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LT1780 Dataheets PDF



Part Number LT1780
Manufacturers Linear Technology
Logo Linear Technology
Description Low Power 5V RS232 Dual Driver/Receiver with 15kV ESD Protection
Datasheet LT1780 DatasheetLT1780 Datasheet (PDF)

LT1780/LT1781 Low Power 5V RS232 Dual Driver/Receiver with ±15kV ESD Protection DESCRIPTIO The LT®1780/LT1781 are dual RS232 driver/receiver pairs with integral charge pump to generate RS232 voltage levels from a single 5V supply. 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 LT1780/LT1781 to survive ±15kV air gap and ±8kV contact ESD tests per IEC 10.

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LT1780/LT1781 Low Power 5V RS232 Dual Driver/Receiver with ±15kV ESD Protection DESCRIPTIO The LT®1780/LT1781 are dual RS232 driver/receiver pairs with integral charge pump to generate RS232 voltage levels from a single 5V supply. 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 LT1780/LT1781 to survive ±15kV air gap and ±8kV contact ESD tests per IEC 1000-4-2, eliminating the need for costly TransZorbs® on the RS232 line pins. The LT1780/ LT1781 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 LT1780/LT1781 are direct upgrades to the LT1180A/ LT1181A, LT1280A/LT1281A and LT1381 for applications which require the utmost ESD protection. The LT1781 is available in 16-pin DIP,SO and SW packages. The LT1780 is supplied in 18-pin DIP and SW 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 10mA Max Supply Current ESD Protection to IEC 1000-4-2 Level 4 ±15kV Air Gap, ±8kV Contact 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 APPLICATI s s s s s S Portable Computers Battery-Powered Systems Power Supply Generator Terminals Modems TYPICAL APPLICATI 2 0.1µF 4 LT1780 5 0.1µF 6 12 LOGIC INPUTS 7 3 17 5V INPUT V + OUT 0.1µF V – OUT 0.1µF DRIVER OUTPUT RL = 3k CL = 2500pF 15 RS232 OUTPUT 11 13 8 14 5k RECEIVER OUTPUT R CL = 50pF RS232 OUTPUT RS232 INPUT INPUT LOGIC OUTPUTS 10 18 9 5k 16 RS232 INPUT ON/OFF 1780/81 • TA01 U UO UO Output Waveforms 1780/81 • TA02 1 LT1780/LT1781 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 17 16 15 14 13 12 11 10 ON/OFF VCC GND TR1 OUT REC1 IN REC1 OUT TR1 IN TR2 IN REC2 OUT ORDER PART NUMBER LT1780CN LT1780CSW N PACKAGE 18-LEAD PLASTIC DIP SW PACKAGE 18-LEAD PLASTIC SO 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 Industrial and 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 8 q q (Note 3), TA = 25°C SHUTDOWN (Note 4) LT1780 Only C1 = C2 = C3 = C4 = 0.1µF LT1780 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 W W U W (Note 1) Short-Circuit Duration V + ................................................................... 30 sec V – ................................................................... 30 sec Driver Output .............................................. Indefinite Receiver Output .......................................... Indefinite Operating Temperature Range ..................... 0°C to 70°C Storage Temperature Range ................ – 65°C to 150°C Lead Temperature (Soldering, 10 sec)................. 300°C TOP VIEW C1+ V+ C1 – C2+ C2 – V– TR2 OUT REC2 IN 1 2 3 4 5 6 7 8 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 LT1781CN LT1781CS LT1781CSW S PACKAGE SW PACKAGE N PACKAGE 16-LEAD PLASTIC DIP 16-LEAD PLASTIC SO 16-LEAD PLASTIC SO TJMAX = 125°C, θJA = 90°C/ W, θJC = 46°C/W (N) TJMAX = 125°C, θJA = 95°C/ W, θJC = 34°C/W (S) TJMAX = 125°C, θJA = 95°C/ W, θJC = 27°C/W (SW) MAX UNITS V V mA mA µA ms ms V V µA kHz V V V V q q q 0.8 – .


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