LTC1334 Single 5V RS232/RS485 Multiprotocol Transceiver U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO The LTC ®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 0.1µF 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 10µA. 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: 0.1µF Low Supply Current: 8mA Typical 10µA 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 U APPLICATIO S ■ ■ ■ ■ Low Power RS485/RS422/RS232/EIA562 Interface Software-Selectable Multiprotocol Interface Port Cable Repeaters Level Translators 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. U TYPICAL APPLICATIO 2 1 28 27 27 28 1 3 LTC1334 VCC1 5V RX OUT DR ENABLE DR IN 5V 5V DR IN DR IN RX OUT RX OUT 26 24 LTC1334 4 5 23 22 13 12 RS485 INTERFACE 120Ω 7 8 20 9 10 5V 5V RS232 INTERFACE 26 17 11 4000-FT 24-GAUGE TWISTED PAIR 0V 3 18 120Ω 6 21 2 0V 9 19 21 8 20 4 24 19 11 18 10 5 25 17 13 6 22 16 12 7 23 15 14 14 15 RX OUT VCC2 5V DR ENABLE DR IN 5V 5V RX OUT RX OUT DR IN DR IN ALL CAPACITORS: 0.1µF MONOLITHIC CERAMIC TYPE LTC1334 • TA01 1 LTC1334 U U RATI GS W W W W AXI U U ABSOLUTE PACKAGE/ORDER I FOR ATIO (Note 1) 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 ........................................... 0°C to 70°C Industrial ............................................ – 40°C to 85°C Storage Temperature Range ................ – 65°C to 150°C Lead Temperature (Soldering, 10 sec)................ 300°C ORDER PART NUMBER TOP VIEW C1+ C1– 2 28 C2+ 27 C2 – VDD 3 26 VCC A1 4 25 RB1 B1 5 24 RA1 Y1 6 23 DZ1/DE1 22 DY1 1 Z1 7 SEL1 8 21 LB SEL2 9 20 ON/OFF Z2 10 Y2 11 19 DY2 18 DZ2/DE2 B2 12 17 RA2 A2 13 16 RB2 GND 14 15 VEE 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 = 125°C, θJA = 90°C/W (G) TJMAX = 125°C, θJA = 56°C/W (NW) TJMAX = 125°C, θJA = 85°C/W (SW) Consult factory for Military grade parts. DC ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, C1 = C2 = C3 = C4 = 0.1µF (Notes 2, 3) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS RS485 Driver (SEL1 = SEL2 = High) VOD1 Differential Driver Output Voltage (Unloaded) IO = 0 ● VOD2 Differential Driver Output Voltage (With Load) Figure 1, R = 50Ω (RS422) Figure 1, R = 27Ω (RS485) ● ● 6 V 6 6 V V ∆VOD Change in Magnitude of Driver Differential Output Voltage for Complementary Output States Figure 1, R = 27Ω or R = 50Ω ● 0.2 V VOC Driver Common Mode Output Voltage Figure 1, R = 27Ω or R = 50Ω ● 3 V ∆VOC Change in Magnitude of Driver Common Mode Output Voltage for Complementary Output States Figure 1, R = 27Ω or R = 50Ω ● 0.2 V IOSD Driver Short-Circuit Current – 7V ≤ VO ≤ 12V, VO = High – 7V ≤ VO ≤ 12V, VO = Low (Note 4) ● ● 250 250 mA mA IOZD