SC28C94

• New low overhead interrupt control
• All commercial parts meet industrial timing and temperatureparameters
• Four Philips Semiconductors industry-standard UARTs
• Eight byte receive FIFO and eight byte transmit FIFO for eachUART
• Programmable data format: 5 to 8 data bits plus parity Odd, even, no parity or force parity 1, 1.5 or 2 stop bits programmable in 1/16-bit increments
• Baud rate for the receiver and transmitter selectable from: 23 fixed rates: 50 to 230.4K baud Non-standard rates to 1.0Mbaud User-definedratesfromthe programmable counter/timerassociated with each of two blocks External 1x or 16x clock
• Parity, framing, and overrun error detection
• False start bit detection
• Line break detection and generation
• Programmable channel mode Normal (full-duplex), automatic echo, local loop back, remoteloopback
• Programmable interrupt priorities
• Identification of highest priority interrupt
• Global interrupt register set provides data from interruptingchannel
• Vectored interrupts with programmable vector format
• IACKN and programmable DTACKN signals
• Built-in baud rate generator with choice of 18 rates
• Four I/O pins per UART for modem controls, clocks, etc.
• Power down mode
• High-speed CMOS technology
• 52-pin PLCC and 48-pin DIP
• Commercial and industrial temperature ranges available
• On-chip crystal oscillator
• TTL compatible
• Single +5V power supply with low power mode
• Two multifunction programmable 16-bit counter/timers
• 1MHz 16x mode operation
• 10ns data bus release time
• "Watch Dog" timer for each receiver

The SC28C94 quad universal asynchronous receiver/transmitter(QUART) combines four enhanced Philips Semiconductorsindustry-standard UARTs with an innovative interrupt scheme thatcan vastly minimize host processor overhead.  It is implementedusing Philips Semiconductors' high-speed CMOS process thatcombines small die size and cost with low power consumption.

The operating speed of each receiver and transmitter SC28C94can beselected independently at one of eighteen fixed baud rates, a 16Xclock derived from a programmable counter/timer, or an external 1Xor 16X clock. The baud rate generator and counter/timer canoperate directly from a crystal or from external clock inputs. Theability to independently program the operating speed of the receiverand transmitter make the QUART particularly attractive fordual-speed channel applications such as clustered terminalsystems.

Each receiver SC28C94 is buffered with eight character FIFOs (first-in-first-outmemories) and one shift register to minimize the potential forreceiver overrun and to reduce interrupt overhead in interrupt drivensystems. In addition, a handshaking capability is provided to disablea remote UART transmitter when the receiver buffer is full.  (RTScontrol)The 28C94 provides a power-down mode in which the oscillator isstopped and the register contents are stored. This results in reducedpower consumption on the order of several magnitudes. TheQUART is fully TTL compatible and operates from a single +5Vpower supply.