®1344A features software-selectable multiprotocol cable terminators. E
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LTC1344A Software-Selectable Cable Terminator
®1344A features software-selectable multiprotocol cable terminators. Each terminator configured RS422 (V.11) minimum differential load, V.35 T-network load open circuit with RS232 (V.28) RS423 (V.10) transceivers that provide their termination. When combined with LTC1543 LTC1544, LTC1344A forms complete software-selectable multiprotocol serial port. data latch feature allows sharing select lines between multiple interface ports. LTC1344A similar LTC1344 except difference Mode Selection table. LTC1344A available 24-lead SSOP.
Software-Selectable Cable Termination for: RS232 (V.28) RS423 (V.10) RS422 (V.11) RS485 RS449 EIA530 EIA530-A V.35 V.36 X.21 Outputs Won't Load Line with Power
APPLICATIONS
Data Networking Data Router
registered trademarks Linear Technology Corporation.
TYPICAL APPLICATION
Multiprotocol Serial Interface with DB-25 Connector
SCTE
Daisy-Chained Control OutputLTC1544
LTC1543
(141)
(106)
(109)
(107)
(108) (105) SHIELD (101)
(102)
(104)
(115)
SCTE SCTE (113) (103) (114)
DB-25 CONNECTOR
LTC1344A
1344A TA01
LTC1344A ABSOLUTE MAXIMUM RATINGS
(Note
PACKAGE/ORDER ATIO
VIEW DCE/DTE LATCH
Positive Supply Voltage (VCC) Negative Supply Voltage (VEE) 13.2V Input Voltage (Logic Inputs) (VEE 0.3V) (VCC 0.3V) Input Voltage (Load Inputs) ±18V Power Dissipation 600mW Operating Temperature Range LTC1344AC 70°C LTC1344AI 40°C 85°C Storage Temperature Range 65°C 150°C Lead Temperature (Soldering, sec). 300°C
ORDER PART NUMBER LTC1344ACG LTC1344AIG
PACKAGE 24-LEAD PLASTIC SSOP TJMAX 150°C, 100°C/W
Consult factory Military grade parts.
ELECTRICAL CHARACTERISTICS
±5%, ±5%, TMIN TMAX (Notes unless otherwise noted.
SYMBOL Supplies RV.35 Supply Current Differential Mode Impedance Common Mode Impedance Digital Pins Loads (Figure (Commercial) Loads (Figure (Commercial) Loads (Figure (Industrial) Loads (Figure (Industrial) RV.11 Differential Mode Impedance Loads (Figure (Commercial) Loads (Figure (Commercial) Loads (Figure (Industrial) Loads (Figure (Industrial) ILEAK High Impedance Leakage Current Input High Voltage Input Voltage Input Current Loads, Logic Input Pins Logic Input Pins Logic Input Pins Logic Inputq
PARAMETER
CONDITIONS
UNITS
Terminator Pinq
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 reference ground unless otherwise specified. Note typicals given 25°C.
LTC1344A TYPICAL PERFORMANCE CHARACTERISTICS
V.11 V.35 Differential Mode Impedance Temperature
DIFFERENTIAL MODE IMPEDANCE DIFFERENTIAL MODE IMPEDANCE
DIFFERENTIAL MODE IMPEDANCE
1344
TEMPERATURE (°C)
V.11 V.35 Differential Mode Impedance Negative Supply Voltage (VEE)
25°C COMMON MODE IMPEDANCE
DIFFERENTIAL MODE IMPEDANCE
COMMON MODE IMPEDANCE
VOLTAGE
1344
V.35 Common Mode Impedance Supply Voltage (VCC)
25°C
COMMON MODE IMPEDANCE
COMMON MODE IMPEDANCE
SUPPLY CURRENT (µA)
VOLTAGE
1344
V.11 V.35 Differential Mode Impedance Common Mode Voltage
25°C
V.11 V.35 Differential Mode Impedance Supply Voltage (VCC)
25°C
COMMON MODE VOLTAGE VOLTAGE
1344
1344
V.35 Common Mode Impedance Temperature
V.35 Common Mode Impedance Common Mode Voltage
25°C
TEMPERATURE (°C)
1344
COMMON MODE VOLTAGE
1344
V.35 Common Mode Inpedance Negative Supply Voltage (VEE)
25°C
Supply Current Temperature
VOLTAGE
1344
TEMPERATURE (°C)
1344
LTC1344A
FUNCTIONS
(Pin Level Mode Select Input. data latched when LATCH high. (Pin Negative Supply Voltage Input. connect directly LTC1543 pin. Connect capacitor ground. (Pin Load Center Tap. (Pin Load Node (Pin Load Node (Pin Load Node (Pin Load Node (Pin Load Center Tap. (Pin Load Node (Pin 10): Load Node (Pin 11): Load Center Tap. (Pin 12): Ground Connection Load Load (Pin 13): Ground Connection Load Load (Pin 14): Positive Supply Input. 4.75V 5.25V. (Pin 15): Load Node (Pin 16): Load Node (Pin 17): Load Node (Pin 18): Load Node (Pin 19): Load Node (Pin 20): Load Node LATCH (Pin 21): Level Logic Signal Latch Input. When LATCH input buffers DCE/ transparent. When LATCH high logic pins latched into their respective input buffers. data latch allows select lines shared between multiple ports. DCE/DTE (Pin 22): Level Mode Select Input. mode selected when high mode when low. data DCE/DTE latched when LATCH high. (Pin 23): Level Mode Select Input data latched when LATCH high. (Pin 24): Level Mode Select Input data latched when LATCH high.
