21

A product Line of

Diodes Incorporated

PI6CG33201C

www.diodes.com

January 2020

Diodes Incorporated

PI6CG33201C

Document Number DS42291 Rev 3-2

Crystal Capacitor Calculation

Crystal circuit connection

The following diagram shows PI6CG33201C crystal circuit connection with a parallel crystal. For the CL=8pF crystal, it is suggested

to use C1=8pF, C2=8pF. C1 and C2 can be adjusted to fine tune to the target ppm of crystal oscillator according to different board

layouts based on the following formular in the Crystal Capacitor Calculation diagram.

C1

8pF

Crystal�(C

L�=�8pF)

C2

8pF

XTAL_IN

XTAL_OUT

FL2500262Q

Crystal Oscillator Circuit

Recommended Crystal Specification

Diodes recommends:

a) FL2500217, SMD 3.2x2.5(4P), 25MHz, CL=8pF, +/-20ppm, https://www.diodes.com/assets/Datasheets/FL.pdf

b) FH2500016, SMD 2.5x2.0(4P), 25MHz, CL=8pF, +/-30ppm, https://www.diodes.com/assets/Datasheets/FH.pdf

c) FW2500031, SMD 2.0x1.6(4P), 25MHz, CL=8pF, +/-30ppm, https://www.diodes.com/assets/Datasheets/FW.pdf

d) US2500003, SMD 1.6x1.2(4P), 25MHz, CL=12pF, +/-30ppm, https://www.diodes.com/assets/Datasheets/US.pdf

XTAL_IN

XTAL_OUT

Cb

C1

C2

Cj

Rd

Rf

Cb

Pseudo

sine

Cj

CL= crystal spec. loading cap.

Cj = chip in/output cap. (3~5pF)

Cb = PCB trace/via cap. (2~4pF)

C1, C2 = load cap. components

Rd = drive level res. (100Ω)

Final choose/trim C1=C2=2 *CL - (Cb +Cj) for the target +/-ppm

Example: C1=C2=2*(18pF) – (4pF+5pF)=27pF