PIC16F5X
4.0
4.1
OSCILLATOR
CONFIGURATIONS
Oscillator Types
TABLE 4-1:
Osc
Type
XT
CAPACITOR SELECTION FOR
CERAMIC RESONATORS
Cap. Range
C1
Cap. Range
C2
Resonator
Freq.
The PIC16F5X devices can be operated in four differ-
ent oscillator modes. The user can program two Con-
figuration bits (FOSC1:FOSC0) to select one of these
four modes:
•
•
•
•
LP:
XT:
HS:
RC:
Low-power Crystal
Crystal/Resonator
High-speed Crystal/Resonator
Resistor/Capacitor
455 kHz
68-100 pF
68-100 pF
2.0 MHz
15-33 pF
15-33 pF
4.0 MHz
10-22 pF
10-22 pF
HS
8.0 MHz
10-22 pF
10-22 pF
16.0 MHz
10 pF
10 pF
These values are for design guidance only. Since
each resonator has its own characteristics, the user
should consult the resonator manufacturer for
appropriate values of external components.
4.2
Crystal Oscillator/Ceramic
Resonators
TABLE 4-2:
Osc
Type
LP
XT
CAPACITOR SELECTION FOR
CRYSTAL OSCILLATOR
Cap.Range
C1
15 pF
15-30 pF
15-30 pF
15-30 pF
15-30 pF
15 pF
15 pF
15 pF
15 pF
15 pF
Cap. Range
C2
15 pF
200-300 pF
100-200 pF
15-100 pF
15-30 pF
15 pF
15 pF
15 pF
15 pF
15 pF
In XT, LP or HS modes, a crystal or ceramic resonator
is connected to the OSC1/CLKIN and OSC2/CLKOUT
pins to establish oscillation (Figure 4-1). The
PIC16F5X oscillator design requires the use of a
parallel cut crystal. Use of a series cut crystal may give
a frequency outside of the crystal manufacturers
specifications. When in XT, LP or HS modes, the
device can have an external clock source drive the
OSC1/CLKIN pin (Figure 4-2).
Crystal
Freq.
32 kHz
(1)
100 kHz
200 kHz
455 kHz
1 MHz
2 MHz
4 MHz
4 MHz
8 MHz
20 MHz
FIGURE 4-1:
CRYSTAL/CERAMIC
RESONATOR OPERATION
(HS, XT OR LP OSC
CONFIGURATION)
OSC1
HS
Note 1:
C1
(1)
PIC16F5X
Sleep
XTAL
OSC2
RS
(2)
C2
(1)
Note 1:
2:
3:
RF
(3)
To internal
logic
For V
DD
> 4.5V, C1 = C2
≈
30 pF is
recommended.
These values are for design guidance only. Rs may
be required in HS mode, as well as XT mode, to
avoid overdriving crystals with low drive level specifi-
cations. Since each crystal has its own characteris-
tics, the user should consult the crystal manufacturer
for appropriate values of external components.
Note 1:
This device has been designed to perform
to the parameters of its data sheet. It has
been tested to an electrical specification
designed to determine its conformance
with these parameters. Due to process
differences in the manufacture of this
device, this device may have different
performance characteristics than its
earlier version. These differences may
cause this device to perform differently in
your application than the earlier version of
this device.
2:
The user should verify that the device
oscillator starts and performs as
expected. Adjusting the loading capacitor
values and/or the Oscillator mode may be
required.
See Capacitor Selection tables for
recommended values of C1 and C2.
A series resistor (RS) may be required.
RF varies with the Oscillator mode chosen
(approx. value = 10 MΩ).
FIGURE 4-2:
EXTERNAL CLOCK INPUT
OPERATION (HS, XT OR LP
OSC CONFIGURATION)
OSC1
PIC16F5X
OSC2
Clock from
ext. system
Open
©
2007 Microchip Technology Inc.
DS41213D-page 21
MICROCHIP [ MICROCHIP TECHNOLOGY ]