TEST CIRCUITS
51.5 51.5 LTC1344A
1344
Figure Differential V.11 V.35 Impedance Measurement
LTC1344A 51.5 51.5
1344
Figure V.35 Common Mode Impedance Measurement
LTC1344A
SELECTIO
LTC1344A MODE NAME V.10/RS423 RS530A RS530 X.21 V.35 RS449/V.36 V.28/RS232 Cable
DCE/DTE
don't care, logic low, logic high
51.5 51.5
V.11 Mode
V.35 V.35 V.11 V.35 V.35 V.11 V.35 V.11 V.11 V.11 V.11 V.35 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.35 V.35 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.35 V.35 V.11 V.11 V.11
LTC1344A 51.5 51.5 LTC1344A 51.5 51.5 LTC1344A
V.35 Mode
High-Z Mode
1344
Figure LTC1344A Mode
LTC1344A
APPLICATIONS INFORMATION
Multiprotocol Cable Termination most difficult problems facing designer multiprotocol serial interface allow transmitters receivers different electrical standards share connector pins. some cases transmitters receivers each interface standard simply tied together appropriate circuitry enabled. biggest problem still remains: switch various cable termination required different standards. Traditional implementations have included switching resistors with expensive relays requiring user change termination modules every time interface standard changed. Custom cables have been used with termination cable head. Another method uses separate termination built board, custom cable which routes signals appropriate termination. Switching termination using FETs difficult because FETs must remain even though signal voltage beyond supply voltage drivers power off.
LTC1344A solves cable termination switching problem software control. LTC1344A provides termination V.10 (RS423), V.11 (RS422), V.28 (RS232) V.35 electrical protocols. V.10 (RS423) Termination typical V.10 unbalanced interface shown Figure V.10 single-ended generator output with ground connected differential receiver with input connected input connected signal return ground Usually cable termination required V.10 interfaces receiver inputs must compliant with impedance curve shown Figure V.10 mode, both switches turned only cable termination input impedance V.10 receiver.
GENERATOR
BALANCED INTERCONNECTING CABLE
LOAD CABLE TERMINATION RECEIVER
1344
Figure Typical V.10 Interface
51.5 LTC1344A 51.5 3.25mA -10V 3.25mA
1344
V.10 RECEIVER
Figure V.10 Interface Using LTC1344A
V.11 (RS422) Termination typical V.11 balanced interface shown Figure V.11 differential generator with outputs with ground connected differential receiver with ground inputs connected connected V.11 interface requires differential termination receiver that minimum value 100. receiver inputs must also compliant with impedance curve shown Figure V.11 mode, switch turned turned cable terminated with impedance.
LTC1344A
APPLICATIONS INFORMATION
GENERATOR BALANCED INTERCONNECTING CABLE LOAD CABLE TERMINATION RECEIVER
1344
Figure Typical V.11 Interface
51.5 LTC1344A 51.5 3.25mA -10V 3.25mA
1344
V.11 RECEIVER
Figure V.11 Interface Using LTC1344A
V.28 (RS232) Termination typical V.28 unbalanced interface shown Figure V.28 single-ended generator output with ground connected single-ended receiver with input connected ground connected signal return ground V.28 standard requires terminating resistor ground which included almost compliant receivers shown Figure Because termination included receiver, both switches LTC1344A turned off.
GENERATOR
BALANCED INTERCONNECTING CABLE
LOAD CABLE TERMINATION RECEIVER
1344
Figure Typical V.28 Interface
51.5 LTC1344A V.28 RECEIVER
51.5
1344
Figure V.28 Interface Using LTC1344A
V.35 Termination typical V.35 balanced interface shown Figure V.35 differential generator with outputs with ground connected differential receiver with ground inputs connected connected V.35 interface requires T-network termination receiver generator end. V.35 mode both switches LTC1344A turned shown Figure differential impedance measured connector must impedance between shorted terminals ground must ±15. input impedance V.35 receiver connected parallel with T-network inside LTC1344A, which could cause overall impedance fail specification
LTC1344A
APPLICATIONS INFORMATION
GENERATOR BALANCED INTERCONNECTING CABLE
LOAD CABLE TERMINATION RECEIVER
V.35 DRIVER
Figure Typical V.35 Interface
51.5 51.5 -0.8mA
1344
LTC1344A
V.35 RECEIVER
Figure V.35 Receiver Using LTC1344A
receiver input impedance side. Linear Technology's V.35 receivers meet RS485 input impedance specification shown Figure which insures compliance with V.35 specification when used with LTC1344A.
