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LTC1334 Single 5V RS232/RS485 Multiprotocol Transceiver
FEATURES
s s s s s s s s s
DESCRIPTIO
s s
Four RS232 Transceivers or Two RS485 Transceivers on One Chip Operates from a Single 5V Supply Withstands Repeated 10kV ESD Pulses Uses Small Charge Pump Capacitors: 0.1F Low Supply Current: 8mA Typical 10A Supply Current in Shutdown Self-Testing Capability in Loopback Mode Power-Up/Down Glitch-Free Outputs Driver Maintains High Impedance in Three-State, Shutdown or with Power Off Thermal Shutdown Protection Receiver Inputs Can Withstand 25V
The LTC (R)1334 is a low power CMOS bidirectional transceiver featuring two reconfigurable interface ports. It can be configured as two RS485 differential ports, as two dual RS232 single-ended ports or as one RS485 differential port and one dual RS232 single-ended port. An onboard charge pump requires four 0.1F capacitors to generate boosted positive and negative supplies, allowing the RS232 drivers to meet the RS232 5V output swing requirement with only a single 5V supply. A shutdown mode reduces the ICC supply current to 10A. The RS232 transceivers are in full compliance with RS232 specifications. The RS485 transceivers are in full compliance with RS485 and RS422 specifications. All interface drivers feature short-circuit and thermal shutdown protection. An enable pin allows RS485 driver outputs to be forced into high impedance, which is maintained even when the outputs are forced beyond supply rails or power is off. Both driver outputs and receiver inputs feature 10kV ESD protection. A loopback mode allows the driver outputs to be connected back to the receiver inputs for diagnostic self-test.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
s s s s
Low Power RS485/RS422/RS232/EIA562 Interface Software-Selectable Multiprotocol Interface Port Cable Repeaters Level Translators
TYPICAL APPLICATIO
2 3 LTC1334 VCC1 5V RX OUT DR ENABLE DR IN 5V 5V DR IN DR IN RX OUT RX OUT 26 24 23 22 21 20 19 18 17 16 15 1 28
27
4 5 120 6 7 8 9 11 10 13 12 14 5V 0V
RS485 INTERFACE 120
13 12 11 10 5V 9 8 4 5 6 7 14
4000-FT 24-GAUGE TWISTED PAIR
RS232 INTERFACE
0V
ALL CAPACITORS: 0.1F MONOLITHIC CERAMIC TYPE
LTC1334 * TA01
U
27 28 1 LTC1334 2 3 26 17 18 19 21 20 24 25 22 23 15 VCC2 5V RX OUT DR ENABLE DR IN 5V 5V RX OUT RX OUT DR IN DR IN
U
U
1
LTC1334 ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW C1+ 1 28 C2+ 27 C2 - 26 VCC 25 RB1 24 RA1 23 DZ1/DE1 22 DY1 21 LB 20 ON/OFF 19 DY2 18 DZ2/DE2 17 RA2 16 RB2 15 VEE C1- 2 VDD 3 A1 4 B1 5 Y1 6 Z1 7 SEL1 8 SEL2 9 Z2 10 Y2 11 B2 12 A2 13 GND 14
Supply Voltage (VCC) ............................................. 6.5V Input Voltage Drivers ................................... - 0.3V to (VCC + 0.3V) Receivers ............................................. - 25V to 25V ON/OFF, LB, SEL1, SEL2 ........ - 0.3V to (VCC + 0.3V) Output Voltage Drivers ................................................. - 18V to 18V Receivers ............................... - 0.3V to (VCC + 0.3V) Short-Circuit Duration Output ........................................................ Indefinite VDD, VEE, C1+, C1-, C2+, C2 - .......................... 30 sec Operating Temperature Range Commercial ........................................... 0C to 70C Industrial ............................................ - 40C to 85C Storage Temperature Range ................ - 65C to 150C Lead Temperature (Soldering, 10 sec)................ 300C
ORDER PART NUMBER LTC1334CG LTC1334CNW LTC1334CSW LTC1334IG LTC1334ISW
G PACKAGE NW PACKAGE 28-LEAD PLASTIC SSOP 28-LEAD PDIP WIDE SW PACKAGE 28-LEAD PLASTIC SO WIDE TJMAX = 125C, JA = 90C/W (G) TJMAX = 125C, JA = 56C/W (NW) TJMAX = 125C, JA = 85C/W (SW)
Consult factory for Military grade parts.
