Crystals vs. Ceramic Resonators
Crystals vs. Ceramic Resonators
(OP)
I'm bumping up the clock speed on a PIC project (16F72) from the internal 4 MHz to an external 20 MHz. I can use a 20 MHz crystal with two external caps to the tune of $0.80, or a 20 MHz ceramic resonator with internal caps to the tune of $0.40 (which is about half of the size, to boot). Accuracy is not an issue.
However, reading the PIC's datasheet, Microchip lists a max clock speed in the ceramic resonator section at 16 MHz (I'm not sure if this IS the maximum possible, only the maximum listed with tested cap values).
So, other than accuracy over time/temp, is there any advantage/disadvantage to using a ceramic resonator with internal caps compared to a crystal with external caps?
However, reading the PIC's datasheet, Microchip lists a max clock speed in the ceramic resonator section at 16 MHz (I'm not sure if this IS the maximum possible, only the maximum listed with tested cap values).
So, other than accuracy over time/temp, is there any advantage/disadvantage to using a ceramic resonator with internal caps compared to a crystal with external caps?





RE: Crystals vs. Ceramic Resonators
An important issue is the start up conditions -I mean power supply’s rise time- and using of parallel crystal type like PIC controllers use. Regarding this, in my case, serial crystals do the job as parallel ones in these conditions. Anyway, you should check this.
So, if you don’t have any special requirement, ceramic resonators are OK for most applications.
RE: Crystals vs. Ceramic Resonators
RE: Crystals vs. Ceramic Resonators
RE: Crystals vs. Ceramic Resonators
That's part of the confusion. The device is specified for up to 20 MHz operation. The datasheet lists capacitor values to use as a rough guide for various frequency ranges and oscillator types. The section on crystals lists cap values up to 20 MHz, but the resonator section only lists cap values up to 16 MHz. Now, I'm not saying the datasheet specifies the device will only work up to 16 MHz when using a resonator, only that cap values are specified up to that range.
I was trying to determine if there was something completely different between crystals and ceramics that would lower the possible frequency range. I have found a 20 MHz ceramic with built-in caps that can be had for about $0.30 in bulk. A similar speed crystal with external caps is going to cost me around $0.75 in bulk, and is about twice the size (with caps).
RE: Crystals vs. Ceramic Resonators
RE: Crystals vs. Ceramic Resonators
silicon oscillator e.g. LCT1799
<nbucska@pcperipherals.com>
RE: Crystals vs. Ceramic Resonators