DESCRIPTIO Software-Selectable Transceiver Supports: RS232, RS449

The Datasheet Archive - 100 Million Datasheets from 7500 Manufacturers.

DESCRIPTIO Software-Selectable Transceiver Supports: RS232, RS449

Datasheet Thumbnail

Top Searches for this datasheet

LTC2846 3.3V Software-Selectable Multiprotocol Transceiver with Termination
DESCRIPTIO
Software-Selectable Transceiver Supports: RS232, RS449, EIA530, EIA530-A, V.35, V.36, X.21 Operates from Single 3.3V Supply Rheinland North America Inc. Certified NET1, NET2 TBR2 Compliant, Report No.: TBR2/050101/02, TBR2/051501/02 1.2MHz Boost Switching Regulator 3.3V Conversion On-Chip Cable Termination Complete Port with LTC2844 LTC2845 Small Footprint
APPLICATIO
LTC2846 3-driver/3-receiver multiprotocol transceiver with on-chip cable termination. When combined with LTC2844 LTC2845, this chip forms complete software-selectable interface port that supports RS232, RS449, EIA530, EIA530-A, V.35, V.36 X.21 protocols. necessary cable termination provided inside LTC2846. LTC2846 boost regulator that takes 3.3V input switches 1.2MHz, allowing tiny, cost capacitors inductors less height. output drives internal charge pump that requires only five space-saving surface mounted capacitors. LTC2846 available 36-lead SSOP surface mount package.
registered trademarks Linear Technology Corporation.
Data Networking Data Routers
TYPICAL APPLICATIO
Complete Multiprotocol Serial Interface with DB-25 Connector
SCTE
LTC2844
(141)
(106)
(109)
(107)
(108) (105) SHIELD (101)
(102)
(104)
(115)
DB-25 CONNECTOR
2846 TA01
LTC2846 (114) SCTE SCTE (113) (103)
2846f
LTC2846
ABSOLUTE
(Note
RATI
PACKAGE/ORDER ATIO
VIEW PGND SHDN
Voltage. 0.3V 6.5V Voltage 0.3V 6.5V Input Voltage Transmitters 0.3V (VCC 0.3V) Receivers Logic Pins 0.3V (VCC 0.3V) Output Voltage Transmitters (VEE 0.3V) (VDD 0.3V) Receivers 0.3V (VIN 0.3V) 0.3V 0.3V Short-Circuit Duration Transmitter Output Indefinite Receiver Output Indefinite Voltage 0.4V Voltage 0.3V 2.5V Current into ±1mA SHDN Voltage 0.3V Operating Temperature Range LTC2846C 70°C LTC2846I 40°C 85°C Storage Temperature Range 65°C 150°C Lead Temperature (Soldering, sec). 300°C
ORDER PART NUMBER
SGND
CHARGE PUMP BOOST SWITCHING REGULATOR
LTC2846CG LTC2846IG
D3/R1 D3/R1
DCE/DTE
PACKAGE 36-LEAD PLASTIC SSOP TJMAX 125°C, 90°C/W, 35°C/W
SOLDERED CIRCUIT BOARD TYPICALLY 60°C/W
Consult Marketing parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL Supplies Supply Current (DCE Mode, Digital Pins VIN) PARAMETER
denotes specifications which apply over full operating temperature range, otherwise specifications 25°C. 3.3V, VSHDN VIN, unless otherwise noted. (Notes
CONDITIONS RS530, RS530-A, X.21 Modes, Load RS530, RS530-A, X.21 Modes, Full Load V.35 Mode V.28 Mode, Load V.28 Mode, Full Load No-Cable Mode RS530, RS530-A, X.21 Modes, Full Load V.35 Mode, Full Load V.28 Mode, Full Load V.11 V.28 Mode, Load V.35 Mode V.28 Mode, with Load V.28 Mode, with Load, 10mA
UNITS
2846f
Internal Power Dissipation (DCE Mode)
Positive Charge Pump Output Voltage
LTC2846
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER Negative Charge Pump Output Voltage
denotes specifications which apply over full operating temperature range, otherwise specifications 25°C. 3.3V, VSHDN VIN, unless otherwise noted. (Notes
CONDITIONS V.28 Mode, Load V.28 Mode, Full Load V.35 Mode RS530, RS530-A, X.21 Modes, Full Load No-Cable Mode/Power-Off Normal Operation DCE/DTE SHDN DCE/DTE SHDN DCE/DTE DCE/DTE SHDN SHDN 1.6mA VIN, VIN, 1.95k (Figure (Figure (Figure (Figure (Figure (Figure VOUT
