ad7306供电的RS-232、RS-422收发器

　　The AD7306 line driver/receiver is a 5 V monolithic product which provides an interface between TTL signal levels and dual standard EIA RS-232/RS-422 signal levels. The part contains two RS-232 drivers， one RS-422 driver， one RS-232 receiver， and one receiver path which can be configured either as RS-232 or as RS-422. An internal charge pump voltage converter facilitates operation from a single +5 V power supply. The internal charge pump generates ±10 V levels allowing RS-232 output levels to be developed without the need for external bipolar power supplies. A highly efficient charge pump design allows operation using non polarized， miniature 0.1 µF capacitors. This gives a considerable saving in printed circuit board space over conventional products which can use up to 10 µF capacitors. The charge pump output voltages may also be used to power external circuitry which requires dual supplies. The RS-232 channels are suitable for communications rates up to 100 kHz and the RS-422 channels are suitable for high speed communications up to 5 MHz. The RS-422 transmitter complementary outputs are closely matched and feature low timing skew between the complementary outputs. This is often an essential requirement to meet tight system timing specifications. All inputs feature ESD protection， all driver outputs feature high source and sink current capability and are internally protected against short circuits on the outputs. An epitaxial layer is used to guard against latch-up. The part is available in a 24-lead SOIC and 24-pin plastic DIP package.