MC14490 Ver la hoja de datos (PDF) - Motorola => Freescale
Número de pieza
componentes Descripción
Fabricante
MC14490 Datasheet PDF : 9 Pages
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ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ SWITCHING CHARACTERISTICS (CL = 50 pF, TA = 25_C)
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ Output Rise Time
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ All Outputs
Characteristic
Symbol
tTLH
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ Output Fall Time
Oscillator Output
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ Debounce Outputs
tTHL
tTHL
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ Propagation Delay Time
Oscillator Input to Debounce Outputs
tPHL
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ tPLH
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ Clock Frequency (50% Duly Cycle)
fcl
(External Clock)
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ Setup Time (See Figure 1)
tsu
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ Maximum External Clock Input
Rise and Fall Time
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ Oscillator Input
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ Oscillator Frequency
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ OSCout
Cext ≥ 100 pF*
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ Note: These equations are intended to be a design guide.
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ Laboratory experimentation may be required. Formulas
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ are typically ± 15% of actual frequencies.
tr, tf
fosc, typ
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ * The formulas given are for the typical characteristics only at 25_C.
VDD
Vdc
5.0
10
15
5.0
10
15
5.0
10
15
5.0
10
15
5.0
10
15
5.0
10
15
5.0
10
15
5.0
10
15
5.0
10
15
Min
Typ #
Max
—
180
360
—
90
180
—
65
130
—
100
200
—
50
100
—
40
80
—
60
120
—
30
60
—
20
40
—
285
570
—
120
240
—
95
190
—
370
740
—
160
320
—
120
240
—
2.8
1.4
—
6
3.0
—
9
4.5
100
50
—
80
40
—
60
30
—
No Limit
1.5
Cext (in µF)
4.5
Cext (in µF)
6.5
Cext (in µF)
Unit
ns
ns
ns
MHz
ns
ns
Hz
#Data labelled “Typ” is not to be used for design purposes but is intended as an indication of the IC’s potential performance.
*POWER–DOWN CONSIDERATIONS
Large values of Cext may cause problems when powering down the MC14490 because of the amount of energy stored in the
capacitor. When a system containing this device is powered down, the capacitor may discharge through the input protection
diodes at Pin 7 or the parasitic diodes at Pin 9. Current through these internal diodes must be limited to 10 mA, therefore the
turn–off time of the power supply must not be faster than t = (VDD – VSS) Cext / (10 mA). For example, If VDD – VSS = 15 V and
Cext = 1 µF, the power supply must turn off no faster than t = (15 V) (1 µF) / 10 mA = 1.5 ms. This is usually not a problem
because power supplies are heavily filtered and cannot discharge at this rate.
When a more rapid decrease of the power supply to zero volts occurs, the MC14490 may sustain damage. To avoid this possi-
bility, use external clamping diodes, D1 and D2, connected as shown in Figure 2.
VDD
OSCin
50%
0V
tPLH
Aout
50% 90%
10%
D1
Cext
D2
tr
VDD
VDD
tPHL
Aout
90% 50%
10%
7
9
OSCin OSCout
tf
OSCin
VDD
50%
0V
tsu
Ain
50%
VDD
0V
MC14490
Figure 1. Switching Waveforms
Figure 2. Discharge Protection During Power Down
MOTOROLA CMOS LOGIC DATA
MC14490
299
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