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Final Electrical Specifications
LTC1544 Software-Selectable Multiprotocol Transceiver
February 1998
FEATURES
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DESCRIPTION
The LTC(R)1544 is a 4-driver/4-receiver multiprotocol transceiver. The LTC1544 and LTC1543 form the core of a complete software-selectable DTE or DCE interface port that supports the RS232, RS449, EIA530, EIA530-A, V.35, V.36 or X.21 protocols. Cable termination may be implemented using the LTC1344A software-selectable cable termination chip or by using existing discrete designs. The LTC1544 runs from a 5V supply and the charge pump on the LTC1543. The part is available in a 28-lead SSOP surface mount package.
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Software-Selectable Transceiver Supports: RS232, RS449, EIA530, EIA530-A, V.35, V.36, X.21 Detecon Inc. Certified NET1 and NET2 Compliant (Test Report No. NET2/102201/97) TBR2 Compliant Software-Selectable Cable Termination Using the LTC1344A Complete DTE or DCE Port with LTC1543, LTC1344A Operates from Single 5V Supply with LTC1543
APPLICATIONS
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Data Networking CSU and DSU Data Routers
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
DTE or DCE Multiprotocol Serial Interface with DB-25 Connector
LL CTS DSR DCD DTR RTS RXD RXC TXC SCTE TXD
LTC1544 D1 R4 R3 R2 R1 D3 D2 D1 R3 R2 R1
LTC1543 D3 D2 D1
18
13 5
10 8
22 6
23 20 19 4
1
7
16 3
9
17
12 15 11 24 14
DB-25 CONNECTOR
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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LTC1344A
2
DSR B
DSR A (109)
LL A (141)
CTS B
CTS A (106)
DTR B
DTR A (108)
RTS B
RTS A (105)
SHIELD (101)
SG (102)
RXD B
RXD A (104)
RXC B
RXC A (115)
DCD B
DCD A (107)
SCTE B
SCTE A (113)
TXD B
TXD A (103)
TXC B
TXC A (114)
1544 TA01
1
LTC1544
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
TOP VIEW VCC VDD D1 D2 D3 R1 R2 R3 D4 1 2 3 D1 4 5 6 7 8 9 R1 R2 R3 D4 R4 D2 D3 25 D1 B 24 D2 A 23 D2 B 22 D3/R1 A 21 D3/R1 B 20 R2 A 19 R2 B 18 R3 A 17 R3 B 16 D4/R4 A 15 INVERT G PACKAGE 28-LEAD PLASTIC SSOP 28 VEE 27 GND 26 D1 A
Supply Voltage, VCC ................................................ 6.5V Input Voltage Transmitters ........................... - 0.3V to (VCC + 0.3V) Receivers ............................................... - 25V to 25V Logic Pins .............................. - 0.3V to (VCC + 0.3V) Output Voltage Transmitters .......................................... - 18V to 18V Receivers ................................ - 0.3V to (VCC + 0.3V) Logic Pins .............................. - 0.3V to (VCC + 0.3V) VEE ........................................................ - 10V to 0.3V VDD ....................................................... - 0.3V to 10V Short-Circuit Duration Transmitter Output ..................................... Indefinite Receiver Output .......................................... Indefinite VEE .................................................................. 30 sec Operating Temperature Range ..................... 0C to 70C Storage Temperature Range ................ - 65C to 150C Lead Temperature (Soldering, 10 sec)................. 300C
ORDER PART NUMBER LTC1544CG
R4 10 M0 11 M1 12 M2 13 DCE/DTE 14
TJMAX = 155C, JA = 65C/ W
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
SYMBOL Supplies ICC VCC Supply Current (DCE Mode, All Digital Pins = GND or VCC) PARAMETER
VCC = 5V, VDD = 8V, VEE = - 7V for V.28, - 5.5V for V.10, V.11 (Notes 2, 3)
MIN TYP 2.7 95 1 1 10 2.1 14 25 1 12 10 0.2 0.2 1 12 10 300 54 MAX UNITS mA mA mA mA A mA mA mA mA mA A mA mA mA mA A mW mW
CONDITIONS RS530, RS530-A, X.21 Modes, No Load RS530, RS530-A, X.21 Modes, Full Load V.28 Mode, No Load V.28 Mode, Full Load No-Cable Mode RS530, RS530-A, X.21 Modes, No Load RS530, X.21 Modes, Full Load RS530-A, Full Load V.28 Mode, No Load V.28 Mode, Full Load No-Cable Mode RS530, RS530-A, X.21 Modes, NoLoad RS530, RS530-A, X.21 Modes, Full Load V.28 Mode, No Load V.28 Mode, Full Load No-Cable Mode RS530, RS530-A, X.21 Modes, Full Load V.28 Mode, Full Load
q q q q
120 2 2 200
IEE
VEE Supply Current (DCE Mode, All Digital Pins = GND or VCC) VEE = - 5.6V (RS530, RS530-A Modes) VEE = - 8.46V (V.28 Mode)
IDD
