SC28L91

•Member of IMPACT family: 3.3 to 5.0 volt , 40°C to +85°C and68K for 80xxx bus interface for all devices.
• A full-duplex independent asynchronous receiver/transmitter
• 16 character FIFOs for each receiver and transmitter
• Pin programming selects 68K or 80xxx-bus interface
• 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
• Programmable baud rate for each receiver and transmitterselectable from: 28 fixed rates: 50 to 230.4 k baud Other baud rates to 1 MHz at 16X Programmable user-defined rates derived from a programmablecounter/timer 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 Remote loop back Multi-drop mode (also called 'wake-up' or '9-bit')
•Multi-function 7-bit input port (includes IACKN) Can serve as clock or control inputs Change of state detection on four inputs Inputs have typically >100k pull-up resistors Change of state detectors for modem control
•Multi-function 8-bit output port Individual bit set/reset capability Outputs can be programmed to be status/interrupt signals FIFO status for DMA interface
• Versatile interrupt system Single interrupt output with eight maskable interruptingconditions Output port can be configured to provide a total of up to sixseparate interrupt outputs that may be wire ORed. Each FIFO can be programmed for four different interrupt levels Watch dog timer for the receiver
•Maximum data transfer rates:1X 1Mb/sec, 16X 1Mb/sec
• Automatic wake-up mode for multi-drop applications
• Start-end break interrupt/status with mid-character break detect.
• On-chip crystal oscillator
• Power down mode
• Receiver time-out mode
• Single +3.3V or +5V power supply

The SC28L91 is a new member of the IMPACT family of SerialCommunications Controllers. It is a single channel UART operatingat 3.3 and 5.0 volts Vcc, 8 or 16 byte FIFOs and is quite compatiblewith software of the SC28L92 and previous UARTs offered byPhilips. It is a new part that is similar to our previous one channelpart but is vastly improved. The improvements being: 16 characterreceiver, 16 character transmit FIFOs, watch dog timer for thereceiver, mode register 0 is added, extended baud rate, over allfaster bus and data speeds, programmable receiver and transmitterinterrupts and versatile I/O structure. (The previous one channelpart, SCC2691, is NOT being discontinued.)Pin programming will allow the device to operate with either theMotorola or Intel bus interface. Bit 3 of the MR0 register allows thedevice to operate in an 8-byte FIFO mode if strict compliance withan 8-byte FIFO structure is required.

The Philips Semiconductors SC28L91 Universal AsynchronousReceiver/Transmitter (UART) is a single-chip CMOS-LSIcommunications device that provides a full-duplex asynchronousreceiver/transmitter channel in a single package. It interfacesdirectly with microprocessors and may be used in a polled orinterrupt driven system with modem and DMA interface.

The operating mode and data format of the channel can beprogrammed independently. Additionally, the receiver andtransmitter can select its operating speed as one of 28 fixed baudrates; a 16X clock derived from a programmable counter/timer, or anexternal 1X or 16X clock. The baud rate generator and counter/timercan operate directly from a crystal or from external clock inputs. Theability to independently program the operating speed of the receiverand transmitter make the UART particularly attractive for dual-speedchannel applications such as clustered terminal systems.

The receiver and transmitter is buffered by 8 or 16 character FIFOsto minimize the potential of receiver overrun, transmitter underrunand to reduce interrupt overhead in interrupt driven systems. Inaddition, a flow control capability is provided via RTS/CTS signalingto disable a remote transmitter when the receiver buffer is full.

DMA interface is and other general purpose signals are provided onthe SC28L91 via a multipurpose 7-bit input port and a multipurpose8-bit output port. These can be used as general-purpose ports orcan be assigned specific functions (such as clock inputs orstatus/interrupt outputs, FIFO conditions) under program control.

The SC28L91 is available in two package versions: a 44-pin PLCCand 44-pin plastic quad flat pack (PQFP).