When compared to previous generations of iButton data loggers, the DS1925 offers slower minimum sample rates. Over the years, customers have expressed a desire for a temperature data logger that retains logged data, even when the battery depletes during a mission. The DS1925 addresses this issue, but not without some compromises:
1) Programming the non-volatile memory used in the DS1925 takes significantly more current than the SRAM used in the other DS192x devices. This higher current consumption comes at the expense of sample rate. The current surge needed to program the memory causes the battery voltage to dip, so extra time is needed for the battery voltage to recover. A one second sample rate, for example, would cause the battery voltage to drop on the first temperature conversion, and it would continue to drop on subsequent conversions until the device experienced a power-on-reset (POR) condition.
2) A higher capacity battery potentially solves the problem, but these are offered in sizes that would require a new iButton can construction. An iButton data logger with different physical dimensions would be incompatible with existing customer infrastructure.