Three-State Output Current (Y, Z) – 7V ≤ VO ≤ 12V ● ±500 µA 2.0 1.5 35 10 ±5 RS232 Driver (SEL1 = SEL2 = Low) VO Output Voltage Swing Figure 4, RL = 3k, Positive Figure 4, RL = 3k, Negative ● ● IOSD Output Short-Circuit Current VO = 0V ● 5 –5 6.5 – 6.5 V V ±60 mA Driver Inputs and Control Inputs VIH Input High Voltage D, DE, ON/OFF, SEL1, SEL2, LB ● VIL Input Low Voltage D, DE, ON/OFF, SEL1, SEL2, LB ● IIN Input Current D, SEL1, SEL2 DE, ON/OFF, LB ● ● 2 2 V –4 0.8 V ±10 – 15 µA µA LTC1334 DC ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, C1 = C2 = C3 = C4 = 0.1µF (Notes 2, 3) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS 0.2 0.3 V V RS485 Receiver (SEL1 = SEL2 = High) VTH Differential Input Threshold Voltage – 7V ≤ VCM ≤ 12V, LTC1334C –7V ≤ VCM ≤ 7V, LTC1334I ∆VTH Input Hysteresis VCM = 0V IIN Input Current (A, B) VIN = – 7V VIN = 12V ● ● RIN Input Resistance – 7V ≤ VIN ≤ 12V ● 12 Input Low Threshold Input High Threshold ● ● 0.8 ● ● – 0.2 –0.3 70 mV – 0.8 1.0 mA mA 24 kΩ RS232 Receiver (SEL1 = SEL2 = Low) VTH Receiver Input Threshold Voltage ∆VTH Receiver Input Hysteresis RIN Receiver Input Resistance V V 2.4 0.6 VIN = ±10V 3 5 3.5 4.6 V 7 kΩ Receiver Output VOH Receiver Output High Voltage IO = – 3mA, VIN = 0V, SEL1 = SEL2 = Low ● VOL IOSR Receiver Output Low Voltage IO = 3mA, VIN = 3V, SEL1 = SEL2 = Low ● Short-Circuit Current 0V ≤ VO ≤ VCC ● IOZR Three-State Output Current ON/OFF = Low ● ROB Inactive “B” Output Pull-Up Resistance (Note 5) ON/OFF = High, SEL1 = SEL2 = High 50 kΩ 0.2 7 V 0.4 V 85 mA ±10 µA Power Supply Generator VDD VDD Output Voltage No Load, ON/OFF = High IDD = – 10mA, ON/OFF = High 8.5 7.6 V V VEE VEE Output Voltage No Load, ON/OFF = High IEE = 10mA, ON/OFF = High – 7.7 – 6.9 V V Power Supply ICC VCC Supply Current No Load, SEL1 = SEL2 = High No Load Shutdown, ON/OFF = 0V 8 10 ● ● 25 100 mA µA AC ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, C1 = C2 = C3 = C4 = 0.1µF (Notes 2, 3) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS RS232 Mode (SEL1 = SEL2 = Low) SR Slew Rate Figure 4, RL = 3k, CL = 15pF Figure 4, RL = 3k, CL = 1000pF ● ● 4 0.22 30 V/µs V/µs 1.9 3.1 µs tT Transition Time Figure 4, RL = 3k, CL = 2500pF ● tPLH Driver Input to Output Figures 4, 9, RL = 3k, CL = 15pF ● 0.6 4 µs tPHL Driver Input to Output Figures 4, 9, RL = 3k, CL = 15pF ● 0.6 4 µs tPLH Receiver Input to Output Figures 5, 10 ● 0.3 6 µs tPHL Receiver Input to Output Figures 5, 10 ● 0.4 6 µs RS485 Mode (SEL1 = SEL2 = High) t PLH Driver Input to Output Figures 2, 6, RL = 54Ω, CL = 100pF ● 20 40 70 ns t PHL Driver Input to Output Figures 2, 6, RL = 54Ω, CL = 100pF ● 20 40 70 ns tSKEW Driver