Datasheet

PIC12F510/16F506
DS41268D-page 58 © 2007 Microchip Technology Inc.
10.2 Oscillator Configurations
10.2.1 OSCILLATOR TYPES
The PIC12F510/16F506 devices can be operated in up
to six different oscillator modes. The user can program
up to three Configuration bits (FOSC<1:0>
[PIC12F510], FOSC<2:0> [PIC16F506]). To select one
of these modes:
•LP: Low-Power Crystal
•XT: Crystal/Resonator
•HS: High-Speed Crystal/Resonator
(PIC16F506 only)
•INTOSC: Internal 4/8 MHz Oscillator
•EXTRC: External Resistor/Capacitor
•EC: External High-Speed Clock Input
(PIC16F506 only)
10.2.2 CRYSTAL OSCILLATOR/CERAMIC
RESONATORS
In HS (PIC16F506), 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 10-1). The PIC12F510/
16F506 oscillator designs require the use of a parallel
cut crystal. Use of a series cut crystal may give a fre-
quency out of the crystal manufacturers specifications.
When in HS (PIC16F506), XT or LP modes, the device
can have an external clock source drive the (GP5/
RB5)/OSC1/CLKIN pin (Figure 10-2). When the part is
used in this fashion, the output drive levels on the
OSC2 pin are very weak. This pin should be left open
and unloaded. Also, when using this mode, the external
clock should observe the frequency limits for the clock
mode chosen (HS, XT or LP).
FIGURE 10-1: CRYSTAL OPERATION
(OR CERAMIC
RESONATOR)
(HS, XT OR LP OSC
CONFIGURATION)
FIGURE 10-2: EXTERNAL CLOCK INPUT
OPERATION (HS, XT OR
LP OSC
CONFIGURATION)
TABLE 10-1: CAPACITOR SELECTION FOR
CERAMIC RESONATORS –
PIC12F510/16F506
(1)
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.
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.
Osc.
Type
Resonator
Freq.
Cap. Range
C1
Cap. Range
C2
XT 4.0 MHz 30 pF 30 pF
HS
(2)
16 MHz 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
components.
2: PIC16F506 only.
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.
3: RF approx. value = 10 MΩ.
C1
(1)
C2
(1)
XTAL
OSC2
OSC1
RF
(3)
Sleep
To internal
logic
RS
(2)
PIC12F510
PIC16F506
Clock from
ext. system
OSC1
OSC2
Open
PIC12F510
PIC16F506