LTC1387
Single 5V RS232/RS485
Multiprotocol Transceiver
DESCRIPTIO
EA U
F T RES
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Two RS232 Transceivers or One RS485 Transceiver The LTC 1387 is a low power reconfigurable CMOS bidi-
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Operates from a Single 5V Supply rectional transceiver. It can be configured as an RS485
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Guaranteed Receiver Output with Inputs differential port or as two RS232 single-ended ports. An
Floating or Shorted to Ground onboard charge pump uses four 0.1m F capacitors to
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Logic Selectable Fast/Slow RS485 Driver Slew Rate generate boosted positive and negative supplies, allowing
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Low Supply Current: 7mA Typical the RS232 drivers to meet 5V output swing require-
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5m A Supply Current in Shutdown ments with only a single 5V supply. A shutdown mode
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Self-Testing Capability in Loopback Mode reduces the I supply current to 5m A.
CC
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Separate Driver and Receiver Enable Controls
The RS232 transceivers are in full compliance with RS232
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Driver Maintains High Impedance in Three-State,
specification. The RS485 transceiver is in full compliance
Shutdown or with Power Off
with RS485 and RS422 specifications. The RS485 re-
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Receiver Inputs Can Withstand 25V
ceiver assumes a known output state when the inputs are
floating or shorted to ground. All interface drivers feature
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short-circuit and thermal shutdown protection. An enable
APPLICATIONS
pin allows RS485 driver outputs to be forced into high
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Point-of-Sale Terminals
impedance which is maintained even when the outputs are
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Software Selectable Multiprotocol Interface Ports
forced beyond supply rails or the power is off. A loop back
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Low Power RS485/RS422/RS232/EIA562 Interface
mode allows the driver outputs to be connected back to the
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Cable Repeaters
receiver inputs for diagnostic self-test.
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Level Translators
The LTC1387 is available in 20-pin plastic SSOP and SW
packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATI
2 1 20 19 19 20 1 2
3
3
LTC1387 LTC1387
18
V
CC2
18
5V
V
CC1
5V
4
4
17 17
RS485 INTERFACE
5 5 RECOUT
RECOUT
120W
120W
6
6
15 15
DR IN
7 7 DR IN
4000-FT 24-GAUGE TWISTED PAIR
14
14
SLEW
SLEW
8 9
9
8
5V DR ENABLE
DR ENABLE 5V
13 12
13
12
5V 5V 5V
5V
11 10 10 11
ALL CAPACITORS: 0.1m F MONOLITHIC CERAMIC TYPE
LTC1387 TA01
1
O
U
ULTC1387
AB OLUEXAI U RAT GS /
S T I PACKAGE ORDER I FOR ATIO
(Note 1)
ORDER PART
Supply Voltage (V ) ............................................. 6.5V
TOP VIEW
CC
NUMBER
Input Voltage + +
C1 1 20 C2
Drivers ................................... 0.3V to (V + 0.3V)
CC C1 2 19 C2
Receivers ............................................. 25V to 25V
V 3 18 V LTC1387CG
DD CC
485/232, ON, DXEN A 4 17 R LTC1387CSW
A
B 5 16 R
RXEN, SLEW ........................... 0.3V to (V + 0.3V) B LTC1387IG
CC
Y 6 15 D
Y LTC1387ISW
Output Voltage
Z 7 14 D /SLEW
Z
Drivers ................................................. 18V to 18V
485/232 8 13 ON
Receivers ............................... 0.3V to (V + 0.3V)
CC
DXEN 9 12 RXEN
Short-Circuit Duration
GND 10 11 V
EE
Output ........................................................ Indefinite
+ +
G PACKAGE SW PACKAGE
V , V , C1 , C1 , C2 , C2 .......................... 30 sec
DD EE
20-LEAD PLASTIC SSOP 20-LEAD PLASTIC SO
Operating Temperature Range
LTC1387C .............................................. 0 C to 70 C
T = 125 C, q = 120 C/W (G)
JMAX JA
T = 125 C, q = 75 C/W (SW)
JMAX JA
LTC1387I ........................................... 40 C to 85 C
Storage Temperature Range ................ 65 C to 150 C
Lead Temperature (Soldering, 10 sec)................ 300 C Consult factory for Military grade parts.
DC ELECTRICAL CHARACTERISTICS
T = 25 C, V = 5V, C1 = C2 = C3 = C4 = 0.1m F (Notes 2, 3), unless otherwise noted.
A CC
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
RS485 Driver (485/232 = High, ON = DXEN = High)
V Differential Driver Output Voltage (Unloaded) I = 0 l 6V
OD1 O
V Differential Driver Output Voltage (With Load) Figure 1, R = 50W (RS422) l 2.0 6 V
OD2
Figure 1, R = 27W (RS485) l 1.5 6 V
D V Change in Magnitude of Driver Differential Figure 1, R = 27W or R = 50W l 0.2 V
OD
Output Voltage for Complementary Output States
V Driver Common Mode Output Voltage Figure 1, R = 27W or R = 50W l 3V
OC
D V Change in Magnitude of Driver Common Mode Figure 1, R = 27W or R = 50W l 0.2 V
OC
Output Voltage for Complementary Output States
I Driver Short-Circuit Current V = 7V, 12V; V = High l 35 250 mA
OSD O O
V = 7V, 12V; V = Low (Note 4) l 10 250 mA
O O
I Three-State Output Current (Y, Z) 7V V 12V 5 500 m A
OZD O
RS232 Driver (485/232 = Low, ON = DXEN = High)
V Output Voltage Swing Figure 4, R = 3k, Positive l 5 6.5 V
O L
Figure 4, R = 3k, Negative l 5 6.5 V
L
I Output Short-Circuit Current V = 0V l 17 60 mA
OSD O
Driver Inputs and Control Inputs
V Input High Voltage D , D , DXEN, RXEN, ON, 485/232, SLEW l2V
Y Z
IH
V Input Low Voltage D , D , DXEN, RXEN, ON, 485/232, SLEW l 0.8 V
Y Z
IL
I Input Current D , D , DXEN, RXEN, ON, 485/232 l 0.1 10 m A
Y Z
IN
SLEW (Note 5) l 5 15 m A
2
U WU U W W W