VDD Supply Current (DCE Mode, All Digital Pins = GND or VCC) VDD = 8.73V
PD
Internal Power Dissipation (DCE Mode, (All Digital Pins = GND or VCC)
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LTC1544
ELECTRICAL CHARACTERISTICS
SYMBOL VIH VIL IIN PARAMETER Logic Input High Voltage Logic Input Low Voltage Logic Input Current D1, D2, D3, D4 M0, M1, M2, DCE, INVERT = GND M0, M1, M2, DCE, INVERT = VCC IO = - 4mA IO = 4mA 0V VO VCC M0 = M1 = M2 = VCC, 0V VO VCC Open Circuit, RL = 1.95k RL = 50 (Figure 1) VOD at 50 > 1/2VOD at RL = 1.95k RL = 50 (Figure 1) RL = 50 (Figure 1) RL = 50 (Figure 1) VOUT = GND - 0.25V VO 0.25V, Power Off or No-Cable Mode or Driver Disabled (Figures 2, 6) (Figures 2, 6) (Figures 2, 6) (Figures 2, 6) (Figures 2, 6) - 7V VCM 7V - 7V VCM 7V - 10V VA,B 10V - 10V VA,B 10V (Figures 2, 7) (Figures 2, 7) (Figures 2, 7) (Figures 2, 7)
q q q q q q q q q q q q q q q q q
VCC = 5V, VDD = 8V, VEE = - 7V for V.28, - 5.5V for V.10, V.11 (Notes 2, 3)
MIN
q q q q q q q q
CONDITIONS
TYP
MAX
UNITS V
Logic Inputs and Outputs 2 0.8 - 100 3 - 50 - 50 4.5 0.3 40 1 5 0.8 50 10 - 30 10 V A A A V V mA A V V V V V mA A ns ns ns ns ns 0.2 15 20 30 15 50 50 0 4 80 80 16 40 0.5 V mV mA k ns ns ns ns
VOH VOL IOSR IOZR V.11 Driver VOD
Output High Voltage Output Low Voltage Output Short-Circuit Current Three-State Output Current Differential Output Voltage
2
VOD VOC VOC ISS IOZ t r, t f t PLH t PHL t t SKEW VTH VTH IIN RIN t r, t f t PLH t PHL t
Change in Magnitude of Differential Output Voltage Common Mode Output Voltage Change in Magnitude of Common Mode Output Voltage Short-Circuit Current Output Leakage Current Rise or Fall Time Input to Output Input to Output Input to Output Difference, tPLH - tPHL Output to Output Skew Input Threshold Voltage Input Hysteresis Input Current (A, B) Input Impedance Rise or Fall Time Input to Output Input to Output Input to Output Difference, tPLH - tPHL
0.2 3 0.2 150 1 2 20 20 0 15 40 40 3 3 - 0.2 100 25 65 65 12
V.11 Receiver
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LTC1544
ELECTRICAL CHARACTERISTICS
SYMBOL V.10 Driver VO Output Voltage Open Circuit, RL = 3.9k RL = 450 (Figure 4) VO at 450 > 0.9VO at RL = 3.9k VO = GND - 0.25V VO 0.25V, Power Off or No-Cable Mode or Driver Disabled RL = 450. CL = 100pF (Figures 4, 8) RL = 450. CL = 100pF (Figures 4, 8) RL = 450. CL = 100pF (Figures 4, 8)
q q q q q
VCC = 5V, VDD = 8V, VEE = - 7V for V.28, - 5.5 for V.10, V.11 (Notes 2, 3)
MIN 4 3.6 TYP MAX 6 UNITS V V mA A s s s 0.25 25 20 30 15 55 109 60
q q q q q q q
PARAMETER
CONDITIONS
ISS IOZ t r, t f t PLH t PHL VTH VTH IIN RIN t r , tf tPLH tPHL t V.28 Driver VO ISS IOZ SR t PLH t PHL VTHL VTLH VTH RIN t r , tf tPLH tPHL
Short-Circuit Current Output Leakage Current Rise or Fall Time Input to Output Input to Output Receiver Input Threshold Voltage Receiver Input Hysteresis Receiver Input Current Receiver Input Impedance Rise or Fall Time Input to Output Input to Output Input to Output Difference, tPLH - tPHL Output Voltage Short-Circuit Current Output Leakage Current Slew Rate Input to Output Input to Output Input Low Threshold Voltage Input High Threshold Voltage Receiver Input Hysterisis Receiver Input Impedance Rise or Fall Time Input to Output Input to Output
150 0.1 2 1 1 - 0.25 100
V.10 Receiver V mV mA k ns ns ns ns 10 150 1 4 1.3 1.3 1.5 2 0 3 1.6 0.1 5 15
q q
50 0.5
- 10V VA 10V - 10V VA 10V (Figures 5, 9) (Figures 5, 9) (Figures 5, 9) (Figures 5, 9) Open Circuit RL = 3k (Figure 4) VO = GND - 0.25V VO 0.25V, Power Off or No-Cable Mode or Driver Disabled RL = 3k, CL = 2500pF (Figures 4, 8) RL = 3k, CL = 2500pF (Figures 4, 8) RL = 3k, CL = 2500pF (Figures 4, 8)
q q
5
8.5
V V mA A V/s s s V V V k ns ns ns
100 30 2.5 2.5 0.8 0.3 7 100 350
V.28 Receiver
q q q
- 15V VA 15V (Figures 5, 9) (Figures 5, 9) (Figures 5, 9)
q
60 150
The q denotes specifications which apply over the full operating temperature range. Note 1: Absolute Maximum Ratings are those beyond which the safety of a device may be impaired.
Note 2: All currents into device pins are positive; all currents out of device are negative. All voltages are referenced to device ground unless otherwise specified. Note 3: All typicals are given for VCC = 5V, VDD = 8V, VEE = - 7V for V.28, - 5.5V for V.10, V.11 and TA = 25C.