DC ELECTRICAL CHARACTERISTICS
SYMBOL VOD1 VOD2 VOD VOC VOC IOSD IOZD VO IOSD VIH VIL IIN PARAMETER Differential Driver Output Voltage (Unloaded) Differential Driver Output Voltage (With Load) Change in Magnitude of Driver Differential Output Voltage for Complementary Output States Driver Common Mode Output Voltage Change in Magnitude of Driver Common Mode Output Voltage for Complementary Output States Driver Short-Circuit Current Three-State Output Current (Y, Z) Output Voltage Swing Output Short-Circuit Current Input High Voltage Input Low Voltage Input Current RS485 Driver (SEL1 = SEL2 = High) IO = 0
The q denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 5V, C1 = C2 = C3 = C4 = 0.1F (Notes 2, 3)
CONDITIONS
q q q q q q q q q
MIN
TYP
MAX 6
UNITS V V V V V V mA mA A V V
Figure 1, R = 50 (RS422) Figure 1, R = 27 (RS485) Figure 1, R = 27 or R = 50 Figure 1, R = 27 or R = 50 Figure 1, R = 27 or R = 50 - 7V VO 12V, VO = High - 7V VO 12V, VO = Low (Note 4) - 7V VO 12V Figure 4, RL = 3k, Positive Figure 4, RL = 3k, Negative VO = 0V D, DE, ON/OFF, SEL1, SEL2, LB D, DE, ON/OFF, SEL1, SEL2, LB D, SEL1, SEL2 DE, ON/OFF, LB
2.0 1.5
6 6 0.2 3 0.2
35 10 5 5 -5 6.5 - 6.5
250 250 500
RS232 Driver (SEL1 = SEL2 = Low)
q q q
60 2 0.8 -4 10 - 15
Driver Inputs and Control Inputs
q q q q
2
U
mA V V A A
W
U
U
WW
W
LTC1334
DC ELECTRICAL CHARACTERISTICS
SYMBOL VTH VTH IIN RIN VTH VTH RIN VOH VOL IOSR IOZR ROB VDD VEE PARAMETER Differential Input Threshold Voltage Input Hysteresis Input Current (A, B) Input Resistance Receiver Input Threshold Voltage Receiver Input Hysteresis Receiver Input Resistance Receiver Output High Voltage Receiver Output Low Voltage Short-Circuit Current Three-State Output Current Inactive "B" Output Pull-Up Resistance (Note 5) VDD Output Voltage VEE Output Voltage RS485 Receiver (SEL1 = SEL2 = High)
The q denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 5V, C1 = C2 = C3 = C4 = 0.1F (Notes 2, 3)
CONDITIONS - 7V VCM 12V, LTC1334C -7V VCM 7V, LTC1334I VCM = 0V VIN = - 7V VIN = 12V - 7V VIN 12V Input Low Threshold Input High Threshold VIN = 10V IO = - 3mA, VIN = 0V, SEL1 = SEL2 = Low IO = 3mA, VIN = 3V, SEL1 = SEL2 = Low 0V VO VCC ON/OFF = Low ON/OFF = High, SEL1 = SEL2 = High No Load, ON/OFF = High IDD = - 10mA, ON/OFF = High No Load, ON/OFF = High IEE = 10mA, ON/OFF = High No Load, SEL1 = SEL2 = High No Load Shutdown, ON/OFF = 0V
q q q q q q q q q q q
MIN - 0.2 -0.3
TYP
MAX 0.2 0.3
UNITS V V mV mA mA k V V V k V
70 - 0.8 1.0 12 0.8 2.4 0.6 3 3.5 7 50 8.5 7.6 - 7.7 - 6.9 8 10 25 100 5 4.6 0.2 0.4 85 10 7 24
RS232 Receiver (SEL1 = SEL2 = Low)
q q
Receiver Output V mA A k V V V V mA A
Power Supply Generator
Power Supply ICC VCC Supply Current
AC ELECTRICAL CHARACTERISTICS
SYMBOL SR tT tPLH tPHL tPLH tPHL t PLH t PHL tSKEW tr, tf PARAMETER Slew Rate Transition Time Driver Input to Output Driver Input to Output Receiver Input to Output Receiver Input to Output Driver Input to Output Driver Input to Output Driver Output to Output Driver Rise and Fall Time RS232 Mode (SEL1 = SEL2 = Low)
The q denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 5V, C1 = C2 = C3 = C4 = 0.1F (Notes 2, 3)
CONDITIONS Figure 4, RL = 3k, CL = 15pF Figure 4, RL = 3k, CL = 1000pF Figure 4, RL = 3k, CL = 2500pF Figures 4, 9, RL = 3k, CL = 15pF Figures 4, 9, RL = 3k, CL = 15pF Figures 5, 10 Figures 5, 10 Figures 2, 6, RL = 54, CL = 100pF Figures 2, 6, RL = 54, CL = 100pF Figures 2, 6, RL = 54, CL = 100pF Figures 2, 6, RL = 54, CL = 100pF
q q q q q q q
MIN
TYP
MAX 30
UNITS V/s V/s s s s s s ns ns ns ns
4 0.22 1.9 0.6 0.6 0.3 0.4 20 20 3 40 40 5 15 3.1 4 4 6 6 70 70 15 40
RS485 Mode (SEL1 = SEL2 = High)
q q q q
3
LTC1334
AC ELECTRICAL CHARACTERISTICS
SYMBOL tZL tZH tLZ tHZ t PLH t PHL tSKEW PARAMETER Driver Enable to Output Low Driver Enable to Output High Driver Disable from Low Driver Disable from High Receiver Input to Output Receiver Input to Output Differential Receiver Skew, tPLH - tPHL RS485 Mode (SEL1 = SEL2 = High)
The q denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 5V, C1 = C2 = C3 = C4 = 0.1F (Notes 2, 3)
CONDITIONS Figures 3, 7, CL = 100pF, S1 Closed Figures 3, 7, CL = 100pF, S2 Closed Figures 3, 7, CL = 15pF, S1 Closed Figures 3, 7, CL = 15pF, S2 Closed Figures 2, 8, RL = 54, CL = 100pF Figures 2, 8, RL = 54, CL = 100pF Figures 2, 8, RL = 54, CL = 100pF
q q q q q q
MIN
TYP 50 50 50 60
MAX 90 90 90 90 140 140
UNITS ns ns ns ns ns ns ns
20 20
60 70 10
Note 1: Absolute Maximum Ratings are those values beyond which the safety of the device cannot be guaranteed. Note 2: All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to device ground unless otherwise specified. Note 3: All typicals are given at VCC = 5V, C1 = C2 = C3 = C4 = 0.1F and TA = 25C.
