RFHCS362F-I/SO View Datasheet(PDF) - Microchip Technology

Part Name

Description

MFG CO.

RFHCS362F-I/SO

KEELOQ® Code Hopping Encoder with UHF ASK/FSK Transmitter

Microchip Technology 

6.3.1

CRYSTAL OSCILLATOR ASK

OPERATION

The rfHCS362G/362F crystal oscillator can be config-

ured for ASK operation. Figure 6-1 shows an example

ASK circuit.

Capacitor C1 trims the crystal load capacitance to the

desired circuit load capacitance and places the crystal

on the desired frequency.

rfHCS362G/362F

FIGURE 6-1: EXAMPLE ASK EXTERNAL

CRYSTAL CIRCUIT

XTAL

X1

rfHCS362G/

362F

C1

TABLE 6-2: 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

© 2011 Microchip Technology Inc.

DS41189B-page 27

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