DESCRIPTIO RS232 Transceivers RS485 Transceiver Operates from Sin
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LTC1387 Single RS232/RS485 Multiprotocol Transceiver
DESCRIPTIO
RS232 Transceivers RS485 Transceiver Operates from Single Supply Guaranteed Receiver Output with Inputs Floating Shorted Ground Logic Selectable Fast/Slow RS485 Driver Slew Rate Supply Current: Typical Supply Current Shutdown Self-Testing Capability Loopback Mode Separate Driver Receiver Enable Controls Driver Maintains High Impedance Three-State, Shutdown with Power Receiver Inputs Withstand ±25V
®1387 power reconfigurable CMOS bidirectional transceiver. configured RS485 differential port RS232 single-ended ports. onboard charge pump uses four 0.1µF capacitors generate boosted positive negative supplies, allowing RS232 drivers meet output swing requirements with only single supply. shutdown mode reduces supply current 5µA. RS232 transceivers full compliance with RS232 specification. RS485 transceiver full compliance with RS485 RS422 specifications. RS485 receiver assumes known output state when inputs floating shorted ground. interface drivers feature short-circuit thermal shutdown protection. enable allows RS485 driver outputs forced into high impedance which maintained even when outputs forced beyond supply rails power off. loop back mode allows driver outputs connected back receiver inputs diagnostic self-test. LTC1387 available 20-pin plastic SSOP packages.
registered trademarks Linear Technology Corporation.
APPLICATIONS
Point-of-Sale Terminals Software Selectable Multiprotocol Interface Ports Power RS485/RS422/RS232/EIA562 Interface Cable Repeaters Level Translators
TYPICAL APPLICATI
LTC1387
VCC1
RECOUT
RS485 INTERFACE
SLEW ENABLE
4000-FT 24-GAUGE TWISTED PAIR
CAPACITORS: 0.1µF MONOLITHIC CERAMIC TYPE
LTC1387 TA01
LTC1387 VCC2 RECOUT SLEW ENABLE
LTC1387 ABSOLUTE
(Note
RATI
PACKAGE/ORDER ATIO
VIEW DZ/SLEW RXEN PACKAGE 20-LEAD PLASTIC
Supply Voltage (VCC) 6.5V Input Voltage Drivers 0.3V (VCC 0.3V) Receivers 485/232, DXEN RXEN, SLEW 0.3V (VCC 0.3V) Output Voltage Drivers Receivers 0.3V (VCC 0.3V) Short-Circuit Duration Output Indefinite VDD, VEE, C1+, C1-, C2+, Operating Temperature Range LTC1387C 70°C LTC1387I 40°C 85°C Storage Temperature Range 65°C 150°C Lead Temperature (Soldering, sec). 300°C
ORDER PART NUMBER LTC1387CG LTC1387CSW LTC1387IG LTC1387ISW
485/232 DXEN PACKAGE 20-LEAD PLASTIC SSOP
TJMAX 125°C, 120°C/W TJMAX 125°C, 75°C/W (SW)
Consult factory Military grade parts.
ELECTRICAL CHARACTERISTICS
SYMBOL VOD1 VOD2 IOSD IOZD IOSD PARAMETER Differential Driver Output Voltage (Unloaded) Differential Driver Output Voltage (With Load) Change Magnitude Driver Differential Output Voltage Complementary Output States Driver Common Mode Output Voltage Change Magnitude Driver Common Mode Output Voltage Complementary Output States Driver Short-Circuit Current Three-State Output Current Output Voltage Swing Output Short-Circuit Current Input High Voltage Input Voltage Input Current RS485 Driver (485/232 High, DXEN High)
25°C, 0.1µF (Notes unless otherwise noted.
CONDITIONS
UNITS
Figure (RS422) Figure (RS485) Figure Figure Figure 12V; High 12V; (Note Figure Positive Figure Negative DXEN, RXEN, 485/232, SLEW DXEN, RXEN, 485/232, SLEW DXEN, RXEN, 485/232 SLEW (Note
RS232 Driver (485/232 Low, DXEN High)
Driver Inputs Control Inputs
±0.1
LTC1387
ELECTRICAL CHARACTERISTICS
SYMBOL IOSR IOZR PARAMETER Differential Input Threshold Voltage Input Hysteresis Input Current Input Resistance Receiver Input Voltage Threshold Receiver Input Hysteresis Receiver Input Resistance Receiver Output High Voltage Receiver Output Voltage Short-Circuit Current Three-State Output Current Output Voltage Output Voltage RS485 Receiver (485/232 High, RXEN High)
25°C, 0.1µF (Notes unless otherwise noted.
