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| LT1280A/LT1281A Low Power 5V RS232 Dual Driver/Receiver with 0.1F Capacitors DESCRIPTIO The LT (R)1280A/LT1281A are dual RS232 driver/receiver pairs with integral charge pump to generate RS232 voltage levels from a single 5V supply. These circuits feature rugged bipolar design to provide operating fault tolerance and ESD protection unmatched by competing CMOS designs. Using only 0.1F external capacitors, these circuits consume only 40mW of power, and can operate to 120kbaud even while driving heavy capacitive loads. New ESD structures on the chip allow the LT1280A/LT1281A to survive multiple 10kV strikes, eliminating the need for costly TransZorbs(R) on the RS232 line pins. The LT1280A/ LT1281A are fully compliant with EIA RS232 standards. Driver outputs are protected from overload, and can be shorted to ground or up to 30V without damage. During shutdown or power-off conditions, driver and receiver outputs are in a high impedance state, allowing line sharing. The LT1281A is available in 16-pin DIP and SO packages. The LT1280A is supplied in 18-pin DIP and SO packages for applications which require shutdown. , LTC and LT are registered trademarks of Linear Technology Corporation. TransZorb is a registered trademark of General Instruments, GSI FEATURES s s s s s s s s s s s s s s 10mA Max Supply Current ESD Protection over 10kV Uses Small Capacitors: 0.1F 120kBaud Operation for RL = 3k, CL = 2500pF 250kBaud Operation for RL = 3k, CL = 1000pF Outputs Withstand 30V Without Damage CMOS Comparable Low Power: 40mW Operates from a Single 5V Supply Rugged Bipolar Design Outputs Assume a High Impedance State When Off or Powered Down Meets All RS232 Specifications Available With or Without Shutdown Absolutely No Latch-up Available in SO Package APPLICATI s s s s s S Portable Computers Battery-Powered Systems Power Supply Generator Terminals Modems TYPICAL APPLICATI + 0.1F 2 4 LT1280A 17 3 5V INPUT + 0.1F 7 0.1F 15 V+ OUT DRIVER OUTPUT RL = 3k CL = 2500pF + 0.1F 5 6 12 V - OUT RS232 OUTPUT LOGIC INPUTS 11 13 8 14 5k RS232 OUTPUT RS232 INPUT RECEIVER OUTPUT R CL = 50pF LOGIC OUTPUTS 10 18 INPUT 9 5k 16 RS232 INPUT LT1280A * TA02 ON/OFF LT1280A * TA01 U UO + UO Output Waveforms 1 LT1280A/LT1281A ABSOLUTE AXI U RATI GS Supply Voltage (VCC) ................................................ 6V V + ........................................................................ 13.2V V - ...................................................................... -13.2V Input Voltage Driver ........................................................... V - to V + Receiver ............................................... - 30V to 30V ON/OFF ................................................. - 0.3V to 12V Output Voltage Driver ...................................... V+ - 30V to V - + 30V Receiver .................................... - 0.3V to VCC + 0.3V PACKAGE/ORDER I FOR ATIO TOP VIEW NC C1+ V+ C1 - C2+ C2 - V- TR2 OUT REC2 IN 1 2 3 4 5 6 7 8 9 18 ON/OFF 17 VCC 16 GND 15 TR1 OUT 14 REC1 IN 13 REC1 OUT 12 TR1 IN 11 TR2 IN 10 REC2 OUT ORDER PART NUMBER LT1280ACN LT1280AIN LT1280ACSW LT1280AISW N PACKAGE 18-LEAD PDIP SW PACKAGE 18-LEAD PLASTIC SO WIDE TJMAX = 125C, JA = 80C/ W, JC = 36C/W (N) TJMAX = 125C, JA = 90C/ W, JC = 26C/W (SW) Consult factory for Military grade parts. ELECTRICAL CHARACTERISTICS