What capacitors should I use with LaunchPad?

alenc007

What capacitors should I use with LaunchPad? [Copy link]

The LaunchPad G2 development kit comes with a 32.768KHz crystal oscillator, but no capacitors. What does "CL: 12.5pF +/- 20ppm" on the package mean?

蓝雨夜

Baidu

Load capacitance CL (Load capacitance) is the total effective capacitance across the two ends of the crystal in the circuit (not the matching capacitance of the crystal oscillator). It mainly affects the load resonant frequency and the equivalent load resonant resistance. Together with the crystal, it determines the operating frequency of the oscillator circuit. By adjusting the load capacitance, the operating frequency of the oscillator can be fine-tuned to the nominal value. More precisely, the load capacitance of a passive crystal is a very important parameter, because passive crystals are passive components. The so-called passive components cannot work by themselves and need external components to assist in their work. Passive crystals are such components!

strong161

20ppm is the temperature drift, that is, don't use a very bad crystal! Otherwise, the clock will be inaccurate, and communications that require the clock may go wrong.

wsmysyn

The above person said it very clearly.

qwqwqw2088

For crystal oscillators, temperature drift parameters are very important

alenc007

Blue Rain Night published on 2019-6-24 16:42 Baidu Load capacitance CL (Load capacitance), it is the total effective capacitance across the two ends of the crystal in the circuit (not the matching capacitance of the crystal oscillator)...

How do I calculate the equivalent capacitance? Should I calculate it in series or in parallel? One end of these two capacitors is connected to the crystal oscillator, and the other end is connected to the ground.

alan000345

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