LT1280A/LT1281A Low Power 5V RS232 Dual Driver/Receiver with 0.1µF Capacitors DESCRIPTIO U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 10mA Max Supply Current ESD Protection over ±10kV Uses Small Capacitors: 0.1µF 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 UO APPLICATI ■ ■ ■ ■ 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. Portable Computers Battery-Powered Systems Power Supply Generator Terminals Modems , LTC and LT are registered trademarks of Linear Technology Corporation. TransZorb is a registered trademark of General Instruments, GSI UO ■ S The LT ®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 0.1µF 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® 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. TYPICAL APPLICATI + 0.1µF 2 17 4 3 5V INPUT V+ + + 5 7 15 11 8 13 14 0.1µF RS232 OUTPUT RS232 OUTPUT 10 18 RECEIVER OUTPUT R CL = 50pF INPUT 9 5k DRIVER OUTPUT RL = 3k CL = 2500pF RS232 INPUT 5k LOGIC OUTPUTS ON/OFF V – OUT + 6 12 LOGIC INPUTS OUT 0.1µF LT1280A 0.1µF Output Waveforms RS232 INPUT LT1280A • TA02 16 LT1280A • TA01 1 LT1280A/LT1281A W W W AXI U U ABSOLUTE RATI GS (Note 1) 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 Short-Circuit Duration V + ................................................................... 30 sec V – ................................................................... 30 sec Driver Output .............................................. Indefinite Receiver Output .......................................... Indefinite Operating Temperature Range LT1280AC/LT1281AC ............................. 0°C to 70°C LT1280AI/LT1281AI .......................... – 40°C to 85°C Storage Temperature Range ................ – 65°C to 150°C Lead Temperature (Soldering, 10 sec)................. 300°C U W U PACKAGE/ORDER I FOR ATIO TOP VIEW ORDER PART NUMBER TOP VIEW C1+ NC 1 18 ON/OFF C1+ 2 17 VCC V+ 2 V+ 3 16 GND C1 – 3 14 TR1 OUT C1 – 4 15 TR1 OUT C2+ 4 13 REC1 IN C2+ 5 14 REC1 IN C2 – 5 12 REC1 OUT C2 – 6 13 REC1 OUT V– 7 12 TR1 IN TR2 OUT 8 11 TR2 IN REC2 IN 9 10 REC2 OUT LT1280ACN LT1280AIN LT1280ACSW LT1280AISW ORDER PART NUMBER 16 VCC 1 15 GND V– 6 11 TR1 IN TR2 OUT 7 10 TR2 IN REC2 IN 8 9 LT1281ACN LT1281AIN LT1281ACSW LT1281AISW REC2 OUT N PACKAGE 16-LEAD PDIP SW PACKAGE 16-LEAD PLASTIC SO WIDE N PACKAGE 18-LEAD PDIP SW PACKAGE 18-LEAD PLASTIC SO WIDE TJMAX = 125°C, θJA = 90°C/ W, θJC = 46°C/W (N) TJMAX = 125°C, θJA = 95°C/ W, θJC = 27°C/W (SW) TJMAX = 125°C, θJA = 80°C/ W, θJC = 36°C/W (N) TJMAX = 125°C, θJA = 90°C/ W, θJC = 26°C/W (SW) Consult factory for Military grade parts. ELECTRICAL CHARACTERISTICS (Note 2) PARAMETER Power Supply Generator V + Output V – Output Supply Current (VCC) CONDITIONS Supply Current When OFF (VCC) Supply Rise Time Shutdown to Turn-On ON/OFF Pin Thresholds Shutdown (Note 4) LT1280A Only C1 = C2 = C3 = C4 = 0.1µF LT1280A Only Input Low Level (Device Shutdown) Input High Level (Device Enabled) 0V ≤ VON/OFF ≤ 5V ON/OFF Pin Current Oscillator Frequency Driver Output Voltage Swing Logic Input Voltage Level 2 MIN TYP 7.9 – 7.0 8 (Note 3), TA = 25°C ● ● ● ● 0.8 ● – 15 1 0.2 0.2 1.2 1.6 MAX 10 14 10 2.4 80 130 Load = 3k to GND Input Low Level (VOUT = High) Input High Level (VOUT = Low) Positive Negative ● ● ● ● 5.0 2.0 7.5 – 6.3 1.4 1.4 – 5.0 0.8 UNITS V V mA mA µA ms ms V V µA kHz V V V V LT1280A/LT1281A ELECTRICAL CHARACTERISTICS (Note 2) PARAMETER CONDITIONS Logic Input Current 0.8V ≤ VIN ≤ 2.0V Output Short-Circuit Current VOUT = 0V Output Leakage Current Shutdown VOUT = ±30V (Note 4) Data Rate (Note 7) RL = 3k, CL = 2500pF RL = 3k, CL = 1000pF 120 250 Slew Rate RL = 3k, CL = 51pF RL = 3k, CL = 2500pF 4 Propagation Delay MIN ● ±9 TYP MAX 5 20 Output Transition tHL High-to-Low (Note 5) Output Transition tLH Low-to-High µA 17 10 ● UNITS mA µA 100 kBaud kBaud 15 7 30 V/µs V/µs 0.6 0.5 1.3 1.3 µs µs Receiver Input Voltage Thresholds Input Low Threshold (VOUT = High) Input High Threshold (VOUT = Low) Input Low Input High C Grade C Grade I Grade I Grade Hysteresis Input Resistance V IN = ±10V Output Leakage Current Output Voltage Shutdown (Note 4) 0 ≤ VOUT ≤ VCC Output Low, IOUT = – 1.6mA Output High, IOUT = 160µA (VCC = 5V) Output Short-Circuit Current ● ● 0.8 ● ● 0.2 ● 0.1 0.4 1.0 3 5 7 kΩ 10 0.4 3.5 1 0.2 4.2 µA V V – 20 20 250 350 – 10 mA mA ns ns ● ● ● Sinking Current, VOUT = VCC Sourcing Current, VOUT = 0V Output Transition tHL High-to-Low (Note 6) Output Transition tLH Low-to-High Propagation Delay The ● denotes specifications which apply over the 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: 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 = 0.1µF. All outputs are open, with all driver inputs tied high. 10 1.3 1.7 1.3 1.7 V V V V 2.4 3.0 V 600 600 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. U W TYPICAL PERFOR A CE CHARACTERISTICS Driver Maximum Output Voltage vs Load Capacitance Driver Minimum Output Voltage vs Load Capacitance 8.0 Driver Output Voltage 10 –4.0 8 7.0 20k BAUD 6.5 60k BAUD 6.0 120k BAUD 5.5 DRIVER OUTPUT VOLTAGE (V) –4.5 PEAK OUTPUT VOLTAGE (V) PEAK OUTPUT VOLTAGE (V) 7.5 120k BAUD –5.0 60k BAUD –5.5 20k BAUD –6.0 –6.5 RL = 3k 6 4 2 0 –2 –4 VCC = 5.5V VCC = 5V VCC = 4.5V OUTPUT HIGH OUTPUT LOW VCC = 4.5V VCC = 5V VCC = 5.5V –6 –8 5.0 –7.0 0 1 2 3 4 5 6 7 8 LOAD CAPACITANCE (nF) 9 10 LT1280A • TPC01 0 1 2 3 4 5 6 7 8 LOAD CAPACITANCE (nF) 9 10 LT1280A • TPC02 –10 –55 –25 50 25 0 75 TEMPERATURE (°C) 100 125 LT1280A • TPC03 3 LT1280A/LT1281A U W