DESCRIPTIO Software-Selectable Cable Termination for: RS232 (V.28
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LTC1344 Software-Selectable Cable Terminator
DESCRIPTIO
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
1344 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 LTC1343, LTC1344 forms complete software-selectable multiprotocol serial port. data latch feature allows sharing select lines between multiple interface ports. LTC1344 available 24-lead SSOP.
registered trademarks Linear Technology Corporation.
APPLICATIO
Data Networking Data Router
TYPICAL APPLICATION
SCTE
Daisy-Chained Control OutputLTC1343 LTC1343
DB-25 CONNECTOR
LTC1344
(107)
(140)
(106)
(108)
(105)
SHIELD (101)
SGND (102)
(142)
(104)
(115)
(109)
SCTE
SCTE (113)
(103)
(141)
(114)
1344 TA01
LTC1344 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) 0.3V 0.3V Input Voltage (Load Inputs) ±18V Operating Temperature Range LTC1344C 70°C LTC1344I 40°C 85°C Storage Temperature Range 65°C 150°C Lead Temperature (Soldering, sec). 300°C
ORDER PART NUMBER LTC1344CG LTC1344IG
PACKAGE 24-LEAD PLASTIC SSOP TJMAX 150°C, 100°C/W
Consult factory Military grade parts.
denotes specifications which apply over full operating temperature range, otherwise specifications 25°. ±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) ILEAK High Impedance Leakage Current Input High Voltage Input Voltage Input Current Loads, (Commercial) Logic Input Pins Logic Input Pins Logic Input Pins Logic Inputq
ELECTRICAL CHARACTERISTICS
PARAMETER CONDITIONS
UNITS
Terminator Pinq
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.
LTC1344 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)
COMMON MODE IMPEDANCE
DIFFERENTIAL MODE IMPEDANCE
COMMON MODE IMPEDANCE
VOLTAGE
1344
V.35 Common Mode Impedance Supply Voltage (VCC)
COMMON MODE IMPEDANCE
COMMON MODE IMPEDANCE
SUPPLY CURRENT (µA)
VOLTAGE
1344
V.11 V.35 Differential Mode Impedance Common Mode Voltage
V.11 V.35 Differential Mode Impedance Supply Voltage (VCC)
COMMON MODE VOLTAGE VOLTAGE
1344
1344
V.35 Common Mode Impedance Temperature
V.35 Common Mode Impedance Common Mode Voltage
TEMPERATURE (°C)
1344
COMMON MODE VOLTAGE
1344
V.35 Common Mode Inpedance Negative Supply Voltage (VEE)
Supply Current Temperature
VOLTAGE
1344
TEMPERATURE (°C)
1344
LTC1344
FUNCTIONS
(Pin Level Mode Select Input. data latched when LATCH high. (Pin Negative Supply Voltage Input. connect directly LTC1343 pin. (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 input buffers DCE/DTE transparent. When 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
1344
Figure Differential V.11 V.35 Impedance Measurement
51.5 51.5
1344
Figure V.35 Common Mode Impedance Measurement
LTC1344
SELECTIO
LTC1344 MODE NAME V.10/RS423 RS530A Reserved X.21 V.35 RS530/RS449/V.36 V.28/RS232 Cable
DCE/DTE
don't care, logic low, logic high
51.5 51.5
V.11 Mode
V.11 V.35 V.35 V.11 V.11 V.35 V.35 V.11 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.35 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
51.5 51.5 51.5 51.5
1344
V.35 Mode Figure LTC1344 Mode
Hi-Z Mode
LTC1344
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 terminations 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 separate terminations built board, custom cable routes signals appropriate termination. Switching terminations using FETs difficult because FETs must remain even though signal voltage beyond supply voltage drivers power off. LTC1344 solves cable termination switching problem software control. LTC1344 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 inputs connected input connected signal return ground receiver's ground separate from signal return. 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.
3.25mA GENERATOR BALANCED INTERCONNECTING CABLE LOAD CABLE TERMINATION RECEIVER
1344
Figure Typical V.10 Interface
51.5 LTC1344 51.5 3.25mA -10V
1344
V.10 RECEIVER
Figure V.10 Interface Using LTC1344
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 different 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.
LTC1344
APPLICATIONS INFORMATION
GENERATOR BALANCED INTERCONNECTING CABLE LOAD CABLE TERMINATION RECEIVER
1344
Figure Typical V.11 Interface
51.5 LTC1344 51.5 3.25mA -10V 3.25mA
1344
V.11 RECEIVER
Figure V.11 Interface Using LTC1344
V.28 (RS232) Termination typical V.28 unbalanced interface shown Figure V.28 single-ended generator output with ground connected single-ended receiver with inputs 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 LTC1344 turned off.