Note 4: Short-circuit current for RS485 driver output low state folds back above VCC. Peak current occurs around VO = 3V. Note 5: The "B" RS232 receiver output is disabled in RS485 mode (SEL1 = SEL2 = high). The unused output driver goes into a high impedance mode and has a resistor to VCC. See Applications Information section for more details.
TYPICAL PERFORMANCE CHARACTERISTICS
Receiver Output High Voltage vs Temperature
5.0 4.9 4.8 IOUT = 3mA VCC = 5V
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
4.7 4.6 4.5 4.4 4.3 4.2 4.1 4.0 -50 -25 50 0 75 25 TEMPERATURE (C) 100 125
TIME (ns)
4
UW
LTC1334 * TPC01
Receiver Output Low Voltage vs Temperature
0.5 IOUT = 3mA VCC = 5V 0.4 20 18 16 14 0.3 12 10 8 6 0.1 4 2 0 -50 -25 50 0 75 25 TEMPERATURE (C) 100 125
RS485 Receiver Skew tPLH - tPHL vs Temperature
VCC = 5V
0.2
0 -50 -25
50 0 75 25 TEMPERATURE (C)
100
125
LTC1334 * TPC02
LTC1334 * TPC03
LTC1334 TYPICAL PERFORMANCE CHARACTERISTICS
Receiver Output Current vs Output High Voltage
20 18 16
OUTPUT CURRENT (mA)
INPUT THRESHOLD VOLTAGE (V)
TA = 25C VCC = 5V OUTPUT CURRENT (mA)
14 12 10 8 6 4 2 0 2.0 2.5 3.5 4.0 3.0 OUTPUT VOLTAGE (V) 4.5 5.0
Charge Pump Output Voltage vs Temperature
10 8 6
OUTPUT VOLTAGE (V)
VDD (-10mA LOAD)
SUPPLY CURRENT (mA)
4 2 0 -2 -4 -6 -8 -10 -50 -25 VCC = 5V
SUPPLY CURRENT (mA)
VDD (NO LOAD)
VEE (10mA LOAD) VEE (NO LOAD) 50 0 75 25 TEMPERATURE (C) 100 125
RS485 Driver Differential Output Voltage vs Temperature
2.6
DIFFERENTIAL OUTPUT CURRENT (mA)
DIFFERENTIAL OUTPUT VOLTAGE (V)
2.5 2.4 2.3 2.2 2.1 2.0 1.9 1.8 1.7
RL = 54 VCC = 5V
40 30 20
TIME (s)
1.6 -50 -25
50 0 75 25 TEMPERATURE (C)
UW
LTC1334 * TPC04
Receiver Output Current vs Output Low Voltage
40 35 30 25 20 15 10 5 0 0 0.5 1.0 1.5 2.0 OUTPUT VOLTAGE (V) 2.5 3.0 TA = 25C VCC = 5V
2.0
RS232 Receiver Input Threshold Voltage vs Temperature
VCC = 5V 1.8 1.6 1.4 1.2 1.0 0.8 -50 -25 INPUT HIGH
INPUT LOW
50 25 75 0 TEMPERATURE (C)
100
125
LTC1334 * TPC05
LTC1334 * TPC06
Supply Current vs Temperature (RS485)
25 VCC = 5V NO LOAD SEL 1 = SEL 2 = HIGH 10 9 8 7 6 5 4 3 2 1 0 -50 -25 50 25 0 75 TEMPERATURE (C) 100 125
Supply Current vs Temperature (RS232)
VCC = 5V NO LOAD SEL 1 = SEL 2 = HIGH
20
15
10
5
0 -50 -25
50 0 75 25 TEMPERATURE (C)
100
125
LTC1334 * TPC07
LTC1334 * TPC08
LTC1334 * TPC09
RS485 Driver Differential Output Current vs Output Voltage
70 60 50
9 15
RS485 Driver Skew vs Temperature
VCC = 5V 12
TA = 25C VCC = 5V
6
3
10 0 0 3 4 DIFFERENTIAL OUTPUT VOLTAGE (V) 1 2 5
0 -50 -25
100
125
50 0 75 25 TEMPERATURE (C)
100
125
LTC1334 * TPC10
LTC1334 * TPC11
LTC1334 * TPC12
5
LTC1334 TYPICAL PERFORMANCE CHARACTERISTICS
RS485 Driver Output High Voltage vs Output Current
-80 -70
OUTPUT CURRENT (mA)
120
OUTPUT SHORT-CIRCUIT CURRENT (mA)
-60 -50 -40 -30 -20 -10 0 0
OUTPUT CURRENT (mA)
1
3 OUTPUT VOLTAGE (V)
2
RS232 Driver Output Voltage vs Temperature
10 30
OUTPUT SHORT-CIRCUIT CURRENT (mA)
8 6 OUTPUT HIGH
25 20 15 10 5
OUTPUT LEAKAGE CURRENT (A)
OUTPUT VOLTAGE (V)