PARAMETER Power Supply Generator V + Output V - Output Supply Current (VCC) Supply Current When OFF (VCC) Supply Rise Time Shutdown to Turn-On ON/OFF Pin Thresholds ON/OFF Pin Current Oscillator Frequency Driver Output Voltage Swing Logic Input Voltage Level CONDITIONS (Note 2) MIN TYP 7.9 - 7.0 8 q q (Note 3), TA = 25C Shutdown (Note 4) LT1280A Only C1 = C2 = C3 = C4 = 0.1F LT1280A Only Input Low Level (Device Shutdown) Input High Level (Device Enabled) 0V VON/OFF 5V Load = 3k to GND Input Low Level (VOUT = High) Input High Level (VOUT = Low) 2 U U W WW U W (Note 1) Short-Circuit Duration V + ................................................................... 30 sec V - ................................................................... 30 sec Driver Output .............................................. Indefinite Receiver Output .......................................... Indefinite Operating Temperature Range LT1280AC/LT1281AC ............................. 0C to 70C LT1280AI/LT1281AI .......................... - 40C to 85C Storage Temperature Range ................ - 65C to 150C Lead Temperature (Soldering, 10 sec)................. 300C TOP VIEW C1+ 1 16 VCC 15 GND 14 TR1 OUT 13 REC1 IN 12 REC1 OUT 11 TR1 IN 10 TR2 IN 9 REC2 OUT ORDER PART NUMBER LT1281ACN LT1281AIN LT1281ACSW LT1281AISW V+ 2 C1 - 3 C2+ 4 C2 - 5 V- 6 TR2 OUT 7 REC2 IN 8 N PACKAGE 16-LEAD PDIP SW PACKAGE 16-LEAD PLASTIC SO WIDE TJMAX = 125C, JA = 90C/ W, JC = 46C/W (N) TJMAX = 125C, JA = 95C/ W, JC = 27C/W (SW) MAX UNITS V V mA mA A ms ms V V A kHz V V V V q q q 0.8 - 15 1 0.2 0.2 1.2 1.6 130 10 14 10 2.4 80 Positive Negative q q q q 5.0 7.5 - 6.3 1.4 1.4 - 5.0 0.8 2.0 LT1280A/LT1281A ELECTRICAL CHARACTERISTICS PARAMETER Logic Input Current Output Short-Circuit Current Output Leakage Current Data Rate (Note 7) Slew Rate Propagation Delay Receiver Input Voltage Thresholds CONDITIONS 0.8V VIN 2.0V VOUT = 0V (Note 2) MIN q TYP 5 17 10 MAX 20 100 UNITS A mA A kBaud kBaud 9 q Shutdown VOUT = 30V (Note 4) RL = 3k, CL = 2500pF RL = 3k, CL = 1000pF RL = 3k, CL = 51pF RL = 3k, CL = 2500pF Output Transition tHL High-to-Low (Note 5) Output Transition tLH Low-to-High Input Low Threshold (VOUT = High) Input High Threshold (VOUT = Low) Input Low Input High V IN = 10V Shutdown (Note 4) 0 VOUT VCC Output Low, IOUT = - 1.6mA Output High, IOUT = 160A (VCC = 5V) Sinking Current, VOUT = VCC Sourcing Current, VOUT = 0V Output Transition tHL High-to-Low (Note 6) Output Transition tLH Low-to-High C Grade C Grade I Grade I Grade 120 250 4 15 7 0.6 0.5 q q q q q q q q 30 1.3 1.3 V/s V/s s s V V V V V k A V V mA mA ns ns 0.8 0.2 0.1 3 1.3 1.7 1.3 1.7 0.4 5 1 0.2 4.2 - 20 20 250 350 2.4 3.0 1.0 7 10 0.4 - 10 600 600 Hysteresis Input Resistance Output Leakage Current Output Voltage Output Short-Circuit Current Propagation Delay 3.5 10 The q denotes specifications which apply over the operating temperature range (0C TA 70C for commercial grade, and - 40C TA 85C for industrial grade. Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: Testing done at VCC = 5V and VON/OFF = 3V, unless otherwise specified. Note 3: Supply current is measured as the average over several charge pump cycles. C + = C - = C1 = C2 = 0.1F. All outputs are open, with all driver inputs tied high. Note 4: Supply current measurements in shutdown are performed with VON/OFF 0.1V. Note 5: For driver delay measurements, RL = 3k and CL = 51pF. Trigger points are set between the driver's input logic threshold and the output transition to the zero crossing (t HL = 1.4V to 0V and tLH = 1.4V to 0V). Note 6: For receiver delay measurements, CL = 51pF. Trigger points are set between the receiver's input logic threshold and the output transition to standard TTL/CMOS logic threshold (t HL = 1.3V to 2.4V and tLH = 1.7V to 0.8V). Note 7: Data rate operation guaranteed by slew rate, short-circuit current and propagation delay tests. TYPICAL PERFOR A CE CHARACTERISTICS Driver Maximum Output Voltage vs Load Capacitance 8.0 7.5 PEAK OUTPUT VOLTAGE (V) DRIVER OUTPUT VOLTAGE (V) PEAK OUTPUT VOLTAGE (V) 7.0 20k BAUD 6.5 60k BAUD 6.0 5.5 5.0 0 1 2 345678 LOAD CAPACITANCE (nF) 9 10 120k BAUD UW LT1280A * TPC01 Driver Minimum Output Voltage vs Load Capacitance -4.0 -4.5 120k BAUD -5.0 60k BAUD -5.5 -6.0 -6.5 -7.0 0 1 2 345678 LOAD CAPACITANCE (nF) 9 10 20k BAUD 10 8 6 4 2 0 -2 -4 -6 -8 Driver Output Voltage RL = 3k VCC = 5.5V VCC = 5V VCC = 4.5V OUTPUT HIGH OUTPUT LOW VCC = 4.5V VCC = 5V VCC = 5.5V -10 -55 -25 50 25 0 75 TEMPERATURE (C) 100 125 LT1280A * TPC02 LT1280A * TPC03 3 LT1280A/LT1281A TYPICAL PERFOR A CE CHARACTERISTICS Receiver Input Thresholds 3.00 2.75 THRESHOLD VOLTAGE (V) 2.25 2.00 1.75 1.50 1.25 1.00 0.75 0.50 -55 -25 50 25 0 75 TEMPERATURE (C) 100 125 INPUT LOW INPUT HIGH THRESHOLD VOLTAGE (V) 2.50 SUPPLY CURRENT (mA) Supply Current 25 100 SHORT-CIRCUIT CURRENT (mA) 20 LEAKAGE CURRENT ( A) SUPPLY CURRENT (mA) 2 DRIVERS LOADED RL = 3k 15 1 DRIVER LOADED RL = 3k 10 NO LOAD 5 0 -55 -25 50 25 0 75 TEMPERATURE (C) Receiver Short-Circuit Current 50 16 14 SHORT-CIRCUIT CURRENT (mA) 40 SLEW RATE (V/s) 30 20 10 0 -55 -25 50 25 0 75 TEMPERATURE (C) 4 UW LT1280A * TPC04 Supply Current vs Data Rate 50 2 DRIVERS ACTIVE RL = 3k CL = 2500pF 3.0 2.5 2.0 1.5 1.0 ON/OFF Thresholds 40 30 ON THRESHOLD 20 OFF THRESHOLD 0.5 0 -55 -25 10 0 0 25 50 75 100 DATA RATE (kBAUD) 125 150 50 25 75 0 TEMPERATURE (C) 100 125 LT1280A * TPC05 LT1280A * TPC06 Driver Leakage in Shutdown 30 25 20 15 Driver Short-Circuit Current ISC+ 10 1 VOUT = 30V VOUT = -30V ISC- 10 5 0 -55 -25 100 125 0.1 -55 -25 50 25 0 75 TEMPERATURE (C) 100 125 50 25 75 0 TEMPERATURE (C) 100 125 LT1280A * TPC07 LT1280A * TPC08 LT1280A * TPC09 Slew Rate vs Load Capacitance RX ISC- RX ISC+ 12 10 8 +SLEW 6 -SLEW 4 2 100 125 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 LOAD CAPACITANCE (nF) LT1280A * TPC11 LT1280A * TPC10 LT1280A/LT1281A TYPICAL PERFOR A CE CHARACTERISTICS Shutdown to Driver Outputs 10V DRIVER 1 OUTPUT 5V GND GND DRIVER 2 OUTPUT - 5V - 10V ON/OFF PIN INPUT LT1280A * TPC12 LT1280A * TPC13 PI FU CTIO S VCC: 5V Input Supply Pin. This pin should be decoupled with a 0.1F ceramic capacitor close to the package pin. Insufficient supply bypassing can result in low output drive levels and erratic charge pump operation. GND: Ground Pin. ON/OFF: A TTL/CMOS Compatible Operating Mode Control. A logic low puts the LT1280A in shutdown mode. Supply current drops to zero and both driver and receiver outputs assume a high impedance state. A logic high fully enables the device. V +: Positive Supply Output (RS232 Drivers). V + 2VCC - 1.5V. This pin requires an external charge storage capacitor C 0.1F, tied to ground or VCC. Larger value capacitors may be used to reduce supply ripple. With multiple