LT1780/LT1781 Low Power 5V RS232 Dual Driver/Receiver with 15kV ESD Protection DESCRIPTIO FEATURES n The LT 1780/LT1781 are dual RS232 driver/receiver pairs 10mA Max Supply Current n with integral charge pump to generate RS232 voltage ESD Protection to IEC 1000-4-2 Level 4 levels from a single 5V supply. Using only 0.1F external 15kV Air Gap, 8kV Contact n capacitors, these circuits consume only 40mW of power, Uses Small Capacitors: 0.1F n and can operate to 120kbaud even while driving heavy 120kBaud Operation for R = 3k, C = 2500pF L L n capacitive loads. New ESD structures on the chip allow the 250kBaud Operation for R = 3k, C = 1000pF L L n LT1780/LT1781 to survive 15kV air gap and 8kV con- Outputs Withstand 30V Without Damage n tact ESD tests per IEC 1000-4-2, eliminating the need for CMOS Comparable Low Power: 40mW n costly TransZorbs on the RS232 line pins. The LT1780/ Operates from a Single 5V Supply n LT1781 are fully compliant with EIA RS232 standards. Rugged Bipolar Design n Driver outputs are protected from overload, and can be Outputs Assume a High Impedance State When Off shorted to ground or up to 30V without damage. During or Powered Down n SHUTDOWN or power-off conditions, driver and receiver Meets All RS232 Specifications n outputs are in a high impedance state, allowing line Available With or Without Shutdown n sharing. Absolutely No Latch-up The LT1780/LT1781 are direct upgrades to the LT1180A/ LT1181A, LT1280A/LT1281A and LT1381 for applications APPLICATI S which require the utmost ESD protection. n Portable Computers The LT1781 is available in 16-pin DIP,SO and SW pack- n Battery-Powered Systems ages. The LT1780 is supplied in 18-pin DIP and SW n Power Supply Generator packages for applications which require SHUTDOWN. n Terminals , LTC and LT are registered trademarks of Linear Technology Corporation. n Modems TransZorb is a registered trademark of General Instruments, GSI. TYPICAL APPLICATI 2 17 Output Waveforms 5V INPUT 0.1F 4 3 + V OUT 0.1F DRIVER LT1780 OUTPUT 5 7 = 3k R L V OUT C = 2500pF L 0.1F 0.1F 6 12 15 RECEIVER RS232 OUTPUT OUTPUT LOGIC R C = 50pF INPUTS L 11 8 RS232 OUTPUT 13 14 RS232 INPUT INPUT 5k LOGIC OUTPUTS 10 9 RS232 INPUT 1780/81 TA02 5k 18 16 ON/OFF 1780/81 TA01 1 O U UO ULT1780/LT1781 ABSOLUTEXAI U RATI GS (Note 1) Short-Circuit Duration Supply Voltage (V ) ................................................ 6V CC + + V ................................................................... 30 sec V ........................................................................ 13.2V V ................................................................... 30 sec V ...................................................................... 13.2V Driver Output .............................................. Indefinite Input Voltage + Receiver Output .......................................... Indefinite Driver ........................................................... V to V Operating Temperature Range ..................... 0C to 70C Receiver ............................................... 30V to 30V Storage Temperature Range ................ 65C to 150C ON/OFF ................................................. 0.3V to 12V Lead Temperature (Soldering, 10 sec)................. 300C Output Voltage + Driver ...................................... V 30V to V + 30V Receiver .................................... 0.3V to V + 0.3V CC PACKAGE/ORDER I FOR ATIO TOP VIEW TOP VIEW ORDER ORDER + 1 ON/OFF NC 18 C1 1 16 V PART CC PART + + 2 V C1 17 NUMBER V 2 15 GND NUMBER CC + 3 GND V 16 C1 3 14 TR1 OUT LT1780CN LT1781CN + 4 TR1 OUT C1 15 C2 4 13 REC1 IN + LT1780CSW LT1781CS 5 REC1 IN C2 14 C2 5 12 REC1 OUT LT1781CSW 6 REC1 OUT C2 13 V 6 11 TR1 IN 7 TR1 IN V 12 TR2 OUT 7 10 TR2 IN 8 TR2 IN TR2 OUT 11 REC2 IN 8 9 REC2 OUT 9 REC2 OUT REC2 IN 10 N PACKAGE S PACKAGE SW PACKAGE 16-LEAD PLASTIC DIP 16-LEAD PLASTIC SO 16-LEAD PLASTIC SO N PACKAGE SW PACKAGE 18-LEAD PLASTIC DIP 18-LEAD PLASTIC SO T = 125C, = 90C/ W, = 46C/W (N) JMAX JA JC T = 125C, = 80C/ W, = 36C/W (N) T = 125C, = 95C/ W, = 34C/W (S) JMAX JA JC JMAX JA JC T = 125C, = 90C/ W, = 26C/W (SW) T = 125C, = 95C/ W, = 27C/W (SW) JMAX JA JC JMAX JA JC Consult factory for Industrial and Military grade parts. (Note 2) ELECTRICAL CHARACTERISTICS PARAMETER CONDITIONS MIN TYP MAX UNITS Power Supply Generator + V Output 7.9 V V Output 7 V Supply Current (V ) (Note 3), T = 25C 8 10 mA CC A l 14 mA Supply Current When OFF (V ) SHUTDOWN (Note 4) LT1780 Only l 110 A CC Supply Rise Time C1 = C2 = C3 = C4 = 0.1F 0.2 ms SHUTDOWN to Turn-On LT1780 Only 0.2 ms ON/OFF Pin Thresholds Input Low Level (Device SHUTDOWN) l 0.8 1.2 V Input High Level (Device Enabled) l 1.6 2.4 V ON/OFF Pin Current 0V V 5V l 15 80 A ON/OFF Oscillator Frequency 130 kHz Driver Output Voltage Swing Load = 3k to GND Positive l 5.0 7.5 V Negative l 6.3 5 V Logic Input Voltage Level Input Low Level (V = High) l 1.4 0.8 V OUT Input High Level (V = Low) l 2.0 1.4 V OUT 2 U WU U W W W