2
2
3
27
26
2
3
27
26
2
3
27
26
2
3
27
26
V
V
CC
V
DD
V
CC
V
CC
V
DD
V
CC
DD
DD
25
24
25
24
25
24
25
24
R
R
D
D
R
R
D
D
R
R
B1
A1
Z1
Y1
B1
A1
Z1
Y1
B1
R
R
B1
A1
A1
6
23
22
6
23
22
6
23
22
6
23
22
Y1
Z1
Y1
Z1
Y1
Z1
Y1
Z1
DE1
DE1
7
8
7
8
7
8
7
8
D
Y1
D
Y1
SEL1 = 0V
SEL1 = 5V
SEL1 = 0V
SEL1 = 5V
21
21
21
21
LB
LB
LB
LB
20
19
9
20
19
20
19
20
19
ON
9
9
9
SEL2 = 5V
Z2
ON
ON
ON
SEL2 = 0V
Z2
SEL2 = 0V
Z2
SEL2 = 5V
Z2
10
10
10
10
D
Y2
DE2
D
Y2
D
Z2
R
A2
R
B2
D
Y2
D
Z2
R
A2
R
B2
D
Y2
DE2
11
18
17
11
18
17
11
18
17
11
18
17
Y2
Y2
Y2
Y2
R
R
A2
R
R
A2
16
15
16
15
16
15
16
15
B2
B2
14
14
14
14
GND
V
EE
GND
GND
GND
V
EE
V
EE
V
EE
LTC1334 • BD02
8
LTC1334
TEST CIRCUITS
V
CC
Z
3V
3V
SEL
R
S1
SEL
R
C
C
L
L
Z
500Ω
B
A
V
OD
D
DR OUT
R
L
Y
DE
3V
V
OC
15pF
C
L
S2
R
Y
LTC1334 • F03
LTC1334 • F01
LTC1334 • F02
Figure 1. RS422/RS485
Driver Test Load
Figure 2. RS485 Driver/Receiver
Timing Test Circuit
Figure 3. RS485 Driver Output
Enable/Disable Timing Test Load
0V
SEL
0V
0V
SEL
Y, Z
D
SEL
R
Y, Z
A, B
D
R
L
C
L
V
V
OUT
IN
15pF
LTC1334 • F05
LTC1334 • F04
Figure 4. RS232 Driver
Swing/Timing Test Circuit
Figure 5. RS232 Receiver
Timing Test Circuit
U
W
SWITCHI G WAVEFOR S
3V
f = 1MHz: t ≤ 10ns: t ≤ 10ns
r
f
1.5V
1.5V
D
0V
t
t
PHL
PLH
V
O
O
90%
90%
V
DIFF
= V(Z) – V(Y)
Z – Y
–V
50%
10%
50%
10%
1/2 V
O
t
r
t
f
Y
Z
V
O
t
t
SKEW
LTC1334 • F06
SKEW
Figure 6. RS485 Driver Propagation Delays
9
LTC1334
U
W
SWITCHI G WAVEFOR S
3V
f = 1MHz: t ≤ 10ns: t ≤ 10ns
r
f
1.5V
DE
1.5V
0V
t
t
LZ
ZL
5V
Y, Z
2.3V
2.3V
OUTPUT NORMALLY LOW
OUTPUT NORMALLY HIGH
0.5V
0.5V
V
OL
OH
0V
t
t
HZ
ZH
V
Z, Y
LTC1334 • F07
Figure 7. RS485 Driver Enable and Disable Times
V
OD2
f = 1MHz: t ≤ 10ns: t ≤ 10ns
r
f
INPUT
0V
t
B – A
–V
0V
OD2
t
PLH
PHL
OUTPUT
V
OH
R
1.5V
1.5V
V
OL
LTC1334 • F08
Figure 8. RS485 Receiver Propagation Delays
3V
0V
1.5V
1.5V
D
t
t
PLH
PHL
V
O
O
LTC1334 • F09
Y, Z
0V
0V
–V
Figure 9. RS232 Driver Propagation Delays
V
IH
1.7V
1.3V
A, B
V
IL
t
t
PLH
PHL
V
OH
LTC1334 • F10
2.4V
R
0.8V
V
OL
Figure 10. RS232 Receiver Propagation Delays
10
LTC1334
O U
W
U
PPLICATI
S I FOR ATIO
A
In RS485 mode, an internal 4µA current source pulls the
driver enable pin high if left open. The RS485 receiver has
a 4µA current source at the noninverting input. If both the
RS485 receiver inputs are open, the output goes to a high
state. Both the current sources are disabled in the RS232
mode. The receiver output B is inactive in RS485 mode
and has a 50k pull-up resistor to provide a known output
state in this mode.