0.25V, Power
UNITS
fOSC
Charge Pump Oscillator Frequency Charge Pump Rise Time Logic Input High Voltage Logic Input Voltage Logic Input Current
Logic Inputs Outputs ±0.1 -160 0.5VODO 0.67VODO ±150 ±100
IOSR IOZR V.11 Driver VODO VODL SKEW
Output High Voltage Output Voltage Output Short-Circuit Current Three-State Output Current
Open Circuit Differential Output Voltage Loaded Differential Output Voltage Change Magnitude Differential Output Voltage Common Mode Output Voltage Change Magnitude Common Mode Output Voltage Short-Circuit Current Output Leakage Current Rise Fall Time Input Output Rising Input Output Falling Input Output Difference, tPLH tPHL Output Output Skew
No-Cable Mode Driver Disabled (Figures (Figures (Figures (Figures (Figures
2846f
LTC2846
ELECTRICAL CHARACTERISTICS
SYMBOL V.35 Driver VOA, SKEW tPLH tPHL V.28 Driver Output Voltage Short-Circuit Current Power-Off Resistance Slew Rate Input Output Input Output Differential Output Voltage Single-Ended Output Voltage Transmitter Output Offset Transmitter Output High Current Transmitter Output Current Transmitter Output Leakage Current Transmitter Differential Mode Impedance Transmitter Common Mode Impedance Rise Fall Time Input Output Input Output Input Output Difference, tPLH tPHL Output Output Skew Differential Receiver Input Threshold Voltage Receiver Input Hysteresis Receiver Differential Mode Impedance Receiver Common Mode Impedance Rise Fall Time Input Output Input Output Input Output Difference, tPLH tPHL PARAMETER Input Threshold Voltage Input Hysteresis Input Impedance Rise Fall Time Input Output Rising Input Output Falling Input Output Difference, tPLH tPHL V.11 Receiver
denotes specifications which apply over full operating temperature range, otherwise specifications 25°C. 3.3V, VSHDN VIN, unless otherwise noted. (Notes
CONDITIONS (Figure 50pF (Figures 50pF (Figures 50pF (Figures 50pF (Figures Open Circuit, 1.95k (Figure With Load, (Figure Open Circuit, 1.95k (Figure (Figure
0.25V
UNITS
±1.2 ±0.66 ±1.2 ±0.6
±0.44
±0.55
±100
(Figure (Figures (Figures (Figures (Figures (Figures (Figure (Figure (Figure 50pF (Figures 50pF (Figures 50pF (Figures 50pF (Figures Open Circuit (Figure VOUT Power No-Cable Mode (Figures 2500pF (Figures 2500pF (Figures
V.35 Receiver ±150 V/µs
2846f
±8.5
LTC2846
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER V.28 Receiver VTHL Input Threshold Voltage VTLH Input High Threshold Voltage Receiver Input Hysteresis Receiver Input Impedance Rise Fall Time tPLH Input Output tPHL Input Output Boost Switching Regulator (Note Operating Voltage Feedback Voltage Bias Current Quiescent Current Quiescent Current Shutdown VFB(LR) Reference Line Regulation Switching Frequency DCMAX Maximum Duty Cycle ILIM Switch Current Limit VSAT Switch VCESAT ILEAK Switch Leakage Current
denotes specifications which apply over full operating temperature range, otherwise specifications 25°C. 3.3V, VSHDN VIN, unless otherwise noted. (Notes
CONDITIONS (Figure (Figure (Figure 50pF (Figures 50pF (Figures 50pF (Figures
UNITS
0.05 1.255 0.01 0.01 0.01
1.280 0.05
1.230
1.255V VSHDN 2.4V, Switching VSHDN 3.6V
(Note 900mA
0.85
Note Absolute Maximum Ratings those values beyond which life device impaired. Note currents into device pins positive; currents device negative. voltages referenced device ground unless otherwise specified.
Note typicals given 3.3V, CVCC CVIN 10µF, CVDD 1µF, CVEE 3.3µF 25°C. Note Boost Regulator specified unless otherwise noted. Note Current limit guaranteed design and/or correlation static test.
