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UR5HC418 데이터시트 PDF




Semtech Corporation에서 제조한 전자 부품 UR5HC418은 전자 산업 및 응용 분야에서
광범위하게 사용되는 반도체 소자입니다.


 

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부품번호 UR5HC418 기능
기능 AT / PS/2 - Compatible Keyboard Encoder
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UR5HC418 데이터시트, 핀배열, 회로
DeskCoderTM UR5HC418
AT / PS/2 - Compatible
Keyboard Encoder
HID & SYSTEM MANAGEMENT PRODUCTS, KEYCODERTM FAMILY
DESCRIPTION
The DeskCoderTM keyboard encoder
functions as a versatile, low-power
desktop keyboard encoder, while
providing two bi-directional
channels for communication with a
BIOS-compatible system as well as
any optional keyboard-compatible
devices, such as a 101/102/104
desktop keyboard, OCR, barcode
reader, etc.
The DeskCoderTM fully supports the
IBM standard keyboard communi-
cation protocol; each key press
generates one of the scan codes
designated in the IBM Technical
Reference Manuals. The keyboard
encoder handles the scanning,
debounce, and encoding of 128
keys organized on an 8 x 16 matrix.
In addition to the system’s keyboard
communication port, the UR5HC418
provides a fully functional keyboard
input port that can be used by a
standard 101/102/104 keyboard or
another 8042-compatible device,
such as an external numeric
keypad, an OCR, or a bar-code
reader. Input from both the matrix
and the external device is
multiplexed and presented to the
system as if it were coming from a
single source.
The DeskCoderTM is ideal for use in
low-power, low-cost and high-
reliability AT / PS/2 - compatible
keyboard designs.
Note: A version of the IC that
supports the PC/XT protocol is also
available. Contact Semtech for
more information.
FEATURES
• Interfaces contact switch matrix
keyboards to a BIOS-compatible
system
• Single IC desktop keyboard
encoder
• Provides interface for an external
keyboard/keypad or other 8042-
compatible devices
• AT / PS/2 - compatible
APPLICATIONS
• Desktop computers
• Instrumentation
• Industrial keyboards
PIN ASSIGNMENTS
• Implements all functions of a
101/102/104 keyboard
• Low-power HCMOS
microcontroller, suitable for 3-volt
battery-operated systems
• Available in DIP, PLCC and QFP
packages
• Custom versions available in small
or large quantities
• Point of sales terminals
• Public information kiosks
_RESET 1
40 VCC
_IRQ 2
39 OSCI
VX 3
38 OSCO
NL 4
37 EKC1
R6 5
36 R7
RP 6
35 SL
KD 7
34 R5
KC 8
33 R4
EKC 9
32 R3
EKD 10 DIP 31 R2
CL 11
30 R1
C0 12
29 R0
C1 13
28 C8
C2 14
27 C9
C3 15
26 C10
C4 16
25 C11
C5 17
24 C12
C6 18
23 C13
C7 19
22 C14
VSS/GND 20
21 C15
RP
KD
KC
EKC
EKD
CL
C0
C1
C2
C3
C4
6
7
12
17
18
R6
RP
KD
KC
EKC
EKD
CL
C0
C1
C2
C3
1
1
PLCC
23
QFP
40
39 R7
SL
R5
R4
R3
34 R2
R1
R0
C8
C9
29 C10
28
NL
R5
R4
R3
R2
R1
R0
C8
C9
C10
C11
DeskCoder and KeyCoder are trademarks of
Semtech Corporation. All other trademarks
belong to their respective companies.
Copyright ©1997-2001 Semtech Corporation
DOC5-418-DS-109
1
www.semtech.com




