PIC16C63A/65B/73B/74B
TABLE 13-1: CERAMIC RESONATORS
Note 1: Higher capacitance increases the stability
of the oscillator, but also increases the
start-up time.
Ranges Tested:
Mode
Freq
OSC1
OSC2
XT
455 kHz
2.0 MHz
4.0 MHz
68 - 100 pF
15 - 68 pF
15 - 68 pF
68 - 100 pF
15 - 68 pF
15 - 68 pF
2: Since each resonator/crystal has its own
characteristics, the user should consult
the resonator/crystal manufacturer for
appropriate values of external compo-
nents.
HS
8.0 MHz
16.0 MHz
10 - 68 pF
10 - 22 pF
10 - 68 pF
10 - 22 pF
Note: These values are for design guidance only.
3: Rs may be required in HS mode, as well
as XT mode, to avoid overdriving crystals
with low drive level specification.
See notes following Table 13-1 and Table 13-2.
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
± 0.3%
± 0.5%
± 0.5%
± 0.5%
± 0.5%
4: Oscillator performance should be verified
at the expected voltage and temperature
extremes in which the application is
expected to operate.
13.2.3
RC OSCILLATOR
Note: Resonators used did not have built-in capacitors.
For timing insensitive applications, the “RC” device
option offers additional cost savings. The RC oscillator
frequency is a function of the supply voltage, the resis-
tor (REXT) and capacitor (CEXT) values, and the operat-
ing temperature. The oscillator frequency will vary from
unit to unit due to normal process variation. The differ-
ence in lead frame capacitance between package
types will also affect the oscillation frequency, espe-
cially for low CEXT values. The user also needs to take
into account variation due to tolerance of external R
and C components used. Figure 13-3 shows how the
R/C combination is connected to the PIC16CXX.
TABLE 13-2: CAPACITOR SELECTION FOR
CRYSTAL OSCILLATOR
Osc Type
Crystal
Freq
Cap. Range
C1
Cap. Range
C2
LP
32 kHz
200 kHz
200 kHz
1 MHz
33 pF
15 pF
33 pF
15 pF
XT
HS
47-68 pF
15 pF
47-68 pF
15 pF
The oscillator frequency, divided by 4, is available on
the OSC2/CLKOUT pin, and can be used for test pur-
poses or to synchronize other logic (see Figure 3-2 for
waveform).
4 MHz
15 pF
15 pF
4 MHz
15 pF
15 pF
8 MHz
15-33 pF
15-33 pF
15-33 pF
15-33 pF
FIGURE 13-3:
RC OSCILLATOR MODE
20 MHz
VDD
Note: These values are for design guidance only.
See notes following Table 13-1 and Table 13-2.
REXT
Crystals Used:
Internal
OSC1
Clock
32 kHz
200 kHz
1 MHz
Epson C-001R32.768K-A
STD XTL 200.000KHz
ECS ECS-10-13-1
± 20 PPM
± 20 PPM
± 50 PPM
± 50 PPM
± 30 PPM
± 30 PPM
CEXT
VSS
PIC16CXX
OSC2/CLKOUT
4 MHz
ECS ECS-40-20-1
FOSC/4
8 MHz
EPSON CA-301 8.000M-C
EPSON CA-301 20.000M-C
Recommended Values: REXT = 3 kW to 100 kW
CEXT = 20 pf to 30 pF
20 MHz
2000 Microchip Technology Inc.
DS30605C-page 87
MICROCHIP [ MICROCHIP ]