TYPICAL PERFOR CHARACTERISTICS
V.11 Mode Data Rate
(mA) (mA) (mA)
25°C
1000 10000
2846
DATA RATE (kBd)
V.35 Mode Data Rate
V.28 Mode Data Rate
25°C
25°C
1000 DATA RATE (kBd)
10000
2846
DATA RATE (kBd)
2846
2846f
LTC2846 TYPICAL PERFOR CHARACTERISTICS
V.11 Mode Temperature
(mA)
(mA)
125.5 125.0 124.5 124.0 123.5
(mA)
TEMPERATURE (°C)
TEMPERATURE (°C)
Boost Switching Regulator SHDN Current Voltage
CURRENT LIMIT
SHDN CURRENT (µA)
25°C SHDN VOLTAGE
2846
FREQUENCY (MHz)
100°C
EFFICIENCY
2846
V.35 Mode Temperature
128.0 127.5 127.0 126.5 126.0
V.28 Mode Temperature
37.5 37.0 36.5 36.0 35.5 35.0 34.5 34.0 33.5 TEMPERATURE (°C)
3846
123.0
2846
Boost Switching Regulator Current Limit Duty Cycle
1.30 25°C 1.25
Boost Switching Regulator Oscillator Frequency Temperature
DUTY CYCLE
1.20
1.15
1.10
1.05
TEMPERATURE (°C)
2846
2846
Efficiency Load Current
LOAD CURRENT (mA)
2846 TA01b
25°C 3.3V
2846f
LTC2846
CTIO
(Pin Connect. PGND (Pin Boost Switching Regulator Power Ground. PGND SGND. (Pin Input Supply Pin. Input supply boost switching regulator. 3.6V. Bypass with 10µF capacitor ground. SHDN (Pin Boost Switching Regulator Shutdown Pin. 2.4V more enable regulator. Ground shut down. (Pin Capacitor Negative Terminal. Connect capacitor between C1-. (Pin Capacitor Positive Terminal. Connect capacitor between (Pin Generated Positive Supply Voltage V.28. Connect capacitor ground. (Pin Input Supply Pin. Input supply transceiver. 4.75V 5.25V. Connect output switching regulator. (Pin Level Driver Input. (Pin 10): Level Driver Input. (Pin 11): Level Driver Input. (Pin 12): CMOS Level Receiver Output with Pull-Up when Three-Stated. (Pin 13): CMOS Level Receiver Output with Pull-Up when Three-Stated. (Pin 14): CMOS Level Receiver Output with Pull-Up when Three-Stated. (Pin 15): Level Mode Select Input with Pull-Up VIN. Table (Pin 16): Level Mode Select Input with Pull-Up VIN. Table (Pin 17): Input Supply Pin. Input supply transceiver. 3.6V. Connect (Pin 18): Level Mode Select Input with Pull-Up VIN. Table DCE/DTE (Pin 19): Level Mode Select Input with Pull-Up VIN. Table (Pin 20): Receiver Noninverting Input. (Pin 21): Receiver Inverting Input. (Pin 22): Receiver Noninverting Input. (Pin 23): Receiver Inverting Input. D3/R1 (Pin 24): Receiver Noninverting Input Driver Noninverting Output. D3/R1 (Pin 25): Receiver Inverting Input Driver Inverting Output. (Pin 26): Driver Noninverting Output. (Pin 27): Driver Inverting Output. (Pin 28): Driver Noninverting Output. (Pin 29): Driver Inverting Output. (Pin 30): Transceiver Ground. (Pin 31): Generated Negative Supply Voltage. Connect 3.3µF capacitor GND. (Pin 32): Capacitor Negative Terminal. Connect capacitor between (Pin 33): Capacitor Positive Terminal. Connect capacitor between SGND (Pin 34): Boost Switching Regulator Signal Ground. PGND SGND. (Pin 35): Boost Switching Regulator Feedback Pin. Reference voltage 1.255V. Connect resistive divider here. Minimize trace area (Pin 36): Boost Switching Regulator Switch Pin. Connect inductor/diode here. Minimize trace area this reduce EMI.