TYPICAL PERFOR A CE CHARACTERISTICS Receiver Input Thresholds Supply Current vs Data Rate 3.00 3.0 2 DRIVERS ACTIVE RL = 3k CL = 2500pF 2.50 SUPPLY CURRENT (mA) 40 2.25 INPUT HIGH 2.00 1.75 INPUT LOW 1.50 1.25 1.00 2.5 THRESHOLD VOLTAGE (V) 2.75 THRESHOLD VOLTAGE (V) ON/OFF Thresholds 50 30 20 10 2.0 ON THRESHOLD 1.5 1.0 OFF THRESHOLD 0.5 0.75 50 25 0 75 TEMPERATURE (°C) 100 0 125 0 25 125 50 75 100 DATA RATE (kBAUD) LT1280A • TPC04 LEAKAGE CURRENT ( µA) SUPPLY CURRENT (mA) 10 1 DRIVER LOADED RL = 3k NO LOAD 5 0 –55 –25 50 25 0 75 TEMPERATURE (°C) 100 125 Driver Short-Circuit Current 10 VOUT = 30V 1 VOUT = –30V 0.1 –55 –25 50 25 0 75 TEMPERATURE (°C) LT1280A • TPC07 100 Receiver Short-Circuit Current ISC+ 20 15 ISC– 10 5 0 –55 –25 50 25 75 0 TEMPERATURE (°C) Slew Rate vs Load Capacitance 14 40 12 RX ISC– RX ISC+ 20 10 8 +SLEW 6 –SLEW 4 10 2 0 –55 –25 50 25 0 75 TEMPERATURE (°C) 100 125 LT1280A • TPC10 4 0 0 100 125 LT1280A • TPC09 16 SLEW RATE (V/µs) SHORT-CIRCUIT CURRENT (mA) 125 25 LT1280A • TPC08 50 30 125 30 100 15 100 LT1280A • TPC06 Driver Leakage in Shutdown Supply Current 2 DRIVERS LOADED RL = 3k 50 25 75 0 TEMPERATURE (°C) LT1280A • TPC05 25 20 0 –55 –25 150 SHORT-CIRCUIT CURRENT (mA) 0.50 –55 –25 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/LT1281A U W TYPICAL PERFOR A CE CHARACTERISTICS Driver Output Waveforms Shutdown to Driver Outputs 10V DRIVER 1 OUTPUT 5V DRIVER OUTPUT RL = 3k CL = 2500pF GND GND DRIVER 2 OUTPUT – 5V DRIVER OUTPUT RL = 3k – 10V ON/OFF PIN INPUT LT1280A • TPC12 LT1280A • TPC13 U U U PI FU CTIO S VCC: 5V Input Supply Pin. This pin should be decoupled with a 0.1µF 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 ≥ 0.1µF, 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 ≥ 0.1µF. 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 ≥ 0.1µF: 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 –. 5 LT1280A/LT1281A U ESD PROTECTIO ESD Test Circuit 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. 1 + + + 0.1µF RS232 LINE PINS PROTECTED TO ±10kV 18 17 C1+ 3 V+ 4 C1– 5 C2+ RX1 IN 14 6 C2 – RX1 OUT 13 7 V– 0.1µF + ON/OFF 2 0.1µF 0.1µF NC LT1280A 5V VCC GND + 16 0.1µF DR1 OUT 15 RS232 LINE PINS PROTECTED TO ±10kV DR1 IN 12 DR2 IN 11 8 DR2 OUT RX2 OUT 10 9 RX2 IN 1280A ESD TC UO TYPICAL APPLICATI Supporting an LT1039 (Triple Driver/Receiver) SHUTDOWN 5V 18 TTL INPUT TTL INPUT VCC ON/OFF LT1280A 17 11 8 12 15 18 RS232 OUTPUT TTL INPUT RS232 OUTPUT TTL INPUT TTL INPUT TTL OUTPUT 14 13 RS232 INPUT TTL OUTPUT VCC ON/OFF LT1039 15 4 13 6 11 8 16 3 + 1µF + 1µF 9 10 2 RS232 INPUT RS232 OUTPUT RS232 OUTPUT RS232 INPUT TTL OUTPUT 14 5 RS232 INPUT 30k 5k C1+ 4 C1– 5 C2 + 6 C2 – TTL OUTPUT 7 12 RS232 INPUT 30k GND 16 6 RS232 OUTPUT 30k 5k TTL OUTPUT 17 V+ 3 V– 