4 2 0 -2 -4 -6 -8 -10 -50 -25 50 0 75 25 TEMPERATURE (C) 100 125 OUTPUT LOW VCC = 5V RL = 3k
PIN FUNCTIONS
C1+ (Pin 1): Commutating Capacitor C1 Positive Terminal. Requires 0.1F external capacitor between Pins 1 and 2. C1- (Pin 2): Commutating Capacitor C1 Negative Terminal. VDD (Pin 3): Positive Supply Output for RS232 Drivers. Requires an external 0.1F capacitor to ground. A1 (Pin 4): Receiver Input. B1 (Pin 5): Receiver Input. Y1 (Pin 6): Driver Output. Z1 (Pin 7): Driver Output. SEL1 (Pin 8): Interface Mode Select Input. SEL2 (Pin 9): Interface Mode Select Input. Z2 (Pin 10): Driver Output. Y2 (Pin 11): Driver Output. B2 (Pin 12): Receiver Input. A2 (Pin 13): Receiver Input. GND (Pin 14): Ground. VEE (Pin 15): Negative Supply Output. Requires an external 0.1F capacitor to ground.
6
UW
TA = 25C VCC = 5V 4 5
LTC1334 * TPC13
LTC1334 * TPC16
RS485 Driver Output Low Voltage vs Output Current
160 TA = 25C VCC = 5V
RS485 Driver Output Short-Circuit Current vs Temperature
VCC = 5V 140 120 100 80 60 40 -50 -25
100 80 60 40 20 0
SINK (VOUT = 5V)
SOURCE (VOUT = 0V)
0
1
2 3 4 OUTPUT VOLTAGE (V)
5
50 25 75 0 TEMPERATURE (C)
100
125
LTC1334 * TPC14
LTC1334 * TPC15
RS232 Driver Short-Circuit Current vs Temperature
500 VOUT = 0V VCC = 5V SOURCE 450 400 350 300 250 200 150 100 50 0 -50 -25 50 25 75 0 TEMPERATURE (C) 100 125
Driver Output Leakage Current (Disable/Shutdown) vs Temperature
VCC = 5V
SINK
0 -50 -25
50 0 75 25 TEMPERATURE (C)
100
125
LTC1334 * TPC17
LTC1334 * TPC18
U
U
U
LTC1334 PI FU CTIO S
RB2 (Pin 16): Receiver Output. RA2 (Pin 17): Receiver Output. DZ2/DE2 (Pin 18): RS232 Driver Input in RS232 Mode. RS485 Driver Enable with internal pull-up in RS485 mode. DY2 (Pin 19): Driver Input. ON/OFF (Pin 20): A high logic input enables the transceivers. A low puts the device into shutdown mode and reduces ICC to 10A. This pin has an internal pull-up. LB (Pin 21): Loopback Control Input. A low logic level enables internal loopback connections. This pin has an internal pull-up. DY1 (Pin 22): Driver Input. DZ1/DE1 (Pin 23): RS232 Driver Input in RS232 Mode. RS485 Driver Enable with internal pull-up in RS485 mode. RA1 (Pin 24): Receiver Output. RB1 (Pin 25): Receiver Output. VCC (Pin 26): Positive Supply; 4.75V VCC 5.25V C2 - (Pin 27): Commutating Capacitor C2 Negative Terminal. Requires 0.1F external capacitor between Pins 27 and 28. C2 + (Pin 28): Commutating Capacitor C2 Positive Terminal.
C1+ C1- VDD A1 B1 Y1 Z1 SEL1 SEL2 Z2 Y2 B2 A2 GND 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 27 26 25 24 23 22 21 20 19 18 17 16 15 C2 + C2 - VCC RB1 RA1 DZ1/DE1 DY1 LB ON/OFF DY2 DZ2/DE2 RA2 RB2 VEE
FU CTIO TABLES
RS485 Driver Mode
ON/OFF 1 1 1 1 0 INPUTS SEL DE 1 1 1 1 1 1 1 1 0 X D 0 1 X X X CONDITIONS No Fault No Fault Thermal Fault X X OUTPUTS Z Y 0 1 Z Z Z 1 0 Z Z Z
RS485 Receiver Mode
ON/OFF 1 1 1 0 INPUTS SEL 1 1 1 1 B-A < - 0.2V > 0.2V Inputs Open X OUTPUTS RA RB* 0 1 1 Z 1 1 1 Z
*See Note 5 of Electrical Characteristics table.
