what dies parallel cut mean on the crystals?

[Guest Ryan]

hi!

i'm a bit confused about the crystal to be used on the internal oscillator on the PIC's. what does parallel cut mean?  how do i know which crystal to use? How do i know im using the right crystal?

Hope someone can help me...

thanks!

Ryan

[TK.]

Hi Ryan,

crystals with parallel cut are optimized for parallel resonance with the oscillator. If you would use a crystal with serial cut (which can mostly be found in radio modules), the PIC won't run with the correct frequency. It must run at 40 MHz (external: 10 MHz), otherwise the MIDI baudrate will be wrong.

Unfortunately every distributor has it's own way on identicating the crystal type. I can only say: if the type is not declared, it's a parallel cut crystal with a probability of 99%

Best Regards, Thorsten.

FAQMARKER

[Guest Ryan]

Hi!

    I found this crystal... im not sure if it would work it says something about the capacitance load. Im not sure what it is.

here's the item description:

Microprocessor crystal unit, HC-49/U, 30 Ohm max equivalent series resistance, 10 MHz, frequency tolerance (+/-) 30 ppm, parallel resonance fundamental mode, 18 pF load capacitance, primary function crystal, 2 pin, leaded termination

datasheet here:

http://www.raltron.com/products/pdfspecs/crystal_hc_49_45_51.pdf

Thanks in advance

Ryan