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LTC1544
PIN FUNCTIONS
VCC (Pin 1): Positive Supply for the Transceivers. 4.75V VCC 5.25V. VDD (Pin 2): Positive Supply Voltage for V.28. Connect to VDD Pin 3 on LTC1543 or 8V supply. D1 (Pin 3): TTL Level Driver 1 Input. D2 (Pin 4): TTL Level Driver 2 Input. D3 (Pin 5): TTL Level Driver 3 Input. R1 (Pin 6): CMOS Level Receiver 1 Output. R2 (Pin 7): CMOS Level Receiver 2 Output. R3 (Pin 8): CMOS Level Receiver 3 Output. D4 (Pin 9): TTL Level Driver 4 Input. R4 (Pin 10): CMOS Level Receiver 4 Output. M0 (Pin 11): TTL Level Mode Select Input 0 with Pull-Up to VCC. M1 (Pin 12): TTL Level Mode Select Input 1 with Pull-Up to VCC. M2 (Pin 13): TTL Level Mode Select Input 2 with Pull-Up to VCC. DCE/DTE (Pin 14): TTL Level Mode Select Input with Pull-Up to VCC. INVERT (Pin 15): TTL Level Mode Select Input with PullUp to VCC. D4/R4 A (Pin 16): Receiver 4 Inverting Input and Driver 4 Output. R3 B (Pin 17): Receiver 3 Noninverting Input. R3 A (Pin 18): Receiver 3 Inverting Input. R2 B (Pin 19): Receiver 2 Noninverting Input. R2 A (Pin 20): Receiver 2 Inverting Input. D3/R1 B (Pin 21): Receiver 1 Noninverting Input and Driver 3 Noninverting Output. D3/R1 A (Pin 22): Receiver 1 Inverting Input and Driver 3 Inverting Output. D2 B (Pin 23): Driver 4 Noninverting Output. D2 A (Pin 24): Driver 4 Inverting Output. D1 B (Pin 25): Driver 3 Noninverting Output. D1 A (Pin 26): Driver 1 Inverting Output. GND (Pin 27): Ground. VEE (Pin 28): Negative Supply Voltage. Connect to VEE Pin 26 on LTC1543 or to - 8V supply.
TEST CIRCUITS
A RL 50 VOD RL 50 B VOC
CL 100pF CL 100pF
Figure 1. V.11 Driver Test Circuit
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B A
RL 100
B A
R
15pF
1544 F01
1544 F02
Figure 2. V.11 Driver/Receiver AC Test Circuit
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LTC1544
TEST CIRCUITS
50 D B VOD A 50 50 A 15pF
1544 F03
125
VCM
50 125 B R
Figure 3. V.35 Driver/Receiver Test Circuit
D
A CL RL
D
A
A
R 15pF
1544 F04
1544 F04
Figure 4. V.10/V.28 Driver Test Circuit
Figure 5. V.10/V.28 Receiver Test Circuit
ODE SELECTIO
M2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1
LTC1544 MODE NAME Not Used (Default V.11) RS530A RS530 X.21 V.35 RS449/V.36 V.28/RS232 No Cable Not Used (Default V.11) RS530A RS530 X.21 V.35 RS449/V.36 V.28/RS232 No Cable
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M1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 M0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 DCE/DTE 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 INVERT 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 D1 V.11 V.11 V.11 V.11 V.28 V.11 V.28 Z V.11 V.11 V.11 V.11 V.28 V.11 V.28 Z D2 V.11 V.10 V.11 V.11 V.28 V.11 V.28 Z V.11 V.10 V.11 V.11 V.28 V.11 V.28 Z D3 Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z R1 V.11 V.11 V.11 V.11 V.28 V.11 V.28 Z V.11 V.11 V.11 V.11 V.28 V.11 V.28 Z R2 V.11 V.10 V.11 V.11 V.28 V.11 V.28 Z V.11 V.10 V.11 V.11 V.28 V.11 V.28 Z R3 V.11 V.11 V.11 V.11 V.28 V.11 V.28 Z V.11 V.11 V.11 V.11 V.28 V.11 V.28 Z D4 Z Z Z Z Z Z Z Z V.10 V.10 V.10 V.10 V.28 V.10 V.28 Z R4 V.10 V.10 V.10 V.10 V.28 V.10 V.28 Z Z Z Z Z Z Z Z Z
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LTC1544
ODE SELECTIO
M2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1
LTC1544 MODE NAME Not Used (Default V.11) RS530A RS530 X.21 V.35 RS449/V.36 V.28/RS232 No Cable Not Used (Default V.11) RS530A RS530 X.21 V.35 RS449/V.36 V.28/RS232 No Cable
SWITCHI G TI E WAVEFOR S
5V D 0V VO B-A -VO A VO B t SKEW t SKEW
1544 F06
1.5V t PLH 50% tr 90% 10%
f = 1MHz : t r 10ns : t f 10ns
VDIFF = V(A) - V(B) 1/2 VO
Figure 6. V.11, V.35 Driver Propagation Delays
VOD2 B-A -VOD2 VOH R VOL
0V t PLH 1.5V
f = 1MHz : t r 10ns : t f 10ns
Figure 7. V.11, V.35 Receiver Propagation Delays
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M1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 M0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 DCE/DTE 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 INVERT 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 D1 V.11 V.11 V.11 V.11 V.28 V.11 V.28 Z V.11 V.11 V.11 V.11 V.28 V.11 V.28 Z D2 V.11 V.10 V.11 V.11 V.28 V.11 V.28 Z V.11 V.10 V.11 V.11 V.28 V.11 V.28 Z D3 V.11 V.11 V.11 V.11 V.28 V.11 V.28 Z V.11 V.11 V.11 V.11 V.28 V.11 V.28 Z R1 Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z R2 V.11 V.10 V.11 V.11 V.28 V.11 V.28 Z V.11 V.10 V.11 V.11 V.28 V.11 V.28 Z R3 V.11 V.11 V.11 V.11 V.28 V.11 V.28 Z V.11 V.11 V.11 V.11 V.28 V.11 V.28 Z D4 V.10 V.10 V.10 V.10 V.28 V.10 V.28 Z Z Z Z Z Z Z Z Z R4 Z Z Z Z Z Z Z Z V.10 V.10 V.10 V.10 V.28 V.10 V.28 Z
