APPLICATION NOTE 643

Pre-emphasis Improves RS-485 Communications


Abstract: Driver preemphasis extends the distance and increases the data rate of reliable RS-485 communication by reducing intersymbol interference (ISI) caused by long cables. The original application note was published to explain the principles of preemphasis and in Appendix A demonstrate MAX3291 and MAX3292 products. The introduction of new products MAX22500E and MAX22502E extend RS-485 performance to 100Mbps, and these new products are described in Appendix B to show how Maxim continues to expand the applications and use of popular RS-485 transceivers.