2846f
LTC2846
BLOCK DIAGRA
PGND SHDN
DCE/DTE
BOOST SWITCHING REGULATOR SGND SHDN CHARGE PUMP 51.5 51.5 D3/R1 MODE SELECTION LOGIC 51.5
2846
D3/R1
51.5 51.5
51.5
2846f
LTC2846
TEST CIRCUITS
2846
100pF 100pF
2846
Figure V.11 Driver Test Circuit
Figure V.11 Driver Test Circuit
2846
2(VB 2846
Figure Input Impedance Test Circuit
Figure V.11, V.35 Receiver Test Circuit
2846
2846
2846
Figure V.35 Driver Open-Circuit Test
Figure V.35 Driver Test Circuit
Figure V.35 Driver Common Mode Impedance Test Circuit
51.5
2846
51.5
2846
2846
Figure V.35 Driver Test Circuit
Figure V.35 Receiver Test Circuit
Figure Receiver Common Mode Impedance Test Circuit
2846
2846
Figure V.28 Driver Test Circuit
Figure V.28 Receiver Test Circuit
2846f
LTC2846
SELECTIO
Table
Mode Name
(Note (Note
DCE/ D1,2
Used (Default V.11) RS530A RS530 X.21 V.35 RS449/V.36 V.28/RS232 Cable
Used (Default V.11) RS530A RS530 X.21 V.35 RS449/V.36 V.28/RS232 Cable
V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.35 V.35 V.35 V.35 V.35 V.35 V.35 V.35 V.35 V.35 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.28 V.28 V.28 V.28 V.28
Note Driver inputs level compatible. Note Unused receiver inputs terminated with ground. addition, always terminated differential impedence (see Block Diagram page Note Receiver Outputs CMOS level compatible have weak pull when
SWITCHI WAVEFOR
SKEW SKEW
2846
1.5V
Figure V.11, V.35 Driver Propagation Delays
VOD2 -VOD2 1.65V OUTPUT 1MHz 10ns 10ns INPUT 1.65V
2846
Figure V.11, V.35 Receiver Propagation Delays
2846f
(Note
(Note
(Note
(Note
R2,R3
(Note
(Note
(Note
CMOS CMOS CMOS CMOS CMOS CMOS CMOS CMOS CMOS CMOS CMOS CMOS CMOS CMOS 9.3V 9.3V 9.3V 9.3V 9.3V 8.7V 4.7V 9.3V 9.3V 9.3V 9.3V 9.3V 8.7V 4.7V -6.5V -8.5V 0.3V -6.5V -8.5V 0.3V
V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.11 V.35 V.35 V.35 V.35 V.11 V.11 V.11 V.11 V.28 V.28
V.11 V.11 V.11 V.11 V.11 V.11 CMOS V.11 V.11 V.11 V.11 V.11 V.11 CMOS V.11 V.11 V.11 V.11 V.11 V.11 CMOS V.11 V.11 V.11 V.11 V.11 V.11 CMOS V.35 V.35 V.35 V.35 V.35 V.35 CMOS V.11 V.11 V.11 V.11 V.11 V.11 CMOS V.28 V.28 V.28 CMOS
Note values shown typical values 3.3V 25°C with LTC2846 under full load each mode. Note values shown typical values 3.3V 25°C with LTC2846 under full load each mode.
1MHz 10ns 10ns
1.5V
LTC2846
SWITCHI WAVEFOR
1.5V 1.5V
2846
Figure V.28 Driver Propagation Delays
1.5V 1.65V 1.5V 1.65V
2846
Figure V.28 Receiver Propagation Delays
APPLICATIO ATIO
Overview
LTC2846 consists boost switching regulator, charge pump 3-driver/3-receiver transceiver. boost switching regulator generates from 3.3V input power charge pump transceiver. charge pump generates supplies. LTC2846's VCC, supplies used power companion chip like LTC2844 LTC2845. receiver outputs driven between interface with 3.3V logic. LTC2846 LTC2844 form complete softwareselectable interface port that supports RS232, RS449, EIA530, EIA530-A, V.35, V.36 X.21 protocols. Cable termination provided on-chip, eliminating need discrete termination designs. complete DCE-to-DTE interface operating EIA530 mode shown Figure LTC2846 half each port used generate appropriately terminate clock data signals. LTC2844 used generate control signals along with (Local Loopback).
Mode Selection interface protocol selected using mode select pins (see Table example, port configured V.35 interface, mode selection pins should control signals, drivers receivers will operate V.28 (RS232) electrical mode. clock data signals, drivers receivers will operate V.35 electrical mode. DCE/DTE will configure port mode when high, when low. interface protocol selected simply plugging appropriate interface cable into connector. mode pins routed connector left unconnected wired ground cable shown Figure internal pull-up current sources will ensure binary when left unconnected. mode selection also accomplished using jumpers connect mode pins ground VIN.