1.5V t PHL 90% tf 50% 10%
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INPUT
0V t PHL
OUTPUT
1.5V
1544 F07
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LTC1544
SWITCHI G TI E WAVEFOR S
3V D 0V VO A -VO tf 1.5V t PHL 3V 0V -3V -3V tr 0V 1.5V t PLH 3V
1544 F08
Figure 8. V.10, V.28 Driver Propagation Delays
VIH A VIL VOH R VOL 1.3V t PHL 1.7V t PLH 2.4V 0.8V
1544 F09
Figure 9. V.10, V.28 Receiver Propagation Delays
APPLICATIONS INFORMATION
Overview The LTC1543/LTC1544 form the core of a complete software-selectable DTE or DCE interface port that supports the RS232, RS449, EIA530, EIA530-A, V.35, V.36 or X.21 protocols. Cable termination may be implemented using the LTC1344A software-selectable cable termination chip or by using existing discrete designs. A complete DCE-to-DTE interface operating in EIA530 mode is shown in Figure 10. The LTC1543 of each port is used to generate the clock and data signals. The LTC1544 is used to generate the control signals along with LL (Local Loop-back).The LTC1344A cable termination chip is used only for the clock and data signals because they must support V.35 cable termination. The control signals do not need any external resistors. Mode Selection The interface protocol is selected using the mode select pins M0, M1 and M2 (see the Mode Selection table). For example, if the port is configured as a V.35 interface, the mode selection pins should be M2 = 1, M1 = 0, M0 = 0. For the control signals, the drivers and receivers will operate in V.28 (RS232) electrical mode. For the clock and data signals, the drivers and receivers will operate in V.35 electrical mode. The DCE/DTE pin will configure the port for DCE mode when high, and DTE when low. The interface protocol may be selected simply by plugging the appropriate interface cable into the connector. The mode pins are routed to the connector and are left unconnected (1) or wired to ground (0) in the cable as shown in Figure 11. The internal pull-up current sources will ensure a binary 1 when a pin is left unconnected and that the LTC1543/ LTC1544 and the LTC1344A enter the no-cable mode when the cable is removed. In the no-cable mode the LTC1543/LTC1544 supply current drops to less than 200A and all LTC1543/LTC1544 driver outputs and LTC1344A resistive terminations are forced into a high impedance state. The mode selection may also be accomplished by using jumpers to connect the mode pins to ground or VCC.
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LTC1544
DTE
SERIAL CONTROLLER TXD LTC1543 D1 LTC1344A TXD LTC1344A 103
DCE
LTC1543 R3 SERIAL CONTROLLER TXD
SCTE
D2
SCTE
103
R2
SCTE
D3
R1
TXC
R1
103
TXC
D3
TXC
RXC
R2
103
RXC
D2
RXC
RXD
R3
103
RXD
D1
RXD
LTC1544 RTS D1 RTS
LTC1544 R3 RTS
DTR
D2
DTR
R2
DTR
D3
R1
DCD
R1
DCD
D3
DCD
DSR
R2
DSR
D2
DSR
CTS
R3
CTS LL
D1
CTS
LL
D4 R4
R4 D4
LL
1544 F10
Figure 10. Complete Multiprotocol Interface in EIA530 Mode
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LTC1544
APPLICATIONS INFORMATION
LATCH LTC1344A DCE/ DTE M2 22 (DATA) M0 LTC1543 M1 M2 DCE/DTE 17 18 19 21 23 M1 M0 (DATA) 24 1 CONNECTOR 21
LTC1544 DCE/DTE M2 M1 M0 (DATA) 21 19 18 17
1544 F11
Figure 11: Single Port DCE V.35 Mode Selection in the Cable
Cable Termination Traditional implementations have included switching resistors with expensive relays, or requiring the user to change termination modules every time the interface standard has changed. Custom cables have been used with the termination in the cable head or separate terminations are built on the board and a custom cable routes the signals to the appropriate termination. Switching the terminations with FETs is difficult because the FETs must remain off even though the signal voltage is beyond the supply voltage for the FET drivers or the power is off. Using the LTC1344A along with the LTC1543/LTC1544 solves the cable termination switching problem. Via software control, the LTC1344A provides termination for the V.10 (RS423), V.11 (RS422), V.28 (RS232) and V.35 electrical protocols.