Basic Theory of Operation
The LTC1334 has two interface ports. Each port may be
configured as a pair of single-ended RS232 transceivers
or as a differential RS485 transceiver by forcing the
port’s selection input to a low or high, respectively. The
LTC1334 provides two RS232 drivers and two RS232
receivers or one RS485 driver and one RS485 receiver
per port. All the interface drivers feature three-state
outputs. Interface outputs are forced into high imped-
ance when the driver is disabled, in the shutdown mode
or with the power off.
Aloopbackmodeenablesinternalconnectionsfromdriver
outputstoreceiverinputsforself-testwhentheLBpinhas
a low logic state. The driver outputs are not isolated from
the external loads. This allows transmitter verification
undertheloadedcondition.Aninternal4µAcurrentsource
pulls the LB pin high if left open and disables the loopback
configuration.
All the interface driver outputs are fault-protected by a
current limiting and thermal shutdown circuit. The ther-
mal shutdown circuit disables both the RS232 and RS485
driver outputs when the die temperature reaches 150°C.
The thermal shutdown circuit reenables the drivers when
the die temperature cools to 130°C.
RS232/RS485 Applications
The LTC1334 can support both RS232 and RS485 levels
with a single 5V supply as shown in Figure 11.
InRS485mode,shutdownmodeorwiththepoweroff,the
inputresistanceofthereceiveris24k.Theinputresistance
drops to 5k in RS232 mode.
Multiprotocol Applications
A logic low at the ON/OFF pin shuts down the device and
forces all the outputs into a high impedance state. A logic
high enables the device. An internal 4µA current source to
VCC pulls the ON/OFF pin high if it is left open.
The LTC1334 is well-suited for software controlled inter-
face mode selection. Each port has a selection pin as
shown in Figure 12. The single-ended transceivers sup-
port both RS232 and EIA562 levels. The differential trans-
ceivers support both RS485 and RS422.
1
28
C2
0.1µF
0.1µF
C1
LTC1334
2
27
26
24
23
3
4
5
V
CC
V
DD
5V
0.1µF
0.1µF
RX OUT
DR ENABLE
RS485 I/O
120Ω
6
7
22
DR IN
21
20
8
9
5V
5V
5V
11
10
13
19
18
17
16
15
RS232 DR OUT
RS232 DR OUT
RS232 RX IN
DR IN
≥ ±5V INTO
3kΩ LOAD
DR IN
RX OUT
RX OUT
12
14
RS232 RX IN
V
EE
0.1µF
LTC1334 • F11
Figure 11. RS232/RS485 Interfaces
11
LTC1334
O U
S
W
U
PPLICATI
A
I FOR ATIO
28
1
Each receiver in the LTC1334 is designed to present one
unit load (5kΩ nominal for RS232 and 12kΩ minimum for
RS485)tothecable.SomeRS485andRS422applications
call for terminations, but these are only necessary at two
nodes in the system and they must be disconnected when
operating in the RS232 mode. A relay is the simplest, low-
est cost method of switching terminations. In Figure 12
TERM1 and TERM2 select 120Ω terminations as needed.
