RFPIC12C509AG Datasheet, PDF (37/104 Pages) Microchip Technology – 18/20-Pin 8-Bit CMOS Microcontroller with UHF ASK/FSK Transmitter

rfPIC12C509AG/509AF
7.3.1
CRYSTAL OSCILLATOR ASK
OPERATION
The rfPIC12C509AG or 509AF crystal oscillator can be
configured for ASK operation. Figure 7-2 shows an
example ASK circuit.
Capacitor C1 trims the crystal load capacitance to the
circuit load capacitance and places the crystal on the
desired frequency.
FIGURE 7-2: EXAMPLE ASK EXTERNAL
CRYSTAL CIRCUIT
XTAL
X1
rfPIC12C509AG/
509AF
C1
TABLE 7-2: XTAL OSC APPROXIMATE FREQ. VS. CAPACITANCE (ASK MODE) ⁽¹⁾
C1
Predicted Frequency
(MHz)
PPM from 13.55 MHz
Transmit Frequency (MHz) (32 *
fXTAL)
22 pF
13.551438
+106
433.646
39 pF
13.550563
+42
433.618
100 pF
13.549844
-12
433.595
150 pF
13.549672
-24
433.5895
470 pF
13.549548
-33
433.5856
1000 pF
13.549344
-48
433.579
Note 1: Standard Operating Conditions (unless otherwise stated) TA = 25°C, RFEN = 1, VDDRF = 3V,
fXTAL = 13.55 MHz
© 2001 Microchip Technology Inc.
Preliminary
DS70031A-page 35