Output to Output Figures 2, 6, RL = 54Ω, CL = 100pF ● 5 15 ns tr, tf Driver Rise and Fall Time Figures 2, 6, RL = 54Ω, CL = 100pF ● 3 15 40 ns 3 LTC1334 AC ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, C1 = C2 = C3 = C4 = 0.1µF (Notes 2, 3) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS RS485 Mode (SEL1 = SEL2 = High) tZL Driver Enable to Output Low Figures 3, 7, CL = 100pF, S1 Closed ● 50 90 ns tZH tLZ Driver Enable to Output High Figures 3, 7, CL = 100pF, S2 Closed ● 50 90 ns Driver Disable from Low Figures 3, 7, CL = 15pF, S1 Closed ● 50 90 ns tHZ Driver Disable from High Figures 3, 7, CL = 15pF, S2 Closed ● 60 90 ns t PLH Receiver Input to Output Figures 2, 8, RL = 54Ω, CL = 100pF ● 20 60 140 ns t PHL Receiver Input to Output Figures 2, 8, RL = 54Ω, CL = 100pF ● 20 70 140 ns tSKEW Differential Receiver Skew, tPLH – tPHL Figures 2, 8, RL = 54Ω, CL = 100pF 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 = 0.1µF and TA = 25°C. 10 ns 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. U W TYPICAL PERFORMANCE CHARACTERISTICS Receiver Output High Voltage vs Temperature Receiver Output Low Voltage vs Temperature 5.0 0.5 18 0.4 OUTPUT VOLTAGE (V) 4.8 OUTPUT VOLTAGE (V) 20 IOUT = 3mA VCC = 5V IOUT = 3mA VCC = 5V 4.7 4.6 4.5 4.4 4.3 14 0.3 0.2 8 2 50 0 75 25 TEMPERATURE (°C) 100 125 LTC1334 • TPC01 4 10 4 4.1 4.0 –50 –25 12 6 0.1 4.2 VCC = 5V 16 TIME (ns) 4.9 RS485 Receiver Skew tPLH – tPHL vs Temperature 0 –50 –25 50 0 75 25 TEMPERATURE (°C) 100 125 LTC1334 • TPC02 0 –50 –25 50 0 75 25 TEMPERATURE (°C) 100 125 LTC1334 • TPC03 LTC1334 U W TYPICAL PERFORMANCE CHARACTERISTICS Receiver Output Current vs Output High Voltage 40 TA = 25°C VCC = 5V 18 2.0 TA = 25°C VCC = 5V 35 OUTPUT CURRENT (mA) 16 14 12 10 8 6 VCC = 5V INPUT THRESHOLD VOLTAGE (V) 20 OUTPUT CURRENT (mA) RS232 Receiver Input Threshold Voltage vs Temperature Receiver Output Current vs Output Low Voltage 30 25 20 15 10 4 5 2 0 0 2.0 2.5 3.5 4.0 3.0 OUTPUT VOLTAGE (V) 4.5 5.0 0 0.5 1.0 1.5 2.0 OUTPUT VOLTAGE (V) Charge Pump Output Voltage vs Temperature VCC = 5V –2 –4 VEE (10mA LOAD) VEE (NO LOAD) –10 –50 –25 50 0 75 25 TEMPERATURE (°C) 8 10 5 100 125 VCC = 5V NO LOAD SEL 1 = SEL 2 = HIGH 7 6 5 4 3 1 100 125 50 25 0 75 TEMPERATURE (°C) –25 100 0 –50 –25 125 2.2 2.1 2.0 1.9 1.8 1.7 100 125 LTC1334 • TPC10 125 RS485 Driver Skew vs Temperature 15 VCC = 5V TA = 25°C VCC = 5V 60 12 50 TIME (µs) DIFFERENTIAL OUTPUT CURRENT (mA) 2.3 100 LTC1334 • TPC09 70 2.4 50 0 75 25 TEMPERATURE (°C) LTC1334 • TPC08 RS485 Driver Differential Output Current vs Output Voltage RL = 54Ω VCC = 5V 50 0 75 25 TEMPERATURE (°C) 50 25 75 0 TEMPERATURE (°C) 2 0 –50 2.6 