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NC NC CABLE
V.10 (RS423) Interface A typical V.10 unbalanced interface is shown in Figure 12. A V.10 single-ended generator output A with ground C is connected to a differential receiver with inputs A' connected to A, and input B' connected to the signal return ground C. The receiver's ground C' is separate from the signal return. Usually, no cable termination is required for V.10 interfaces, but the receiver inputs must be compliant with the impedance curve shown in Figure 13. The V.10 receiver configuration in the LTC1543/LTC1544 and the LTC1344A is shown in Figure 14. In V.10 mode switches S1 and S2 inside the LTC1344A and S3 inside the LTC1543/LTC1544 are turned off. Switch S4 inside the LTC1543/LTC1544 shorts the noninverting receiver input to ground so the B input at the connector can be left floating. The cable termination is then the 30k input impedance to ground of the LTC1543/LTC1544 V.10 receiver.
LTC1544
APPLICATIONS INFORMATION
GENERATOR BALANCED INTERCONNECTING CABLE
LOAD CABLE TERMINATION RECEIVER
A
A'
C
B'
C'
Figure 12. Typical V.10 Interface
IZ 3.25mA
-10V
-3V VZ 3V 10V
-3.25mA
Figure 13. V.10 Receiver Input Impedance
V.11 (RS422) Interface A typical V.11 balanced interface is shown in Figure 15. A V.11 differential generator with outputs A and B with ground C is connected to a differential receiver with ground C', inputs A' connected to A, B' connected to B. The V.11 interface has a differential termination at the receiver end that has a minimum value of 100. The termination resistor is optional in the V.11 specification, but for the high speed clock and data lines, the termination is required to prevent reflections from corrupting the data. The receiver inputs must also be compliant with the impedance curve shown in Figure 13. In V.11 mode, all switches are off except S1 inside the LTC1344A which connects a 103 differential termination impedance to the cable as shown in Figure 16.
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A' A R1 51.5 S1 S2 R2 51.5 B'
1544 F12
LTC1344A
R8 6k S3
R5 20k R6 10k
LTC1543 LTC1544
RECEIVER
R3 124
B
R4 20k S4 GND
R7 10k
C'
1544 F14
Figure 14. V.10 Receiver Configuration
GENERATOR
BALANCED INTERCONNECTING CABLE
LOAD CABLE TERMINATION RECEIVER
A
A' 100 MIN
B C
1544 F13
B' C'
1544 F15
Figure 15. Typical V.11 Interface
A' A R1 51.5 S1 S2 R2 51.5 B' LTC1344A R8 6k S3 R5 20k R6 10k R3 124 LTC1543 LTC1544
RECEIVER
B
R4 20k S4 GND
R7 10k
C'
1544 F16
Figure 16. V.11 Receiver Configuration
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LTC1544
APPLICATIONS INFORMATION
V.28 (RS232) Interface A typical V.28 unbalanced interface is shown in Figure 17. A V.28 single-ended generator output A with ground C is connected to a single-ended receiver with input A' connected to A, ground C' connected via the signal return ground C. In V.28 mode all switches are off except S3 inside the LTC1543/LTC1544 which connects a 6k (R8) impedance to ground in parallel with 20k (R5) plus 10k (R6) for a combined impedance of 5k as shown in Figure 18. The noninverting input is disconnected inside the LTC1543/ LTC1544 receiver and connected to a TTL level reference voltage for a 1.4V receiver trip point.
BALANCED INTERCONNECTING CABLE
GENERATOR
LOAD CABLE TERMINATION RECEIVER
A
A'
C
C'
Figure 17. Typical V.28 Interface
A' A R1 51.5 S1 S2 R2 51.5 B' LTC1344A R8 6k S3 R5 20k R6 10k LTC1543 LTC1544 A' A RECEIVER R1 51.5 S1 R4 20k S4 B' GND
1544 F18
R3 124
R7 10k
B
C'
Figure 18. V.28 Receiver Configuration Figure 20. V.35 Receiver Configuration
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V.35 Interface A typical V.35 balanced interface is shown in Figure 19. A V.35 differential generator with outputs A and B with ground C is connected to a differential receiver with ground C', inputs A' connected to A, B' connected to B. The V.35 interface requires a T or delta network termination at the receiver end and the generator end. The receiver differential impedance measured at the connector must be 100 10, and the impedance between shorted terminals (A' and B') and ground C' must be 150 15. In V.35 mode, both switches S1 and S2 inside the LTC1344A are on, connecting the T network impedance as shown in Figure 20. Both switches in the LTC1543/LTC1544 are off.
BALANCED INTERCONNECTING CABLE
GENERATOR
LOAD CABLE TERMINATION RECEIVER
A 50
A' 50
125
125
1544 F17
50 B C B' C'
50
1544 F19
Figure 19. Typical V.35 Interface
LTC1344A
R8 6k S3
R5 20k R6 10k
LTC1543 LTC1544
RECEIVER
S2 R2 51.5
R3 124
B
R4 20k S4 GND
R7 10k
C'
1544 F20
LTC1544
APPLICATIONS INFORMATION
The 30k input impedance of the receiver is placed in parallel with the T network termination, but does not affect the overall input impedance significantly. The generator differential impedance must be 50 to 150 and the impedance between shorted terminals (A and B) and ground C must be 150 15. For the generator termination, switches S1 and S2 are both on and the top side of the center resistor is brought out to a pin so it can be bypassed with an external capacitor to reduce common mode noise as shown in Figure 21. Any mismatch in the driver rise and fall times or skew in the driver propagation delays will force current through the center termination resistor to ground, causing a high frequency common mode spike on the A and B terminals. The common mode spike can cause EMI problems that are reduced by capacitor C1 which shunts much of the common mode energy to ground rather than down the cable.