U
U
U
U
U
RS232 Driver Mode
ON/OFF 1 1 1 0 INPUTS SEL 0 0 0 0 D 0 1 X X CONDITIONS No Fault No Fault Thermal Fault X OUTPUTS Y, Z 1 0 Z Z
RS232 Receiver Mode
ON/OFF 1 1 1 0 INPUTS SEL 0 0 0 0 A, B 0 1 Inputs Open X OUTPUTS RA, RB 1 0 1 Z
7
LTC1334
BLOCK DIAGRA SM
Interface Configuration with Loopback Disabled
PORT 1 = RS232 MODE PORT 2 = RS232 MODE 1 28 C1 VDD A1 B1 Y1 Z1 SEL1 = 0V 2 3 4 5 6 7 8 21 20 19 18 17 16 15 27 26 25 24 23 22 VCC RB1 RA1 DZ1 DY1 LB ON DY2 DZ2 RA2 RB2 VEE 9 10 11 12 13 14 C2 C1 VDD A1 B1 Y1 Z1 SEL1 = 5V PORT 1 = RS485 MODE PORT 2 = RS232 MODE 1 28 2 3 4 5 6 7 8 21 20 19 18 17 16 15 27 26 25 24 23 22 VCC RB1 RA1 DE1 DY1 LB ON DY2 DZ2 RA2 RB2 VEE 9 10 11 12 13 14 C2 C1 VDD A1 B1 Y1 Z1 SEL1 = 0V PORT 1 = RS232 MODE PORT 2 = RS485 MODE 1 28 2 3 4 5 6 7 8 21 20 19 18 17 16 15 27 26 25 24 23 22 VCC RB1 RA1 DZ1 DY1 LB ON DY2 DE2 RA2 RB2 VEE 9 10 11 12 13 14 C2 C1 VDD A1 B1 Y1 Z1 SEL1 = 5V PORT 1 = RS485 MODE PORT 2 = RS485 MODE 1 28 2 3 4 5 6 7 8 21 20 19 18 17 16 15 27 26 25 24 23 22 VCC RB1 RA1 DE1 DY1 LB ON DY2 DE2 RA2 RB2 VEE C2
SEL2 = 0V Z2 Y2 B2 A2 GND
9 10 11 12 13 14
PORT 1 = RS232 MODE PORT 2 = RS232 MODE 1 28
C1 VDD
2 3
27 26 25 24 VCC
RB1
RA1 DZ1 DY1 LB ON DY2 DZ2 RA2 RB2 VEE GND 14 9 10 11 Y1 Z1 SEL1 = 5V 6 7 8
Y1 Z1 SEL1 = 0V
6 7 8
23 22
21 20
SEL2 = 0V Z2 Y2
9 10 11
19 18 17 16
GND
14
15
8
W
SEL2 = 0V Z2 Y2 B2 A2 GND
SEL2 = 5V Z2 Y2 B2 A2 GND
SEL2 = 5V Z2 Y2 B2 A2 GND
LTC1334 * BD01
Interface Configuration with Loopback Enabled
PORT 1 = RS485 MODE PORT 2 = RS232 MODE 1 28 C2 C1 VDD 2 3 27 26 25 24 23 22 21 20 19 18 17 16 15 VCC RB1 RA1 DE1 DY1 LB ON DY2 DZ2 RA2 RB2 VEE GND Y1 Z1 SEL1 = 0V C2 C1 VDD
PORT 1 = RS232 MODE PORT 2 = RS485 MODE 1 28 2 3 27 26 25 24 6 7 8 21 20 19 18 17 16 14 15 23 22 VCC RB1 RA1 DZ1 DY1 LB ON DY2 DE2 RA2 RB2 VEE GND SEL2 = 5V Z2 Y2 Y1 Z1 SEL1 = 5V C2 C1 VDD
PORT 1 = RS485 MODE PORT 2 = RS485 MODE 1 28 2 3 27 26 25 24 6 7 8 21 9 10 11 20 19 18 17 16 14 15 23 22 VCC RB1 RA1 DE1 DY1 LB ON DY2 DE2 RA2 RB2 VEE C2
SEL2 = 0V Z2 Y2
SEL2 = 5V Z2 Y2
9 10 11
LTC1334 * BD02
LTC1334 TEST CIRCUITS
Z R VOD R Y
LTC1334 * F01 LTC1334 * F02 LTC1334 * F03
VCC 3V D VOC SEL Z RL DE 3V Y CL A CL B 3V SEL R 15pF 500 DR OUT CL S2
S1
Figure 1. RS422/RS485 Driver Test Load
Figure 2. RS485 Driver/Receiver Timing Test Circuit
Figure 3. RS485 Driver Output Enable/Disable Timing Test Load
0V SEL D Y, Z
D 0V SEL Y, Z VIN A, B 0V SEL R VOUT 15pF
LTC1334 * F05
CL
RL
LTC1334 * F04
Figure 4. RS232 Driver Swing/Timing Test Circuit
Figure 5. RS232 Receiver Timing Test Circuit
SWITCHI G WAVEFOR S
3V D 0V tPLH VO Z-Y -VO 50% 10% 1.5V
Y VO Z tSKEW tSKEW
LTC1334 * F06
W
U
f = 1MHz: tr 10ns: tf 10ns
1.5V tPHL
90%
VDIFF = V(Z) - V(Y)
90% 50% 10% tf
tr
1/2 VO
Figure 6. RS485 Driver Propagation Delays
9
LTC1334
SWITCHI G WAVEFOR S
3V DE 0V tZL 5V Y, Z VOL tZH VOH Z, Y 0V
LTC1334 * F07
VOD2 B-A -VOD2 tPLH VOH R VOL 0V
3V D 0V tPHL VO Y, Z -VO 0V
LTC1334 * F09
1.5V
VIH A, B VIL tPHL VOH R VOL 0.8V tPLH 2.4V
LTC1334 * F10
