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PDF MC14490 Data sheet ( Hoja de datos )
| Número de pieza | MC14490 | |
| Descripción | Hex Contact Bounce Eliminator | |
| Fabricantes | Motorola Semiconductors | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de MC14490 (archivo pdf) en la parte inferior de esta página. Total 9 Páginas | ||
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MOTOROLA
SEMICONDUCTOR TECHNICAL DATA
MC14490
Hex Contact Bounce Eliminator
The MC14490 is constructed with complementary MOS enhancement
mode devices, and is used for the elimination of extraneous level changes
that result when interfacing with mechanical contacts. The digital contact
bounce eliminator circuit takes an input signal from a bouncing contact and
generates a clean digital signal four clock periods after the input has
stabilized. The bounce eliminator circuit will remove bounce on both the
“make” and the “break” of a contact closure. The clock for operation of the
MC14490 is derived from an internal R–C oscillator which requires only an
external capacitor to adjust for the desired operating frequency (bounce
delay). The clock may also be driven from an external clock source or the
oscillator of another MC14490 (see Figure 5).
NOTE: Immediately after power–up, the outputs of the MC14490 are in
indeterminate states.
• Diode Protection on All Inputs
• Six Debouncers Per Package
• Internal Pullups on All Data Inputs
• Can Be Used as a Digital Integrator, System Synchronizer, or Delay
Line
• Internal Oscillator (R–C), or External Clock Source
• TTL Compatible Data Inputs/Outputs
• Single Line Input, Debounces Both “Make” and “Break” Contacts
• Does Not Require “Form C” (Single Pole Double Throw) Input Signal
• Cascadable for Longer Time Delays
• Schmitt Trigger on Clock Input (Pin 7)
• Supply Voltage Range = 3.0 V to 18 V
• Chip Complexity: 546 FETs or 136.5 Equivalent Gates
L SUFFIX
CERAMIC
CASE 620
P SUFFIX
PLASTIC
CASE 648
DW SUFFIX
SOIC
CASE 751G
ORDERING INFORMATION
MC14490P
MC14490L
MC14490DW
Plastic
Ceramic
SOIC
TA = – 55° to 125°C for all packages.
Ain 1
OSCin 7
OSCout 9
Bin 14
Cin 3
Din 12
Ein 5
Fin 10
+VDD
OSCILLATOR
AND
TWO–PHASE
CLOCK GENERATOR
BLOCK DIAGRAM
DATA
4–BIT STATIC SHIFT REGISTER
SHIFT LOAD
φ1
φ2
IDENTICAL TO ABOVE STAGE
IDENTICAL TO ABOVE STAGE
IDENTICAL TO ABOVE STAGE
IDENTICAL TO ABOVE STAGE
IDENTICAL TO ABOVE STAGE
φ1 φ2
φ1 φ2
φ1 φ2
φ1 φ2
φ1 φ2
φ1 φ2
1/2–BIT
DELAY
φ1 φ2
15 Aout
VDD = PIN 16
VSS = PIN 8
2 Bout
13 Cout
4 Dout
11 Eout
6 Fout
REV 3
1/94
©MMOotoTrOolaR, IOncL. A199C5MOS LOGIC DATA
MC14490
297
1 page  
+VDD
PULLUP RESISTOR
1 Ain
“FORM A”
CONTACT
(INTERNAL)
OSCin 7
Cext 9
OSCout
OSCILLATOR
AND
TWO–PHASE
CLOCK GENERATOR
φ1
φ2
DATA
4–BIT STATIC SHIFT REGISTER
SHIFT LOAD
φ1 φ2
1/2 BIT
DELAY
φ1 φ2
Figure 4. Typical “Form A” Contact Debounce Circuit
(Only One Debouncer Shown)
15
Aout
OPERATING CHARACTERISTICS
The single most important characteristic of the MC14490
is that it works with a single signal lead as an input, making
it directly compatible with mechanical contacts (Form A
and B).
The circuit has a built–in pullup resistor on each input. The
worst case value of the pullup resistor (determined from the
Electrical Characteristics table) is used to calculate the con-
tact wetting current. If more contact current is required, an
external resistor may be connected between VDD and the
input.
Because of the built–in pullup resistors, the inputs cannot
be driven with a single standard CMOS gate when VDD is be-
low 5 V. At this voltage, the input should be driven with paral-
leled standard gates or by the MC14049 or MC14050
buffers.
The clock input circuit (pin 7) has Schmitt trigger shaping
such that proper clocking will occur even with very slow clock
edges, eliminating any need for clock preshaping. In addi-
tion, other MC14490 oscillator inputs can be driven from a
single oscillator output buffered by an MC14050 (see Fig-
ure 5). Up to six MC14490s may be driven by a single buffer.
The MC14490 is TTL compatible on both the inputs and
the outputs. When VDD is at 4.5 V, the buffered outputs can
sink 1.6 mA at 0.4 V. The inputs can be driven with TTL as a
result of the internal input pullup resistors.
Cext 1/6 MC14050
OSCin 7 9 OSCout
OSCin 7
NO CONNECTION
9 OSCout
FROM
CONTACTS
MC14490
TO SYSTEM
LOGIC
FROM CONTACTS
MC14490
TO SYSTEM
LOGIC
OSCin 7
NO CONNECTION
9 OSCout
FROM CONTACTS
MC14490
TO SYSTEM
LOGIC
Figure 5. Typical Single Oscillator Debounce System
MOTOROLA CMOS LOGIC DATA
MC14490
301
5 Page | ||
| Páginas | Total 9 Páginas | |
| PDF Descargar | [ Datasheet MC14490.PDF ] | |
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