SC28L202A1D 查看數據表（PDF） - Philips Electronics

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SC28L202A1D

Dual universal asynchronous receiver/transmitter (DUART)

Philips Electronics 

Philips Semiconductors

Dual UART

Objective specification

SC28L202

DESCRIPTION

The 28L202 is a high performance dual UART. Its functional and

programming features closely match but greatly extend those of

previous Philips dual channel UARTs. Its configuration on power up

is similar that of the SC26C92. Its differences from the SC26C92

are: 256–character receiver, 256 character transmit FIFOs, 3 and 5

volt compatibility, 8 I/O ports for each UART – 16 total, arbitrating

interrupt system and overall faster buss and data speeds. It is

fabricated in an advanced 0.5 micron CMOS process that allows

stand by current of less that 10 microamperes.

It is a member of the IMPACT® line of Data Communications parts

Pin or register programming will allow the device to operate with

either the Motorola or Intel bus interface by changing the function of

some pins (reset is inverted, DACKN, and IACKN enabled for

example).

The Philips Semiconductors 28L202 Dual Universal Asynchronous

Receiver/Transmitter (DUART) is a single–chip CMOS–LSI

communications device that provides two 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 use of the Interrupt system provides

intelligent interrupt vectors.

The operating mode and data format of each channel may be

programmed independently. Additionally, each receiver and

transmitter can select its operating speed as one of twenty–seven

fixed baud rates; a 16X clock derived from one of two programmable

counter/timers, 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 and bridges.

Each receiver and transmitter is buffered by 256 character FIFOs to

nearly eliminate the potential of receiver overrun, transmitter

underrun and to reduce interrupt overhead in interrupt driven

systems. In addition, a flow control capability (Xon/Xoff and

RTS/CTS) is provided to disable a remote transmitter when the

receiver buffer is full.

Also provided on the 28L202 is a multipurpose 8–bit I/O for each

channel. These can be used as general–purpose I/O ports or can be

assigned specific functions (such as clock inputs or status and

interrupt outputs) under program control. Normally they will be used

for modem control and DMA interface. All ports have change of state

detectors and input sections are always active making output

signals available to the internal circuits and the control processor.

The 28L202 are available in 52–pin plastic quad flat pack (PQFP),

or 56-pin TSSOP packages.

FEATURES

• Member of IMPACT family: 3.3 to 5.0 volt , –40°C to +85°C and

68K for 80xxx bus interface for all devices.

• Dual full–duplex independent asynchronous receiver/transmitters

• 256 character FIFOs for each receiver and transmitter

• Powers up to 9600 baud, 1 stop bit, no parity, 1 stop bit, interrupt

disabled, all I/O set to input.

• Pin programming to 68K or 80xxx bus interface

• Three character recognition system per channel, used as:

– General purpose character recognition

– Xon/Xoff character recognition

– Address recognition Wake up (multi–drop or “9 bit”) mode

– System provides 4 levels of automation on a recognition event

• Programmable data format

– 5 to 8 data bits plus parity and 9 bit mode

– Odd, even, no parity or force parity

– 9/16,1, 1.5 or 2 stop bits

• 16–bit programmable Counter/Timer

• Programmable baud rate for each receiver and transmitter

selectable from:

– 27 fixed rates: 50 to 2.0 Meg baud (includes MIDDI® rate)

– Other baud rates via external clocks and C/T

– Programmable user–defined rates derived from a

programmable Counter/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 8 bit I/O input port per channel loosely assigned to

each channel.

– Can serve as clock or control inputs

– Change of state detection on eight inputs

– Inputs have typically >100Mohm pull–up resistors

– Modem and DMA interface

• Versatile arbitrating interrupt system

– Interrupt system totally supports ‘single query’ polling

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

separate interrupt type outputs that may be wire ORed

(switched to open drain).

– Each FIFO can be independently programmed for any of 256

interrupt levels

– Watch dog timer for each receiver

• Maximum data transfer rates: 1X – 3 Mb/sec, 16X – 2 Mb/sec

• Automatic wake–up mode for multi–drop applications

• Start–end break interrupt/status

• Detects break which originates in the middle of a character

• On–chip crystal oscillator

• Power down mode at less than 10 µa

• Receiver time–out mode

• Single +3.3V or +5V power supply

2000 Feb 10

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