2846f
LTC2846
APPLICATIO ATIO
SERIAL CONTROLLER LTC2846
SCTE
LTC2844
Figure Complete Multiprotocol Interface EIA530 Mode
When cable removed, leaving mode pins unconnected, LTC2846/LTC2844 will enter no-cable mode. this mode LTC2846/LTC2844 supply current drops less than 900µA LTC2846/LTC2844 driver outputs forced into high impedance state. same time, receivers LTC2846 differentially terminated with other receivers
LTC2846 SERIAL CONTROLLER SCTE SCTE LTC2844
2846
LTC2846 LTC2844 terminated with ground. Cable Termination Traditional implementations used expensive relays switch resistors required user change termination modules every time interface standard
2846f
LTC2846
APPLICATIO ATIO
(DATA) LTC2846 DCE/DTE
DCE/DTE LTC2844 (DATA)
2846
Figure Single Port V.35 Mode Selection Cable
selected. Switching terminations with FETs difficult because FETs must remain when signal voltage beyond supply voltage. Alternatively, custom cables contain termination cable head route signals various terminations board. LTC2846/LTC2844 chip solves cable termination switching problem automatically providing appropriate termination switching on-chip V.10 (RS423), V.11 (RS422), V.28 (RS232) V.35 electrical protocols. V.10 (RS423) Interface V.10 drivers receivers necessary RS449, EIA530, EIA530-A, V.36 X.21 protocols implemented LTC2844 LTC2845. typical V.10 unbalanced interface shown Figure V.10 single-ended generator with output ground connected differential receiver with input connected ground connected signal return ground Usually, cable termination required V.10 interfaces, receiver inputs must compliant with impedance curve shown Figure V.10 receiver configuration LTC2844 LTC2845 shown Figure V.10 mode, switch inside LTC2844 LTC2845 turned off. noninverting input disconnected inside LTC2844
CONNECTOR CABLE
GENERATOR BALANCED INTERCONNECTING CABLE LOAD CABLE TERMINATION RECEIVER
2846
Figure Typical V.10 Interface
3.25mA
-10V
-3.25mA
2846
Figure V.10 Receiver Input Impedance
2846f
LTC2846
APPLICATIO ATIO
RECEIVER LTC2844
2846
Figure V.10 Receiver Configuration
BALANCED INTERCONNECTING CABLE
GENERATOR
LOAD CABLE TERMINATION RECEIVER
Figure Typical V.11 Interface
LTC2845 receivers connected ground. cable termination then input impedance ground LTC2844 LTC2845 V.10 receiver. V.11 (RS422) Interface
typical V.11 balanced interface shown Figure V.11 differential generator with outputs ground connected differential receiver with input connected input connected ground connected signal return ground V.11 interface differential termination receiver that minimum value 100. termination resistor optional V.11 specification, high speed clock data lines, termination essential prevent reflections from corrupting data. receiver inputs must also compliant with impedance curve shown Figure V.11 mode, switches except LTC2846's receivers which connects differential
there switch receivers However, simplicity, termination networks LTC2846 treated identically assumed that switch exists always closed receivers.
1Actually,
51.5 51.5 RECEIVER LTC2846
2846
Figure V.11 Receiver Configuration
termination impedance cable shown Figure 231. LTC2844 LTC2845 only handle control signals, termination other than their V.11 receivers' input impedance necessary. V.28 (RS232) Interface typical V.28 unbalanced interface shown Figure V.28 single-ended generator with output ground connected single-ended receiver with input connected ground connected signal return ground
GENERATOR BALANCED INTERCONNECTING CABLE LOAD CABLE TERMINATION RECEIVER
2846
2846
Figure Typical V.28 Interface
51.5 51.5 RECEIVER LTC2846
2846
Figure V.28 Receiver Configuration
2846f
LTC2846
APPLICATIO ATIO
V.28 mode, closed inside LTC2846/LTC2844 which connects (R8) impedance ground parallel with (R5) plus (R6) combined impedance shown Figure Proper termination only provided when input receivers floating, since LTC2846's receivers remains V.28 mode1. noninverting input disconnected inside LTC2846/LTC2844 receiver connected level reference voltage give 1.4V receiver trip point. V.35 Interface typical V.35 balanced interface shown Figure V.35 differential generator with outputs ground connected differential receiver with input connected input connected ground connected signal return ground V.35 interface requires delta network termination receiver generator end. receiver differential impedance measured connector must
GENERATOR BALANCED INTERCONNECTING CABLE LOAD CABLE TERMINATION RECEIVER
Figure Typical V.35 Interface
51.5 51.5 RECEIVER LTC2846
2846
10µF
Figure V.35 Receiver Configuration
Figure Charge Pump
2846f
±10, impedance between shorted terminals ground (C') must ±15. V.35 mode, both switches inside LTC2846 connecting network impedance shown Figure input impedance receiver placed parallel with network termination, does affect overall input impedance significantly. generator differential impedance must impedance between shorted terminals ground must ±15. No-Cable Mode no-cable mode intended case when cable disconnected from connector. charge pump, bias circuitry, drivers receivers turned off, driver outputs forced into high impedance state, supply current transceiver drops less than 300µA while supply current drops less than 10µA. Note that LTC2846's receivers continue terminated differential impedance. Charge Pump LTC2846 uses internal capacitive charge pump generate shown Figure voltage doubler generates about voltage inverter generates about 7.5V VEE. Three surface mounted tantalum ceramic capacitors required capacitor should minimum 3.3µF. capacitors should placed close possible LTC2846 reduce EMI.
