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
C3
C4
C5
C6
VDD2
_RESET
VSS2
VDD
C15
R0
R1
R2
R3
R4
R5
R6
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 1A at room
temperature; 10A at 85C
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
1A at room temperature and 10A
at 85C. 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
USAR A Semtech Company
Datasheet
USAR SerialCoder
TM
UR5HC703-600-FQ
Preliminary
USAR KeyCoder
TM
family
product specifications
Descri
DOC5-703-600-DS-102
2
USAR -- A Semtech Company
Ordering Code
Functional Diagram
TxD
4
Data
Buffer
Key
Matrix
Interface
Communication
Interface
Matrix
Scan Logic
Reset Logic
Oscillator
Power Supply
_RESET
OSCIN
_OSCOUT
8
16
R0-R7
C0-C15
USAR SerialCoder
TM
Package Options
Pitch in mm's
Ta=-20 C to +85 C
32-pin, Plastic LQFP
0.8
UR5HC703-600-FG
Other Materials
Type
Order number
USAR SerialCoder
TM
Eval Kit
Evaluation Kit
EVK5-703-600-XXX
USAR A Semtech Company
Datasheet
USAR SerialCoder
TM
UR5HC703-600-FQ
Preliminary
USAR KeyCoder
TM
family
product specifications
DOC5-703-600-DS-102
3
USAR -- A Semtech Company
Pin Definitions
Pin Numbers
Mnemonic
LQFP
Type
Name and Function
Power Supply
Vdd, Vdd2
8,5
PWR
Positive Supply Voltage
Vss, Vss2
11,7
PWR
Negative Power Supply:
Signal Ground
Reset
_RESET
6
I
Hardware reset pin: Reset Input
for orderly start-up. Low logic level is
required until power supply reaches
minimum operating voltage
Oscillator pins
OSCI
9
I
Oscillator input: Connect ceramic
resonator with built-in load capacitors
or CMOS clock from external oscillator
2 MHz operating frequency
_OSCO
10
O
Oscillator Output: Connect
ceramic
resonator with built-in load capacitors
or keep open if external oscillator
is used
Host Interface
TxD
27
0
Serial Data Output: Idle at high
voltage (logical 1), non-inverted Data
(direct connection to the UART)
Scanned
matrix pins
ROW0-ROW7
18-25
I, pup
Row matrix inputs: With pulsed
pull-up current sources
COL0-COL15
1-4,
O, nD
Column matrix output
12-17
26,28-32
Descri
USAR SerialCoder
TM
UR5HC703-600-FQ
Preliminary
USAR KeyCoder
TM
family
product specifications
Descri
Protocol
Serial transmissions are at the rate of 9600 Baud, 8 data bits, no parity,
least significant bit is transmitted first, Idle/Stop level is High (logical 1),
Start bit level is Low (logical 0), non-inverted Data.
Within 5ms after the power-up the IC sends a two-Byte Identifications String
of 0xF9, 0xFB. These two Bytes are transmitted only once after each reset
of the IC.
These two ID values also represent key release action in the locations
[Row=1, Column=15] and [Row=3, Column=15] on the key Matrix. Since
the values of these Bytes represent release action of the keys, extraneous
characters will never be generated, even if synchronization between the
Driver and IC is lost, or power fluctuations/erroneous resets are applied to
the chip. If logistics of the Driver do not permit "shared" use of the
Identification Values 0xF9 and 0xFB, then the user is advised not to
incorporate keys in the locations [Row=1, Column=15] and
[Row=3, Column=15] for the key Matrix design.
Subsequent single-Byte transmissions indicate the Row (0-7), Column
(0-15), and Press/Release action for each change of the state of every key.
If after the current key release all of the keys on the key Matrix are in the
released state, the last transmission is repeated. Host's Driver looking for
two Bytes with exactly the same value and key release indication (b7=1)
can recognize that the keyboard is completely idle.
Byte Transmission
Bit Number
Comment
b7
0 for key press, 1 for key release
b6
Column location in the key Matrix (0-15)
b5
b4
b3
b2
Row location in the key Matrix (0-7)
b1
b0
DOC5-703-600-DS-102
4
USAR -- A Semtech Company
USAR A Semtech Company
Datasheet
USAR A Semtech Company
Datasheet
USAR SerialCoder
TM
UR5HC703-600-FQ
Preliminary
USAR KeyCoder
TM
family
product specifications
Sample Schematic for the USAR UR5HC703-600-FG
DOC5-703-600-DS-102
5
USAR -- A Semtech Company
REV
0.7
App Circuit for UR5HC703-600-FG
(C)1999-2000, USAR Systems - A Semtech Company
To Keyboard Matrix
C 3
1
C 4
2
C 5
3
C 6
4
V D D 2
5
R E S E T
6
V S S 2
7
V D D
8
OSCIN
9
OSCOUT
10
VSS
11
C7
12
C8
13
C9
14
C10
15
C11
16
C 1 5
1 7
R 0
1 8
R 1
1 9
R 2
2 0
R 3
2 1
R 4
2 2
R 5
2 3
R 6
2 4
R7
25
C12
26
TXD
27
C13
28
C14
29
C0
30
C1
31
C2
32
U1
UR5HC703_600_FG
32-pin LQFP
GND
GROUND
POWER
CMOS_TTL_TxD
9600 Baud
IDLE=HIGH
Y1
2.00MHz
C2
2.2uF
10V
TxD
GND
GND
C1
.1uF
GND
GND
GND
OUT
1
GND
3
VDD
2
U2
Voltage Detector
2.2V or Higher
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