1.3V
Figure 10. RS232 Receiver Propagation Delays
10
W
1.5V
U
f = 1MHz: tr 10ns: tf 10ns
1.5V tLZ
2.3V OUTPUT NORMALLY LOW OUTPUT NORMALLY HIGH 2.3V tHZ 0.5V 0.5V
Figure 7. RS485 Driver Enable and Disable Times
f = 1MHz: tr 10ns: tf 10ns
INPUT
0V tPHL 1.5V
LTC1334 * F08
OUTPUT 1.5V
Figure 8. RS485 Receiver Propagation Delays
1.5V tPLH 0V
Figure 9. RS232 Driver Propagation Delays
1.7V
LTC1334
APPLICATI S I FOR ATIO
Basic Theory of Operation The LTC1334 has two interface ports. Each port may be configured as a pair of single-ended RS232 transceivers or as a differential RS485 transceiver by forcing the port's selection input to a low or high, respectively. The LTC1334 provides two RS232 drivers and two RS232 receivers or one RS485 driver and one RS485 receiver per port. All the interface drivers feature three-state outputs. Interface outputs are forced into high impedance when the driver is disabled, in the shutdown mode or with the power off. All the interface driver outputs are fault-protected by a current limiting and thermal shutdown circuit. The thermal shutdown circuit disables both the RS232 and RS485 driver outputs when the die temperature reaches 150C. The thermal shutdown circuit reenables the drivers when the die temperature cools to 130C. In RS485 mode, shutdown mode or with the power off, the input resistance of the receiver is 24k. The input resistance drops to 5k in RS232 mode. A logic low at the ON/OFF pin shuts down the device and forces all the outputs into a high impedance state. A logic high enables the device. An internal 4A current source to VCC pulls the ON/OFF pin high if it is left open.
C1 VDD 0.1F RS485 I/O 120
0.1F 2 3 4 5 6 7 5V 8 9
5V INTO 3k LOAD
RS232 DR OUT RS232 DR OUT RS232 RX IN RS232 RX IN
Figure 11. RS232/RS485 Interfaces
U
In RS485 mode, an internal 4A current source pulls the driver enable pin high if left open. The RS485 receiver has a 4A current source at the noninverting input. If both the RS485 receiver inputs are open, the output goes to a high state. Both the current sources are disabled in the RS232 mode. The receiver output B is inactive in RS485 mode and has a 50k pull-up resistor to provide a known output state in this mode. A loopback mode enables internal connections from driver outputs to receiver inputs for self-test when the LB pin has a low logic state. The driver outputs are not isolated from the external loads. This allows transmitter verification under the loaded condition. An internal 4A current source pulls the LB pin high if left open and disables the loopback configuration. RS232/RS485 Applications The LTC1334 can support both RS232 and RS485 levels with a single 5V supply as shown in Figure 11. Multiprotocol Applications The LTC1334 is well-suited for software controlled interface mode selection. Each port has a selection pin as shown in Figure 12. The single-ended transceivers support both RS232 and EIA562 levels. The differential transceivers support both RS485 and RS422.
