RFPIC12C509AG Microchip Technology Inc., RFPIC12C509AG Datasheet - Page 46

• Manufacturer Part Number: RFPIC12C509AG
• Description: 18/20-pin 8-bit Cmos Microcontroller With Uhf Ask/fsk Transmitter
• Manufacturer: Microchip Technology Inc.

rfPIC12C509AG/509AF
8.2
8.2.1
The oscillator frequency is a primary factor in determin-
ing PICmicro microcontroller unit (MCU) current draw.
As a rough guideline, the rfPIC12C509AG/509AF
draws approximately 250 A per MHz.
The rfPIC12C509AG/509AF can be operated in four
different oscillator modes. The user can program two
configuration bits (FOSC1:FOSC0) to select one of
these four modes:
• LP:
• XT:
• INTRC: Internal 4 MHz Oscillator
• EXTRC: External Resistor/Capacitor
8.2.2
In XT or LP modes, a crystal or ceramic resonator is
connected to the GP5/OSC1/CLKIN and GP4/OSC2
pins
rfPIC12C509AG/509AF oscillator design requires the
use of a parallel cut crystal. Use of a series cut crystal
may give a frequency out of the crystal manufacturers
specifications. When in XT or LP modes, the device
can have an external clock source drive the GP5/
OSC1/CLKIN pin (Figure 8-3).
FIGURE 8-2:
DS70031A-page 44
Note 1: See Capacitor Selection tables for
to
C2
C1
2: A series resistor (RS) may be required
3: RF approximate value = 10 M .
Oscillator Configurations
(1)
(1)
Low Power Crystal
Crystal/Resonator
establish
CRYSTAL OSCILLATOR / CERAMIC
RESONATORS
recommended values of C1 and C2.
for AT strip cut crystals.
OSCILLATOR TYPES
RS
XTAL
(2)
CRYSTAL OPERATION (OR
CERAMIC RESONATOR)
(XT OR LP OSC
CONFIGURATION)
OSC1
OSC2
oscillation
rfPIC12C509AG/509AF
RF
(3)
(Figure 8-2).
To internal
SLEEP
logic
The
Preliminary
FIGURE 8-3:
TABLE 8-1:
TABLE 8-2:
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.
Note 1: For V
These values are for design guidance only. Rs may
be required to avoid overdriving crystals with low
drive level specification. Since each crystal has its
own characteristics, the user should consult the crys-
tal manufacturer for appropriate values of external
components.
Clock from
ext. system
Type
Type
Osc
Osc
XT
LP
XT
recommended.
4.0 MHz
Resonator
Resonator
32 kHz
200 kHz
1 MHz
4 MHz
Open
Freq
Freq
DD
EXTERNAL CLOCK INPUT
OPERATION (XT OR LP OSC
CONFIGURATION)
CAPACITOR SELECTION
FOR CERAMIC RESONATORS
- rfPIC12C509AG/509AF
CAPACITOR SELECTION
FOR CRYSTAL OSCILLATOR -
rfPIC12C509AG/509AF
(1)
> 4.5V, C1 = C2
©
Cap. Range
Cap.Range
2001 Microchip Technology Inc.
47-68 pF
15 pF
15 pF
15 pF
30 pF
rfPIC12C509AG/509AF
OSC2
OSC1
C1
C1
30 pF is
Cap. Range
Cap. Range
47-68 pF
30 pF
15 pF
15 pF
15 pF
C2
C2