CONDITIONS Input Threshold Input High Threshold ±10V 3mA, 485/232 3mA, 485/232 RXEN Load, DXEN RXEN High 5mA, DXEN RXEN High Load, DXEN RXEN High 5mA, DXEN RXEN High Load, DXEN RXEN High Shutdown, DXEN RXEN
0.20
0.20
UNITS
±0.1
RS232 Receiver (485/232 Low, RXEN High)
Receiver Output RXEN High)
Power Supply Generator
Power Supply Supply Current
ELECTRICAL CHARACTERISTICS
SYMBOL tPLH tPHL tPLH tPHL tSKEW PARAMETER Slew Rate Transition Time Driver Input Output Driver Input Output Receiver Input Output Receiver Input Output Driver Input Output Driver Input Output Driver Output Output Driver Rise Fall Time RS232 Mode DXEN RXEN High, 485/232 Low)
25°C, 0.1µF (Notes unless otherwise noted.
CONDITIONS Figure 15pF Figure 1000pF Figure 2500pF Figures 15pF Figures 15pF Figures Figures Figures 100pF Figures 100pF Figures 100pF Figures 100pF
UNITS V/µs V/µs
0.22
RS485 Mode (Fast Slew Rate, DXEN High, 485/232 High, SLEW High)
LTC1387
ELECTRICAL CHARACTERISTICS
SYMBOL tSKEW tSKEW PARAMETER Driver Enable Output Driver Enable Output High Driver Disable from Driver Disable from High Driver Input Output Driver Input Output Driver Output Output Driver Rise Fall Time Driver Enable Output Driver Enable Output High Driver Disable from Driver Disable from High Receiver Input Output Receiver Input Output Differential Receiver Skew, tPLH tPHL Receiver Enable Output Receiver Enable Output High Receiver Disable from Receiver Disable from High
25°C, 0.1µF (Notes unless otherwise noted.
CONDITIONS Figures 100pF, Closed Figures 100pF, Closed Figures 15pF, Closed Figures 15pF, Closed Figures 100pF Figures 100pF Figures 100pF Figures 100pF Figures 100pF, Closed Figures 100pF, Closed Figures 15pF, Closed Figures 15pF, Closed Figures 100pF Figures 100pF Figures 100pF Figures 15pF, Closed Figures 15pF, Closed Figures 15pF, Closed Figures 15pF, Closed
1500 1500 1500 1500 1500
UNITS
RS485 Mode (Fast Slew Rate, DXEN High, 485/232 High, SLEW High)
RS485 Mode (Slow Slew Rate, DXEN High, 485/232 High, SLEW Low)
RS485 Mode RXEN High, 485/232 High)
Receiver Output Enable/Disable High)
denotes specifications which apply over full operating temperature range. Note Absolute Maximum Ratings those values beyond which life device impaired. Note currents into device pins positive; currents device pins negative. voltages referenced device ground unless otherwise specified.
Note typicals given 0.1µF 25°C. Note Short-circuit current RS485 driver output state folds back above VCC. Peak current occurs around Note SLEW includes internal pull-up RS485 mode.
FUNCTIONS
(Pin Commutating Capacitor Positive Terminal. Requires external 0.1µF capacitor between Pins (Pin Commutating Capacitor Negative Terminal. (Pin Charge Pump Positive Supply Output. Requires external 0.1µF capacitor ground. (Pin Receiver Input Inverting input RS232 receiver RS232 mode; inverting RS485 receiver input RS485 mode. (Pin Receiver Input Inverting input RS232 receiver RS232 mode; noninverting RS485 receiver input RS485 mode. (Pin Driver Output Inverting RS232 driver output RS232 mode; inverting RS485 driver output RS485 mode. (Pin Driver Output Inverting RS232 driver output RS232 mode; noninverting RS485 driver output RS485 mode.
