±15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications

The MAX3322E/MAX3323E 3.0V to 5.5V powered EIA/TIA-232 and V.28/V.24 communications interfaces are designed for multidrop applications with low power requirements, high data-rate capabilities, and enhanced electrostatic discharge (ESD) protection. All RS-232 inputs and outputs are protected to ±15kV using the IEC 1000-4-2 Air-Gap Discharge method, ±8kV using the IEC 1000-4-2 Contact Discharge method, and ±15kV using the Human Body Model.

The MAX3322E/MAX3323E have pin-selectable 5kΩ /high-impedance RS-232 receivers. These devices are capable of receiving data in high-impedance mode. In multidrop applications, one receiver has a 5kΩ input resistance, while the other receivers are high impedance to ensure the RS-232 standard is observed. Logic control permits selection of the functional mode: high impedance or RS-232 standard load. The transmitters are enabled by logic control to allow the multiplexing of the inputs to a single UART.

A proprietary low-dropout transmitter output stage enables true RS-232 performance from a 3.0V to 5.5V supply with a dual charge pump. The charge pump requires only four small 0.1µF capacitors for operation from a 3.3V supply. The MAX3322E/MAX3323E are capable of running at data rates up to 250kbps while maintaining RS-232-compliant output levels. The MAX3322E/MAX3323E have a unique VL pin that allows operation in mixed-logic voltage systems. Both input and output logic levels are pin programmable through the VL pin.

The MAX3322E is a 2Tx/2Rx device for hardware handshaking in standard RS-232 mode, and the MAX3323E is a 1Tx/1Rx, required in most multidrop applications.

The MAX3322E is offered in a space-saving TSSOP package. The MAX3323E is offered in 16-pin DIP and space-saving TSSOP packages.

Applications

* Bar-Code Scanners * Data Splitters * Industrial Data Acquisition * Video Security

* Pin-Selectable 5kΩ/High-Impedance Receivers

* Transmitter Outputs Three-Stated by Logic Control

* VL Pin for Compatibility with Mixed Voltage Systems

* 1Tx/1Rx (MAX3323E) or 2Tx/2Rx (MAX3322E) Versions

* 250kbps Data Rate

* 1µA Low-Power Shutdown

* High ESD Protection for RS-232 I/O Pins

* ±15kVHuman Body Model

* ±8kVIEC 1000-4-2 Contact Discharge

* ±15kVIEC 1000-4-2 Air-Gap Discharge