Try Searching the JLCPCB Assembled Library for **16MHz**: 

Hi Andy and Maximillian! I went through all JLCPCB assembly supported 16MHz crystals and yes you are right Maximillian! There is no crystals available which has two pads at the side.  So, I guess you just have to order this seperately and solder it by yourself. Or use through hole model to ease up with the soldering. Regards, Markus Virtanen HW / Electronics Designer

@MaximilianBurger, @markus_jidoka, If you are designing your own PCB then it does not have to use a crystal in the same package as the one on the prototype board. If the tracking around the crystal pins on the AtMega328p-Au is laid out as closely as possible (including any ground plane or guard tracks) to the prototype board then any 16MHz crystal of the same cut and load capacitance specifications should be OK. To find those parameters out, you will have to find the specifications for the crystal as recommended in the datasheet or applications notes for the AtMega328p-Au prototype board or the device itself.

For info, a search of LCSC.com for: 16mhz crystal 49smd 49ssmd brings up 17 candidates but as you have already found none are available from JLCPCB.

Hey guys, thanks for your fast replies :) Would this circuit work? The Crystal is this part: [Crystal-Specs](https://lcsc.com/product-detail/SMD-Crystal-Resonators_Abracon-LLC-ABM8W-16-0000MHZ-8-D1X-T3_C193746.html)  It's a different package, but this part is available for JLCPCB-assembly and the specs should work. Kind regards, Max

Based on the specs, it appears #2 and #4 should be grounded. I use a similar crystal (C13738) for my ATMEGA328P (SMT assembled), and haven't had any problems.

You cannot just drop a crystal and suitably scaled load caacitors into an oscillator circuit. You have to take account of PCB and device parastitic capacitances. A total of 4pF load (CL) capacitance (8pF + 8pF in series as you have in the image) is probably too low. You prototype board would appear to be using a crystal specified for something like a CL = 9pF but that may include a few more pF for the tracks and device parasitics. You need to read and think about section 9.2 Clock Sources, 9.3 Low Power Crystal Oscillator and 9.4 Full Swing Crystal Oscillator in: [http://ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061B.pdf](http://ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061B.pdf) and: [http://ww1\.microchip\.com/downloads/en/Appnotes/Atmel\-8128\-Best\-Practices\-for\-the\-PCB\-Layout\-of\-Oscillators\_ApplicationNote\_AVR186\.pdf](http://ww1.microchip.com/downloads/en/Appnotes/Atmel-8128-Best-Practices-for-the-PCB-Layout-of-Oscillators_ApplicationNote_AVR186.pdf) where an individual capacitor value of between 12pf and 22pF is recommended (C1 and C2 in Figs 9.2 and 9.3). Also: [http://www.microchip.com//wwwAppNotes/AppNotes.aspx?appnote=en590907](http://www.microchip.com//wwwAppNotes/AppNotes.aspx?appnote=en590907)

Can you find the spec of the crystal from a BOM for the proto board?

Hey guys, you're quick support is just amazing. @andyfierman Thanks for the links...i didn't know that this kind of helpful documents exist(especially the last one). Do I have to calculate the track-capacities or am I go to go with 22pf, if I place the crystal right next to the Microcontroller, route the tracks as short as possible and ground the caps straight to the ground layer? @bwinter What capacitors did you use for your crystal and did you apply any special Design-Rules? ([your Crystal-Specs](https://lcsc.com/product-detail/SMD-Crystal-Resonators_Yangxing-Tech-X322516MLB4SI_C13738.html)) Thanks guys for you're answers. Max

If you read: [https://blog.adafruit.com/2012/01/24/choosing-the-right-crystal-and-caps-for-your-design/](https://blog.adafruit.com/2012/01/24/choosing-the-right-crystal-and-caps-for-your-design/) and assume that Cstray = 5pF then for a crystal with a CL of 12pF (which JLCPCB list with LCSC part number C12668) then using: **C1\, C2 = 2\*CL – 2\*Cstray** you get a C1 and C2 capacitor value of: 2*(12-5)pF = 14pF. Given that Ctray is guessed at 5pF using C1 = C2 = 15pF gets you back to a preferred value. Or use: **C1 = C2 = Cx** **CL = Cx/+Cstray** then you can choose C1 and C2 and then select a crystal with a suitable CL.

@MaximilianBurger Hello ; Thank you for the time taken to write for us here @andyfierman Thank you for the assistance. @MaximilianBurger The main post is about the appropriate crystal for the ATmega MCU, I have experienced the following part as it shows the below image to make the ATMega328P breath and it worked like charm (without external load capacitance) but if you are willing to use capacitors then it has to be very well measured the values to prevent the overload of the crystal  The part has a [C13738](https://lcsc.com/product-detail/SMD-Crystal-Resonators_Yangxing-Tech-X322516MLB4SI_C13738.html/?href=jlc-SMT) Ref. number and it is available for assembly. you can get the part datasheet through the following link : [https://datasheet.lcsc.com/szlcsc/Yangxing-Tech-X322516MLB4SI_C13738.pdf](https://datasheet.lcsc.com/szlcsc/Yangxing-Tech-X322516MLB4SI_C13738.pdf) Sorry for the image that shows two crystals, one is use and the other one is just the same as used in Arduino Nano board but it is not available in JLCPCB SMT Parts library. Anything else, just drop a comment :)

@JLCPCBsupport, @MaximilianBurger, That crystal has a CL of 9pF so, with no external capacitors, you are relying on Cstray to make it work. Cstray by it's nature is very much layout dependent so it is not good practice to rely on that. Strictly for a relaible design, you should measure Cstray (which is not an easy task) and then go through the procedure detailed in here: [http://www\.st\.com/internet/com/TECHNICAL\_RESOURCES/TECHNICAL\_LITERATURE/APPLICATION\_NOTE/CD00221665\.pdf](http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/APPLICATION_NOTE/CD00221665.pdf) to eastablish the crystal choice and C1, C2 values. The next best option is to calculate the values as I described above and then try a range ot C1 and C2 values to see at what extremes the crystal either does not work or takes too long to start and then choose C1 and C2 as close as possible to the middle of that range. You may in extreme cases have to try a crystal with a different value for CL. :)

Hey guys, it's been along time. I just wanted to inform you, that today my assembled PCB from JLCPCB arrived and it worked straight away. I finally used the crystal (C13738) mentioned before in this thread. Thanks for your help, I learned alot.

@MaximilianBurger That's a good news, I'm happy that you've got the needed support. Welcome if you need any further assistance.