5V RS232 Transceiver with 3V Logic Interface

The LT1342 is an advanced low power three-driver, five-receiver RS232 transceiver. The LT1342 operates from a 5V supply and a 3V logic supply. Receiver outputs can interface directly to 3V logic circuits. Included on the chip is a shutdown pin for reducing supply current to near zero. All receivers and drivers assume high impedance states during shutdown.

The driver disable function provides additional control of operating mode. When driver disable is high the charge pump and drivers turn off. Receivers continue to operate during driver disable.

New ESD structures on the chip allow the LT1342 to survive multiple ±10kV strikes, eliminating the need for costly TransZorbs® on the RS232 line pins.

The LT1342 is fully compliant with all EIA RS232 specifications and operates in excess of 120kbaud even driving heavy capacitive loads.

Applications

* Notebook Computers

* Palmtop Computers

*

ESD Protection Over ±10kV

* 3V Logic Interface

* Uses Small Capacitors: 0.1µF, 0.2µF

* 1µA Supply Current in Shutdown

* Low Power Driver Disable Operating Mode

* Pin Compatible with LT1137A

*

120kBaud Operation for RL = 3k, CL = 2500pF

*

250kBaud Operation for RL = 3k, CL = 1000pF

* CMOS Comparable Low Power: 60mW

* Easy PC Layout: Flowthrough Architecture

* Rugged Bipolar Design

* Outputs Assume a High Impedance State When Off or Powered Down

* Absolutely No Latch-Up