GENERATOR
BALANCED INTERCONNECTING CABLE
LOAD CABLE TERMINATION RECEIVER
1344
Figure Typical V.28 Interface
51.5 LTC1344 V.28 RECEIVER
51.5
1344
Figure V.28 Interface Using LTC1344
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 LTC1344 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 LTC1344, which cause overall impedance fail specification
LTC1344
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
LTC1344
V.35 RECEIVER
Figure V.35 Receiver Using LTC1344
side. However, Linear Technology's V.35 receivers meet RS485 input impedance specification shown Figure which insures compliance with V.35 specification when used with LTC1344. generator differential impedance must impedance between shorted terminals
LTC1344
51.5 51.5 100pF
1344
1344
Figure V.35 Driver Using LTC1344
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 LTC1344s, 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.
LTC1344
TYPICAL APPLICATIONS
Figure shows typical application LTC1344 using LTC1343 mixed mode transceiver chip generate clock data signals serial interface. LTC1344 supply generated from LTC1343 charge pump select lines LATCH shared both chips. Each driver output receiver input connected LTC1344 termination ports. Each electrical protocol then chosen using digital select lines.
LTC1344
DCE/DTE LATCH
DCE/DTE LATCH
LTC1343 DCE/DTE LATCH
Figure Typical Application Using LTC1344
100pF 100pF
100pF
3.3µF
TXD+ TXD- SCTE SCTE
RXD+ RXD- TXC+ SCTE+ SCTE TXD+ TXD-
1344
RXD+ RXD-
LTC1344
TYPICAL APPLICATIONS
Controller Selectable Multiprotocol Port with DB-25 Connector
100pF 100pF 100pF
DTE_LL/DCE_DTE_TXD/DCE_RXD DTE_SCT/DEC_RXC LTC1343 CHARGE PUMP 3.3µF
DTE_TXC/DCE_TXC DTE_RXC/DCE_SCTE DTE_RXD/DCE_TXD DTE_TM/DCE_LL
100k
CTRL LATCH INVERT
LTC1343 LATCH CHARGE PUMP
DTE_RL/DCE_RL DTE_RTS/DCE_CTS DTE_DTR/DCE_DSR
DTE_DCD/DCE_DCD DTE_DSR/DCE_DTR DTE_CTS/DCE_RTS
100k DCE/DTE
CTRL LATCH INVERT
LTC1344
LATCH
DCE/
DB-25 CONNECTOR
SCTE SCTE
SCTE SCTE
SGND SHIELD
3.3µF
1344 TA02
LTC1344
TYPICAL APPLICATIONS
Cable Selectable Multiprotocol Port with DB-25 Connector
100pF 100pF 100pF
LTC1343 CHARGE PUMP 3.3µF
DTE_TXD/DCE_RXD DTE_SCTE/DEC_RXC
DTE_TXC/DCE_TXC DTE_RXC/DCE_SCTE DTE_RXD/DCE_TXD
100k
CTRL LATCH INVERT
LTC1343
CHARGE PUMP
DTE_RTS/DCE_CTS DTE_DTR/DCE_DSR
DTE_DCD/DCE_DCD DTE_DSR/DCE_DTR DTE_CTS/ DCE_RTS
100k
CTRL LATCH INVERT
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.
LTC1344
LATCH
DCE/
DB-25 CONNECTOR
SCTE SCTE
SCTE SCTE
SGND SHIELD
3.3µF
DCE/DTE
1344 TA03
CABLE WIRING MODE SELECTION MODE V.35 EIA-530, RS449, V.36, X.21 RS232
CABLE WIRING DTE/DCE SELECTION MODE
LTC1344
PACKAGE DESCRIPTION
5.20 5.38** (0.205 0.212)
0.13 0.22 (0.005 0.009)
0.55 0.95 (0.022 0.037)
NOTE: DIMENSIONS MILLIMETERS *DIMENSIONS INCLUDE MOLD FLASH. MOLD FLASH SHALL EXCEED 0.152mm (0.006") SIDE **DIMENSIONS INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL EXCEED 0.254mm (0.010") SIDE
RELATED PARTS
PART NUMBER LTC1334 LTC1343 LTC1345 LTC1346A LTC1344A LTC1543 LTC1544 LTC1545 DESCRIPTION Single Supply RS232/RS485 Transceiver Multiprotocol Serial Transceiver Single Supply V.35 Transceiver Dual Supply V.35 Transceiver Multiprotocol Cable Terminator, Compatible LTC1344 Multiprotocol Serial 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 Allows Separate RS449 Mode Dr/3 Data Signals Dr/4 Control Signals Dr/5 Control Signals,
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, 95035-7417
(408)432-1900 FAX: (408) 434-0507 www.linear-tech.com
Dimensions inches (millimeters) unless otherwise noted. Package 24-Lead Plastic SSOP (0.209)
(LTC 05-08-1640)
8.07 8.33* (0.318 0.328)
7.65 7.90 (0.301 0.311)
1.73 1.99 (0.068 0.078)
0.65 (0.0256)
0.25 0.38 (0.010 0.015)
0.05 0.21 (0.002 0.008)
SSOP 1098
1344fa LT/TP 0300 PRINTED
LINEAR TECHNOLOGY CORPORATION 1996
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