Exar Corporation 48720 Kato Road, Fremont CA, 94538 (510) 668-7000 FAX (510) 668-7017 www.exar.com
XR16M654/654D
1.62V TO 3.63V QUAD UART WITH 64-BYTE FIFO
MAY 2008
REV. 1.0.0
GENERAL DESCRIPTION
The XR16M6541 (M654) is an enhanced quad
Universal Asynchronous Receiver and Transmitter
(UART) each with 64 bytes of transmit and receive
FIFOs, programmable transmit and receive FIFO
trigger levels, automatic hardware and software flow
control, and data rates of up to 16 Mbps at 4X
sampling rate. Each UART has a set of registers that
provide the user with operating status and control,
receiver error indications, and modem serial interface
controls.
An internal loopback capability allows
onboard diagnostics. The M654 is available in a 48-
pin QFN, 64-pin LQFP, 68-pin PLCC, 80-pin LQFP
and 100-pin QFP packages. The 64-pin and 80-pin
packages only offer the 16 mode interface, but the
48, 68 and 100 pin packages offer an additional 68
mode interface which allows easy integration with
Motorola processors.
The XR16M654IV (64-pin)
offers
three
state
interrupt
output
while
the
XR16M654DIV provides continuous interrupt output.
The 100 pin package provides additional FIFO status
outputs (TXRDY# and RXRDY# A-D), separate
infrared transmit data outputs (IRTX A-D) and
channel C external clock input (CHCCLK). The
XR16M654 is compatible with the industry standard
ST16C554 and ST16C654/654D.
NOTE: 1 Covered by U.S. Patent #5,649,122.
FEATURES
Pin-to-pin compatible with ST16C454, ST16C554,
TI’s TL16C754B and NXP’s SC16C654B
Intel or Motorola Data Bus Interface select
Four independent UART channels
■ Register Set Compatible to 16C550
■ Data rates of up to 16 Mbps
■ 64 Byte Transmit FIFO
■ 64 Byte Receive FIFO with error tags
■ 4 Selectable TX and RX FIFO Trigger Levels
■ Automatic Hardware (RTS/CTS) Flow Control
■ Automatic Software (Xon/Xoff) Flow Control
■ Progammable Xon/Xoff characters
■ Wireless Infrared (IrDA 1.0) Encoder/Decoder
■ Full modem interface
1.62V to 3.63V supply operation
Sleep Mode with automatic wake-up
Crystal oscillator or external clock input
APPLICATIONS
Portable Appliances
Telecommunication Network Routers
Ethernet Network Routers
Cellular Data Devices
Factory Automation and Process Controls
FIGURE 1. XR16M654 BLOCK DIAGRAM
XTAL1
XTAL2
Crystal Osc/Buffer
Data Bus
Interface
UART Channel A
64 Byte TX FIFO
64 Byte RX FIFO
BRG
IR
ENDEC
TX & RX
UART
Regs
1.62V to 3.6V VCC
GND
654 BLK
TXB, RXB, IRTXB, DTRB#,
DSRB#, RTSB#, CTSB#,
CDB#, RIB#
UART Channel B
(same as Channel A)
A2:A0
D7:D0
CSA#
16/68#
CSB#
INTA
INTB
IOW#
IOR#
Reset
INTSEL
CHCCLK
TXRDY# A-D
RXRDY# A-D
UART Channel C
(same as Channel A)
TXA, RXA, IRTXA, DTRA#,
DSRA#, RTSA#, CTSA#,
CDA#, RIA#
TXC, RXC, IRTXC, DTRC#,
DSRC#, RTSC#, CTSC#,
CDC#, RIC#
UART Channel D
(same as Channel A)
TXD, RXD, IRTXD, DTRD#,
DSRD#, RTSD#, CTSD#,
CDD#, RID#
CSC#
CSD#
INTC
INTD
CLKSEL