A
LTC1344A
51.5 S1 ON
V.35 DRIVER 124
S2 ON
51.5 B C1 100pF C
1544 F21
Figure 21. V.35 Driver Using the LTC1344A
5V
4
+
VCC
GND
25
C4 1F
1544 F22
Figure 22. Charge Pump
+
U
W
U
U
No-Cable Mode The no-cable mode (M0 = M1 = M2 = 1) is intended for the case when the cable is disconnected from the connector. The charge pump, bias circuitry, drivers and receivers are turned off, the driver outputs are forced into a high impedance state, and the supply current drops to less than 200A. It can also be used to share I/O lines with other drivers and receivers without loading down the signals. Charge Pump The LTC1543 uses an internal capacitive charge pump to generate VDD and VEE as shown in Figure 22. A voltage doubler generates about 8V on VDD and a voltage inverter generates about - 7.5V for VEE. Four 1F surface mounted tantalum or ceramic capacitors are required for C1, C2, C3 and C4. The VEE capacitor C5 should be a minimum of 3.3F. All capacitors are 16V and should be placed as close as possible to the LTC1543 to reduce EMI. Receiver Fail-Safe All LTC1543/LTC1544 receivers feature fail-safe operation in all modes. If the receiver inputs are left floating or shorted together by a termination resistor, the receiver output will always be forced to a logic high.
3 C3 1F 2 C1 1F 1 C2 + C2 - LTC1543 C1
-
+
VDD C1
+
28
+
27 26
+
C2 1F
VEE
C5 3.3F
13
LTC1544
APPLICATIONS INFORMATION
DTE vs DCE Operation The DCE/DTE pin acts as an enable for Driver 3/Receiver 1 in the LTC1543, and Driver 3/Receiver 1 and Driver 4/ Receiver 4 in the LTC1544. The INVERT pin in the LTC1544 allows the Driver 4/Receiver 4 enable to be high or low true polarity. The LTC1543/LTC1544 can be configured for either DTE or DCE operation in one of two ways: a dedicated DTE or DCE port with a connector of appropriate gender or a port with one connector that can be configured for DTE or DCE operation by rerouting the signals to the LTC1543/LTC1544 using a dedicated DTE cable or dedicated DCE cable. A dedicated DTE port using a DB-25 male connector is shown in Figure 23. The interface mode is selected by logic outputs from the controller or from jumpers to either VCC or GND on the mode select pins. A dedicated DCE port using a DB-25 female connector is shown in Figure 24. A port with one DB-25 connector, but can be configured for either DTE or DCE operation is shown in Figure 25. The configuration requires separate cables for proper signal routing in DTE or DCE operation. For example, in DTE mode, the TXD signal is routed to Pins 2 and 14 via Driver 1 in the LTC1543. In DCE mode, Driver 1 now routes the RXD signal to Pins 2 and 14. Multiprotocol Interface with RL, LL, TM and a DB-25 Connector If the RL, LL and TM signals are implemented, there are not enough drivers and receivers available in the LTC1543/ LTC1544. In Figure 26, the required control signals are handled by the LTC1544 but the clock/data signals use the LTC1343. The LTC1343 has an additional single-ended driver/receiver pair that can handle two more optional control signals such as TM and LL. Cable-Selectable Multiprotocol Interface A cable-selectable multiprotocol DTE/DCE interface is shown in Figure 27. The select lines M0, M1 and DCE/DTE are brought out to the connector. The mode is selected by the cable by wiring M0 (connector Pin 18) and M1 (connector Pin 21) and DCE/DTE (connector Pin 25) to ground (connector Pin 7) or letting them float. If M0, M1 or DCE/ DTE is floating, internal pull-up current sources will pull the signals to VCC. The select bit M2 is hard wired to VCC. When the cable is pulled out, the interface will go into the no-cable mode. Compliance Testing A European standard EN 45001 test report is available for the LTC1543/LTC1544/LTC1344A chipset. A copy of the test report is available from LTC or Detecon Inc. The title of the report is: Test Report No. NET2/102201/97. The location of Detecon Inc. is: DETECON Inc. Type Approval Division 1775 Old Highway 8 St. Paul, MN 55112 USA Tel. +1 (612) 639-0775 Fax. +1 (612) 639-0873