DIFFERENTIAL OUTPUT VOLTAGE (V) 9 15 RS485 Driver Differential Output Voltage vs Temperature 1.6 –50 –25 1.0 10 LTC1334 • TPC07 2.5 INPUT LOW Supply Current vs Temperature (RS232) SUPPLY CURRENT (mA) 2 –8 1.2 LTC1334 • TPC06 VCC = 5V NO LOAD SEL 1 = SEL 2 = HIGH 20 VDD (NO LOAD) SUPPLY CURRENT (mA) OUTPUT VOLTAGE (V) VDD (–10mA LOAD) –6 1.4 0.8 –50 –25 3.0 25 8 0 1.6 Supply Current vs Temperature (RS485) 10 4 INPUT HIGH LTC1334 • TPC05 LTC1334 • TPC04 6 2.5 1.8 40 30 9 6 20 3 10 0 0 1 2 3 4 DIFFERENTIAL OUTPUT VOLTAGE (V) 5 LTC1334 • TPC11 0 –50 –25 50 0 75 25 TEMPERATURE (°C) 100 125 LTC1334 • TPC12 5 LTC1334 U W TYPICAL PERFORMANCE CHARACTERISTICS RS485 Driver Output Low Voltage vs Output Current RS485 Driver Output High Voltage vs Output Current 120 TA = 25°C VCC = 5V 100 OUTPUT CURRENT (mA) –70 160 TA = 25°C VCC = 5V –60 –50 –40 –30 –20 OUTPUT SHORT-CIRCUIT CURRENT (mA) –80 OUTPUT CURRENT (mA) RS485 Driver Output Short-Circuit Current vs Temperature 80 60 40 20 –10 0 0 1 0 2 3 OUTPUT VOLTAGE (V) 4 5 1 0 2 3 4 OUTPUT VOLTAGE (V) 10 OUTPUT VOLTAGE (V) 4 2 VCC = 5V RL = 3k –2 –4 OUTPUT LOW –8 –10 –50 –25 50 0 75 25 TEMPERATURE (°C) 100 125 SOURCE (VOUT = 0V) 60 50 25 75 0 TEMPERATURE (°C) 25 100 125 LTC1334 • TPC15 Driver Output Leakage Current (Disable/Shutdown) vs Temperature 500 VOUT = 0V VCC = 5V 450 OUTPUT LEAKAGE CURRENT (µA) OUTPUT SHORT-CIRCUIT CURRENT (mA) OUTPUT HIGH –6 80 40 –50 –25 5 30 8 SINK (VOUT = 5V) 100 RS232 Driver Short-Circuit Current vs Temperature RS232 Driver Output Voltage vs Temperature 0 120 LTC1334 • TPC14 LTC1334 • TPC13 6 VCC = 5V 140 SOURCE 20 15 10 SINK 5 VCC = 5V 400 350 300 250 200 150 100 50 0 –50 –25 50 25 75 0 TEMPERATURE (°C) LTC1334 • TPC16 100 125 LTC1334 • TPC17 0 –50 –25 50 0 75 25 TEMPERATURE (°C) 100 125 LTC1334 • TPC18 U U U PIN FUNCTIONS C1+ (Pin 1): Commutating Capacitor C1 Positive Terminal. Requires 0.1µF 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 0.1µF capacitor to ground. A1 (Pin 4): Receiver Input. B1 (Pin 5): Receiver Input. Y1 (Pin 6): Driver Output. Z1 (Pin 7): Driver Output. 6 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 0.1µF capacitor to ground. LTC1334 U U U 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 10µA. 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 0.1µF external capacitor between Pins 27 and 28. C2 + (Pin 28): Commutating Capacitor C2 Positive Terminal. C1+ 1 28 C2 + C1– 2 27 C2 – 3 26 4 25 5 24 6 23 7 22 8 21 9 20 10 19 11 18 12 17 13 16 14 15 VDD A1 B1 Y1 Z1 SEL1 SEL2 Z2 Y2 B2 A2 GND VCC RB1 RA1 DZ1/DE1 DY1 LB ON/OFF DY2 DZ2/DE2 RA2 RB2 VEE U U FU CTIO TABLES RS485 Driver Mode ON/OFF RS232 Driver Mode INPUTS SEL