28 LTC1334 27 26 24 23 22 21 20 19 18 17 16 15 RX OUT DR ENABLE DR IN 5V 5V DR IN DR IN RX OUT RX OUT VEE 0.1F
LTC1334 * F11
W
U
UO
1
0.1F
C2 VCC 5V
0.1F
11 10 13 12 14
11
LTC1334
APPLICATI
C1
S I FOR ATIO
1 LTC1334 28 27 0.1F 26 2 3
0.1F VDD 0.1F INPUT A K1A 120
0.1F 25 RX OUT 4
PORT 1 INTERFACE 5V K1* TX2A-5V
INPUT B OUTPUT A K1B 120 OUTPUT B 360k
5 6
24
RX OUT
22 8
DR IN SEL1
7
23 21 20
DR IN/ENABLE LB ON/OFF RX OUT
FMMT619** 7.5k
TERM1 16 13
INPUT A K2A 120 PORT 2 INTERFACE 5V K2* TX2A-5V INPUT B OUTPUT A K2B 120 OUTPUT B 360k FMMT619** 7.5k
12 11
17
RX OUT
19 9
DR IN SEL2
10 14
18 15
DR IN/ENABLE VEE
LTC1334 * F12
0.1F TERM2 *AROMAT CORP (800) 276-6289 **ZETEX (516) 543-7100
Figure 12. Multiprotocol Interface with Optional, Switchable Terminations
1/2 LTC1334 RX OUT DR ENABLE DR IN 5V 24 23 22 8 6 7 76 54 1/2 LTC1334 22 23 24 8 4 5 120 120
Figure 14. Typical Connection for RS485 Interface
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C2 VCC 5V
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Each receiver in the LTC1334 is designed to present one unit load (5k nominal for RS232 and 12k minimum for RS485) to the cable. Some RS485 and RS422 applications call for terminations, but these are only necessary at two nodes in the system and they must be disconnected when operating in the RS232 mode. A relay is the simplest, lowest cost method of switching terminations. In Figure 12 TERM1 and TERM2 select 120 terminations as needed. If terminations are needed in all RS485/RS422 applications, no extra control signals are required; simply connect TERM1 and TERM2 to SEL1 and SEL2. Typical Applications A typical RS232/EIA562 interface application is shown in Figure 13 with the LTC1334. A typical connection for a RS485 transceiver is shown in Figure 14. A twisted pair of wires connects up to 32 drivers and receivers for half duplex multipoint data transmission. The wires must be terminated at both ends with resistors equal to the wire's characteristic impedance. An optional shield around the twisted pair helps to reduce unwanted noise and should be connected to ground at only one end.
1/2 LTC1334 DR IN DR IN RX OUT RX OUT 19 18 17 16 9
LTC1334 * F13
1/2 LTC1334 11 10 12 RS232/ EIA562 LINES 4 5 6 7 24 25 22 23 8 RX OUT RX OUT DR IN DR IN
13 INTERFACE
Figure 13. Typical Connection for RS232/EIA562 Interface
1/2 LTC1334 13 17 12 18 11 10 19 9
RX OUT DR ENABLE DR IN 5V
DR IN RX OUT DR ENABLE 5V
LTC1334 F14
LTC1334
APPLICATI S I FOR ATIO
A typical RS422 connection (Figure 15) allows one driver and ten receivers on a twisted pair of wires terminated with a 100 resistor at one end. A typical twisted-pair line repeater is shown in Figure 16. As data transmission rate drops with increased cable length, repeaters can be inserted to improve transmission rate or to transmit beyond the RS422 4000-foot limit. The LTC1334 can be used to translate RS232 to RS422 interface levels or vice versa as shown in Figure 17. One
DR ENABLE DR IN 5V RX OUT 22 8
1/2 LTC1334 23 6 7
24
4 100 5
Figure 15. Typical Connection for RS422 Interface
17 22 5V RX IN RS232/EIA562 6 TX OUT 5 1/2 LTC1334 7
LTC1334 * F16
24 4 RX IN 100
22
23 8
Figure 16. Typical Cable Repeater for RS422 Interface
5V 17 22 RX IN RS232/EIA562 DR OUT 11 13 23 8 6 RS422
7 LTC1334 4 100 5 9 19 24
Figure 18. Typical Cable Extension for RS232/EIA562 Interface
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port is configured as an RS232 transceiver and the other as an RS485 transceiver. Using two LTC1334s as level translators, the RS232/ EIA562 interface distance can be extended to 4000 feet with twisted-pair wires (Figure 18). AppleTalk(R)/LocalTalk(R) Applications Two AppleTalk applications are shown in Figure 19 and 20 with the LTC1323 and the LTC1334.
AppleTalk and LocalTalk are registered trademarks of Apple Computer, Inc.
