Datasheet

PIC17C7XX
DS30289C-page 18  1998-2013 Microchip Technology Inc.
FIGURE 4-2: CRYSTAL OR CERAMIC
RESONATOR OPERATION
(XT OR LF OSC
CONFIGURATION)
TABLE 4-1: CAPACITOR SELECTION FOR
CERAMIC RESONATORS
FIGURE 4-3: CRYSTAL OPERATION,
OVERTONE CRYSTALS
(XT OSC
CONFIGURATION)
TABLE 4-2: CAPACITOR SELECTION FOR
CRYSTAL OSCILLATOR
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  0.3%
2.0 MHz Murata Erie CSA2.00MG  0.5%
4.0 MHz Murata Erie CSA4.00MG  0.5%
8.0 MHz Murata Erie CSA8.00MT  0.5%
16.0 MHz Murata Erie CSA16.00MX  0.5%
Resonators used did not have built-in capacitors.
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.
C1
C2
XTAL
OSC2
(Note 1)
OSC1
RF
SLEEP
PIC17CXXX
To internal
logic
Osc
Type
Freq C1
(2)
C2
(2)
LF 32 kHz
1 MHz
2 MHz
100-150 pF
10-68 pF
10-68 pF
100-150 pF
10-68 pF
10-68 pF
XT 2 MHz
4 MHz
8 MHz
16 MHz
24 MHz
(1)
32 MHz
(1)
47-100 pF
15-68 pF
15-47 pF
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. R
S 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 Epson C-001R32.768K-A  20 PPM
1.0 MHz ECS-10-13-1  50 PPM
2.0 MHz ECS-20-20-1  50 PPM
4.0 MHz ECS-40-20-1  50 PPM
8.0 MHz ECS ECS-80-S-4
ECS-80-18-1
 50 PPM
16.0 MHz ECS-160-20-1  50 PPM
25 MHz CTS CTS25M  50 PPM
32 MHz CRYSTEK HF-2  50 PPM
C1
C2
0.1 F
SLEEP
OSC2
OSC1
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
C3 blocks DC current to ground.
L1