7 + 1µF + 1µF 1 V+ 9 V– GND 10 LT1280A • TA04 LT1280A/LT1281A U PACKAGE DESCRIPTIO 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) 0.300 – 0.325 (7.620 – 8.255) 0.009 – 0.015 (0.229 – 0.381) ( 0.045 – 0.065 (1.143 – 1.651) 0.020 (0.508) MIN +0.035 0.325 –0.015 +0.889 8.255 –0.381 0.770* (19.558) MAX ) 16 15 14 13 12 11 10 1 2 3 4 5 6 7 9 0.065 (1.651) TYP 0.125 (3.175) MIN 0.100 ± 0.010 (2.540 ± 0.254) 0.255 ± 0.015* (6.477 ± 0.381) 0.018 ± 0.003 (0.457 ± 0.076) 8 N16 1197 *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) 0.020 (0.508) MIN 0.130 ± 0.005 (3.302 ± 0.127) 0.900* (22.860) MAX 0.045 – 0.065 (1.143 – 1.651) ( +0.889 8.255 –0.381 ) 17 16 15 14 13 12 11 10 1 2 3 4 5 6 7 8 9 0.065 (1.651) TYP 0.009 – 0.015 (0.229 – 0.381) +0.035 0.325 –0.015 18 0.125 (3.175) MIN 0.005 (0.127) MIN 0.100 ± 0.010 (2.540 ± 0.254) 0.255 ± 0.015* (6.477 ± 0.381) 0.018 ± 0.003 (0.457 ± 0.076) 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) 0.398 – 0.413* (10.109 – 10.490) 0.010 – 0.029 × 45° (0.254 – 0.737) 0.093 – 0.104 (2.362 – 2.642) 16 0.037 – 0.045 (0.940 – 1.143) 15 14 13 12 11 10 9 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 NOTE 1 0.394 – 0.419 (10.007 – 10.643) 0.009 – 0.013 (0.229 – 0.330) 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 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. 4 5 6 7 8 S16 (WIDE) 0396 7 LT1280A/LT1281A U PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted. SW Package 18-Lead Plastic Small Outline (Wide 0.300) (LTC DWG # 05-08-1620) 0.291 – 0.299** (7.391 – 7.595) 0.447 – 0.463* (11.354 – 11.760) 0.010 – 0.029 × 45° (0.254 – 0.737) 0.093 – 0.104 (2.362 – 2.642) 18 0.037 – 0.045 (0.940 – 1.143) 17 15 16 14 13 12 11 10 0° – 8° TYP 0.050 (1.270) TYP 0.009 – 0.013 (0.229 – 0.330) NOTE 1 0.016 – 0.050 (0.406 – 1.270) 0.004 – 0.012 (0.102 – 0.305) SEE NOTE 0.394 – 0.419 (10.007 – 10.643) 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 1 *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 2 3 4 5 6 7 8 9 S18 (WIDE) 0396 UO TYPICAL APPLICATI Operation Using 5V and 12V Power Supplies 12V INPUT + 0.1µF LOGIC INPUTS 2 17 4 3 5 5V INPUT 7 –12VOUT LT1280A + 6 12 15 11 8 13 14 0.1µF RS232 OUTPUT RS232 OUTPUT RS232 INPUT 5k LOGIC OUTPUTS 10 9 RS232 INPUT 5k ON/OFF 18 16 LT1280A • TA03 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1180A/LT1181A 5V 2-Driver/2-Receiver RS232 Transceivers Pin Compatible with LT1280A/LT1280A LT1381 5V 2-Driver/2-Receiver RS232 Transceiver Narrow 16-Pin SO Package LT1780/LT1781 5V 2-Driver/2-Receiver RS232 Transceiver IEC 1000-4-2 Level 4 Compliance 8 Linear Technology Corporation 12801afa LT/TP 1098 REV A 2K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com LINEAR TECHNOLOGY CORPORATION 1993