L64704 LSI Logic Corporation, L64704 Datasheet - Page 212

• Manufacturer Part Number: L64704
• Description: Satellite Decoder Technical Manual 5/97
• Manufacturer: LSI Logic Corporation

C.2
Requirements
For Oscillator
Circuits
C.3
0 to 20 MHz
Crystal
Oscillator
Figure C.2
Pierce Crystal
Oscillator Circuit
C-2
The following requirements must be met for the oscillator circuits to
operate properly:
LSI Logic’s OSCXX cells are intended to be used with external compo-
nents to form an oscillator circuit, such as the one shown in
The recommended crystal is an AT-cut crystal. The inherent characteris-
tics of such a crystal produce a fundamental frequency (f
20 MHz and third overtone frequencies (f
60 MHz. Oscillation begins when the power is turned on.
Crystals by nature are usually immune to power supply and temperature
variations, thereby providing very stable frequencies over the V
ranges of the ASIC devices. In addition, the duty cycle of the output
waveform for the circuit in
producing a clean symmetrical waveform.
1. R
Oscillator Cells
R
1 to 5 Meg ohms.
C
DC
The V
to start up the oscillator.
The EN pin must be tied to V
be used to enable or disable the oscillator.
DC
1
Crystal
= the DC resistance of the crystal. R
OSCIM
DD
ramp time must be greater than or equal to 1 millisecond
R
C
2
2
Figure C.2
DD
. This means that the EN pin cannot
DC
approaches the ideal of 50%,
should be in the range from
3OT
) between 20 MHz and
F
) less than
Figure
DD
and T
C.2.
A