LTC1334
Single 5V RS232/RS485
Multiprotocol Transceiver
FEATURES
s
s
s
s
s
s
s
s
s
DESCRIPTIO
s
s
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 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
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 10µA.
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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
s
s
s
s
Low Power RS485/RS422/RS232/EIA562 Interface
Software-Selectable Multiprotocol Interface Port
Cable Repeaters
Level Translators
TYPICAL APPLICATIO
2
3
LTC1334
V
CC1
5V
RX OUT
DR ENABLE
DR IN
5V
5V
DR IN
DR IN
RX OUT
RX OUT
26
24
23
22
21
20
19
18
17
16
15
1 28
27
4
5
120Ω
6
7
8
9
11
10
13
12
14
5V
0V
RS485 INTERFACE
120Ω
13
12
11
10
5V
9
8
4
5
6
7
14
4000-FT 24-GAUGE TWISTED PAIR
RS232 INTERFACE
0V
ALL CAPACITORS: 0.1µF MONOLITHIC CERAMIC TYPE
LTC1334 • TA01
U
27
28 1
LTC1334
2
3
26
17
18
19
21
20
24
25
22
23
15
V
CC2
5V
RX OUT
DR ENABLE
DR IN
5V
5V
RX OUT
RX OUT
DR IN
DR IN
U
U
1
LTC1334
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
C1
+
1
C1
–
2
V
DD
3
A1 4
B1 5
Y1 6
Z1 7
SEL1 8
SEL2 9
Z2 10
Y2 11
B2 12
A2 13
GND 14
28 C2
+
27 C2
–
26 V
CC
25 R
B1
24 R
A1
23 D
Z1
/DE1
22 D
Y1
21 LB
20 ON/OFF
19 D
Y2
18 D
Z2
/DE2
17 R
A2
16 R
B2
15 V
EE
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
ORDER PART
NUMBER
LTC1334CG
LTC1334CNW
LTC1334CSW
LTC1334IG
LTC1334ISW
G PACKAGE
NW PACKAGE
28-LEAD PLASTIC SSOP 28-LEAD PDIP WIDE
SW PACKAGE
28-LEAD PLASTIC SO WIDE
T
JMAX
= 125°C,
θ
JA
= 90°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 Military grade parts.
DC ELECTRICAL CHARACTERISTICS
SYMBOL
V
OD1
V
OD2
∆V
OD
V
OC
∆V
OC
I
OSD
I
OZD
V
O
I
OSD
V
IH
V
IL
I
IN
PARAMETER
Differential Driver Output Voltage (Unloaded)
Differential Driver Output Voltage (With Load)
Change in Magnitude of Driver Differential
Output Voltage for Complementary Output States
Driver Common Mode Output Voltage
Change in Magnitude of Driver Common Mode
Output Voltage for Complementary Output States
Driver Short-Circuit Current
Three-State Output Current (Y, Z)
Output Voltage Swing
Output Short-Circuit Current
Input High Voltage
Input Low Voltage
Input Current
RS485 Driver (SEL1 = SEL2 = High)
I
O
= 0
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 = 0.1µF (Notes 2, 3)
CONDITIONS
q
q
q
q
q
q
q
q
q
MIN
TYP
MAX
6
UNITS
V
V
V
V
V
V
mA
mA
µA
V
V
Figure 1, R = 50Ω (RS422)
Figure 1, R = 27Ω (RS485)
Figure 1, R = 27Ω or R = 50Ω
Figure 1, R = 27Ω or R = 50Ω
Figure 1, R = 27Ω or R = 50Ω
– 7V
≤
V
O
≤
12V, V
O
= High
– 7V
≤
V
O
≤
12V, V
O
= Low (Note 4)
– 7V
≤
V
O
≤
12V
Figure 4, R
L
= 3k, Positive
Figure 4, R
L
= 3k, Negative
V
O
= 0V
D, DE, ON/OFF, SEL1, SEL2, LB
D, DE, ON/OFF, SEL1, SEL2, LB
D, SEL1, SEL2
DE, ON/OFF, LB
2.0
1.5
6
6
0.2
3
0.2
35
10
±5
5
–5
6.5
– 6.5
250
250
±500
RS232 Driver (SEL1 = SEL2 = Low)
