The ST16C554D is a universal asynchronous receiverand 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 errorindications and operational status, modem interfacecontrol. System interrupts may be tailored to meetuser requirements. An internal loopback capabilityallows onboard diagnostics. The 554D is available in64 pin TQFP, and 68 pin PLCC packages. The 68 pinPLCC package offer an additional 68 mode whichallows easy integration with Motorola, and other popularmicroprocessors. The ST16C554CQ64 (64 pin)offers three state interrupt control while theST16C554DCQ64 provides constant active interruptoutputs. The 64 pin devices do not offer TXRDY/RXRDY outputs. The 554D combines the packageinterface modes of the 16C554 and 68C554 series ona single integrated chip.