
1
9
16
8
25
32
24
17
UR5HC703-600-FG
LQFP
C2
C1
C0
C14
C13
TxD
C12
R7
OSCIN
_OSCOUT
VSS
C7
C8
C9
C10
C11
C
C
C
C
V
_
V
V
C
R
R
R
R
R
R
R
USAR SerialCoder
TM
UR5HC703-600-FG
USAR SerialCoder
TM
Low-Power Keyboard Encoder
interfaces RS-232
Preliminary
USAR KeyCoder
TM
family
product specifications
Description
Features
8 x 16 Matrix Encoding
9600 Baud 8N1Serial Data Format
IC is independent of the
keyboard layout
Zero-Power
TM
operation,
transparent to the Host
Average current consumption of
less than 1μA at room
temperature; 10μA at 85°C
Customized versions available
TTL/CMOS Output-only
Asynchronous Serial Interface
to the Host (direct connection to
the UART)
Very simple serial protocol —
Two-Byte Identification String on
power-up; single-Byte Matrix-
position for each key-press or
key-release
Robust algorithm for Ghost-key
elimination
Applications
Built-in keyboards for HH
PDAs/Organizers
Add-on accessory keyboards for
Palm and H/PC Devices
Portable Personal Computers
Instrumentation
Remote Control
Cellular Phones
DOC5-703-600-DS-102
1
Pin Assignments
The USAR SerialCoder
TM
UR5HC703 is an extremely
low-power, “off-the-shelf” serial
keyboard encoder. Robust, tiny
and flexible, the IC is a good
match for any application where
the use of complicated keyboard
protocols are not required and
where asynchronous serial
interface hardware is available.
The USAR SerialCoder
TM
provides
unprecedented power
consumption minimization, making
it ideal for use in add-on keyboards
for handheld and cellular / web
phones and single-board systems
designed for portable applications.
The IC provides Zero-Power
TM
operation, transparent to the host.
Power consumption is reduced to
just the circuit’s leakage when all
keys are released. The average
current consumption is less than
1μA at room temperature and 10μA
at 85°C. If a single key or groups
of keys are stuck in the depressed
position, the IC will enter a total
shutdown after a 10-minute wait —
to protect against unintended and
unnecessary discharge of the
batteries in the Host.
Custom versions of the USAR
SerialCoder
TM
are available with
Hardware Handshaking for the
Communication channel, support
for extra-low-power operations of
the Host, various baud rates and
Full-Duplex I/O, etc. The USAR
SerialCoder
TM
is simple to
implement. It requires few external
components and utilizes a tiny, low-
profile 32-pin LQFP package that
measures 7mm x 7mm.
Copyright 2000 USAR Systems, Inc. All rights
reserved.
USAR – A Semtech Company
Datasheet
A Semtech Company