Hi all, so I have this crystal on my pcb. I’m familiar with the one not circled but not this one and why it has four legs. I tested two legs and have continuity and non on the other two. I’m not sure of the internal arrangement and why two legs would be short? Please help identify with datasheet or equivalent. Thanks
Four pin SMT crystals often have two pins that are not connected electrically, instead the extra pins just make attachments to the PCB stronger.
AFAIK continuity tests are not useful for checking a crystal.
This is a “clock crystal.” It is the beating heart of the real-time clock in your circuit. The resonant frequency is 32.768 kHz. This may seem like an odd number, however if you have a 15-stage digital circuit where each stage divides by 2, you end up with a pulse every second.
2^15 = 32768
I am unable to determine a part number for two reasons:
The physical size shouldn’t be too hard if you have a micrometer of dial caliper. You should be able to locate DigiKey part from this list.
The capacitance specification is more challenging. If we select the wrong oscillator loading, the real-time clock will not run at the proper rate. It may be off by a few seconds or a few minutes each day.
From my searching the imaged item looks very similar to the below linked items.
This is a more narrowed list from what @APDahlen had given.
Unfortunately, the capacitive value is still unknown. Without that we would not be able to narrow too much further.
If you happen to have a know good crystal on another board it maybe possible to measure it.