LTC1387
CTIO
485/232 (Pin Interface Mode Select Input. logic input enables RS232 drivers RS232 receivers. high input enables RS485 driver RS485 receiver. DXEN (Pin Driver Enable Input. high logic input enables drivers logic input disables drivers. When disabled, driver outputs high impedance (Pin 10): Ground. (Pin 11): Charge Pump Negative Supply Output. Requires external 0.1µF capacitor ground. RXEN (Pin 12): Receiver Enable Input. high logic input enables receivers logic input disables receivers. When disabled, receiver outputs high impedance. (Pin 13): high logic level input keeps charge pump active regardless state DXEN RXEN inputs. When charge pump active, drivers receivers enabled disabled without waiting charge pump stabilization time (typically 100µs with 0.1µF capacitors). logic state DXEN RXEN inputs will transceiver charge pump shutdown mode reduces 5µA. Whenever transceiver activated from shutdown, charge pump should allowed stabilize before data transmission. When DXEN RXEN high low, charge pump, drivers receivers active driver outputs internally looped back inputs receiver. three control inputs DXEN RXEN configured one-, two- three-wire control: onewire mode three inputs connected together; two-wire mode inputs RXEN connected wire, DXEN separate wire; three-wire mode separate wires each input. Function Tables. DZ/SLEW (Pin 14): Driver Slew Input. RS232 mode, this driver input. RS485 mode, this controls slew rate RS485 driver. With SLEW high, RS485 driver runs maximum (fast) slew rate transmit signals 5MBd. With SLEW low, RS485 driver runs with reduced (slow) slew rate control reflections with improperly terminated cables. slow mode, RS485 driver support data rates 150kBd. This SLEW internal pullup during RS485 mode. (Pin 15): Driver Input. Input RS232 mode; differential driver input RS485 mode. (Pin 16): Receiver Output. Output RS232 mode; output high impedance RS485 mode. (Pin 17): Receiver Output. Output RS232 mode; differential receiver output RS485 mode. (Pin 18): Positive Supply. 4.75V 5.25V. Requires external 0.1µF bypass capacitor ground. (Pin 19): Commutating Capacitor Negative Terminal. Requires external 0.1µF capacitor between Pins (Pin 20): Commutating Capacitor Positive Terminal.
LTC1387
CTIO TABLES
Select Modes
SELECT INPUTS RXEN DXEN RECEIVER DRIVER 485/232 CHARGE PUMP LOOPBACK COMMENTS RS232 Mode, RS232 Mode, RS232 Mode, Off, RS232 Mode, RS232 Mode, Off, RS232 Mode, Off, Off, RS232 Loopback Mode, Shutdown, RS485 RS485 Mode, RS485 Mode, RS485 Mode, Off, RS485 Mode, RS485 Loopback Mode,
RS232 Driver Mode
SELECTED INPUTS 485/232 CONDITIONS Fault Fault Thermal Fault OUTPUTS
RS232 Receiver Mode
SELECTED INPUTS 485/232 Inputs Open OUTPUTS DXEN
RS485 Driver Slew Rate
DXEN INPUTS 485/232 SLEW OUTPUTS SLEW RATE Slow Fast
RS485 Driver Mode
INPUTS 485/232 CONDITIONS Fault Fault Thermal Fault OUTPUTS
RS485 Receiver Mode
RXEN INPUTS 485/232 0.2V 0.2V Inputs Open Shorted Ground OUTPUTS
LTC1387
BLOCK DIAGRAM
RS232 MODE WITHOUT LOOPBACK 485/232 DXEN RXEN
*485/232, DXEN, RXEN
TEST CIRCUITS
LTC1387
Figure RS485 Driver Test Load
DXEN
LTC1387
Figure RS232 Driver Timing Test Circuit
RS485 MODE WITHOUT LOOPBACK 485/232* DXEN SLEW RXEN 485/232 DXEN* RS232 MODE WITH LOOPBACK RS485 MODE WITH LOOPBACK SLEW RXEN* 485/232* RXEN* DXEN*
LTC1387
SLEW
15pF
DXEN RXEN
LTC1387
LTC1387
Figure RS485 Driver/Receiver Timing Test Circuit
Figure RS485 Driver Output Enable/Disable Timing Test Load
15pF
LTC1387
RECEIVER
DXEN RXEN
LTC1387
Figure RS232 Receiver Timing Test Circuit
Figure Receiver Output Enable/Disable Timing Test Load
LTC1387
SWITCHI WAVEFOR
