Chip's Dual UARTs Carry TX/RX FIFO Counters

With on-chip transmit and receive FIFO counters as well as 128-byte FIFO depth and automatic RS-485 half-duplex control, the XR16C2850 and XR16C2852 dual UARTs support data rates up to 1.5 Mbps at 5V and 500 kbps at 3.3V. The FIFO depth of 128 bytes lets the UART send and receive larger data packets to increase the interval between required CPU accesses. The automatic RS-485 half-duplex control on the request-to-send pin changes its logic state at the last stop bit of the last character transmitted to switch the RS-485 line driver and receiver to the receiving mode. This provides faster turnaround between master and remote units and eliminates external logic devices to provide cost and space savings. Applications are industrial automation equipment and PC-based cards. The XR16C2850 comes in a 44-pin PLCC, 40-pin PDIP or 48-pin TQFP and is pin-for-pin and functionally compatible with the ST16C2550. The XR16C2852 is pin-for-pin compatible with the ST16C2552 and PC16552 and comes in a 44-pin PLCC.