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 0.1�F 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 � 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

10mA Max Supply Current ESD Protection over � 10kV Uses Small Capacitors: 0.1�F 120kBaud Operation for 2500pF 250kBaud Operation for = 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

Supply Voltage (VCC)................................................ V �13.2V Input Voltage Driver........................................................... V + Receiver............................................... to 30V ON/OFF................................................. to 12V Output Voltage Driver...................................... + 30V Receiver.................................... 0.3V to VCC + 0.3V

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 = 25�C Shutdown (Note 4) LT1280A Only 0.1�F LT1280A Only Input Low Level (Device Shutdown) Input High Level (Device Enabled) 0V VON/OFF 5V

Short-Circuit Duration V 30 sec V 30 sec Driver Output.............................................. Indefinite Receiver Output.......................................... Indefinite Operating Temperature Range to 85�C Storage Temperature Range................ to 150�C Lead Temperature (Soldering, 10 sec)................. 300�C

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

Shutdown VOUT � 30V (Note = 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 = �10V Shutdown (Note 4) 0 VOUT VCC Output Low, IOUT � 1.6mA Output High, IOUT = 160�A (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

Hysteresis Input Resistance Output Leakage Current Output Voltage Output Short-Circuit Current Propagation Delay

The q denotes specifications which apply over the operating temperature range TA 70�C for commercial grade, and 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. = 0.1�F. 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, = 3k and = 51pF. Trigger points are set between the driver's input logic threshold and the output transition to the zero crossing to 0V and tLH to 0V). Note 6: For receiver delay measurements, = 51pF. Trigger points are set between the receiver's input logic threshold and the output transition to standard TTL/CMOS logic threshold to 2.4V and tLH to 0.8V). Note 7: Data rate operation guaranteed by slew rate, short-circuit current and propagation delay tests.