SCN2681 datasheet(2/30 Pages) PHILIPS

2 / 30 page

Philips Semiconductors

Product specification

SCN2681

Dual asynchronous receiver/transmitter (DUART)

1998 Sep 04

853–1077 19970

DESCRIPTION

The Philips Semiconductors SCN2681 Dual Universal

Asynchronous Receiver/Transmitter (DUART) is a single-chip

MOS-LSI communications device that provides two independent

full-duplex asynchronous receiver/transmitter channels in a single

package. It interfaces directly with microprocessors and may be

used in a polled or interrupt driven system.

The operating mode and data format of each channel can be

programmed independently. Additionally, each receiver and

transmitter can select its operating speed as one of eighteen 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 make the DUART particularly

attractive for dual-speed channel applications such as clustered

terminal systems.

Each receiver is quadruply buffered to minimize the potential of

receiver over-run or to reduce interrupt overhead in interrupt driven

systems. In addition, a flow control capability is provided to disable

a remote DUART transmitter when the buffer of the receiving device

is full.

Also provided on the SCN2681 are a multipurpose 7-bit input port

and a multipurpose 8-bit output port. These can be used as general

purpose I/O ports or can be assigned specific functions (such as

clock inputs or status/interrupt outputs) under program control.

The SCN2681 is available in three package versions: 40-pin and

28–pin, both 0.6” wide DIPs; a compact 24-pin 0.4” wide DIP; and a

44-pin PLCC.

FEATURES

• Dual full-duplex asynchronous receiver/transmitter

• Quadruple buffered receiver data registers

• 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

• Programmable baud rate for each receiver and transmitter

selectable from:

– 22 fixed rates: 50 to 115.2k baud

• 16-bit programmable Counter/Timer

– Non-standard rates to 115.2Kb

– One user-defined rate derived from programmable

timer/counter

– 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 loopback

– Remote loopback

• Multi-function programmable 16-bit counter/timer

• Multi-function 7-bit input port

– Can serve as clock or control inputs

– Change of state detection on four inputs

– 100k

Ω typical pull-up resistor

• Multi-function 8-bit output port

– Individual bit set/reset capability

– Outputs can be programmed to be status/interrupt signals

• Versatile interrupt system

– Single interrupt output with eight maskable interrupting

conditions

– Output port can be configured to provide a total of up to six

separate wire-ORable interrupt outputs

• Maximum data transfer: 1X – 1MB/sec, 16X – 125kB/sec

• Automatic wake-up mode for multidrop applications

• Start-end break interrupt/status

• Detects break which originates in the middle of a character

• On-chip crystal oscillator

• Single +5V power supply

• Commercial and industrial temperature ranges available

• DIP and PLCC packages

ORDERING INFORMATION

ORDER CODE

DESCRIPTION

Commercial

Industrial

DESCRIPTION

VCC = +5V +5%, TA = 0°C to +70°C

VCC = +5V +10%, TA = -40°C to +85°C

Plastic DIP

Plastic LCC

Plastic DIP

Plastic LCC

24-Pin1

SCN2681AC1N24

Not available

SCN2681AE1N24

Not available

28-Pin2

SCN2681AC1N28

Not available

SCN2681AE1N28

Not available

40-Pin2

SCN2681AC1N40

Not available

SCN2681AE1N40

Not available

44-Pin

Not available

SCN2681AC1A44

Not available

SCN2681AE1A44

NOTES:

1. 400mil-wide Dual In-Line Package

2. 600mil-wide Dual In-Line Package

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