transceivers, the V+ and V - pins may be paralleled into common capacitors. V -: Negative Supply Output (RS232 Drivers). V - - (2VCC - 2.5V). This pin requires an external charge storage capacitor C 0.1F. Larger value capacitors may be used to reduce supply ripple. With multiple transceivers, the V+ and V - pins may be paralleled into common capacitors. TR1 IN, TR2 IN: RS232 Driver Input Pins. These inputs are TTL/CMOS compatible. Inputs should not be allowed to float. Tie unused inputs to VCC. TR1 OUT, TR2 OUT: Driver Outputs at RS232 Voltage Levels. Driver output swing meets RS232 levels for loads up to 3k. Slew rates are controlled for lightly loaded lines. Output current capability is sufficient for load conditions up to 2500pF. Outputs are in a high impedance state when in shutdown mode or VCC = 0V. Outputs are fully shortcircuit protected from V - + 30V to V + - 30V. Applying higher voltages will not damage the device if the overdrive is moderately current limited. Short circuits on one output can load the power supply generator and may disrupt the signal levels of the other outputs. The driver outputs are protected against ESD to 10kV for human body model discharges. REC1 IN, REC2 IN: Receiver Inputs. These pins accept RS232 level signals (30V) into a protected 5k terminating resistor. The receiver inputs are protected against ESD to 10kV for human body model discharges. Each receiver provides 0.4V of hysteresis for noise immunity. Open receiver inputs assume a logic low state. REC1 OUT, REC2 OUT: Receiver outputs with TTL/CMOS Voltage Levels. Outputs are in a high impedance state when in shutdown mode to allow data line sharing. Outputs are fully short-circuit protected to ground or VCC with the power ON, OFF or in the shutdown mode. C1 +, C1 -, C2 +, C2 -: Commutating Capacitor Inputs. These pins require two external capacitors C 0.1F: one from C1+ to C1- and another from C2+ to C2 -. C1 should be deleted if a separate 12V supply is available and connected to pin C1+. Similarly, C2 should be deleted if a separate - 12V supply is connected to pin V -. UW Driver Output Waveforms DRIVER OUTPUT RL = 3k CL = 2500pF DRIVER OUTPUT RL = 3k U U U 5 LT1280A/LT1281A ESD PROTECTIO The RS232 line inputs of the LT1280A/LT1281A have onchip protection from ESD transients up to 10kV. The protection structures act to divert the static discharge safely to system ground. In order for the ESD protection to function effectively, the power supply and ground pins of the circuit must be connected to ground through low impedances. The power supply decoupling capacitors and charge pump storage capacitors provide this low impedance in normal application of the circuit. The only constraint is that low ESR capacitors must be used for bypassing and charge storage. ESD testing must be done with pins VCC, VL, V +, V -, and GND shorted to ground or connected with low ESR capacitors. TYPICAL APPLICATI SHUTDOWN 5V 18 VCC ON/OFF LT1280A 17 18 VCC ON/OFF LT1039 17 TTL INPUT 11 TTL INPUT 12 TTL OUTPUT 13 5k 10 5k C1+ C1- C2 + C2 - GND 16 V+ V- TTL OUTPUT + 1F 2 4 + 1F 5 6 6 + UO U ESD Test Circuit 1 2 NC C1+ V+ C1- C2+ C2 - V- LT1280A ON/OFF 5V VCC GND 18 17 16 + 0.1F 0.1F + 3 4 + 0.1F DR1 OUT 15 RX1 IN 14 RX1 OUT 13 DR1 IN 12 DR2 IN 11 RX2 OUT 10 1280A ESD TC + 0.1F 0.1F 5 6 RS232 LINE PINS PROTECTED TO 10kV + 7 RS232 LINE PINS PROTECTED TO 10kV 