LTC1348 3.3V/5V Low Power RS232 3-Driver/5-Receiver Transceiver U DESCRIPTIO FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Low Supply Current: 600µA at 3.3V Supply Current in Shutdown: 0.2µA Supply Current in Receiver Alive Mode: 15µA ESD Protection over ±10kV Operates from a Single 3V to 5.5V Supply Operates to 120kBaud with 0.1µF Flying Capacitors Three-State Outputs Are High Impedance When Off Output Overvoltage Does Not Force Current Back into Supplies RS232 I/O Lines Can Be Forced to ±25V Without Damage Flowthrough Architecture UO APPLICATI ■ ■ ■ ■ S Notebook Computers Palmtop Computers Printers Portable Instruments The LTC®1348 is a 3-driver/5-receiver RS232 transceiver with very low supply current. The charge pump only requires five 0.1µF capacitors. The LTC1348 provides full RS232 output levels when operated over a wide supply range of 3V to 5.5V The transceiver operates in one of four modes: Normal, Receiver Disable, Receiver Alive and Shutdown. In Normal or Receiver Disable mode, ICC is only 600µA at 3.3V and 800µA at 5V in the no load condition. In Shutdown mode, the supply current is further reduced to 0.2µA. In Receiver Alive mode, all five receivers are kept alive and the supply current is 15µA. All RS232 outputs assume a high impedance state in Shutdown or Receiver Alive mode or with the power off. The receiver outputs assume a high impedance state in Receiver Disable or with the power off. The LTC1348 is fully compliant with all data rate and overvoltage RS232 specifications. The transceiver operates up to 120kbaud with all drivers loaded with 1000pF, 3kΩ. Both driver outputs and receiver inputs can be forced to ±25V without damage and can survive multiple ±10kV ESD strikes. , LTC and LT are registered trademarks of Linear Technology Corporation. UO TYPICAL APPLICATI Supply Current 3-Drivers/5-Receivers with Shutdown 2 VCC C1 0.1µF DR 1 OUT RX1 IN DR 2 OUT RX2 IN RX3 IN RX4 IN DR 3 OUT RX5 IN LTC1348 V– 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 C3 0.1µF DR 1 IN RX1 OUT DR 2 IN RX2 OUT RX3 OUT C4 0.1µF 1.6 1.6 1.4 1.4 1.2 1.0 RX5 OUT DREN 0.8 RXEN 0.8 VCC = 3.3V 0.6 0.4 VCC = 3.3V OR 5V 0.2 0 –40 1.0 VCC = 5V RX4 OUT DR 3 IN 1.2 QUIESCENT CURRENT 0.6 SHUTDOWN CURRENT 0.4 SHUTDOWN CURRENT (µA) C2 0.1µF 28 1 SUPPLY CURRENT (mA) V+ C5 0.1µF 0.2 0 –20 0 40 20 TEMPERATURE (˚C) 60 80 LT1348 •TA02 GND LT1348 • TA01 1 LTC1348 U U RATI GS W W W W AXI U U ABSOLUTE PACKAGE/ORDER I FOR ATIO (Note 1) Supply Voltage (VCC) ................................................ 6V Input Voltage Driver ....................................... – 0.3V to V CC + 0.3V Receiver ............................................... – 25V to 25V Driver/Receiver Enable Pin ........ – 0.3V to VCC + 0.3V Output Voltage Driver ................................................... – 25V to 25V Receiver .................................... – 0.3V to VCC + 0.3V Short-Circuit Duration V + ................................................................... 30 sec V – ................................................................... 30 sec Driver Output .............................................. Indefinite Receiver Output .......................................... Indefinite Operating Temperature Range LTC1348C................................................ 0°C to 70°C LTC1348I............................................ – 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 V+ 1 28 V– C2 + 2 27 C3+ C2 – 26 C3 – 3 VCC 4 25 DR1 IN C1 + 5 24 RX1 OUT C1 – 6 23 DR2 IN DR1 OUT 7 22 RX2 OUT RX1 IN 8 21 RX3 OUT DR2 OUT 9 20 RX4 OUT RX2 IN 10 19 DR3 IN RX3 IN 11 18 RX5 OUT RX4 IN 12 17 DREN DR3 OUT 13 16 RXEN RX5 IN 14 LTC1348CG LTC1348CSW LTC1348IG LTC1348ISW 15 GND G PACKAGE 28-LEAD PLASTIC SSOP SW PACKAGE 28-LEAD PLASTIC SO TJMAX = 125°C, θJA = 96°C/W (G) TJMAX = 125°C, θJA = 85°C/W (SW) Consult factory for Military grade parts. DC ELECTRICAL CHARACTERISTICS VCC = 3V to 5.5V, C1 to C4 = 0.1µF, unless otherwise noted. PARAMETER CONDITIONS Any Driver Output Voltage Swing VCC = 3.3V, 3k to GND Logic Input Voltage Level Logic Input Current Output Short-Circuit Current Output Leakage Current Any Receiver Input Voltage Thresholds Hysteresis Input Resistance Output Voltage Output Short-Circuit Current Output Leakage Current 2 Positive Negative Input Low Level (VOUT = High) Input High Level (VOUT = Low), VCC = 3.3V Input High Level (VOUT = Low), VCC = 5V VIN = VCC VIN = 0V VOUT = 0V Shutdown (Note 3) or Receiver Alive Mode (Note 4), VOUT = ±20V Input Threshold (Receiver Alive Mode) Input Low Threshold (Normal Mode) Input High Threshold (Normal Mode) Normal Mode VIN = ±10V Output Low, IOUT = – 1.6mA Output High, IOUT = 160µA Sinking Current, VOUT = VCC Shutdown (Note 3), 0V ≤ VOUT ≤ VCC MIN TYP ● ● 5.0 – 5.0 6.2 – 6.0 ● ● ● 2.0 2.4 0.8 ● ● –5 ±12 ±10 ● 0.8 0.8 3 ● ● ● MAX VCC – 0.6V –3 1.5 1.3 1.7 0.3 5 0.2 – 20 1 5 – 35 ±500 2.4 2.4 7 0.4 10 UNITS V V V V V µA µA mA µA V V V V kΩ V V mA µA LTC1348 DC ELECTRICAL CHARACTERISTICS VCC = 3V to 5.5V, C1 to C4 = 0.1µF, unless otherwise noted. PARAMETER Power Supply Generator V + Output Voltage V – Output Voltage Supply Rise Time Power Supply VCC Supply Current Supply Leakage Current (VCC) Driver/Receiver Enable Threshold Low Driver/Receiver Enable Threshold High Driver/Receiver Enable Threshold High CONDITIONS MIN IOUT = 0mA IOUT = 8mA IOUT = 0mA IOUT = – 8mA Shutdown to Turn-On TYP MAX 8.0 7.5 – 8.0 – 7.0 0.2 No Load (Note 2) VCC = 3.3V No Load (Note 2) VCC = 5V Receiver Alive Mode (Note 4) VCC = 3.3V or 5V Shutdown (Note 3) ● ● ● ● ● ● V V V V ms 0.6 0.8 15 0.2 2.0 2.5 30 10 0.8 TYP 250 8 MAX 2.5 2.5 0.3 0.2 1.0 0.2 4 4 1 1 4 4 ● VCC = 3.3V VCC = 5V UNITS 2.0 2.4 mA mA µA µA V V V AC ELECTRICAL CHARACTERISTICS VCC = 3V to 5.5V, C1 to C4 = 0.1µF, unless otherwise noted. PARAMETER Maximum Data Rate Slew Rate Driver Propagation Delay (TTL to RS232) Receiver Propagation Delay (RS232 to TTL) CONDITIONS RL = 3k, CL = 1000pF, One Driver Switching VCC = 5V, RL = 3k, CL = 51pF VCC = 3.3V, RL = 3k, CL = 2500pF t HLD (Figure 1) t LHD (Figure 1) t HLR (Figure 2) (Normal Mode) t LHR (Figure 2) (Normal Mode) tHLR (Figure 2) (Receiver Alive Mode) tLHR (Figure 2) (Receiver Alive Mode) The ● denotes specifications which apply over the full operating temperature range (0°C ≤ TA ≤ 70°C for Commercial grade and – 40°C ≤ TA ≤ 85°C for Industrial grade). Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: Supply current is measured with driver and receiver outputs unloaded. The VDREN and VRXEN = VCC. MIN 120 30 3 ● ● ● ● ● ● UNITS kbps V/µs V/µs µs µs µs µs µs µs Note 3: Supply current measurement in Shutdown is performed with VDREN and VRXEN = 0V. Note 4: Supply current measurement in Receiver Alive mode is performed with VDREN = 0V and VRXEN = VCC. 3 LTC1348 U W TYPICAL PERFORMANCE CHARACTERISTICS 120kbps 250kbps 64kbps OUTPUT HIGH 20kbps VCC = 3.3V 0.1µF FLYING CAPACITORS ALL DRIVERS LOADED 3kΩ + CL 1 DRIVER DRIVEN OUTPUT LOW 64kbps 20kbps 120kbps 250kbps 0 3000 4000 1000 2000 LOAD CAPACITANCE (pF) 50 7 6 5 4 3 2 1 0 –1 –2 –3 –4 –5 –6 –7 120kbps VCC = 3.3V 0.1µF FLYING CAPACITORS ALL DRIVERS DRIVEN AND LOADED 3kΩ + CL OUTPUT LOW 3000 4000 1000 2000 LOAD CAPACITANCE (pF) 10 VCC = 3V 40 50 20 30 TEMPERATURE (°C) 60 45 VCC = 3.3V 16 ISC– 14 ISC+ 12 10 8 6 250 VCC = 3.3V 35 30 25 20 VOUT = –20V 15 10 VOUT = 20V 5 4 70 150 200 100 DRIVER DATA RATE 40 LEAKAGE CURRENT (µA) OUTPUT LOW 50 0 Driver Leakage in SHUTDOWN vs Temperature (°C) 18 SHORT-CIRCUIT CURRENT (mA) DRIVER OUTPUT VOLTAGE HIGH/LOW VCC = 3V ALL DRIVERS LOADED WITH 3kΩ 0 5000 VCC = 3.3V LTC1348 G03 20 VCC = 3.3V 0 Driver Short-Circuit Current vs Temperature (°C) OUTPUT HIGH 1 OUTPUT LOADED 3kΩ // 2500pF 20 LTC1348 G02 Driver Output Voltage High/Low vs Temperature (°C) VCC = 3.3V 30 10 64kbps LTC1348 G01 7 6 5 4 3 2 1 0 –1 –2 –3 –4 –5 –6 –7 40 20kbps 0 5000 20kbps OUTPUT HIGH 120kbps 3 OUTPUT LOADED 3kΩ // 2500pF 64kbps SUPPLY CURRENT (mA) 7 6 5 4 3 2 1 0 –1 –2 –3 –4 –5 –6 –7 Supply Current vs Driver Data Rate Driver Output Voltage High/Low vs Load Capacitance (CL) DRIVER OUTPUT VOLTAGE HIGH/LOW DRIVER OUTPUT VOLTAGE HIGH/LOW Driver Output Voltage High/Low vs Load Capacitance (CL) 0 –40 0 –20 0 20 40 60 TEMPERATURE (°C) 80 100 0 10 20 30 40 50 TEMPERATURE (°C) 60 70 LTC1348 G04 LTC1348 G05 With VCC = 3.3V All Driver Outputs Loaded with 3kΩ, 1000pF. 1 Driven at 250kbps DRIVEN DRIVER OUTPUT DRIVER INPUT LTC1348 G07 4 LTC1348 G06 LTC1348 U U U PI FU CTIO S VCC: 3V to 5.5V Input Supply Pin. This pin should be decoupled with a 0.1µF ceramic capacitor. efficiency, the capacitor’s effective series resistance should be less than 1Ω. Ceramic capacitors are recommended. GND: Ground Pin. DR IN: RS232 Driver Input Pins. Inputs are TTL/CMOS compatible. The inputs of unused drivers can be left unconnected since 300k input pull-up resistors to VCC are included on chip. To minimize power consumption, the internal driver pull-up resistors are disconnected from VCC in the Shutdown or Receiver Alive mode. RXEN: TTL/CMOS Compatible Enable Pin. Refer to Table 1 for its functional description. DREN: TTL/CMOS Compatible Enable Pin. Refer to Table 1 for its functional description. V+: Positive Supply Output (RS232 Drivers). This pin requires an external capacitor C = 0.1µF for charge storage. The capacitor may be tied to ground or VCC. With multiple devices, the V + and V – pins may be paralleled into common capacitors. For large numbers of devices, increasing the size of the shared common storage capacitors is recommended to reduce ripple. DR OUT: Driver Outputs at RS232 Voltage Levels. Outputs are in a high impedance state when in the Shutdown, Receiver Alive mode or VCC = 0V. The driver outputs are protected against ESD to ±10kV for human body model discharges. V –: Negative