LTC1344A
51.5 51.5 100pF
1344
1344
Figure V.35 Driver Using LTC1344A
generator differential impedance must impedance between shorted terminals ground must ±15. generator termination, switches both side center resistor brought bypassed with external capacitor reduce common mode noise shown Figure mismatch driver rise fall times skew driver propagation delays will force current through center termination resistor ground causing high frequency common mode spike terminals. common mode spike cause problems that reduced capacitor which shunts much common mode energy ground rather than down cable. LATCH LATCH (21) allows select lines (M0, DCE/DTE) shared with multiple LTC1344As, each with LATCH signal. When LATCH held select line input buffers transparent. When LATCH pulled high, select line input buffers latch state Select pins that changes select lines ignored until LATCH pulled again. latch feature used, LATCH should tied ground.
LTC1344A
TYPICAL APPLICATIONS
Controller Selectable Multiprotocol DTE/DCE Port with DB-25 Connector
100pF 100pF 100pF LTC1343 DTE_TXD/DCE_RXD DTE_SCTE/DCE_RXC DB-25 CONNECTOR CHARGE PUMP 3.3µF LATCH LTC1344A
DCE/DTE
DTE_LL/DCE_
SCTE SCTE
DTE_TXC/DCE_TXC
DTE_RXC/DCE_SCTE
DTE_RXD/DCE_TXD
DTE_TM/DCE_LL
100k CTRL LATCH
INVERT 423SET
DTE_RTS/DCE_CTS
DTE_DTR/DCE_DSR
LTC1544
DTE_DCD/DCE_DCD DTE_DSR/DCE_DTR
DTE_CTS/DCE_RTS
DTE_RL/DCE_RL
INVERT
DCE/DTE
DCE/DTE
SHIELD
SCTE SCTE
1344A TA04
LTC1344A
TYPICAL APPLICATIONS
Cable Selectable Multiprotocol DTE/DCE Port with DB-25 Connector
100pF 100pF 100pF
DTE_TXD/DCE_RXD DTE_SCTE/DCE_RXC LTC1543 CHARGE PUMP 3.3µF LATCH
DCE/DTE
SCTE SCTE
SHIELD DB-25 CONNECTOR SCTE SCTE DCE/DTE
DTE_TXC/DCE_TXC
DTE_RXC/DCE_SCTE
DTE_RXD/DCE_TXD
DCE/DTE
DTE_RTS/DCE_CTS
DTE_DTR/DCE_DSR
LTC1544 CABLE WIRING MODE SELECTION MODE V.35 RS449, V.36 RS232 CABLE WIRING DTE/DCE SELECTION MODE
DTE_DCD/DCE_DCD DTE_DSR/DCE_DTR
DTE_CTS/DCE_RTS
DCE/DTE INVERT
LTC1344A
1344A TA05
LTC1344A
PACKAGE
0.205 0.212** (5.20 5.38)
0.005 0.009 (0.13 0.22)
0.022 0.037 (0.55 0.95)
*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
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.
Dimensions inches (millimeters) unless otherwise noted.
Package 24-Lead Plastic SSOP (0.209)
(LTC 05-08-1640)
0.318 0.328* (8.07 8.33)
0.301 0.311 (7.65 7.90)
0.068 0.078 (1.73 1.99)
0.0256 (0.65)
0.010 0.015 (0.25 0.38)
0.002 0.008 (0.05 0.21)
SSOP 0595
LTC1344A
TYPICAL APPLICATIO
Figure shows typical application LTC1344A using LTC1543 mixed mode transceiver chip generate clock data signals serial interface. LTC1344A supply generated from LTC1543 charge pump select lines
LTC1344A
DCE/DTE
DCE/DTE LATCH
LTC1543 DCE/DTE SCTE TXD- SCTE RXD- RXC+ TXD+ RXD+
RXD+ RXD- SCTE+ SCTE- TXD+ TXD-
1344
RELATED PARTS
PART NUMBER LTC1334 LTC1343 LTC1345 LTC1346A LTC1543 LTC1544 DESCRIPTION Single Supply RS232/RS485 Transceiver Multiprotocol Serial Transceiver Single Supply V.35 Transceiver Dual Supply V.35 Transceiver Multiprotocol Serial Transceiver Multiprotocol Serial Transceiver COMMENTS RS485 Dr/Rx RS232 Dr/Rx Pairs Software Selectable Mulitprotocol Interface Dr/3 Data Signals Dr/3 Data Signals Software-Selectable Transceiver Data Signals Software-Selectable Transceiver Control Signal1344af, sn1344a LT/TP 0898 PRINTED
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, 95035-7417
(408)432-1900 FAX: (408) 434-0507 www.linear-tech.com
DCE/DTE shared both chips. Each driver output receiver input connected LTC1344A termination ports. Each electrical protocol then chosen using digital select lines.
100pF 100pF 100pF 3.3µF
Figure Typical Application Using LTC1344A
LINEAR TECHNOLOGY CORPORATION 1998
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