MC14490 ON Semiconductor, MC14490 Datasheet - Page 6

• Manufacturer Part Number: MC14490
• Description: Hex Contact Bounce Eliminator
• Manufacturer: ON Semiconductor

is that it works with a single signal lead as an input, making
it directly compatible with mechanical contacts (Form A
and B).
The worst case value of the pullup resistor (determined from
the Electrical Characteristics table) is used to calculate the
contact wetting current. If more contact current is required,
an external resistor may be connected between V
input.
be driven with a single standard CMOS gate when V
below 5 V. At this voltage, the input should be driven with
The single most important characteristic of the MC14490
The circuit has a built–in pullup resistor on each input.
Because of the built–in pullup resistors, the inputs cannot
FROM CONTACTS
OSC
OSC
C
ext
CONTACT
“FORM A”
in
out
1
7
9
A
in
CLOCK GENERATOR
+V
TWO–PHASE
OSCILLATOR
OSC
DD
AND
in
MC14490
PULLUP RESISTOR
7
C
Figure 4. Typical “Form A” Contact Debounce Circuit
ext
(INTERNAL)
Figure 5. Typical Single Oscillator Debounce System
9
OSC
1/6 MC14050
out
OPERATING CHARACTERISTICS
1
2
TO SYSTEM
(Only One Debouncer Shown)
LOGIC
DD
and the
http://onsemi.com
DD
4–BIT STATIC SHIFT REGISTER
FROM CONTACTS
MC14490
is
SHIFT
CONTACTS
6
FROM
paralleled standard gates or by the MC14049 or MC14050
buffers.
such that proper clocking will occur even with very slow
clock edges, eliminating any need for clock preshaping. In
addition, other MC14490 oscillator inputs can be driven
from a single oscillator output buffered by an MC14050 (see
Figure 5). Up to six MC14490s may be driven by a single
buffer.
the outputs. When V
sink 1.6 mA at 0.4 V. The inputs can be driven with TTL as
a result of the internal input pullup resistors.
DATA
The clock input circuit (pin 7) has Schmitt trigger shaping
The MC14490 is TTL compatible on both the inputs and
LOAD
OSC
OSC
in
7
1
in
MC14490
MC14490
7
2
DD
9 OSC
9 OSC
is at 4.5 V, the buffered outputs can
NO CONNECTION
NO CONNECTION
1/2 BIT
DELAY
out
out
1
TO SYSTEM
TO SYSTEM
LOGIC
LOGIC
2
15
A
out