DE D CONDITIONS OUTPUTS Z Y ON/OFF INPUTS SEL D CONDITIONS OUTPUTS Y, Z 1 1 1 0 No Fault 0 1 1 0 0 No Fault 1 1 1 1 1 No Fault 1 0 1 0 1 No Fault 0 1 1 1 X Thermal Fault Z Z 1 0 X Thermal Fault Z 1 1 0 X X Z Z 0 0 X X Z 0 1 X X X Z Z RS485 Receiver Mode RS232 Receiver Mode ON/OFF INPUTS SEL B–A 1 1 < – 0.2V 0 1 1 > 0.2V 1 1 Inputs Open 0 1 X OUTPUTS RA RB* ON/OFF INPUTS SEL A, B OUTPUTS RA, RB 1 1 0 0 1 1 1 1 0 1 0 1 1 1 0 Inputs Open 1 Z 0 0 X Z Z *See Note 5 of Electrical Characteristics table. 7 LTC1334 W 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 SEL2 = 0V Z2 Y2 B2 A2 GND 2 27 3 26 4 25 5 24 6 23 7 22 8 21 9 20 10 19 11 18 12 17 13 16 14 15 PORT 1 = RS485 MODE PORT 2 = RS232 MODE 1 28 C2 C1 VCC VDD A1 RB1 RA1 B1 DZ1 Y1 DY1 Z1 SEL1 = 5V 2 27 3 26 4 25 5 24 6 23 7 22 8 21 LB ON SEL2 = 0V DY2 Z2 DZ2 Y2 B2 RA2 RB2 A2 VEE GND 9 20 10 19 11 18 12 17 13 16 14 15 PORT 1 = RS232 MODE PORT 2 = RS485 MODE 1 28 C2 C1 VDD VCC A1 RB1 RA1 B1 DE1 Y1 DY1 Z1 SEL1 = 0V 2 27 3 26 4 25 5 24 6 23 7 22 8 21 LB ON SEL2 = 5V DY2 Z2 DZ2 Y2 B2 RA2 RB2 A2 VEE GND 9 20 10 19 11 18 12 17 13 16 14 15 PORT 1 = RS485 MODE PORT 2 = RS485 MODE 1 28 C2 C1 VCC VDD A1 RB1 RA1 B1 DZ1 Y1 DY1 Z1 SEL1 = 5V 2 27 3 26 4 25 5 24 6 23 7 22 8 21 LB ON SEL2 = 5V DY2 Z2 DE2 Y2 B2 RA2 RB2 A2 VEE GND 9 20 10 19 11 18 12 17 13 16 14 15 C2 VCC RB1 RA1 DE1 DY1 LB ON DY2 DE2 RA2 RB2 VEE LTC1334 • BD01 Interface Configuration with Loopback Enabled PORT 1 = RS485 MODE PORT 2 = RS232 MODE 1 28 PORT 1 = RS232 MODE PORT 2 = RS232 MODE 1 28 C1 VDD 2 27 3 26 25 24 Y1 Z1 SEL1 = 0V SEL2 = 0V Z2 Y2 6 23 7 22 8 21 9 20 10 19 11 18 17 16 GND 14 15 C2 C1 VCC VDD 2 27 3 26 25 RB1 24 RA1 DZ1 Y1 DY1 Z1 SEL1 = 5V 6 23 7 22 8 21 LB ON SEL2 = 0V DY2 Z2 DZ2 Y2 9 20 10 19 11 17 RA2 16 RB2 VEE 18 GND 14 15 PORT 1 = RS232 MODE PORT 2 = RS485 MODE 1 28 C2 VCC C1 VDD 2 27 3 26 25 RB1 24 RA1 DE1 Y1 DY1 Z1 SEL1 = 0V 6 23 7 22 8 21 LB ON SEL2 = 5V DY2 Z2 DZ2 Y2 9 20 10 19 11 17 RA2 16 RB2 VEE 18 GND 14 15 PORT 1 = RS485 MODE PORT 2 = RS485 MODE 1 28 C2 C1 VCC VDD 2 27 3 26 25 RB1 24 RA1 DZ1 Y1 DY1 Z1 SEL1 = 5V 6 23 7 22 8 21 LB ON SEL2 = 5V DY2 Z2 DE2 Y2 9 20 10 19 11 18 17 RA2 16 RB2 VEE GND 14 15 LTC1334 • BD02 8 C2 VCC RB1 RA1 DE1 DY1 LB ON DY2 DE2 RA2 RB2 VEE LTC1334 TEST CIRCUITS VCC Z VOD D R 3V 3V R SEL Z B Y CL A S1 SEL R RL DE VOC CL 500Ω DR OUT 15pF CL S2 3V Y LTC1334 • F03 LTC1334 • F02 LTC1334 • F01 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 0V 0V SEL D Y, Z SEL SEL Y, Z D A, B R RL CL VIN VOUT 15pF LTC1334 • F05 LTC1334 • F04 Figure 4. RS232 Driver Swing/Timing Test Circuit Figure 5. RS232 Receiver Timing Test Circuit U W SWITCHI G WAVEFOR S 3V 1.5V D f = 1MHz: tr ≤ 10ns: tf ≤ 10ns 1.5V 0V tPLH tPHL VO 90% Z–Y 50% 10% –VO VDIFF = V(Z) – V(Y) 90% 1/2 VO tr 50% 10% tf Y VO Z tSKEW tSKEW LTC1334 • F06 Figure 6. RS485 Driver Propagation Delays 9 LTC1334 U W SWITCHI G WAVEFOR S 3V 1.5V DE f = 1MHz: tr ≤ 10ns: tf ≤ 10ns 1.5V 0V tZL tLZ 5V Y, Z 2.3V OUTPUT NORMALLY LOW VOL tZH OUTPUT NORMALLY HIGH VOH 0.5V tHZ 0.5V 2.3V Z, Y 0V LTC1334 • F07 Figure 7. RS485 Driver Enable and Disable Times VOD2 0V B–A f = 1MHz: tr ≤ 10ns: tf ≤ 10ns INPUT 0V –VOD2 tPLH R tPHL OUTPUT VOH 1.5V 1.5V VOL LTC1334 • F08 Figure 8. RS485 Receiver Propagation Delays 3V 1.5V 1.5V D 0V tPHL tPLH VO Y, Z LTC1334 • F09 0V 0V –VO Figure 9. RS232 Driver Propagation Delays VIH 1.7V 1.3V A, B VIL tPHL tPLH VOH R VOL 2.4V 0.8V Figure 10. RS232 Receiver Propagation Delays 10 LTC1334 • F10 LTC1334 W U U UO 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 150°C. The thermal shutdown circuit reenables the drivers when the die temperature cools to 130°C. 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 4µA current source to VCC pulls the ON/OFF pin high if it is left open. In RS485 mode, an internal 4µA current source pulls the driver enable pin high if left open. The RS485 receiver has a 4µA 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 4µA 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. 1 C1 0.1µF 2 3 4 5 VDD 0.1µF 28 LTC1334 27 5V ≥ ±5V INTO 3kΩ LOAD RS232 DR OUT RS232 DR OUT RS232 RX IN RS232 RX IN C2 26 24 23 RS485 I/O 120Ω 0.1µF 6 7 22 8 21 9 20 11 19 10 18 13 17 12 16 14 15 RX OUT 0.1µF VCC 5V DR ENABLE DR IN 5V 5V DR IN DR IN RX OUT RX OUT VEE 0.1µF LTC1334 • F11 Figure 11. RS232/RS485 Interfaces 11 LTC1334 W U UO S I FOR ATIO 1 0.1µF C1 U APPLICATI VDD 0.1µF LTC1334 28 2 27 0.1µF 3 26 C2 VCC 5V 0.1µF 25 RX OUT 4 INPUT A K1A 120Ω PORT 1 INTERFACE 6 OUTPUT A 22 K1B 5V K1* TX2A-5V 24 5 INPUT B 8 120Ω 7 OUTPUT B 23 21 360k FMMT619** 20 RX OUT DR IN SEL1 Typical Applications DR IN/ENABLE LB A typical RS232/EIA562 interface application is shown in Figure 13 with the LTC1334. ON/OFF TERM1 7.5k 16 RX OUT 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. 13 INPUT A K2A 120Ω PORT 2 INTERFACE INPUT B 19 K2B 9 120Ω OUTPUT B RX OUT 11 OUTPUT A 5V K2* TX2A-5V 17 12 10 18 14 15 DR IN SEL2 1/2 LTC1334 DR IN/ENABLE 360k 0.1µF 7.5k TERM2 *AROMAT CORP (800) 276-6289 **ZETEX (516) 543-7100 FMMT619** Each receiver in the LTC1334 is designed to present one unit load (5kΩ nominal for RS232 and 12kΩ 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 120Ω 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. VEE DR IN DR IN LTC1334 • F12 RX OUT RX OUT 1/2 LTC1334 19 11 RS232/ 4 24 18 10 EIA562 