UR5HC418 pdf, 반도체, 판매, 대치품
SPECIAL HANDLING
Connection of External
Device
The DeskCoderTM detects the
presence of an external device. If
an external keyboard or other
device is not connected at power-on
and is connected at a later time, the
encoder proceeds with the normal
reset routine in order to properly
initialize the external device. After
communication has been
established, the encoder continues
to check for the presence of the
external device. If the device is
disconnected at a later time, the
encoder becomes aware of it. If a
subsequent connection takes place,
the controller re-initiates a reset
sequence. This unique feature
allows the user to connect or
disconnect an external device at
any time without having to reset the
system.
Shift Status LEDs
Shift Status LEDs (Num Lock, Caps
Lock and Scroll Lock) indicate the
status of the system and are
controlled by commands sent from
the system. Set/Reset Status
Indicator Commands from the
system will be executed both by the
external keyboard and the scanned
matrix.
For example, if the user presses the
Caps Lock Key on either keyboard,
the Caps Lock LED will be effected
on both keyboards. The LED status
indicators are properly set after
each new connection of an external
keyboard.
MODE CONTROL
N-Key Rollover
In this mode, the code(s) corresponding to each key press are transmitted
to the host system as soon as that key is debounced, independently of the
release of other keys.
If a key is defined to be Typematic, the corresponding make code(s) are
transmitted while the key is held pressed. When a key is released, the
corresponding break code(s) are then transmitted to the host system. If the
released key happens to be the most recently pressed, then Typematic
action is terminated. There is no limitation in the number of keys that can
be held pressed at the same time. However, two or more key closures,
occurring within a time interval less than five mS, set an error flag and are
not processed. This procedure protects against effects of accidental key
presses.
“Ghost” Keys
In any scanned contact switch matrix, whenever three keys defining a
rectangle on the switch matrix are pressed at the same time, a fourth key
positioned on the fourth corner of the rectangle is sensed as being
pressed. This is known as the ghostor phantomkey problem. Although
the problem cannot be totally eliminated without using external hardware,
there are methods to neutralize its negative effects for most practical
applications. Keys that are intended to be used in combinations or are
likely to be pressed at the same time by a fast typist (i.e., keys located in
adjacent positions on the keyboard) should be placed in the same row or
column of the matrix whenever possible. Shift Keys (Shift, Alt, Ctrl) should
not reside in the same row (or column) with any other keys.
The DeskCoderTM has built-in
mechanisms to detect the presence of
a ghostkey, thus eliminating the
necessity of external hardware.
Actual key presses
Ghost
Key
Figure 1: Ghostor PhantomKey
Problem
Copyright ©1997-2001 Semtech Corporation
DOC5-418-DS-109
4
www.semtech.com

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UR5HC418 전자부품, 판매, 대치품
IMPLEMENTATION NOTES FOR THE UR5HC418
The following notes pertain to the suggested schematics found on the next
pages.
The built-in oscillator on the UR5HC418 requires the attachment of the 4.00
MHz ceramic resonators with built-in load capacitors. You can use either an
AVX, part number PBRC-1.00 BR; or a Murata part number CSTCC4.00MG
ceramic resonator.
It may also be possible to operate with the 4.00 MHz crystal, albeit with
reduced performance. Due to their high Q, the crystal oscillator circuits
start-up slowly. Since the DeskCoderTM constantly switches the clock on and
off, it is important that a ceramic resonator is used (it starts up much quicker
than the crystal). Resonators are also less expensive than crystals.
Also, if crystal is attached, two load capacitors (33pF to 47pF) should be
added, a capacitor between each side of the crystal and ground.
In both cases, using ceramic resonator with built-in load capacitors, or
crystal with external load capacitors, a feedback resistor of one MegaOhm
should be connected between OSCin and OSCout.
Troubleshoot the circuit by looking at the output pin of the oscillator. If the
voltage it half-way between supply and ground (while the oscillator should
be running) --- the problem is with the load caps / crystal. If the voltage it all
the way at supply or ground (while the oscillator should be running) --- there
are shorts on the PCB.
Note: when the oscillator is intentionally turned off, the voltage on the output
pin of the oscillator is high (at the supply rail).
Copyright ©1997-2001 Semtech Corporation
DOC5-418-DS-109
7
www.semtech.com

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