The ST16C554D is a universal asynchronous receiver and transmitter (UART) with a dual foot print interface. The 554D is an enhanced UART with 16 byte FIFOs, receive trigger levels and data rates up to 1.5Mbps. Onboard status registers provide the user with error indications and operational status, modem interface control. System interrupts may be tailored to meet user requirements. An internal loopback capability allows onboard diagnostics. The 554D is available in 64 pin TQFP, and 68 pin PLCC packages. The 68 pin PLCC package offer an additional 68 mode which allows easy integration with Motorola, and other popular microprocessors. The ST16C554CQ64 (64 pin) offers three state interrupt control while the ST16C554DCQ64 provides constant active interrupt outputs. The 64 pin devices do not offer TXRDY/ RXRDY outputs. The 554D combines the package interface modes of the 16C554 and 68C554 series on a single integrated chip.