PIC12F508/509/16F505
FIGURE 7-1:
CRYSTAL OPERATION
(OR CERAMIC
RESONATOR)
7.2
Oscillator Configurations
7.2.1
OSCILLATOR TYPES
(HS, XT OR LP OSC
CONFIGURATION)
The PIC12F508/509/16F505 devices can be operated
in up to six different oscillator modes. The user can
program up to three configuration bits (FOSC<1:0>
[PIC12F508/509], FOSC<2:0> [PIC16F505]). To select
one of these modes:
(1)
C1
PIC12F508/509
PIC16F505
OSC1
OSC2
Sleep
• LP:
• XT:
• HS:
Low-Power Crystal
Crystal/Resonator
XTAL
(3)
RF
To internal
logic
High-Speed Crystal/Resonator
(PIC16F505 only)
(2)
RS
(1)
C2
• INTRC: Internal 4 MHz Oscillator
• EXTRC: External Resistor/Capacitor
Note 1: See Capacitor Selection tables for
recommended values of C1 and C2.
2: A series resistor (RS) may be required for AT
strip cut crystals.
• EC:
External High-Speed Clock Input
(PIC16F505 only)
3: RF approx. value = 10 MΩ.
7.2.2
CRYSTAL OSCILLATOR/CERAMIC
RESONATORS
In HS (PIC16F505), XT or LP modes, a crystal or
ceramic resonator is connected to the (GP5/RB5)/
OSC1/(CLKIN) and (GP4/RB4)/OSC2/(CLKOUT) pins
to establish oscillation (Figure 7-1). The PIC12F508/
509/16F505 oscillator designs require the use of a
parallel cut crystal. Use of a series cut crystal may give
FIGURE 7-2:
EXTERNAL CLOCK INPUT
OPERATION (HS, XT OR
LP OSC
CONFIGURATION)
a
frequency out of the crystal manufacturers
OSC1
Clock from
ext. system
specifications. When in HS (PIC16F505), XT or LP
modes, the device can have an external clock source
drive the (GP5/RB5)/OSC1/CLKIN pin (Figure 7-2).
PIC12F508/509
PIC16F505
OSC2
Open
Note 1: This device has been designed to per-
form 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 charac-
teristics than its earlier version. These
differences may cause this device to
perform differently in your application
than the earlier version of this device.
TABLE 7-1:
CAPACITOR SELECTION FOR
CERAMIC RESONATORS –
PIC12F508/509/16F505(1)
Osc
Resonator Cap. Range Cap. Range
Type
Freq.
C1
C2
XT
HS(2)
4.0 MHz
16 MHz
30 pF
30 pF
10-47 pF
10-47 pF
Note 1: 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
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.
components.
2: PIC16F505 only.
© 2007 Microchip Technology Inc.
Preliminary
DS41236C-page 41
MICROCHIP [ MICROCHIP ]