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1/2 LTC1334 RX OUT 24 8 54 100 12 5V 1/2 LTC1334 13 17 8 18 11 10
LTC1334 * F15
RX OUT 5V DR ENABLE DR IN
19
5V 23 8 6 TX OUT 7 LTC1334 RS422 4 100 5 RX IN
LTC1334 * F17
13
TX OUT
11
9
19 24
Figure 17. Typical RS232/EIA562 to RS422 Level Translator
24 19 4 100 5 LTC1334 6 7 8 23 22 17 9
LTC1334 * F18
11
DR OUT RS232/EIA562
13
RX IN
5V
13
LTC1334
APPLICATI
1 0.33F TXD TXDEN SHDN RXEN RXDO 2 3 4 5 6 7 8 CHARGE PUMP
S I FOR ATIO
16 15 14 13 12 TXD - 11 TXD + 10 RXD - 9 RXD + EMI 1k EMI EMI EMI 5 TO 22 EMI = 5 TO 22 1k 0.33F 1F 5V
LTC1323CS-16 0.1F
100pF
Figure 19. AppleTalk/LocalTalk Implemented Using the LTC1323CS-16 and LTC1334 Transceivers
5 TO 22 LTC1323CS 1 0.33F CPEN TXD TXI TXDEN SHDN RXEN RXO RXO RXDO 2 3 4 5 6 19 TXD + 7 18 TXO 8 9 10 11 15 RXD- 14 RXD+ 12 13 17 RXI 16 RXI EMI EMI CHARGE PUMP 24 23 22 21 20 TXD - EMI 0.33F 1F EMI =
5 TO 22 OR 100pF OR 100pF
5V 0.1F
120
EMI EMI SEL2 EMI 120 EMI
Figure 20. AppleTalk Direct Connect Using the LTC1323 DTE and the LTC1334 for DCE Transceivers
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1 2 3 0.1F EMI 1k EMI EMI 120 120 1k EMI SEL1, 5V SEL2, 5V FERRITE BEAD OR OR 100pF 100pF FERRITE BEAD NC 7 8 9 10 4 5 6 LTC1334 28 27 26 25 24 23 22 21 20 19 18 17 16 15 0.1F
LTC1334 * F19
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0.1F 5V NC RA1 DE1 DY1 5V 5V NC NC NC NC
11 NC 12 NC NC 13 14
FERRITE BEAD
FERRITE BEAD
100pF 1 2 3 0.1F EMI 120 EMI EMI 120 EMI SEL1 5V 7 8 9 10 11 12 13 14 5 6 23 22 21 20 19 18 17 16 15 0.1F
LTC1334 * F20
28 LTC1334 27 26 25 24 5V NC RA1 0.1F
4
DE1 DY1 5V 5V DY2 DZ2 RA2 NC
EMI EMI NC EMI
LTC1334
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 ARE IN MILLIMETERS *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.152mm (0.006") PER SIDE **DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.254mm (0.010") PER SIDE
0.505 - 0.560* (12.827 - 14.224)
0.600 - 0.625 (15.240 - 15.875)
0.009 - 0.015 (0.229 - 0.381) +0.035 0.625 -0.015 +0.889 -0.381
0.015 (0.381) MIN
(
15.87
)
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
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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Dimensions in inches (millimeters) unless otherwise noted. G Package 28-Lead Plastic SSOP (0.209)
(LTC DWG # 05-08-1640)
10.07 - 10.33* (0.397 - 0.407) 28 27 26 25 24 23 22 21 20 19 18 17 16 15
7.65 - 7.90 (0.301 - 0.311)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 1.73 - 1.99 (0.068 - 0.078)
0 - 8
0.65 (0.0256) BSC
0.25 - 0.38 (0.010 - 0.015)
0.05 - 0.21 (0.002 - 0.008)
G28 SSOP 1098
NW Package 28-Lead PDIP (Wide 0.600)
(LTC DWG # 05-08-1520)
1.455* (36.957) MAX 28 27 26 25 24 23 22 21 20 19 18 17 16 15
1 0.150 0.005 (3.810 0.127)
2
3
4
5
6
7
8
9
10
11
12
13
14
0.045 - 0.065 (1.143 - 1.651)
0.070 (1.778) TYP 0.125 (3.175) MIN 0.035 - 0.080 (0.889 - 2.032) 0.100 (2.54) BSC 0.018 0.003 (0.457 0.076)
N28 1098
15
LTC1334
PACKAGE DESCRIPTION
0.291 - 0.299** (7.391 - 7.595) 0.010 - 0.029 x 45 (0.254 - 0.737) 0 - 8 TYP
0.009 - 0.013 (0.229 - 0.330)
NOTE 1 0.016 - 0.050 (0.406 - 1.270)
NOTE: 1. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS. THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
RELATED PARTS
PART NUMBER LTC485 LT (R) 1137A LTC1320 LTC1321/LTC1322/LTC1335 LTC1323 LTC1347 LTC1387 DESCRIPTION Low Power RS485 Interface Transceiver Low Power RS232 Transceiver AppleTalk Transceiver RS232/EIA562/RS485 Transceivers Single 5V AppleTalk Transceiver 5V Low Power RS232 Transceiver Single 5V RS232/RS485 Transceiver COMMENTS Single 5V Supply, Wide Common Mode Range 15kV IEC-1000-4-2 ESD Protection, Three Drivers, Five Receivers AppleTalk/Local Talk Compliant Configurable, 10kV ESD Protection LocalTalk/AppleTalk Compliant 10kV ESD Three Drivers/Five Receivers, Five Receivers Alive in Shutdown Single Port, Configurable, 10kV ESD
16
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
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Dimensions in inches (millimeters) unless otherwise noted.
SW Package 28-Lead Plastic Small Outline (Wide 0.300)
(LTC DWG # 05-08-1690)
0.697 - 0.712* (17.70 - 18.08) 28 27 26 25 24 23 22 21 20 19 18 17 16 15
NOTE 1
0.394 - 0.419 (10.007 - 10.643)
1 0.093 - 0.104 (2.362 - 2.642)
2
3
4
5
6
7
8
9
10
11
12
13
14 0.037 - 0.045 (0.940 - 1.143)
0.050 (1.270) BSC
0.014 - 0.019 (0.356 - 0.482) TYP
0.004 - 0.012 (0.102 - 0.305)
S28 (WIDE) 1098
1334fa LT/TP 1099 2K REV A * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1995

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