CDP1871A Datasheet, PDF (1/10 Pages) Intersil Corporation – CMOS Keyboard Encoder

REFERENCE APP NOTE 7374
August 1996
CDP1871A,
CDP1871AC
CMOS Keyboard Encoder
Features
• Directly Interfaces with CDP1800-Series Microprocessor
• Low Power Dissipation
• Three-State Outputs
• Scans and Generates Code for 53 Key ASCII Keyboard Plus
32 HEX Keys (SPST Mechanical Contact Switches)
• Shift, Control, and Alpha Lock Input
• RC-Controlled Debounce Circuitry
• Single Supply 4V to 10.5V . . . . . . . . . . . . . (CDP1871A)
4V to 6.5V . . . . . . . . . . . . . (CDP1871AC)
• N-Key Lockout
Ordering Information
PACKAGE
PDIP
PLCC
SBDIP
TEMP. RANGE
5V
-40^oC to +85^oC CDP1871ACE
-40^oC to +85^oC CDP1871ACQ
-40^oC to +85^oC CDP1871ACD
PKG.
10V
NO.
CDP1871AE E40.6
-
N44.65
CDP1871AD D40.6
Burn-In
CDP1871ACDX
-
D40.6
Description
The CDP1871A is a keyboard encoder designed to
directly interface between a CDP1800-series micro-
processor and a mechanical keyboard array, providing
up to 53 ASCII coded keys and 32 HEX coded keys,
as shown in the system diagram (Figure 1).
The keyboard may consist of simple single-pole
single-throw (SPST) mechanical switches. Inputs are
provided for alpha-lock, control, and shift functions,
allowing 160 unique codes. An external R-C input is
available for user-selectable debounce times. The N-
key lock-out feature prevents unwanted key codes if
two or more keys are pressed simultaneously.
The CDP1871A and CDP1871AC are functionally
identical. They differ in that the CDP1871A has a
recommended operating voltage range of 4V to 10.5V,
and the CDP1871AC has a recommended operating
voltage range 4V to 6.5V. These types are supplied in
40 lead dual-in-line ceramic packages (D suffix), and
40 lead dual-in-line plastic packages (E suffix), and 44
lead plastic chip-carrier packages (Q suffix).
Pinouts
40 LEAD PDIP, CERDIP
TOP VIEW
D1 1
D2 2
D3 3
D4 4
D5 5
D6 6
D7 7
D8 8
D9 9
D10 10
D11 11
S1 12
S2 13
S3 14
S4 15
S5 16
S6 17
S7 18
S8 19
V_SS 20
40 V_DD
39 SHIFT
38 CONTROL
37 ALPHA
36 DEBOUNCE
35 RTP
34 TPB
33 DA
32 BUS 7
31 BUS 6
30 BUS 5
29 BUS 4
28 BUS 3
27 BUS 2
26 BUS 1
25 BUS 0
24 CS4
23 CS3
22 CS2
21 CS1
44 LEAD PLCC
(Q Suffix) TOP VIEW
6 5 4 3 2 1 44 43 42 41 40
D5 7
39
D6 8
38
D7 9
37
D8 10
36
D9 11
35
D10 12
34
D11 13
33
S1
14
32
S2
15
31
S3
16
30
S4
17
29
18 19 20 21 22 23 24 25 26 27 28
RPT
TPB
DA
BUS 7
BUS 6
BUS 5
BUS 4
BUS 3
BUS 2
BUS 1
NC
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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File Number 1374.2