SP304

The SP304 is a proprietary single-chip device that contain both RS-232 and RS-422 protocol line drivers and receivers. It is pinforpin compatible with the Sipex SP302. Like the SP302,its configuration may be changed at any time by logic levels on two control lines. In any configuration,the SP304 fully meets the requirements of both the EIA RS-232D and RS-422 data communication standards. The SP304 enhancements include improved isolation from external signals and a true highimpedance driver output in the loopback test mode, and no power up sequence requirements.

The RS-232 line driver circuits convert TTL logic level inputs into inverted RS-232 output signals. The RS-422 line drivers convert TTL logic levels into RS-422 differential output signals.The RS-422 line driver outputs feature high source and sink current capability. All line drivers are internally protected against short circuits on their outputs.

The RS-232 receivers convert the EIA RS-232 input signals to inverted TTL output logic levels.The RS-422 receivers convert the EIA RS-422 differential input signals into non-inverted TTL output logic levels. Receiver input filtering provides excellent high frequency noise immunity.Input pulses with widths less than 1ms are completely ignored. The RS-232 receivers have the additional feature of voltage hysteresis, which helps eliminate spurious output transitions that might result from low amplitude noise voltages during slower-speed signal transitions.

A loopback test mode is provided that puts the driver outputs to a high impedance tri-state level, and routes the driver outputs to their associated receiver inputs. In this configuration,the signal path is non-inverting from the TTL driver input to the receiver TTL output. This operating mode allows the controlling system to perform diagnostic self-test of the RS-232/RS-422 driver/receiver circuitry at speeds up to 3,000 bits per second. In the loopback mode a ±13.2V input range may be applied to the receiver inputs with no interference to the loopback test. In addition, the driver outputs are in a true highimpedance state during loopback.

The SP304 is available in 24-pin single width(0.300") plastic DIP and 28-pin SOIC packages,for operation over the commercial and industrial temperature ranges.