1MHz: 10ns: 10ns (FAST SLEW RATE MODE) 100kHz: 10ns: 10ns (SLOW SLEW RATE MODE) tPLH tSKEW tSKEW
LTC1387
1MHz: 10ns: 10ns (FAST SLEW RATE MODE) 100kHz: 10ns: 10ns (SLOW SLEW RATE MODE) DXEN
LTC1387
tPLH
tPHL
LTC1387
1.5V
1.5V tPHL VDIFF V(A) V(B)
Figure RS485 Driver Propagation Delays
1.5V
1.5V 2.3V OUTPUT NORMALLY OUTPUT NORMALLY HIGH 2.3V 0.5V 0.5V
Figure RS485 Driver Enable Disable Times
1MHz: 10ns: 10ns
INPUT
tPHL 1.5V
LTC1387
OUTPUT 1.5V
Figure RS485 Receiver Propagation Delays
1.5V
1.5V tPLH
Figure RS232 Driver Propagation Delays
LTC1387
SWITCHI WAVEFOR
tPHL 0.8V tPLH 2.4V
LTC1387
RXEN 1.5V
APPLICATI
ATIO
Basic Theory Operating LTC1387 single supply, single-port logic reconfigurable RS485/RS232 transceiver with onboard charge pump. interface port offers flexible combination RS485 driver RS485 receiver RS232 drivers RS232 receivers. RS485 transceiver RS232 transceivers designed share same pins. logic input 485/232 controls selection between RS485 RS232 transceiver modes. RS485 transceiver supports both RS485 RS422 standards, whereas RS232 transceivers support both RS232 EIA562 standards. With four additional control inputs: DXEN, RXEN SLEW, LTC1387 easily reconfigured software adapt various communication needs including one-signal-line RS232 mode. Four examples interface port connections shown Figures through
1.3V
1.7V
Figure RS232 Receiver Propagation Delays
1MHz: 10ns: 10ns
1.5V
1.5V OUTPUT NORMALLY OUTPUT NORMALLY HIGH 1.5V
LTC1387
0.5V 0.5V
Figure Receiver Enable Disable Times
Both interface drivers receivers feature threestate outputs. Driver outputs forced into high impedance when driver disabled, shutdown mode with power off. driver outputs forced beyond power supply levels without damage ±18V. receiver inputs withstand ±25V without damage. receiver input resistance typically RS485 mode, shutdown mode power drops RS232 mode. RS485 mode, DXEN RXEN control threestate outputs driver receiver respectively. SLEW input active during RS485 mode logic level controls differential driver slew rate. This internal pull-up current source during RS485 mode. high logic selects fast differential driver slew rate logic selects slow slew rate. slow slew mode, maximum signal bandwidth reduced, minimizing
LTC1387
APPLICATI ATIO
signal reflection problems. Slow slew rate systems often improperly terminated even unterminated cables with acceptable results. RS485 differential input receiver features offset input threshold 80mV common mode voltage. This allows receiver output have known High output state when inputs open shorted. receiver also features input hysteresis 40mV. charge pump kept active regardless state DXEN RXEN pins keeping High. This improves receiver response time removing 100µs charge pump start-up time. RS232 mode, drivers receivers selected from Function Tables with control inputs RXEN DXEN. receivers feature typical 0.6V input hysteresis.
RS232 INTERFACE
RS485
RS485
RS232 TRANSMIT MODE RXEN DXEN MODE
RS232 RECEIVE MODE RXEN DXEN MODE
Figure Half-Duplex RS232 (1-Channel), Half-Duplex RS485
interface driver outputs fault protected current limiting thermal shutdown circuit. thermal shutdown circuit disables both RS232 RS485 driver outputs when temperature reaches 150°C. thermal shutdown circuit reenables drivers when temperature cools 135°C. loopback mode enables internal connections from driver outputs receiver inputs self-test. driver outputs isolated from external loads during loopback. charge pump generates boosted positive voltage negative voltage true RS232 levels from single supply. charge pump requires four 0.1µF capacitors.
