PIC16CR56AT-LPE/SS View Datasheet(PDF) - Microchip Technology
Part Name
Description
Manufacturer
PIC16CR56AT-LPE/SS Datasheet PDF : 192 Pages
| |||
PIC16C5X
4.3 External Crystal Oscillator Circuit
Either a prepackaged oscillator or a simple oscillator
circuit with TTL gates can be used as an external crys-
tal oscillator circuit. Prepackaged oscillators provide a
wide operating range and better stability. A well-
designed crystal oscillator will provide good perfor-
mance with TTL gates. Two types of crystal oscillator
circuits can be used: one with parallel resonance, or
one with series resonance.
Figure 4-3 shows an implementation example of a par-
allel resonant oscillator circuit. The circuit is designed
to use the fundamental frequency of the crystal. The
74AS04 inverter performs the 180-degree phase shift
that a parallel oscillator requires. The 4.7 k resistor
provides the negative feedback for stability. The 10 k
potentiometers bias the 74AS04 in the linear region.
This circuit could be used for external oscillator
designs.
FIGURE 4-3:
EXAMPLE OF EXTERNAL
PARALLEL RESONANT
CRYSTAL OSCILLATOR
CIRCUIT (USING XT, HS
OR LP OSCILLATOR
MODE)
+5V
10K
4.7K
74AS04
To Other
Devices
74AS04
PIC16C5X
CLKIN
XTAL
Open
10K
OSC2
10K
20 pF 20 pF
Figure 4-4 shows a series resonant oscillator circuit.
This circuit is also designed to use the fundamental fre-
quency of the crystal. The inverter performs a 180-
degree phase shift in a series resonant oscillator cir-
cuit. The 330 k resistors provide the negative feed-
back to bias the inverters in their linear region.
FIGURE 4-4:
EXAMPLE OF EXTERNAL
SERIES RESONANT
CRYSTAL OSCILLATOR
CIRCUIT (USING XT, HS
OR LP OSCILLATOR
MODE)
330K
74AS04
330K
74AS04
0.1 F
XTAL
To Other
Devices
74AS04
PIC16C5X
CLKIN
Open
OSC2
DS30453E-page 16
Preliminary
1997-2013 Microchip Technology Inc.
|
|
Share Link: 