
Exar
Corporation 48720 Kato Road, Fremont CA, 94538
(510) 668-7000
FAX (510) 668-7017
www.exar.com
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ST16C650A
2.90V TO 5.5V UART WITH 32-BYTE FIFO
JANUARY 2004
GENERAL DESCRIPTION
REV. 5.0.0
The ST16C650A
1
(650A) is a 2.90 to 5.5 volt
Universal Asynchronous Receiver and Transmitter
(UART) with 5 volt tolerant inputs. This device
supports Intel and PC ISA mode data bus interfaces
and is software compatible to industry standard
16C450, 16C550, ST16C580 and ST16C650A
UARTs.
The 650A has 32 bytes of TX and RX FIFOs and is
capable of operating up to serial data rates of 3.125
Mbps at 5 volt supply voltage. The internal registers
include the 16C550 register set plus Exar’s enhanced
registers for additional features to support today’s
highly demanding data communication needs. The
enhanced features include automatic hardware and
software flow control, selectable TX and RX trigger
levels, and wireless infrared (IrDA) encoder/decoder.
The device provides a new capability to give user the
ability to program the wireless infrared encoder
output pulse width, hence reducing the power
consumption of a handheld unit.
The ST16C650A device comes in the 44-pin PLCC
and 48-pin TQFP packages in both the commercial
and industrial temperature ranges.
N
OTE
:
1 Covered by US patents #5,649,122.
FEATURES
Added features in top mark date code of "HC YYWW"
and newer:
I
2.90 to 5.5 Volt Operation
I
5 Volt Tolerant Inputs
I
Automatic RS485 Half-Duplex Control Output
I
Programmable Infrared Encoder Pulse Width
I
Sleep Mode with Wake-up Indicator
I
Device ID & Revision
I
Up to 3.125 Mbps Data Rate at 5 Volts
Added feature in top mark date code of "I2 YYWW"
and newer:
I
0 ns address hold time
Intel or PC Mode 8-bit Bus Interface
32-byte Transmit and Receive FIFOs
Automatic Hardware (RTS/CTS) Flow Control
Hardware Flow Control Hysteresis
Automatic Software (Xon/Xoff) Flow Control
APPLICATIONS
Battery Operated Electronics
Handheld Terminal
Personal Digital Assistants
Cellular Phones DataPort
Wireless Infrared Data Communications Systems
F
IGURE
1. B
LOCK
D
IAGRAM
XTAL1/CLK
XTAL2
Crystal Osc/Buffer
DTR#, DSR#,
RTS#, CTS#,
CD#, RI#
Intel,
Motorola
or PC
Data Bus
Interface
32 Byte TX FIFO
Baud Rate Generator
Infrared Encoder and
Pulse Width Control
Transmitter
UART
Configuration
Regs
IOR
IOR#
32 Byte RX FIFO
Infrared
Decoder
Receiver with Auto
Software Flow Control
Modem Control Signals
TX
RX
CTS Flow
Control
RTS Flow
Control
BRG
Prescaler
CS1
CS0
DDIS#
INT
TXRDY#
RDRDY#
A2:A0
D7:D0
IOW
CS2#
SEL
S1
S2
S3
IRQA
IRQB
IOW#
RESET
PC Mode:
COM 1 to 4
Decode Logic