If terminations are needed in all RS485/RS422 applica-
tions, no extra control signals are required; simply con-
nect TERM1 and TERM2 to SEL1 and SEL2.
LTC1334
0.1µF
0.1µF
C1
C2
2
3
27
26
V
CC
V
DD
5V
0.1µF
0.1µF
25
RX OUT
4
INPUT A
K1A
120Ω
INPUT B
24
RX OUT
5
6
PORT 1
INTERFACE
OUTPUT A
K1B
22
DR IN
8
5V
SEL1
120Ω
OUTPUT B
K1*
TX2A-5V
7
23
DR IN/ENABLE
LB
Typical Applications
21
20
A typical RS232/EIA562 interface application is shown in
Figure 13 with the LTC1334.
360k
ON/OFF
RX OUT
FMMT619**
TERM1
7.5k
16
13
A typical connection for a RS485 transceiver is shown in
Figure14. Atwistedpairofwiresconnectsupto32drivers
andreceiversforhalfduplexmultipointdatatransmission.
The wires must be terminated at both ends with resistors
equal to the wire’s characteristic impedance. An optional
shield around the twisted pair helps to reduce unwanted
noise and should be connected to ground at only one end.
INPUT A
K2A
120Ω
INPUT B
17
12
11
RX OUT
PORT 2
INTERFACE
OUTPUT A
K2B
19
9
DR IN
SEL2
5V
120Ω
OUTPUT B
K2*
18
15
10
14
TX2A-5V
1/2 LTC1334
1/2 LTC1334
DR IN/ENABLE
19
18
17
16
9
RS232/
EIA562
4
5
6
7
11
10
13
12
24
25
22
23
8
V
EE
DR IN
DR IN
RX OUT
RX OUT
DR IN
0.1µF
360k
7.5k
LTC1334 • F12
INTERFACE
LINES
FMMT619**
*AROMAT CORP (800) 276-6289
TERM2
RX OUT
RX OUT
**ZETEX (516) 543-7100
DR IN
LTC1334 • F13
Figure 12. Multiprotocol Interface
with Optional, Switchable Terminations
Figure 13. Typical Connection for RS232/EIA562 Interface
1/2 LTC1334
1/2 LTC1334
13
4
5
17
24
RX OUT
12
RX OUT
DR ENABLE
DR IN
23
22
8
18
120Ω
120Ω
DR ENABLE
DR IN
11
10
6
7
19
9
7
6
5
4
5V
5V
1/2
LTC1334
22 23
24 8
DR IN
DR ENABLE
RX OUT
5V
LTC1334 F14
Figure 14. Typical Connection for RS485 Interface
12
LTC1334
O U
W
U
PPLICATI
A
S I FOR ATIO
port is configured as an RS232 transceiver and the other
as an RS485 transceiver.
A typical RS422 connection (Figure 15) allows one driver
andtenreceiversonatwistedpairofwiresterminatedwith
a 100Ω resistor at one end.
Using two LTC1334s as level translators, the RS232/
EIA562 interface distance can be extended to 4000 feet
with twisted-pair wires (Figure 18).
A typical twisted-pair line repeater is shown in Figure 16.
As data transmission rate drops with increased cable
length, repeaters can be inserted to improve transmission
rate or to transmit beyond the RS422 4000-foot limit.
AppleTalk®/LocalTalk® Applications
Two AppleTalk applications are shown in Figure 19 and 20
with the LTC1323 and the LTC1334.
The LTC1334 can be used to translate RS232 to RS422
interface levels or vice versa as shown in Figure 17. One
AppleTalk and LocalTalk are registered trademarks of Apple Computer, Inc.