2846
LTC2846
3.3µF
2846
LTC2846
APPLICATIO ATIO
Switching Regulator
circuit shown Figure provide 480mA drive LTC2846's transceiver well companion chip DTE-DCE interface. shut down mode with SHDN boost switching regulator draws less than 10µA. Ferrite core inductors should used obtain best efficiency, core losses 1.2MHz much lower ferrite cores than cheaper powdered-iron types. Choose inductor that handle least without saturating, ensure that inductor (copper wire resistance) minimize power losses. capacitors output minimize output ripple voltage. Multilayer ceramic capacitors excellent choice, they have extremely available very small packages. Ceramic capacitors also make good choice input decoupling capacitor, should placed close possible switching regulator. Solid tantalum OS-CON capacitors used they will occupy more board area than ceramic will have higher ESR. Schottky diode recommended with switching regulator. Semiconductor MBR0520 very good choice. output voltage, select values according following equation. R2[(5V/1.255V) good value 4.3k which sets current resistor divider chain 1.255V/4.3k 292µA.
3.3V 10µF 5.6µH 10µF 4.3k 480mA
SHDN
BOOST SWITCHING REGULATOR SHDN
C5,C6: TAIYO YUDEN JMK316BJ106ML SEMICONDUCTOR MBR0520 SUMIDA CR43-5R6
Figure Boost Switching Regulator
switching regulator switch current limit This current limit protects switch well external components connected switching regulator. high speed operation boost switching regulator demands careful attention board layout. Figure shows recommended component placement. Receiver Fail-Safe LTC2846/LTC2844 receivers feature fail-safe operation modes. receiver inputs left floating shorted together termination resistor, receiver output will always forced logic high. Operation DCE/DTE acts enable Driver 3/Receiver LTC2846, Driver 3/Receiver Receiver Driver LTC2844. LTC2846/LTC2844 configured either operation ways: dedicated port with connector appropriate gender port with connector that configured operation rerouting signals LTC2846/LTC2844 using dedicated cable dedicated cable. dedicated port using DB-25 male connector shown Figure interface mode selected logic outputs from controller from jumpers either mode select pins. dedicated port using DB-25 female connector shown Figure
SHUTDOWN
2846
2846
Figure Suggested Layout
2846f
LTC2846
TYPICAL APPLICATIO
port with DB-25 connector, that configured either operation shown Figure configuration requires separate cables proper signal routing operation. example, mode, signal routed Pins LTC2846's Driver mode, Driver routes signal Pins Multiprotocol Interface with DB-25 Connector signals implemented, there enough drivers receivers available LTC2846/ LTC2844. Figure required control signals handled LTC2845. LTC2845 additional single-ended driver/receiver pair that handle more optional control signals such Cable-Selectable Multiprotocol Interface cable-selectable multiprotocol DTE/DCE interface shown Figure select lines DCE/DTE brought connector. mode selected cable wiring (connector (connector DCE/DTE (connector ground (connector letting them float. DCE/DTE floating, internal pull-up current sources will pull signals VIN. select floating, therefore, internally pulled high. When cable pulled out, interface will into no-cable mode. Power Dissipation Calculations LTC2846 