5 25 17 13 INTERFACE 6 22 16 12 7 23 LINES 9 RX OUT RX OUT DR IN DR IN 8 LTC1334 • F13 Figure 12. Multiprotocol Interface with Optional, Switchable Terminations Figure 13. Typical Connection for RS232/EIA562 Interface 1/2 LTC1334 13 17 12 1/2 LTC1334 RX OUT DR ENABLE DR IN 5V 24 4 5 23 22 120Ω 120Ω 6 7 8 7 6 5 4 18 11 10 19 9 RX OUT DR ENABLE DR IN 5V 1/2 LTC1334 22 23 24 8 DR IN RX OUT DR ENABLE 5V LTC1334 F14 Figure 14. Typical Connection for RS485 Interface 12 LTC1334 W U U UO APPLICATI S I FOR ATIO port is configured as an RS232 transceiver and the other as an RS485 transceiver. A typical RS422 connection (Figure 15) allows one driver and ten receivers on a twisted pair of wires terminated with a 100Ω resistor at one end. Using two LTC1334s as level translators, the RS232/ EIA562 interface distance can be extended to 4000 feet with twisted-pair wires (Figure 18). 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. AppleTalk®/LocalTalk® Applications Two AppleTalk applications are shown in Figure 19 and 20 with the LTC1323 and the LTC1334. The LTC1334 can be used to translate RS232 to RS422 interface levels or vice versa as shown in Figure 17. One AppleTalk and LocalTalk are registered trademarks of Apple Computer, Inc. 1/2 LTC1334 RX OUT 24 8 DR ENABLE DR IN 22 5V 1/2 LTC1334 5 4 13 17 100Ω 7 12 4 11 RX OUT 5V 8 8 5V RX OUT 1/2 LTC1334 23 6 18 24 100Ω 5 DR ENABLE 19 DR IN 10 LTC1334 • F15 Figure 15. Typical Connection for RS422 Interface 5V 17 22 5V 23 8 6 13 RX IN TX OUT 7 24 22 4 RX IN RS232/EIA562 23 8 TX OUT 100Ω RS422 LTC1334 6 4 11 TX OUT 100Ω 7 5 RX IN 5 1/2 LTC1334 9 LTC1334 • F16 Figure 16. Typical Cable Repeater for RS422 Interface LTC1334 • F17 19 24 Figure 17. Typical RS232/EIA562 to RS422 Level Translator 5V 17 22 RX IN 4 6 13 11 100Ω 7 RS232/EIA562 DR OUT 24 19 RS422 23 8 LTC1334 RS232/EIA562 LTC1334 6 4 11 13 100Ω 5 9 19 24 DR OUT 5 RX IN 7 8 23 22 17 9 LTC1334 • F18 5V Figure 18. Typical Cable Extension for RS232/EIA562 Interface 13 LTC1334 W U U UO APPLICATI S I FOR ATIO 1 LTC1323CS-16 1 0.33µF 2 TXD TXDEN SHDN RXEN RXDO 16 CHARGE PUMP 0.1µF 5V 15 3 14 4 13 0.1µF 0.33µF 1µF EMI 1k EMI 6 11 TXD + 7 10 RXD – 8 9 120Ω 120Ω 1k SEL1, 5V EMI SEL2, 5V 5Ω TO 22Ω FERRITE BEAD 5Ω TO 22Ω EMI = OR 100pF FERRITE BEAD OR 100pF 4 25 24 23 100pF NC 22 7 EMI EMI 26 1k EMI RXD + 3 6 EMI 1k 28 8 21 9 20 10 19 11 NC 12 NC 18 13 16 14 15 NC 0.1µF 27 LTC1334 5 EMI 12 TXD – 5 2 17 5V NC RA1 DE1 DY1 5V 5V NC NC NC NC 0.1µF LTC1334 • F19 Figure 19. AppleTalk/LocalTalk Implemented Using the LTC1323CS-16 and LTC1334 Transceivers 5Ω TO 22Ω EMI = LTC1323CS 24 1 0.33µF 2 CPEN TXD TXI TXDEN SHDN RXEN RXO RXO RXDO CHARGE