q
q
q
±60
2
0.8
–4
±10
– 15
Driver Inputs and Control Inputs
q
q
q
q
2
U
mA
V
V
µA
µA
W
U
U
W W
W
LTC1334
DC ELECTRICAL CHARACTERISTICS
SYMBOL
V
TH
∆V
TH
I
IN
R
IN
V
TH
∆V
TH
R
IN
V
OH
V
OL
I
OSR
I
OZR
R
OB
V
DD
V
EE
PARAMETER
Differential Input Threshold Voltage
Input Hysteresis
Input Current (A, B)
Input Resistance
Receiver Input Threshold Voltage
Receiver Input Hysteresis
Receiver Input Resistance
Receiver Output High Voltage
Receiver Output Low Voltage
Short-Circuit Current
Three-State Output Current
Inactive “B” Output Pull-Up Resistance (Note 5)
V
DD
Output Voltage
V
EE
Output Voltage
RS485 Receiver (SEL1 = SEL2 = High)
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 = 0.1µF (Notes 2, 3)
CONDITIONS
– 7V
≤
V
CM
≤
12V, LTC1334C
–7V
≤
V
CM
≤
7V, LTC1334I
V
CM
= 0V
V
IN
= – 7V
V
IN
= 12V
– 7V
≤
V
IN
≤
12V
Input Low Threshold
Input High Threshold
V
IN
=
±10V
I
O
= – 3mA, V
IN
= 0V, SEL1 = SEL2 = Low
I
O
= 3mA, V
IN
= 3V, SEL1 = SEL2 = Low
0V
≤
V
O
≤
V
CC
ON/OFF = Low
ON/OFF = High, SEL1 = SEL2 = High
No Load, ON/OFF = High
I
DD
= – 10mA, ON/OFF = High
No Load, ON/OFF = High
I
EE
= 10mA, ON/OFF = High
No Load, SEL1 = SEL2 = High
No Load Shutdown, ON/OFF = 0V
q
q
q
q
q
q
q
q
q
q
q
MIN
– 0.2
–0.3
TYP
MAX
0.2
0.3
UNITS
V
V
mV
mA
mA
kΩ
V
V
V
kΩ
V
70
– 0.8
1.0
12
0.8
2.4
0.6
3
3.5
7
50
8.5
7.6
– 7.7
– 6.9
8
10
25
100
5
4.6
0.2
0.4
85
±10
7
24
RS232 Receiver (SEL1 = SEL2 = Low)
q
q
Receiver Output
V
mA
µA
kΩ
V
V
V
V
mA
µA
Power Supply Generator
Power Supply
I
CC
V
CC
Supply Current
AC ELECTRICAL CHARACTERISTICS
SYMBOL
SR
t
T
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
t
SKEW
t
r
, t
f
PARAMETER
Slew Rate
Transition Time
Driver Input to Output
Driver Input to Output
Receiver Input to Output
Receiver Input to Output
Driver Input to Output
Driver Input to Output
Driver Output to Output
Driver Rise and Fall Time
RS232 Mode (SEL1 = SEL2 = Low)
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 = 0.1µF (Notes 2, 3)
CONDITIONS
Figure 4, R
L
= 3k, C
L
= 15pF
Figure 4, R
L
= 3k, C
L
= 1000pF
Figure 4, R
L
= 3k, C
L
= 2500pF
Figures 4, 9, R
L
= 3k, C
L
= 15pF
Figures 4, 9, R
L
= 3k, C
L
= 15pF
Figures 5, 10
Figures 5, 10
Figures 2, 6, R
L
= 54Ω, C
L
= 100pF
Figures 2, 6, R
L
= 54Ω, C
L
= 100pF
Figures 2, 6, R
L
= 54Ω, C
L
= 100pF
Figures 2, 6, R
L
= 54Ω, C
L
= 100pF
q
q
q
q
q
q
q
MIN
TYP
MAX
30
UNITS
V/µs
V/µs
µs
µs
µs
µs
µs
ns
ns
ns
ns
4
0.22
1.9
0.6
0.6
0.3
0.4
20
20
3
40
40
5
15
3.1
4
4
6
6
70
70
15
40
RS485 Mode (SEL1 = SEL2 = High)
q
q
q
q
3
LTC1334
AC ELECTRICAL CHARACTERISTICS
SYMBOL
t
ZL
t
ZH
t
LZ
t
HZ
t
PLH
t
PHL
t
SKEW
PARAMETER
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
PLH
– t
PHL
RS485 Mode (SEL1 = SEL2 = High)
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 = 0.1µF (Notes 2, 3)
CONDITIONS
Figures 3, 7, C