takes 3.3V supply produces with internal switcher approximately efficiency. turn produced from with internal charge pump approximately efficiency respectively. Current drawn internally from translates directly into higher ICC. LTC2846 dissipates power according equation: PDISS(2846) 125% (VCC ICC) refers power dissipated each driver receiver termination cable while number drivers. Conversely, current from drivers dissipate power internal receiver termination where number receivers. LTC2846 Power Dissipation Consider LTC2846 X.21, mode (three V.11 drivers V.11 receivers). From Electrical Characteristics Table, load 14mA, full load 100mA. Each receiver termination (RRT) current going into each receiver termination (100mA 14mA)/3 28.7mA (IRT). (IRT)2 From Equation (2), 82.4mW from Equation (1), power dissipation PDISS(2846) 125% 100mA) 82.4mW 82.4mW 543mW. Consider above example running baud rate 10MBd. From Typical Characteristic "V.11 Mode Data Rate," 10MBd 160mA. increases with baud rate driver transient dissipation. From Equation (1), power dissipation PDISS(2846) 125% 160mA) 82.4mW 82.4mW 918mW. LTC2845 Power Dissipation LTC2845 used form complete port with LTC2846, will running X.21 mode (three V.11 drivers V.10 drivers, V.11 receivers V.10 receivers, with internal termination). addition VCC, uses outputs from LTC2846. Negligible power dissipated large internal receiver termination LTC2845 term Equation omitted. Thus Equation modified follows: PDISS(2845) (VCC ICC) (VDD IDD)
2846f
LTC2846
(VEE IEE)
Since power drawn from supplies LTC2846 (VCC, VEE) less than 100% efficiency, LTC2846 dissipates extra power source PDISS(2845) PDISS1(2846) 125% (VCC ICC) 125% 125% (VDD IDD) 125% 143% (VEE IEE) PDISS(2845) (VCC ICC) (VDD IDD) (VEE IEE) From LTC2845 Electrical Characteristics Table, 5.5V:
load full load with drivers high load full load with both V.10 drivers load full load 2.7mA 110mA 23mA 0.3mA 0.3mA
V.11 drivers driven between while V.10 drivers driven between VEE. Assume that V.11 driver outputs high V.10 driver outputs low. Current going into each V.11 receiver termination (110mA 2.7mA) 23mA/3 28.1mA. Current going into each V.10 receiver termination
2846f
LTC2846
TYPICAL APPLICATIO
5.6µH 3.3V 10µF SHDN LTC2846 CHARGE PUMP BOOST SWITCHING REGULATOR 3.3µF MBR0520 4.3k 10µF
SCTE
DCE/DTE 3.3V (114) (115) (104) SHIELD
LTC2844
DCE/DTE
Figure Controller-Selectable Multiprotocol Port with DB-25 Connector
2846f
(103) SCTE (113) SCTE
DB-25 MALE CONNECTOR
(105) (108)
(109) (107) (106) (141)
3.3V
2846
LTC2846
TYPICAL APPLICATIO
5.6µH 3.3V 10µF SHDN LTC2846 CHARGE PUMP BOOST SWITCHING REGULATOR 3.3µF MBR0520 4.3k 10µF
SCTE DCE/DTE 3.3V (114) SCTE (113) SCTE (103) SGND (102) SHIELD (101) DB-25 FEMALE CONNECTOR
LTC2844
DCE/DTE
Figure Controller-Selectable Port with DB-25 Connector
2846f
(104) (115)
(106) (107)
(109) (108) (105) (141)
3.3V
2846
LTC2846
TYPICAL APPLICATIO
5.6µH 3.3V 10µF SHDN LTC2846 DTE_TXD/DCE_RXD CHARGE PUMP BOOST SWITCHING REGULATOR 3.3µF SCTE SCTE MBR0520 10µF 4.3k
DTE_SCTE/DCE_RXC
DTE_TXC/DCE_TXC DTE_RXC/DCE_SCTE DTE_RXD/DCE_TXD DCE/DTE 3.3V DTE_RTS/DCE_CTS SHIELD DB-25 CONNECTOR SCTE SCTE
DTE_DTR/DCE_DSR
LTC2844
DTE_DCD/DCE_DCD
DTE_DSR/DCE_DTR
DTE_CTS/DCE_RTS
DTE_LL/DCE_LL
DCE/DTE
DCE/DTE
Figure Controller-Selectable Multiprotocol DTE/DCE Port with DB-25 Connector