1/2 LTC1334
RX OUT
24
8
5V
1/2 LTC1334
23
1/2 LTC1334
13
DR ENABLE
DR IN
5
4
6
22
8
17
8
100Ω
RX OUT
5V
7
12
5V
18
19
DR ENABLE
DR IN
4
5
11
10
24
100Ω
RX OUT
LTC1334 • F15
Figure 15. Typical Connection for RS422 Interface
5V
17 22 23
8
6
7
13
5V
TX OUT
RS422
RX IN
RX IN
RS232/EIA562
23
LTC1334
19 24
24 22
8
4
5
6
7
4
5
11
100Ω
TX OUT
100Ω
RX IN
TX OUT
LTC1334 • F17
LTC1334 • F16
1/2 LTC1334
9
Figure 16. Typical Cable Repeater for RS422 Interface
Figure 17. Typical RS232/EIA562 to RS422 Level Translator
5V
19
24
RS422
17 22 23
8
4
5
6
7
11
13
13
11
100Ω
DR OUT
RX IN
RS232/EIA562
DR OUT
RS232/EIA562
LTC1334
LTC1334
6
7
4
5
100Ω
RX IN
23 22 17
9
8
9
19 24
LTC1334 • F18
5V
Figure 18. Typical Cable Extension for RS232/EIA562 Interface
13
LTC1334
O U
W
U
PPLICATI
A
S I FOR ATIO
1
2
3
28
27
26
25
24
LTC1323CS-16
0.1µF
0.1µF
1
2
3
4
16
LTC1334
5V
CHARGE
PUMP
0.33µF
15
14
13
12
5V
0.1µF
0.33µF
1µF
4
NC
EMI
TXD
1k
R
5
6
A1
TXDEN
EMI
EMI
–
+
TXD
23
22
DE1
5
EMI
SHDN
120Ω
120Ω
1k
1k
6
7
8
11 TXD
7
D
Y1
RXEN
RXDO
EMI
EMI
EMI
EMI
–
+
10 RXD
RXD
8
9
21
20
1k
5V
5V
SEL1, 5V
SEL2, 5V
9
10
FERRITE FERRITE
5Ω TO 5Ω TO
22Ω 22Ω
NC
19
18
BEAD
BEAD
NC
NC
=
OR
OR
EMI
11
12
NC
NC
100pF
100pF
100pF
17
16
15
NC
NC
13
14
NC
0.1µF
LTC1334 • F19
Figure 19. AppleTalk/LocalTalk Implemented Using the LTC1323CS-16 and LTC1334 Transceivers
FERRITE FERRITE
5Ω TO 5Ω TO
BEAD
BEAD
22Ω
22Ω
=
OR
OR
EMI
5V
LTC1323CS
100pF
100pF
100pF
1
24
23
22
21
20
1
2
3
28
CHARGE
PUMP
0.33µF
2
3
4
0.1µF
0.1µF
LTC1334
27
26
0.33µF
CPEN
TXD
1µF
5V
0.1µF
–
+
25
24
TXD
5
6
4
NC
R
TXI
EMI
EMI
120Ω
A1
120Ω
TXDEN
5
6
19 TXD
18 TXO
EMI
EMI
EMI
EMI
7
8
SHDN
RXEN
23
22
DE1
120Ω
17 RXI
16 RXI
7
D
Y1
EMI
EMI
9
10
11
8
9
21
20
SEL1
5V
RXO
RXO
5V
5V
EMI
EMI
SEL2
–
15 RXD
10
RXDO
19
18
EMI
D
Y2
120Ω
+
14 RXD
13
11
12
13
14
EMI
D
Z2
EMI
NC
12
17
16
15
R
A2
EMI
NC
0.1µF
LTC1334 • F20
Figure 20. AppleTalk Direct Connect Using the LTC1323 DTE and the LTC1334 for DCE Transceivers
14
LTC1334
U
Dimensions in inches (millimeters) unless otherwise noted.
