Hi there,
Does anybody know of a modern replacement for the VIA VT82885N Real Time Clock? Looks like they stopped being made a long time ago and mine is thoroughly broken - not just out of battery.
I'm trying to get my old Pentium motherboard going.
Thanks in advance.
A "modern replacement" will be designed different and have another form factor. But there are "old" models still being produced.
Comparing the datasheets of the VIA
http://www.datasheet.hk/view_download.p ... _54247.pdf
and the classic DALLAS DS1287
https://pdf1.alldatasheet.com/datasheet-pdf/v … LAS/DS1287.html
or for today´s MAXIM product
https://pdf1.alldatasheet.com/datasheet-pdf/v … IM/DS12887.html
shows that there is merely a difference. The DALLAS is still produced and available. Note that only datecodes "20" (or 21) are really new products.
You will have to leave Pin 20 open since the Dallas has it´s battery built in, leave pin 21 open since the Dallas has no "Ram Clear" function.
Pin 2 and 3 where the crystal oscillator is connected to the VIA chip are "NC" at the DALLAS, because it has it´s own crystal built in.
Then there´s Pin 1 "MOT" = "bus type selection" that´s not present in the VIA chip where it is connected to Ground.
We´ll have to see about that...
"MOT" pin at Vcc -> Motorola Bus type
"MOT" pin at Ground - Intel Bus type
If we assume Intel bus type and since pin 20 + 21 are "NC" in the DALLAS chip I think it can replace the VIA chip without any changes.
Thank you!
I dropped a fresh DS12887 to the RTC socket on my Pentium board and it worked first time. I've been using it for a day or so and all is well, settings are being remembered no problems.
Cheers!