2846f
3.3V
2846
LTC2846
TYPICAL APPLICATIO
5.6µH 3.3V 10µF SHDN LTC2846 DTE_TXD/DCE_RXD CHARGE PUMP BOOST SWITCHING REGULATOR 3.3µF MBR0520 4.3k 10µF
DTE_SCTE/DCE_RXC
DTE_TXC/DCE_TXC DTE_RXC/DCE_SCTE DTE_RXD/DCE_TXD DCE/DTE 3.3V DTE_RTS/DCE_CTS DTE_DTR/DCE_DSR SHIELD SCTE SCTE
LTC2845 DCE/DTE R4EN D4ENB 3.3V
DTE_DCD/DCE_DCD
DTE_DSR/DCE_DTR
DTE_CTS/DCE_RTS DTE_LL/DCE_RI DTE_RI/DCE_LL DTE_TM/DCE_RL DTE_RL/DCE_M0 DCE/DTE
Figure Controller-Selectable Multiprotocol DTE/DCE Port with DB-25 Connector
2846f
SCTE SCTE
DB-25 CONNECTOR
*OPTIONAL
2846
LTC2846
TYPICAL APPLICATIO
5.6µH 3.3V 10µF SHDN LTC2846 DTE_TXD/DCE_RXD CHARGE PUMP BOOST SWITCHING REGULATOR 3.3µF SCTE SCTE MBR0520 4.3k 10µF
DTE_SCTE/DCE_RXC
DTE_TXC/DCE_TXC DTE_RXC/DCE_SCTE DTE_RXD/DCE_TXD DCE/DTE 3.3V SHIELD DB-25 CONNECTOR DTE_RTS/DCE_CTS DCE/DTE SCTE SCTE
DTE_DTR/DCE_DSR
LTC2844 CABLE WIRING MODE SELECTION MODE V.35 RS449, V.36 RS232 CABLE WIRING DTE/DCE SELECTION MODE
2846
DTE_DCD/DCE_DCD
DTE_DSR/DCE_DTR
DTE_CTS/DCE_RTS
DCE/DTE
Figure Cable-Selectable Multiprotocol DTE/DCE Port with DB-25 Connector
2846f
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.
3.3V
LTC2846
PACKAGE DESCRIPTIO
0.42 ±0.03 RECOMMENDED SOLDER LAYOUT 5.00 5.60** (.197 .221)
0.09 0.25 (.0035 .010)
0.55 0.95 (.022 .037)
NOTE: CONTROLLING DIMENSION: MILLIMETERS MILLIMETERS DIMENSIONS (INCHES) DRAWING SCALE *DIMENSIONS INCLUDE MOLD FLASH. MOLD FLASH SHALL EXCEED .152mm (.006") SIDE **DIMENSIONS INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL EXCEED .254mm (.010") SIDE
RELATED PARTS
PART NUMBER
LTC1321 LTC1334 LTC1343 LTC1344A LTC1345 LTC1346A LTC1543 LTC1544 LTC1545 LTC1546 LTC2844 LTC2845
DESCRIPTION
Dual RS232/RS485 Transceiver Single RS232/RS485 Multiprotocol Transceiver Software-Selectable Multiprotocol Transceiver Software-Selectable Cable Terminator Single Supply V.35 Transceiver Dual Supply V.35 Transceiver Software-Selectable Multiprotocol Transceiver Software-Selectable Multiprotocol Transceiver Software-Selectable Multiprotocol Transceiver Software-Selectable Multiprotocol Transceiver 3.3V Software-Selectable Multiprotocol Transceiver 3.3V Software-Selectable Multiprotocol Transceiver
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, 95035-7417
(408) 432-1900 FAX: (408) 434-0507
Package 36-Lead Plastic SSOP (5.3mm)
(Reference 05-08-1640)
12.50 13.10* (.492 .516) 1.25 ±0.12 7.40 8.20 (.291 .323) 0.65 (.079) 0.65 (.0256) 0.22 0.38 (.009 .015) 0.05 (.002)
SSOP 0802
COMMENTS
RS232 Driver/Receiver Pairs RS485 Driver/Receiver Pairs RS232 Driver/Receiver Four RS232 Driver/Receiver Pairs 4-Driver/4-Receiver Data Clock Signals Perfect Terminating LTC1543 (Not Needed with LTC1546) 3-Driver/3-Receiver Data Clock Signals 3-Driver/3-Receiver Data Clock Signals Terminated with LTC1344A Data Clock Signals, Companion LTC1544 LTC1545 Control Signals Companion LTC1546 LTC1543 Control Signals Including 5-Driver/5-Receiver Companion LTC1546 LTC1543 Control Signals Including 3-Driver/3-Receiver with Termination Data Clock Signals Companion LTC2846 Control Signals Including 5-Driver/5-Receiver Companion LTC2846 Control Signals Including
2846f LT/TP 0403 PRINTED
www.linear.com
LINEAR TECHNOLOGY CORPORATION 2002

DESCRIPTIO Software-Selectable Transceiver Supports: RS232, RS449

Top Searches for this datasheet

Other recent searches