Supply Output (RS232 Drivers). This pin requires an external capacitor C = 0.1µF for charge storage. RX IN: Receiver Inputs. These pins can be forced to ±25V without damage. The receiver inputs are protected against ESD to ±10kV for human body model discharges. Each receiver provides 0.4V of hysteresis for noise immunity. In Receiver Alive mode all receivers have no hysteresis. C1+, C1–, C2+, C2–, C3+, C3–: Commutating Capacitor Inputs. These pins require three external capacitors C = 0.1µF: one from C1+ to C1–, another from C2+ to C2– and another from C3+ to C3–. To maintain charge pump RX OUT: Receiver Outputs with TTL/CMOS Voltage Levels. Outputs are in a high impedance state when in the Shutdown or Receiver Disable mode to allow data line sharing. Table 1. Functional Description MODE RX ENABLE DR ENABLE DRIVERS RECEIVERS Shutdown 0 0 All Drivers Shutdown. All Driver Outputs Assume High Impedance. All Driver Pull-Up Resistors Disconnect From VCC. All Receivers Shutdown. All Receiver Outputs Assume High Impedance. ICC TYP Receiver Disable 0 1 All Drivers Alive. All Receiver Outputs in Three-State. Receiver Alive 1 0 All Drivers Shutdown. All Driver Outputs in Three-State. All Driver Pull-Up Resistors Disconnect From VCC. All Receivers Alive. 15µA Normal 1 1 All Drivers Alive. All Receivers Alive. 600µA at 3.3V, 800µA at 5V 0.2µA 600µA at 3.3V, 800µA at 5V 5 LTC1348 U W W SWITCHI G TI E WAVEFOR S DRIVER INPUT VCC 1.4V 1.4V 0V V+ DRIVER OUTPUT 0V 0V t LHD V– VCC 1.7V RX INPUT RX OUTPUT 1.3V 2.4V 0.8V t LHR t HLD 0V t HLR LTC1348 • F01 VCC 0V LTC1348 • F02 Figure 1. Driver Propagation Delay Timing Figure 2. Receiver Propagation Delay Timing TEST CIRCUITS ESD Test Circuit DRIVER OUTPUT DRIVER INPUT DRIVER V+ 51pF 3k 0.1µF 0.1µF VCC LTC1348 • F03 28 LTC1348 3 26 RX OUTPUT RS232 LINE PINS PROTECTED TO ±10kV RX 51pF LTC1348 • F04 0.1µF 0.1µF – 25 C3 DR1 IN 24 RX1 OUT 23 DR2 IN 22 RX2 OUT 21 RX3 OUT 20 RX4 OUT 19 DR3 IN 18 RX5 OUT 17 DREN 16 RXEN 15 GND C2 – 4 6 C1– 7 DR1 OUT 8 RX1 IN 9 DR2 OUT 10 RX2 IN 11 RX3 IN 12 RX4 IN 13 DR3 OUT 14 RX5 IN 0.1µF Figure 3. Driver Timing Test Load V– 27 C3+ C1+ 5 0.1µF RX INPUT 1 C2+ 2 LT1348 • TC Figure 4. Receiver Timing Test Load U W U U APPLICATIONS INFORMATION Power Supply The LTC1348 includes an onboard voltage-tripling charge pump capable of generating ±8V from a single 3.3V supply. This allows the LTC1348 drivers to provide guaranteed ±5V RS232-compliant voltage levels with a 3.3V supply. With all outputs loaded with 3kΩ, the LTC1348 can typically swing ±5V with voltages as low as 2.85V. It will meet the ±3.7V EIA562 levels with supply voltages as 6 low as 2.2V. The charge pump requires three external flying capacitors to operate; 0.1µF ceramic capacitors are adequate for most applications. For applications requiring extremely high data rates or abnormally heavy output loads, 0.33µF flying capacitors are recommended. Bypass and output capacitor values should match those of the flying capacitors and all capacitors should be mounted as close to the package as possible. LTC1348 U U W U APPLICATIONS INFORMATION High Data Rates The LTC1348 maintains true RS232 ±5V minimum driver output even at high data rates. Figure 5 shows a test circuit with 2m wires connecting the two