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Question asked by DolomitiLynx on Aug 10, 2013
Latest reply on Aug 29, 2013 by Kai Liu

Dear All,


I' m designing a microcontroller board based on Kinetis KL25 uC. As a starting point, I have read all the documentations concerning FRDM-KL25 board. My question is about the main Crystal Oscillator: I don't want to use the one used on the FRDM-KL25 board, because I think is too difficult to mount (particularly on the first prototype boards, that will be produced soldering components by hand). I have some difficulties to understand the recommendations done on the datasheet of the micro, so I want to ask you if I am in the correct way.


Here the specifications of the Crystal Quartz I have chosen for my project and the of the Oscillator mounted on FRDM-BOARD:




Frequenza: 8 Mhz

Tolleranza:            20 PPM

Stabilita Frequenza:   50 PPM

Capacitanza di Carico: 18 pF




Frequenza: 8 Mhz

Tolleranza:            30 PPM

Stabilita:             50 PPM

Capacità di Carico     18 pF


Farnell Code:          1640891


Here my three questions:


A) Can I use the CRYSTAL B to clock the uC?

B) Quartz A has four pins, the two crystal connection pins and two gnd pins. Quartz B only two , the crystal connection ones. Is this a problem? What is the function of the two GND pins on QUART A.

C) For the crystal connection to the KL25 uC, I want to use the same circuit proposed on the KL25 schematic, composed by the two 22pF capacitors and the 1 Mega Ohm Resistor. Are this components still OK also with the new Crystal?

D) If the crystal I have chosen is not suitable to work with the KL25 uC, can you propose me suitable Crystal with the same Frequence and a package easy to solder by hand?



Thanks in advance for your courtesly attention.