Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [crystal]

Piezo-electric device cut at a specific resonance frequency, mostly used in oscillators.

A crystal is a piezo-electric device cut at a specific resonance frequency. Due to its high Q-factor and high stability crystals are mostly used in oscillators. Also used to create very narrow-band filters. Frequencies range from a few tens of kHz to a few hundred MHz.

Further reading
MSP430 32-kHz Crystal Oscillators, TI Application Report

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Crystals, Oscillators, and Resonators. What the difference?

I am trying to figure out the difference between crystals, oscillators, and resonators. I'm starting to grasp it but I still have some questions. From my understanding, an oscillator is built from a crystal and two capacitors. What is a resonator…
Alexis K
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Why do we use 32.768 kHz crystals in most circuits?

Why do we use 32.768 kHz crystals in most circuits, for example in RTC circuits? What will happen if I use a 35 or 25 kHz crystal? I assume because the IC internal Xin, Xout pin circuitry should be in CMOS/TTL/NMOS technology. Is it that true?
ramesh6663
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Competing PCB Crystal layout recommendations

This is related to this question: How's my crystal oscillator layout? I'm trying to layout a 12MHz crystal for a micro controller. I've been reading through several recommendations specifically for crystals as well as for high frequency design. For…
helloworld922
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What's special about 14.31818 MHz?

While desoldering useful components off of old computer hardware, I found quite a large number of 14.31818 MHz crystals. This seemed odd to me. Why use such an irregular frequency with a very nontrivial conversion to human time units? At first I…
FlashCactus
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How does a Crystal work?

Specifically, a 2pin and 4pin quartz crystal oscillator. What I know: current is applied and the crystal oscillates in order to provide an oscillating signal. What I want to know: How does the vibration cause an oscillating current? How are 2/4pin…
Sciiiiience
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Why do Arduinos ship w/ 16MHz crystal instead of 20MHz?

Why do Arduino boards ship w/ 16MHz crystal instead of 20MHz? They are spec'ed for operating at 20MHz, after all. I guess there are a few advantages to running more slowly (lower power consumption, longer life), but I must be missing something.
JellicleCat
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What effect does selecting the wrong load capacitance for a crystal have?

I've seen questions such as this one and this one that talk about selecting capacitors that, in series, match up as closely as possible to the load capacitance of the crystal. What effect does selecting the wrong capacitance have? Does it skew the…
Polynomial
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Why is crystal frequency often multiplied inside a microcontroller?

I noticed often times the external crystals frequency is multiplied to arrive at a microcontroller's clock speed. Why is this done? Take, for example, the TI CC2650. In its default configuration, it uses a 24 MHz crystal to arrive at a 48 MHz clock…
Questy
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How can you achieve decent clock accuracy in microcontrollers (e.g., max 1 second drift in a year)? How do digital watch manufacturers accomplish it?

I am learning with microcontrollers (mostly PIC16/18 and AVR) for some time, making various experimental projects. One of things that I found surprisingly challenging is maintaining decent clock accuracy. Most of my projects have internal clocks at…
Petr
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What are 12.000393 MHz crystals used for?

I found them on www.digikey.com, and they're apparently made by different manufacturers, so there must be some use for them. What are they used for? edit and why? The 2400 baud modem doesn't offer an explanation: a 12 Mhz crystal is better for that…
Federico Russo
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How can we test the lifespan of electrical components?

We work with some electronic devices in our projects. We are at the stage where we need to create some test strategy to validate the lifespan (e.g. 1 to 5 years) of our devices for which we provide warranty. We need to standardize this test strategy…
MKSJ
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Crystals and load capacitance

If a crystal has a rated load capacitance of 6 pF, is the right thing to do to put a 6 pF capacitor to GND on either leg of the crystal? I'm using it as the clock source (TOSC) for an XMEGA and it's got a max ESR of 50 kOhm (which is within…
vicatcu
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Why does a mouse need a crystal?

I was looking at this schematic for an old (pre USB) mouse: when I noticed it had a crystal on it (Y1). I was curious why a mouse would need a timer? Wouldn't it be able to use the clock from the computer? Also if it has its own crystal couldn't…
Tyler Hilbert
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What's the schematic to share one crystal with two micros?

How do I share a single crystal (not a complete oscillator module) between two micros? Is it OK to just connect everything as normal for the first micro and also directly connect its XO to the XI of the second microcontroller? I expect to place the…
joeforker
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How does a quartz crystal work?

Could you explain how a quartz crystal works, maybe with a simple schematics with the essential things ? I know it acts like a kind of stabilizer for an oscillator, but nothing more than that.
Stefano Borini
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