14
U
W
U
U
LTC1544
TYPICAL APPLICATIONS
C6 C7 C8 100pF 100pF 100pF 3 VCC 5V 14 3 28 27 CHARGE PUMP 26 25 LTC1543 5 D1 D2 C4 3.3F VCC LATCH 21 8 11 12 13 LTC1344A
+
M2
M1
+
TXD SCTE
C5 1F
24 23 22 21
6 7
D3 20 15 12 17 9 3 16 7 1
TXC
8
R1
19 18
RXC RXD
9
R2
17 16
10 11 12 13 14 M0 M1 M2
R3
15
DCE/DTE
VCC 1 VCC 2 VDD RTS 3 D1 VEE GND 28 27 26 25 24 D2 23 4 19 20 23
DTR
4
5
D3 LTC1544 22 21 20 R2 19 18 R3 17 16 8 10 6 22 5 13 18
DCD
6 7
R1
DSR
CTS
8 10 9 11 12 13 14 M0 M1 M2
LL
R4 D4 INVERT
15
NC
DCE/DTE
M2 M1 M0
Figure 23. Controller-Selectable Multiprotocol DTE Port with DB-25 Connector
+
4
5467
9 10
16 15 18 17 19 20 22 23 24 1 2 14 24 11 TXD A (103) TXD B SCTE A (113) SCTE B
M0
C1 1F
2
2
VEE
DCE/DTE
C3 1F
+
1
U
+
C2 1F
TXC A (114) TXC B RXC A (115) RXC B RXD A (104) RXD B SG SHIELD
DB-25 MALE CONNECTOR
RTS A (105) RTS B DTR A (108) DTR B
DCD A (109) DCD B DSR A (107) DSR B CTS A (106) CTS B LL A (141)
1544 F23
15
LTC1544
TYPICAL APPLICATIONS
C6 C7 C8 100pF 100pF 100pF 3 VCC 5V 14 3 28 27 CHARGE PUMP 26 25 LTC1543 5 D1 D2 C4 3.3F VCC LATCH 21 8 11 12 13 LTC1344A
+
M2
M1
+
RXD RXC
C5 1F
24 23 22 21
6
7
D3 20 15 12 24 11 2 14 7 1
TXC
8
R1
19 18
SCTE TXD
9
R2
17 16
10 11 12 13 NC 14 M0 M1 M2
R3
15
DCE/DTE
VCC 1 VCC 2 VDD CTS 3 D1 VEE GND 28 27 26 25 24 D2 23 5 13 6 22
DSR
4
5
D3 LTC1544 22 21 20 R2 19 18 R3 17 16 8 10 20 23 4 19 18
DCD
6 7
R1
DTR
RTS
8 10 9 11 12 13 NC 14 M0 M1 M2
LL
R4 D4 INVERT
15
NC
DCE/DTE
M2 M1 M0
Figure 24. Controller-Selectable DCE Port with DB-25 Connector
16
+
4
5467
9 10
16 15 18 17 19 20 22 23 24 1 VCC 3 16 17 9 RXD A (104) RXD B RXC A (115) RXC B
M0
C1 1F
2
2
VEE
DCE/DTE
C3 1F
+
1
U
+
C2 1F
TXC A (114) TXC B SCTE A (113) SCTE B TXD A (103) TXD B SGND (102) SHIELD (101)
DB-25 FEMALE CONNECTOR
CTS A (106) CTS B DSR A (107) DSR B
DCD A (109) DCD B DTR A (108) DTR B RTS A (105) RTS B LL A (141)
1544 F24
LTC1544
TYPICAL APPLICATIONS
VCC 5V 14 3 28 27 CHARGE PUMP 26 25 LTC1543 5 D1 D2 C4 3.3F VCC LATCH 21
+
M2
M1
+
DTE_TXD/DCE_RXD DTE_SCTE/DCE_RXC
C5 1F
24 23 22 21
6 7
D3 20 15 12 17 9 3 16 7 1
DTE_TXC/DCE_TXC
8
R1
19 18
DTE_RXC/DCE_SCTE
9
R2
17 16
DTE_RXD/DCE_TXD
10 11 12 M0
R3
15
M1 13 M2 14 DCE/DTE
VCC 1 VCC 2 VDD DTE_RTS/DCE_CTS 3 D1 VEE GND 28 27 26 25 24 D2 23 4 19 20 23
DTE_DTR/DCE_DSR
4
5
D3 LTC1544 22 21 20 R2 19 18 R3 17 16 8 10 6 22 5 13 18
DTE_DCD/DCE_DCD DTE_DSR/DCE_DTR
6 7
R1
DTE_CTS/DCE_RTS
8 10 9 11 12 13 14 M0 M1 M2
DTE_LL/DCE_LL
R4 D4 INVERT
15
NC
DCE/DTE
DCE/DTE M2 M1 M0
Figure 25. Controller-Selectable Multiprotocol DTE/DCE Port with DB-25 Connector
+
4
5467
9 10
16 15 18 17 19 20 22 23 24 1 2 14 24 11 DTE TXD A TXD B SCTE A SCTE B DCE RXD A RXD B RXC A RXC B
M0
C1 1F
2
2
VEE
DCE/DTE
C3 1F
+
1
U
C6 C7 C8 100pF 100pF 100pF
3
8
11
12
13 LTC1344A
+
C2 1F
TXC A TXC B RXC A RXC B RXD A RXD B SG SHIELD
TXC A TXC B SCTE A SCTE B TXD A TXD B
DB-25 CONNECTOR
RTS A RTS B DTR A DTR B
CTS A CTS B DSR A DSR B
DCD A DCD B DSR A DSR B CTS A CTS B LL A
DCD A DCD B DTR A DTR B RTS A RTS B LL A
1544 F25
17
LTC1544
TYPICAL APPLICATIONS
VCC 5V 14 1 44 43 42 41 LTC1343 5 D1 D2 39 38 DTE_TXD/DCE_RXD 6 7 37 36 DTE_SCTE/DCE_RXC D3 35 34 9 10 12 13 D4 33 32 R1 31 30 R2 29 28 R3 27 26 DCE M2 M1 M0 EC 21 19 18 17 VCC 40 GND 24 LB 23 VCC 1 VCC 2 VDD 3 D1 28 27 26 DTE_RTS/DCE_CTS 25 24 D2 23 VCC