test chips. Both chips are run from 3.3V supplies. Figure 6 shows the typical line waveforms with all three drivers, loaded with 1000pF and 3kΩ, toggling simultaneously at 120kbaud. Figure 7 shows V+ 1 + C2 2 0.1µF 3 0.1µF 25 24 6 23 7 22 8 21 9 20 10 19 11 18 12 RX4 IN DR3 OUT 13 17 14 15 1 28 DR1 OUT C1– RX1 IN DR2 OUT RX2 IN RX3 IN 1000pF 27 C3+ RX5 IN 0.1µF 0.1µF 26 C2– 4 VCC C1+ 5 0.1µF V– 28 LTC1348 16 the same circuit with a single 1000pF/3kΩ loaded driver driven at 250kbaud, and the other two drivers loaded but not toggling. This closely approximates the actual behavior of an RS232 serial port, with only one driver (TX) driven at high speed and the other two drivers (RTS and DTR) driven at a relatively low data rate or at DC. Under the same conditions, the LTC1348 can go as fast as 350kbaud and still meet EIA562 (±3.7V) minimum driver output levels. C3– DR1 IN RX1 OUT DR2 IN DRIVER OUTPUT RX2 OUT RX3 OUT RX4 OUT RECEIVER OUTPUT DR3 IN RX5 OUT DREN DRIVER INPUT RXEN GND LTC1348 G06 V+ C2+ 2 0.1µF 0.1µF 3 C2– 4 VCC C1+ 5 6 0.1µF LTC1348 27 C3+ 0.1µF 25 C3– DRIVER 1 IN 24 23 1000pF 22 21 9 DR2 OUT RX2 IN 10 20 11 18 12 17 13 16 14 15 RX3 IN RX4 IN DR3 OUT RX5 IN 19 Figure 6. Driver Test Result at 120kbps 0.1µF 26 – C1 7 DR1 OUT RX1 IN 8 V– RX1 OUT DRIVER 2 IN RX2 OUT RX3 OUT RX4 OUT DRIVER 3 IN DRIVER OUTPUT RX5 OUT DREN RXEN RECEIVER OUTPUT GND 1000pF LT1348 • F05 DRIVER INPUT Figure 5. Data Rate Evaluation Circuit LTC1348 G07 Figure 7. Driver Test Results at 250kbps 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. 7 LTC1348 U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. G Package 28-Lead Plastic SSOP (0.209) (LTC DWG # 05-08-1640) 0.205 – 0.212** (5.20 – 5.38) 0.397 – 0.407* (10.07 – 10.33) 28 27 26 25 24 23 22 21 20 19 18 17 16 15 0.068 – 0.078 (1.73 – 1.99) 0° – 8° 0.005 – 0.009 (0.13 – 0.22) 0.0256 (0.65) BSC 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 0.301 – 0.311 (7.65 – 7.90) 0.010 – 0.015 (0.25 – 0.38) 0.002 – 0.008 (0.05 – 0.21) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 G28 SSOP 0694 SW Package 28-Lead Plastic Small Outline (Wide 0.300) (LTC DWG # 05-08-1620) 0.697 – 0.712* (17.70 – 18.08) 0.291 – 0.299** (7.391 – 7.595) 0.010 – 0.029 × 45° (0.254 – 0.737) 0.093 – 0.104 (2.362 – 2.642) 0.037 – 0.045 (0.940 – 1.143) 28 27 26 25 24 23 22 21 20 19 18 17 16 15 0° – 8° TYP 0.009 – 0.013 (0.229 – 0.330) 0.050 (1.270) TYP NOTE 1 0.014 – 0.019 0.016 – 0.050 (0.356 – 0.482) (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 0.394 – 0.419 (10.007 – 10.643) NOTE 1 0.004 – 0.012 (0.102 – 0.305) *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 1 2 3 4 5 6 7 8 9 10 11 12 13 14 S28 (WIDE) 0396 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1137A 3-DR/5-RX RS232 Transceiver ±15kV IEC-801-2 ESD Protection LTC1327 3-DR/5-RX RS562 Transceiver 3.3V Operation LT1330 3-DR/5-RX RS232 3V Logic Interface LT1331 3-DR/5-RX RS232/RS562 Transceiver 5V RS232 or 3V RS562 Operation LTC1347 3-DR/5-RX Micropower RS232 Transceiver 5 Receivers Active in Shutdown 8 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 ● (408) 432-1900 FAX: (408) 434-0507● TELEX: 499-3977 ● www.linear-tech.com 1348fa LT/GP 0197 5K REV A • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 1994