L
= 100pF, S1 Closed
Figures 3, 7, C
L
= 100pF, S2 Closed
Figures 3, 7, C
L
= 15pF, S1 Closed
Figures 3, 7, C
L
= 15pF, S2 Closed
Figures 2, 8, R
L
= 54Ω, C
L
= 100pF
Figures 2, 8, R
L
= 54Ω, C
L
= 100pF
Figures 2, 8, R
L
= 54Ω, C
L
= 100pF
q
q
q
q
q
q
MIN
TYP
50
50
50
60
MAX
90
90
90
90
140
140
UNITS
ns
ns
ns
ns
ns
ns
ns
20
20
60
70
10
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 = 0.1µF
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 PERFORMANCE CHARACTERISTICS
Receiver Output High Voltage
vs Temperature
5.0
4.9
4.8
I
OUT
= 3mA
V
CC
= 5V
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
4.7
4.6
4.5
4.4
4.3
4.2
4.1
4.0
–50 –25
50
0
75
25
TEMPERATURE (°C)
100
125
TIME (ns)
4
U W
LTC1334 • TPC01
Receiver Output Low Voltage
vs Temperature
0.5
I
OUT
= 3mA
V
CC
= 5V
0.4
20
18
16
14
0.3
12
10
8
6
0.1
4
2
0
–50 –25
50
0
75
25
TEMPERATURE (°C)
100
125
RS485 Receiver Skew
t
PLH
– t
PHL
vs Temperature
V
CC
= 5V
0.2
0
–50 –25
50
0
75
25
TEMPERATURE (°C)
100
125
LTC1334 • TPC02
LTC1334 • TPC03
LTC1334
TYPICAL PERFORMANCE CHARACTERISTICS
Receiver Output Current
vs Output High Voltage
20
18
16
OUTPUT CURRENT (mA)
INPUT THRESHOLD VOLTAGE (V)
T
A
= 25°C
V
CC
= 5V
OUTPUT CURRENT (mA)
14
12
10
8
6
4
2
0
2.0
2.5
3.5
4.0
3.0
OUTPUT VOLTAGE (V)
4.5
5.0
Charge Pump Output Voltage
vs Temperature
10
8
6
OUTPUT VOLTAGE (V)
V
DD
(–10mA LOAD)
SUPPLY CURRENT (mA)
4
2
0
–2
–4
–6
–8
–10
–50 –25
V
CC
= 5V
SUPPLY CURRENT (mA)
V
DD
(NO LOAD)
V
EE
(10mA LOAD)
V
EE
(NO LOAD)
50
0
75
25
TEMPERATURE (°C)
100
125
RS485 Driver Differential Output
Voltage vs Temperature
2.6
DIFFERENTIAL OUTPUT CURRENT (mA)
DIFFERENTIAL OUTPUT VOLTAGE (V)
2.5
2.4
2.3
2.2
2.1
2.0
1.9
1.8
1.7
R
L
= 54Ω
V
CC
= 5V
40
30
20
TIME (µs)
1.6
–50 –25
50
75
0
25
TEMPERATURE (°C)
U W
LTC1334 • TPC04
Receiver Output Current
vs Output Low Voltage
40
35
30
25
20
15
10
5
0
0
0.5
1.0
1.5
2.0
OUTPUT VOLTAGE (V)
2.5
3.0
T
A
= 25°C
V
CC
= 5V
2.0
RS232 Receiver Input Threshold
Voltage vs Temperature
V
CC
= 5V
1.8
1.6
1.4
1.2
1.0
0.8
–50 –25
INPUT HIGH
INPUT LOW
50
25
75
0
TEMPERATURE (°C)
100
125
LTC1334 • TPC05
LTC1334 • TPC06
Supply Current
vs Temperature (RS485)
25
V
CC
= 5V
NO LOAD
SEL 1 = SEL 2 = HIGH
10
9
8
7
6
5
4
3
2
1
0
–50
–25
50
25
0
75
TEMPERATURE (°C)
100
125
Supply Current
vs Temperature (RS232)
V
CC
= 5V
NO LOAD
SEL 1 = SEL 2 = HIGH
20
15
10
5
0
–50 –25
50
0
75
25
TEMPERATURE (°C)
100
125
LTC1334 • TPC07
LTC1334 • TPC08
LTC1334 • TPC09
RS485 Driver Differential Output
Current vs Output Voltage
70
60
50
9
15
RS485 Driver Skew
vs Temperature
V
CC
= 5V
12
T
A
= 25°C
V
CC
= 5V
6
3
10
0
0
3
4
DIFFERENTIAL OUTPUT VOLTAGE (V)
1
2
5
0
–50 –25
100
125
50
0
75
25
TEMPERATURE (°C)
100
125
LTC1334 • TPC10
LTC1334 • TPC11
LTC1334 • TPC12
5
嵌入式系统
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