Real time clocks

mwaurelius · Feb 9, 2015

Hey there,

Continuing my education here. I was desoldering an old K5 motherboard earlier today and one of the components is labeled "Dallas DS12B887 Real Time . . ." I found a manufacturer data sheet easily but it was all about programming and not construction. I was just wondering if I should toss it in with the DIP's and quads, set it in its own pile or toss it out. I've learned the error of previous choices to toss unknown items so I'm asking first. I can tell it's double encapsulated and it's got 19 (!) pins.

I did find a passing description on one post (joem was the OP) but I didn't find it very helpful.

Sorry about the lack of pictures and link. My Internet is out and my phone doesn't have full capability for posts.

g_axelsson · Feb 9, 2015

I don't know that chip code by hart, but Dallas have built a number of real time clocks with a built in battery that could explode if you try to incinerate it. If it is extra thick then I would expect a battery inside but if it has the same form factor as an usual IC then it probably is without integrated battery.
To be on the safe side, cut it in half with some pliers or smash it with a hammer, the gold won't be harmed but you know if there is a battery and you can remove it.

Göran

mwaurelius · Feb 9, 2015

Oh, it was big . . . on the outside. Maybe .75x1x2.5cm. Having been encouraged: Mark smash!

What a disappointment. Battery, check; itty bitty oscillator, check; IC with bond wires, not so much. The aluminum leads went directly to all three subcomponents; the die was tiny, buried directly in the epoxy, and any bond wires were 1.5mm at most - I didn't really see them, even with my 20x loupe.

You know how some members get so focused on a process gone wrong that they won't let go no matter what? Well, this was the other side of that; I tossed it in my plastics junk bin. Less than 100ug isn't worth the irritation.