+
M2
M1
+
DTE_LL/DCE_TM
C5 1F
8
5467
9 10
16 15 18 17 19 20 22 23 24 1 DTE LL A TXD A TXD B SCTE A SCTE B DCE TM A RXD A RXD B RXC A RXC B
M0 18 2 14 24 11 15 12 17 9 3 16 25 7 1
C1 1F
DTE_TXC/DCE_TXC
DTE_RXC/DCE_SCTE
14
DTE_RXD/DCE_TXD
15
DTE_TM/DCE_LL
16 20 22 11 25 R1 100k CTRL LATCH
R4
INVERT 423SET
LB
VEE GND
DTE_DTR/DCE_DSR
4
5
D3 LTC1544 22 21 20 R2 19 18 R3 17 16 8 10 6 22 5 13 21
DTE_DCD/DCE_DCD DTE_DSR/DCE_DTR
6 7
R1
DTE_CTS/DCE_RTS
8 10 9 11 12 13 14 M0 M1 M2
DTE_RL/DCE_RL
R4 D4 INVERT
15
NC
DCE/DTE
DCE/DTE M2 M1 M0
Figure 26. Controller-Selectable Multiprotocol DTE/DCE Port with RL, LL, TM and DB-25 Connector
18
+
4 3
CHARGE PUMP
2 C4 3.3F
VEE
DCE/DTE
C3 1F
+
2
U
C6 C7 C8 100pF 100pF 100pF
3
8
11
12
13 LTC1344A
LATCH
21
+
C2 1F
TXC A TXC B RXC A RXC B RXD A RXD B TM A SG SHIELD
TXC A TXC B SCTE A SCTE B TXD A TXD B LL A
DB-25 CONNECTOR
4 19 20 23
RTS A RTS B DTR A DTR B
CTS A CTS B DSR A DSR B
DCD A DCD B DSR A DSR B CTS A CTS B RL A
DCD A DCD B DTR A DTR B RTS A RTS B RL A
1544 F26
LTC1544
TYPICAL APPLICATIONS
C6 C7 C8 100pF 100pF 100pF 3 VCC 5V 14 3 28 27 CHARGE PUMP 26 25 LTC1543 5 D1 D2 C4 3.3F VCC LATCH 21 8 11 12 13 LTC1344A
+
M2
M1
+
DTE_TXD/DCE_RXD DTE_SCTE/DCE_RXC
C5 1F
24 23 22 21
6
7 8 9
D3 20 15 12 17 9 3 16 7 1 R1 TXC A TXC B RXC A RXC B RXD A RXD B SG SHIELD DB-25 CONNECTOR TXC A TXC B SCTE A SCTE B TXD A TXD B 19 18 R2 17 16 R3 M0 M1 M2 DCE/DTE 15
DTE_TXC/DCE_TXC
DTE_RXC/DCE_SCTE
DTE_RXD/DCE_TXD
10 11 12 NC 13 14
VCC 1 VCC 2 VDD DTE_RTS/DCE_CTS 3 D1 VEE GND 28 27 26 25 24 D2 23
DTE_DTR/DCE_DSR
4
5
D3 LTC1544 22 21 20 R2 19 18 R3 17 16 CABLE WIRING FOR MODE SELECTION MODE V.35 RS449, V.36 RS232 15 NC PIN 18 PIN 7 NC PIN 7 PIN 21 PIN 7 PIN 7 NC CABLE WIRING FOR DTE/DCE SELECTION MODE PIN 25 DTE PIN 7 DCE NC 8 10 6 22 5 13
DTE_DCD/DCE_DCD DTE_DSR/DCE_DTR
6 7
R1
DTE_CTS/DCE_RTS
8
10 9 11 12 NC 13 14 M0 M1 M2
R4 D4
DCE/DTE INVERT
Figure 27. Cable-Selectable Multiprotocol DTE/DCE Port with DB-25 Connector
+
4
5467
9 10
16 15 18 17 19 20 22 23 24 1 VCC 2 14 24 11 DTE TXD A TXD B SCTE A SCTE B DCE RXD A RXD B RXC A RXC B
M0 25 DCE/DTE 21 M1 18 M0 4 RTS A 19 RTS B 20 DTR A 23 DTR B
C1 1F
2
2
VEE
DCE/DTE
C3 1F
+
1
U
+
C2 1F
CTS A CTS B DSR A DSR B
DCD A DCD B DSR A DSR B CTS A CTS B
DCD A DCD B DTR A DTR B RTS A RTS B
1543/44 F27
19
LTC1544
PACKAGE DESCRIPTION
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 DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
RELATED PARTS
PART NUMBER
LTC1321 LTC1334 LTC1343 LTC1344A LTC1345 LTC1346A LTC1543
DESCRIPTION
Dual RS232/RS485 Transceiver Single 5V 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
20
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417q (408) 432-1900 FAX: (408) 434-0507q TELEX: 499-3977 q www.linear-tech.com
U
Dimensions in inches (millimeters) unless otherwise noted.
G Package 28-Lead Plastic SSOP (0.209)
(LTC DWG # 05-08-1640)
0.397 - 0.407* (10.07 - 10.33) 28 27 26 25 24 23 22 21 20 19 18 17 16 15
0.301 - 0.311 (7.65 - 7.90)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 0.068 - 0.078 (1.73 - 1.99)
0 - 8
0.0256 (0.65) BSC
0.010 - 0.015 (0.25 - 0.38)
0.002 - 0.008 (0.05 - 0.21)
G28 SSOP 0694
COMMENTS
Two RS232 Driver/Receiver Pairs or Two RS485 Driver/Receiver Pairs Two RS232 Driver/Receiver or Four RS232 Driver/Receiver Pairs 4-Driver/4-Receiver for Data and Clock Signals Perfect for Terminating the LTC1543 3-Driver/3-Receiver for Data and Clock Signals 3-Driver/3-Receiver for Data and Clock Signals Companion to LTC1544 for Data and Clock Signals
1544i LT/TP 0298 4K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1998

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