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K25C81-FB Datasheet Download - Semtech

Номер произв K25C81-FB
Описание Versatile PC/XC/AT/PS/2 Compatible Keyboard Encoder
Производители Semtech
логотип Semtech логотип 

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K25C81-FB Даташит, Описание, Даташиты
FlexiCoderTM K25C81
Versatile PC/XC/AT/PS/2 Compatible
Keyboard Encoder
HID & SYSTEM MANAGEMENT PRODUCTS, KEYCODERTM FAMILY
DESCRIPTION
The FlexiCoderTM is a versatile, low-
power keyboard encoder. It offers
two bi-directional channels for
communicating with a
PC/XT/AT/PS2 system, and/or any
optional keyboard-compatible
devices, such as an 83 or 101/102
standard desktop keyboard, OCR,
barcode reader, etc. The K25C81
directly interfaces a PC keyboard
port, making custom keyboard to
system communications fully
transparent.
On an 8 x 18 matrix, the
FlexiCoderTM will scan, debounce
and encode up to 144 keys. Scan
codes corresponding to single keys
of the IBM 101 keyboard, or a
combination of these keys when
depressed with Shift, Ctrl, and Alt
keys, are generated with each key
press. Custom keypad input is not
effected by the Shift States of an
external keyboard.
Users can conveniently define key
assignments on the matrix as single
or repeating actions. All keys must
be released between key strokes or
scanning is suspended. The
encoder can buffer up to 122
keycodes, and control inputs and
outputs are provided for interfacing
with contact keyboards.
The FlexiCoderTM is ideal for use
with either BIOS-compatible chip
sets or single-board computers for
PC systems requiring a custom
keyboard / keypad as an alternate
or additional input device. Boards
and evaluation kits are immediately
obtainable and ready to connect.
FEATURES
• Directly interfaces a PC
keyboard port
• Encodes up to 144 custom keys
on an 8 X 18 matrix
• Buffers up to 122 keycodes
• Interfaces to 83/101/102
standard keyboard or other
8042-compatible device
APPLICATIONS
• Custom keyboards/keypads
• Control panels
• Automatic teller machines
• Embedded control systems
• Public Information Kiosks
PIN ASSIGNMENTS
• Enables custom keypad scan
codes to remain unaffected by
the Shift States of an external
keyboard
• Includes jumper-selectable auto-
repeat for designated keys
• Offers two-key inhibit scanning
mode
• Instrumentation
• Test and Measurement equipment
• Point of Sales terminals
• Industrial Controllers
• Medical Instruments
_RESET 1
_IRQ 2
VX 3
C17 4
R6 5
RP 6
KD 7
KC 8
EKC 9
EKD 10
C16 11
C0 12
C1 13
C2 14
C3 15
C4 16
C5 17
C6 18
C7 19
Vss 20
DIP
40 Vcc
39 OSCI
38 OSCO
37 EKC1
36 R7
35 NC
34 R5
33 R4
32 R3
31 R2
30 R1
29 R0
28 C8
27 C9
RP
KD
KC
EKC
EKD
C16
C0
C1
C2
C3
C4
6
7
12
17
18
26 C10
25 C11
24 C12
23 C13
22 C14
21 C15
1
PLCC
23
40
39 R7
NC
R5
R4
R3
34 R2
R1
R0
C8
C9
29 C10
28
R6
RP
KD
KC
EKC
EKD
C16
C0
C1
C2
C3
1
QFP
NC
R5
R4
R3
R2
R1
R0
C8
C9
C10
C11
FlexiCoderTM is a trademark of Semtech Corp. All
other trademarks belong to their respective
companies.
Copyright Semtech, 1997-2001
DOC5-C81-DS-105
1
www.semtech.com







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K25C81-FB Даташит, Описание, Даташиты
FUNCTIONAL DIAGRAM
ORDERING CODE
Package options
40-pin, Plastic DIP
44-pin, Plastic PLCC
44-pin, Plastic QFP
Pitch In mm’s
2.54 mm
1.27 mm
0.8 mm
TA = -40°C to +85°C
K25C81-XX-P
K25C81-XX-FN
K25C81-XX-FB
Data Buffer
Keyboard Encoder
EKC1
Interrupt Control
Row Data Inputs
Column Select Ouputs
R0-R7
8
C0-C17
18
KC PC
Communication
KD Channel
EKC
EKD
8042 Emulation
(Standard Keyboard)
Communication Channel
Mode Control
RP
Copyright Semtech, 1997-2001
DOC5-C81-DS-105
2
www.semtech.com







No Preview Available !

K25C81-FB Даташит, Описание, Даташиты
FUNCTIONAL DESCRIPTION
The FlexiCoderTM consists of six
major sections (see functional
diagram, previous page). These
are the Keyboard Encoder, the
Mode Control Unit, the PC
Communication Channel, the 8042
Emulation Channel, the Interrupt
Control Unit and the Data Buffer.
These sections communicate with
each other and operate
concurrently.
The controller continuously scans a
keyboard organized as an 8 row by
18 column matrix, for a maximum of
144 keys. Smaller-size keyboards
can be connected provided that all
unused row pins are connected to
Vcc. The microcontroller selects
one of the 18 column lines (C0-C17)
every 512 µS and then reads the
row data lines (R0-R7).
A key closure is detected as a zero
in the corresponding position of the
matrix. A complete scan cycle for
the entire keyboard takes approxi-
mately 9.2 mS. Each key press is
debounced for a period of 20 mS.
Once the key is verified, the
corresponding key code(s) are
loaded into the transmit buffer of
the PC Keyboard Communication
Channel.
PIN DEFINITIONS
Mnemonic
Vcc
Vss
OSCI
OSCO
_RESET
DIP
40
20
39
38
1
_IRQ
VX
RP
2
3
6
KC
KD
EKD
EKC
EKC1
8
7
10
9
37
C0-C7
C8-C15
C16
C17
12-19
28-21
11
4
R0-R5
R6
R7
NC
29-34
5
36
35
PLCC
44
22
43
42
1
2
4
7
9
8
11
10
41
3-17
18
19-21
31-24
12
5
32-37
6
39
38, 3
18, 23
40
QFP
38
17
37
36
41
42
43
2
4
3
6
5
35
8-15
26-18
7
44
27-32
1
34
16, 33
22, 39
40
TYPE
I
I
I
O
I
I
I
I
I/O
I/O
I/O
I/O
I
O
O
I/O
I
I
I
-
-
Name and Function
Power Supply: +5V
Ground
Oscilator Input
Oscilator Output
Reset: apply 0 V to provide orderly
start-up.
Must be tied to Vcc
Tie to Vcc.
Rollover Mode Selection: tie to
Vcc to select N-Key Rollover. Tie to
Ground to select Two-Key Inhibit
Mode.
Keyboard Clock: connects to PC’s
keyboard port Clock Line.
Keyboard Data: connects to PC’s
keyboard port Data Line.
External Keyboard Data:
connects to external keyboard Data
Line.
External Keyboard Clock:
connects to external keyboard Clock
Line.
External Keyboard Clock 2:
connects to external keyboard Clock
Line and is used to generate an
interrupt for every Clock Line transition.
This signal must be inverted for PC/XT
keyboards.
Column Select Outputs: select
one of columns.
Keyboard type selection: this pin
is used both as outputs for column
select and as input for standard
keyboard-type selection.
Row data inputs
No Connects: these pins are
unused.
Note: An underscore before a pin mnemonic denotes an active low signal.
Copyright Semtech, 1997-2001
DOC5-C81-DS-105
3
www.semtech.com










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