There are four devices in the SC16IS7xx Bridge Family. Two of them are single channel UART and two of them are dual channel UART. Within the single channel UART one offers SPI speed up to 4Mbps, while the other offers a SPI speed limit of 15Mbps. The same thing can be said for the two dual channel UART devices; the only difference is the SPI speed limitation of 4Mbps and 15Mbps. These devices also support IrDA interface up to 115.2Kbit/s. The IrDA pins share the same pin out as the UART pins; therefore, you must select the UART function to work as normal UART or IrDA. The IrDA block does requires an external IrDA optical transceiver to communicate with another device through the IrDA link.