SCC2691

Full-duplex asynchronous receiver/transmitter
Quadruple buffered receiver data register
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
16-bit programmable Counter/Timer
Baud rate for the receiver and transmitter selectable from:
¤ 22 fixed rates: 50 to 115.2K baud
¤ Non-standard rates to 115.2kb
¤ Non-standard user-defined rate derived from programmabl timer/ counter
¤ External 1X or 16X clock
Parity, framing, and overrun detection
False start bit detection
Line break detection and generation
Programmable channel mode
¤ Normal (full-duplex)
¤ Automatic echo
¤ Local  loopback
¤ Remote Loopback
Multi-function programmable 16-bit counter/timer
Single interrupt output with seven maskable interrupting conditions
On-chip crystal oscillator
Low power mode
TTL compatible
Single +5V power supply
Commercial (0 to +70) and industrial (-40 to +85) temperature versions available
SOL, PLCC and 300 mil wide DIP packages available

The Philips Semiconductors SCC2691 Universal Asynchronous Receiver/Transmitter (UART) is a single-chip CMOS-LSI communications device that provides a full-duplex asynchronous receiver/transmitter. It is fabricated with Philips Semiconductors CMOS technology which combines the benefits of high density and
low power consumption.

The operating speed of the receiver and transmitter SCC2691 can be selected independently as one of 18 fixed baud rates, a 16X clock derived from a programmable counter/timer, or an external 1X or 16X clock. The baud rate generator and counter/timer can operate directly from a crystal or from external clock inputs. The ability to independently program the operating speed of the receiver and transmitter makethe UART particularly attractive for dual-speed channel applications such as clustered terminal systems.

The receiver SCC2691 is quadruple buffered to minimize the potential of receiver overrun or to reduce interrupt overhead in interrupt driven systems. In addition, a handshaking capability is provided to disable a remote UART transmitter when the receiver buffer is full.

The UART SCC2691 provides a power-down mode in which the oscillator is frozen but the register contents are stored. This results in reduced power consumption on the order of several magnitudes.

The UART SCC2691 is fully TTL compatible and operates from a single +5V power supply.