There are two different datasheets.
- DS3231S# ..... 0°C to +70°C SO16
- DS3231SN# . -40°C to +85°C SO16
- DS3231MZ+ ...-45°C to +85°C SO8
- DS3231MZ/V+ -45°C to +85°C SO8
- DS3231M+ .... -45°C to +85°C SO16
When rated for below freezing, it means the package moisture seal is better but resonator drift will be greater at extreme temps. Therefore the same chip with 3.5ppm in the commercial range may be 5ppm in the military range ( or Winnipeg temp range ;) with the same quality
SO8 means Small Outline 8 pin. This the basic difference. There may be more if you read the spec. ..your job...
Note that a
“+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the
drawing pertains to the package regardless of RoHS status.
For context one month has 2,592,000 seconds so 3 ppm error translates to a clock error of 3parts/million *2.59million seconds/month = 7.77 seconds error per month or a frequency error of the same ratio.
Since the clock error versus Temperature is parabolic around room temp error increases in either temperature extreme.
But there are two error components to any resonator error.
I expect but have not read specs that all chips have the same basic code functions, but you must verify.