PIC17C752-08/CL MICROCHIP [Microchip Technology], PIC17C752-08/CL Datasheet - Page 17

• Manufacturer Part Number: PIC17C752-08/CL
• Description: High-Performance 8-Bit CMOS EPROM Microcontrollers with 10-bit A/D
• Manufacturer: MICROCHIP [Microchip Technology]

4.1.3
In the EC oscillator mode, the OSC1 input can be
driven
OSC1/CLKIN
OSC2/CLKOUT pin is the CLKOUT output (4 T
FIGURE 4-4:
1998 Microchip Technology Inc.
Clock from
ext. system
by
EXTERNAL CLOCK OSCILLATOR
CLKOUT
(F
OSC
CMOS
/4)
pin
EXTERNAL CLOCK INPUT
OPERATION (EC OSC
CONFIGURATION)
drivers. In
is
hi-impedance
OSC2
OSC1
PIC17CXXX
this
mode,
and
OSC
).
the
the
4.1.4
Either a prepackaged oscillator can be used or a simple
oscillator circuit with TTL gates can be built. Prepack-
aged oscillators provide a wide operating range and
better stability. A well-designed crystal oscillator will
provide good performance with TTL gates. Two types
of crystal oscillator circuits can be used: one with series
resonance, or one with parallel resonance.
Figure 4-5
oscillator circuit. The circuit is designed to use the fun-
damental frequency of the crystal.
inverter performs the 180-degree phase shift that a par-
allel oscillator requires. The 4.7 k
the negative feedback for stability. The 10 k
ometer biases the 74AS04 in the linear region. This
could be used for external oscillator designs.
FIGURE 4-5:
Figure 4-6
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
circuit. The 330
back to bias the inverters in their linear region.
FIGURE 4-6:
74AS04
330
10k
EXTERNAL CRYSTAL OSCILLATOR
CIRCUIT
shows implementation of a parallel resonant
+5V
shows a series resonant oscillator circuit.
0.1 F
20 pF
XTAL
10 k
74AS04
XTAL
4.7 k
EXTERNAL PARALLEL
RESONANT CRYSTAL
OSCILLATOR CIRCUIT
EXTERNAL SERIES
RESONANT CRYSTAL
OSCILLATOR CIRCUIT
resistors provide the negative feed-
74AS04
330
20 pF
PIC17C7XX
10 k
74AS04
74AS04
To Other
Devices
DS30289A-page 17
resistor provides
To Other
Devices
The 74AS04
PIC17CXXX
PIC17CXXX
OSC1
potenti-
OSC1