8 DR2 OUT 9 RX2 IN Supporting an LT1039 (Triple Driver/Receiver) 8 RS232 OUTPUT RS232 OUTPUT TTL INPUT 15 13 4 6 RS232 OUTPUT RS232 OUTPUT 15 TTL INPUT TTL INPUT 14 RS232 INPUT TTL OUTPUT 11 16 30k 8 3 RS232 OUTPUT RS232 INPUT 9 RS232 INPUT TTL OUTPUT 14 30k 5 RS232 INPUT TTL OUTPUT 3 7 12 30k 1 9 V+ V- GND 10 7 RS232 INPUT + 1F 1F LT1280A * TA04 LT1280A/LT1281A PACKAGE DESCRIPTIO U Dimensions in inches (millimeters) unless otherwise noted. N Package 16-Lead PDIP (Narrow 0.300) (LTC DWG # 05-08-1510) 0.130 0.005 (3.302 0.127) 0.020 (0.508) MIN 0.770* (19.558) MAX 16 15 14 13 12 11 10 9 0.300 - 0.325 (7.620 - 8.255) 0.045 - 0.065 (1.143 - 1.651) 0.009 - 0.015 (0.229 - 0.381) 0.065 (1.651) TYP 1 0.125 (3.175) MIN 0.100 0.010 (2.540 0.254) 0.018 0.003 (0.457 0.076) 2 3 4 5 6 7 8 N16 1197 ( +0.035 0.325 -0.015 +0.889 8.255 -0.381 ) 0.255 0.015* (6.477 0.381) *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm) N Package 18-Lead PDIP (Narrow 0.300) (LTC DWG # 05-08-1510) 0.300 - 0.325 (7.620 - 8.255) 0.130 0.005 (3.302 0.127) 0.045 - 0.065 (1.143 - 1.651) 0.900* (22.860) MAX 18 17 16 15 14 13 12 11 10 0.020 (0.508) MIN 0.009 - 0.015 (0.229 - 0.381) 0.065 (1.651) TYP 0.125 (3.175) MIN 0.005 (0.127) MIN 0.100 0.010 (2.540 0.254) 1 0.018 0.003 (0.457 0.076) 2 3 4 5 6 7 8 9 ( +0.035 0.325 -0.015 +0.889 8.255 -0.381 ) 0.255 0.015* (6.477 0.381) N18 1197 *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm) SW Package 16-Lead Plastic Small Outline (Wide 0.300) (LTC DWG # 05-08-1620) 0.291 - 0.299** (7.391 - 7.595) 0.010 - 0.029 x 45 (0.254 - 0.737) 0 - 8 TYP 0.050 0.004 - 0.012 (1.270) (0.102 - 0.305) NOTE 1 TYP 0.014 - 0.019 0.016 - 0.050 (0.356 - 0.482) (0.406 - 1.270) 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 0.009 - 0.013 (0.229 - 0.330) NOTE 1 0.394 - 0.419 (10.007 - 10.643) 0.093 - 0.104 (2.362 - 2.642) 0.037 - 0.045 (0.940 - 1.143) 16 15 0.398 - 0.413* (10.109 - 10.490) 14 13 12 11 10 9 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 S16 (WIDE) 0396 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 LT1280A/LT1281A PACKAGE DESCRIPTIO 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) 0.050 (1.270) TYP 0.004 - 0.012 (0.102 - 0.305) SEE NOTE 0.394 - 0.419 (10.007 - 10.643) 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 1 2 3 4 5 6 7 8 9 S18 (WIDE) 0396 TYPICAL APPLICATI 12V INPUT 12 LOGIC INPUTS 15 11 13 8 14 5k LOGIC OUTPUTS 10 9 5k ON/OFF 18 16 LT1280A * TA03 RELATED PARTS PART NUMBER LT1180A/LT1181A LT1381 LT1780/LT1781 DESCRIPTION 5V 2-Driver/2-Receiver RS232 Transceivers 5V 2-Driver/2-Receiver RS232 Transceiver 5V 2-Driver/2-Receiver RS232 Transceiver COMMENTS Pin Compatible with LT1280A/LT1280A Narrow 16-Pin SO Package IEC 1000-4-2 Level 4 Compliance 8 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com + U Dimensions in inches (millimeters) unless otherwise noted. SW Package 18-Lead Plastic Small Outline (Wide 0.300) (LTC DWG # 05-08-1620) 0.447 - 0.463* (11.354 - 11.760) 0.093 - 0.104 (2.362 - 2.642) 0.037 - 0.045 (0.940 - 1.143) 18 17 16 15 14 13 12 11 10 0.014 - 0.019 (0.356 - 0.482) TYP UO Operation Using 5V and 12V Power Supplies 2 4 17 3 7 LT1280A 6 0.1F -12VOUT 5V INPUT + 0.1F 5 RS232 OUTPUT RS232 OUTPUT RS232 INPUT RS232 INPUT 12801afa LT/TP 1098 REV A 2K * PRINTED IN USA (c) LINEAR TECHNOLOGY CORPORATION 1993 |
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