SCN2681 Просмотр технического описания (PDF) - Philips Electronics
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SCN2681 Datasheet PDF : 30 Pages
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Philips Semiconductors
Dual asynchronous receiver/transmitter (DUART)
Product specification
SCN2681
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
– 100kΩ 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
24-Pin1
28-Pin2
40-Pin2
Commercial
VCC = +5V +5%, TA = 0°C to +70°C
Plastic DIP
Plastic LCC
SCN2681AC1N24
Not available
SCN2681AC1N28
Not available
SCN2681AC1N40
Not available
Industrial
VCC = +5V +10%, TA = -40°C to +85°C
Plastic DIP
Plastic LCC
SCN2681AE1N24
Not available
SCN2681AE1N28
Not available
SCN2681AE1N40
Not available
44-Pin
Not available
NOTES:
1. 400mil-wide Dual In-Line Package
2. 600mil-wide Dual In-Line Package
SCN2681AC1A44
Not available
SCN2681AE1A44
1998 Sep 04
2
853–1077 19970
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