PUMP 21 5 20 TXD – 100pF 0.1µF 19 TXD + 7 18 TXO 2 0.33µF 1µF 28 3 26 EMI EMI 4 25 120Ω 24 120Ω EMI EMI 16 RXI 10 15 RXD– 14 RXD+ 13 5V EMI EMI EMI EMI EMI SEL1 5V SEL2 EMI 120Ω EMI EMI EMI NC EMI NC RA1 5 23 6 120Ω 17 RXI 0.1µF 27 LTC1334 0.1µF 6 12 OR 100pF 1 23 4 11 FERRITE BEAD 5V 22 9 OR 100pF 3 8 FERRITE BEAD 5Ω TO 22Ω 22 7 8 21 9 20 10 19 11 18 12 17 13 16 14 15 DE1 DY1 5V 5V DY2 DZ2 RA2 NC 0.1µF LTC1334 • F20 Figure 20. AppleTalk Direct Connect Using the LTC1323 DTE and the LTC1334 for DCE Transceivers 14 LTC1334 U PACKAGE DESCRIPTION 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 5.20 – 5.38** (0.205 – 0.212) 1.73 – 1.99 (0.068 – 0.078) 0° – 8° 0.13 – 0.22 (0.005 – 0.009) 0.65 (0.0256) BSC 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 0.05 – 0.21 (0.002 – 0.008) 0.25 – 0.38 (0.010 – 0.015) 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 2 3 4 5 6 7 8 9 10 11 12 13 14 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 15.87 +0.889 –0.381 ) 0.150 ± 0.005 (3.810 ± 0.127) 0.045 – 0.065 (1.143 – 1.651) 0.015 (0.381) MIN 0.070 (1.778) TYP 0.125 (3.175) MIN *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm) 0.035 – 0.080 (0.889 – 2.032) 0.018 ± 0.003 (0.457 ± 0.076) 0.100 (2.54) BSC 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. N28 1098 15 LTC1334 U PACKAGE DESCRIPTION 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 0.394 – 0.419 (10.007 – 10.643) NOTE 1 0.291 – 0.299** (7.391 – 7.595) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 0.037 – 0.045 (0.940 – 1.143) 0.093 – 0.104 (2.362 – 2.642) 0.010 – 0.029 × 45° (0.254 – 0.737) 0° – 8° TYP 0.009 – 0.013 (0.229 – 0.330) 0.050 (1.270) BSC NOTE 1 0.016 – 0.050 (0.406 – 1.270) 0.004 – 0.012 (0.102 – 0.305) 0.014 – 0.019 (0.356 – 0.482) TYP 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 S28 (WIDE) 1098 *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 DESCRIPTION COMMENTS LTC485 Low Power RS485 Interface Transceiver Single 5V Supply, Wide Common Mode Range LT ® 1137A Low Power RS232 Transceiver ±15kV IEC-1000-4-2 ESD Protection, Three Drivers, Five Receivers LTC1320 AppleTalk Transceiver AppleTalk/Local Talk Compliant LTC1321/LTC1322/LTC1335 RS232/EIA562/RS485 Transceivers Configurable, 10kV ESD Protection LTC1323 Single 5V AppleTalk Transceiver LocalTalk/AppleTalk Compliant 10kV ESD LTC1347 5V Low Power RS232 Transceiver Three Drivers/Five Receivers, Five Receivers Alive in Shutdown LTC1387 Single 5V RS232/RS485 Transceiver Single Port, Configurable, 10kV ESD 16 Linear Technology Corporation 1334fa LT/TP 1099 2K REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com LINEAR TECHNOLOGY CORPORATION 1995