PIC17C7XX_13 Datasheet, PDF (18/306 Pages) Microchip Technology – High-Performance 8-bit CMOS EPROM Microcontrollers with 10-bit A/D

PIC17C7XX
FIGURE 4-2:
CRYSTAL OR CERAMIC
RESONATOR OPERATION
(XT OR LF OSC
CONFIGURATION)
OSC1
C1
XTAL
RF
SLEEP
OSC2
(Note 1)
C2
PIC17CXXX
To internal
logic
See Table 4-1 and Table 4-2 for recommended values of C1
and C2.
Note 1: A series resistor (Rs) may be required for AT strip
cut crystals.
TABLE 4-1: CAPACITOR SELECTION FOR
CERAMIC RESONATORS
Oscillator
Type
Resonator
Frequency
Capacitor Range
C1 = C2⁽¹⁾
LF
455 kHz
2.0 MHz
15 - 68 pF
10 - 33 pF
XT
4.0 MHz
8.0 MHz
16.0 MHz
22 - 68 pF
33 - 100 pF
33 - 100 pF
Higher capacitance increases the stability of the oscillator,
but also increases the start-up time. These values are for
design guidance only. Since each resonator has its own
characteristics, the user should consult the resonator manu-
facturer for appropriate values of external components.
Note 1: These values include all board capacitances on
this pin. Actual capacitor value depends on
board capacitance.
Resonators Used:
455 kHz Panasonic EFO-A455K04B
2.0 MHz Murata Erie CSA2.00MG
4.0 MHz Murata Erie CSA4.00MG
8.0 MHz Murata Erie CSA8.00MT
16.0 MHz Murata Erie CSA16.00MX
Resonators used did not have built-in capacitors.
 0.3%
 0.5%
 0.5%
 0.5%
 0.5%
DS30289C-page 18
FIGURE 4-3:
CRYSTAL OPERATION,
OVERTONE CRYSTALS
(XT OSC
CONFIGURATION)
C1
OSC1
C2
OSC2
SLEEP
C3
L1
0.1 F
PIC17CXXX
To filter the fundamental frequency:
1
L1*C2
=
(2f)²
Where f = tank circuit resonant frequency. This should be
midway between the fundamental and the 3rd overtone
frequencies of the crystal.
C3 blocks DC current to ground.
TABLE 4-2: CAPACITOR SELECTION FOR
CRYSTAL OSCILLATOR
Osc
Type
Freq
C1⁽²⁾
C2⁽²⁾
LF
32 kHz
100-150 pF
100-150 pF
1 MHz
10-68 pF
10-68 pF
2 MHz
10-68 pF
10-68 pF
XT
2 MHz
47-100 pF
4 MHz
15-68 pF
8 MHz
15-47 pF
16 MHz
24 MHz⁽¹⁾
32 MHz⁽¹⁾
15-47 pF
15-47 pF
10-47 pF
47-100 pF
15-68 pF
15-47 pF
15-47 pF
15-47 pF
10-47 pF
Higher capacitance increases the stability of the oscillator,
but also increases the start-up time and the oscillator cur-
rent. These values are for design guidance only. RS may be
required in XT mode to avoid overdriving the crystals with
low drive level specification. Since each crystal has its own
characteristics, the user should consult the crystal manufac-
turer for appropriate values for external components.
Note 1: Overtone crystals are used at 24 MHz and
higher. The circuit in Figure 4-3 should be used
to select the desired harmonic frequency.
2: These values include all board capacitances on
this pin. Actual capacitor value depends on
board capacitance.
Crystals Used:
32.768 kHz
1.0 MHz
2.0 MHz
4.0 MHz
8.0 MHz
16.0 MHz
25 MHz
32 MHz
Epson C-001R32.768K-A
ECS-10-13-1
ECS-20-20-1
ECS-40-20-1
ECS ECS-80-S-4
ECS-80-18-1
ECS-160-20-1
CTS CTS25M
CRYSTEK HF-2
 20 PPM
 50 PPM
 50 PPM
 50 PPM
 50 PPM
 50 PPM
 50 PPM
 50 PPM
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