PACKAGE DESCRIPTION
G Package
28-Lead Plastic SSOP (0.209)
(LTC DWG # 05-08-1640)
10.07 – 10.33*
(0.397 – 0.407)
28 27 26 25 24 23 22 21 20 19 18
16 15
17
7.65 – 7.90
(0.301 – 0.311)
5
7
8
1
2
3
4
6
9
10 11 12 13 14
5.20 – 5.38**
(0.205 – 0.212)
1.73 – 1.99
(0.068 – 0.078)
0° – 8°
0.65
(0.0256)
BSC
0.13 – 0.22
0.55 – 0.95
(0.005 – 0.009)
(0.022 – 0.037)
0.05 – 0.21
(0.002 – 0.008)
0.25 – 0.38
(0.010 – 0.015)
NOTE: DIMENSIONS ARE IN MILLIMETERS
*DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.152mm (0.006") PER SIDE
**DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.254mm (0.010") PER SIDE
G28 SSOP 1098
NW Package
28-Lead PDIP (Wide 0.600)
(LTC DWG # 05-08-1520)
1.455*
(36.957)
MAX
28
27
26
25
24
23
22
21
20
19
18
17
16
15
0.505 – 0.560*
(12.827 – 14.224)
1
2
3
5
7
9
4
6
8
10
11
12
13
14
0.600 – 0.625
(15.240 – 15.875)
0.045 – 0.065
(1.143 – 1.651)
0.150 ± 0.005
(3.810 ± 0.127)
0.015
(0.381)
MIN
0.070
(1.778)
TYP
0.009 – 0.015
(0.229 – 0.381)
+0.035
0.625
0.035 – 0.080
(0.889 – 2.032)
–0.015
0.125
(3.175)
MIN
0.018 ± 0.003
(0.457 ± 0.076)
+0.889
15.87
(
)
–0.381
0.100
(2.54)
BSC
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
N28 1098
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
15
LTC1334
U
Dimensions in inches (millimeters) unless otherwise noted.
PACKAGE DESCRIPTION
SW Package
28-Lead Plastic Small Outline (Wide 0.300)
(LTC DWG # 05-08-1690)
0.697 – 0.712*
(17.70 – 18.08)
28 27 26 25 24 23 22 21 20 19 18
16 15
17
0.394 – 0.419
(10.007 – 10.643)
NOTE 1
0.291 – 0.299**
(7.391 – 7.595)
2
3
5
7
8
9
10 11 12 13 14
1
4
6
0.037 – 0.045
(0.940 – 1.143)
0.093 – 0.104
(2.362 – 2.642)
0.010 – 0.029
(0.254 – 0.737)
× 45°
0° – 8° TYP
0.050
(1.270)
BSC
0.004 – 0.012
(0.102 – 0.305)
0.009 – 0.013
NOTE 1
(0.229 – 0.330)
0.014 – 0.019
(0.356 – 0.482)
TYP
0.016 – 0.050
(0.406 – 1.270)
NOTE:
1. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS.
THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS
S28 (WIDE) 1098
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC485
LT®1137A
Low Power RS485 Interface Transceiver
Low Power RS232 Transceiver
AppleTalk Transceiver
Single 5V Supply, Wide Common Mode Range
±15kV IEC-1000-4-2 ESD Protection, Three Drivers, Five Receivers
AppleTalk/Local Talk Compliant
LTC1320
LTC1321/LTC1322/LTC1335
LTC1323
RS232/EIA562/RS485 Transceivers
Single 5V AppleTalk Transceiver
5V Low Power RS232 Transceiver
Single 5V RS232/RS485 Transceiver
Configurable, 10kV ESD Protection
LocalTalk/AppleTalk Compliant 10kV ESD
LTC1347
Three Drivers/Five Receivers, Five Receivers Alive in Shutdown
Single Port, Configurable, 10kV ESD
LTC1387
1334fa LT/TP 1099 2K REV A • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 1995
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
16
●
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(408)432-1900 FAX:(408)434-0507 www.linear-tech.com
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