I've been converting my current SBC design over to 3.3V to make my life easier interfacing to an XC9572XL CPLD and a TinyFPGA, but I've run into a bit of a snag. I am doing one final prototype on breadboard and I have had zero luck finding anybody that stocks 3.6864 MHz, 3.3V, thru-hole oscillators. Does anyone know any place that actually stocks such beasts? I know they exist because they're on some manufacturer data sheets, but nobody stocks 'em...which isn't really surprising.

For my final build on a real PCB I have no problem using SMD parts; in fact I already have them here. I just need something for my prototype. Worst case I suppose I can rig up my 5V oscillator through a spare 74LVC245 as a voltage level converter.

ABRACON ACOL-3.6864MHZ-EK, ACHL-3.6864MHZ-EK, but Mouser doesn't have them on stock.
No luck at Digikey, Farnell, Avnet, Arrow and RS either.

Same thing for 7.3728MHz and 14.7456MHz oscillators.

From the datasheet, XC9572XL seems to have 5V tolerant I\O pins (you better check).

It's not hard to hack SMD parts onto a through-hole project, so that's one option you may wish to consider. There are a LOT of ways this can work (see example below), so don't be afraid to be creative. Just find the easiest scheme that provides the connections you need!

Edit: see also Arlet's post here.

-- Jeff

_________________
In 1988 my 65C02 got six new registers and 44 new full-speed instructions!
https://laughtonelectronics.com/Arcana/ ... mmary.html

The inputs on the XC9572XL are 5V tolerant, but the TinyFPGA pins are not. More importantly the outputs from the 3.3V parts will not be recognized as a logic "1" by any 65Cxx series parts so things like chip selects from the CPLD and the PHI2 output coming from the FPGA would all need logic level conversion. Also there is just so much more stuff available 3.3V; for example I am able to replace my 90ns 32K EEPROM with a 70ns 512K flash ROM in a PLCC-32 package.

Other than crystal oscillator the only gotcha I've run into is that I'll still need 5V to run my ATmega that controls the keyboard port and game ports, mostly because those devices need/prefer 5V. I use an ATX power supply so that's not a big deal.

Maybe I'll come up with a PCB and have OSHPark make them for me, should only cost a few bucks for something that small. I just don't want to wait ~2 weeks to continue my build so in the mean time I'll probably go with the 5V osc + 74LVC245 as a temporary measure.

Hmm that may actually work. I have some perf board I can cut down to size and use to mount it up. I will give that a shot!

A piece of perf board and a little soldering and I'm all set! The red mark is pin 1.

Quick...

'n dirty!!


Y' might want to add some sort of bypass capacitor, though (soldered directly to the assembly, as with my hack job above).

_________________
In 1988 my 65C02 got six new registers and 44 new full-speed instructions!
https://laughtonelectronics.com/Arcana/ ... mmary.html