LTC1387 DZ/SLEW RXEN DXEN 485/232 DX/RX CONTROLLER RXEN DXEN MODE RS485 TRANSMIT MODE RXEN DXEN MODE RS485 RECEIVE MODE RXEN DXEN MODE SHUTDOWN MODE RXEN DXEN MODE
1387
LTC1387
APPLICATI
INTERFACE
ATIO
LTC1387
RS232
RS485
RS232
RS485
DZ/SLEW RXEN DXEN 485/232
Figure Full-Duplex RS232 (1-Channel), Half-Duplex RS485
LTC1387 RS232 RS485 INTERFACE RS232 RS485 DZ/SLEW RXEN DXEN 485/232 RXEN DXEN MODE RS485 CONTROLLER RS232 MODE RXEN DXEN MODE RS485 MODE RXEN DXEN MODE SHUTDOWN MODE RXEN DXEN MODE
1387
RS485
Figure Full-Duplex RS232 (1-Channel), Full-Duplex RS485/RS422
LTC1387 RS232 RS232 INTERFACE RS232 RS232 RS485 DZ/SLEW RXEN DXEN 485/232 RS485 RS485 CONTROLLER DX2/SLEW RXEN DXEN MODE RS232 MODE RXEN DXEN MODE RS485 MODE RXEN DXEN MODE SHUTDOWN MODE RXEN DXEN MODE
1387
RS485
Figure Full-Duplex RS232 (2-Channel), Full-Duplex RS485/RS422 with SLEW Control
Information furnished Linear Technology Corporation believed accurate reliable. However, responsibility assumed use. Linear Technology Corporation makes representation that interconnection circuits described herein will infringe existing patent rights.
CONTROLLER RS232 MODE RXEN DXEN MODE RXEN DXEN MODE RS485 TRANSMIT MODE RXEN DXEN MODE RS485 RECEIVE MODE RXEN DXEN MODE SHUTDOWN MODE RXEN DXEN MODE
1387
LTC1387
PACKAGE DESCRIPTION
0.205 0.212** (5.20 5.38)
0.0256 (0.65) *DIMENSIONS INCLUDE MOLD FLASH. MOLD FLASH SHALL EXCEED 0.006" (0.152mm) SIDE **DIMENSIONS INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL EXCEED 0.010" (0.254mm) SIDE 0.005 0.009 (0.13 0.22) 0.022 0.037 (0.55 0.95)
0.291 0.299** (7.391 7.595) 0.010 0.029 (0.254 0.737) 0.093 0.104 (2.362 2.642) 0.037 0.045 (0.940 1.143)
0.009 0.013 (0.229 0.330)
0.050 0.004 0.012 (1.270) (0.102 0.305) 0.014 0.019 (0.356 0.482) NOTE: IDENT, NOTCH CAVITIES BOTTOM PACKAGES MANUFACTURING OPTIONS. PART SUPPLIED WITH WITHOUT OPTIONS NOTE 0.016 0.050 (0.406 1.270) *DIMENSION DOES INCLUDE MOLD FLASH. MOLD FLASH SHALL EXCEED 0.006" (0.152mm) SIDE **DIMENSION DOES INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL EXCEED 0.010" (0.254mm) SIDE
RELATED PARTS
PART NUMBER LTC485 1137A LTC1320 LTC1321/LTC1322/LTC1335 LTC1323 LTC1334 LTC1347 DESCRIPTION Power RS485 Interface Transceiver Power RS232 Transceiver AppleTalk Transceiver RS232/EIA562/RS485 Transceivers Single AppleTalk Transceiver Single Supply RS232/RS485 Transceiver Power RS232 Transceiver
AppleTalk LocalTalk registered trademarks Apple Computer Corp.
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, 95035-7417 (408) 432-1900 FAX: (408) 434-0507q TELEX: 499-3977 www.linear-tech.com
Dimensions inches (millimeters) unless otherwise noted. Package 20-Lead Plastic SSOP (0.209)
(LTC 05-08-1640)
0.278 0.289* (7.07 7.33) 0.068 0.078 (1.73 1.99) 0.301 0.311 (7.65 7.90)
0.010 0.015 (0.25 0.38)
0.002 0.008 (0.05 0.21)
SSOP 0595
Package 20-Lead Plastic Small Outline (Wide 0.300)
(LTC 05-08-1620)
0.496 0.512* (12.598 13.005)
NOTE
0.394 0.419 (10.007 10.643)
(WIDE) 0396
COMMENTS Single Supply, Wide Common Mode Range ±15kV IEC-1000-4-2 Protection, Three Drivers, Five Receivers AppleTalk /LocalTalk Compliant Configurable AppleTalk /LocalTalk Compliant 10kV Single Supply, Configurable Three Drivers/Five Receivers, Five Receivers Alive Shutdown
1387f LT/GP 0197 PRINTED
LINEAR TECHNOLOGY CORPORATION 1997
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