1) Write-Protection voltage (Vtp) on the DS1220Y and DS1225Y are determined by an internal voltage-divider circuit (~1.26 x VBat). As the internal battery in the module degrades, the corresponding Vtp also degrades, resulting in a change in the response of the module to system power loss. The AB/AD versions have a precision band-gap reference voltage that is independent of the battery.
2) Storage and handling of battery-backed products can be critical to achieve the expected 10 years of potential data retention from a new module. The DS1220Y and DS1225Y do not contain the Freshness Seal circuitry, which means the 10 year warranty begins with date of manufacture, as opposed to the date of customer's first use on AB/AD versions. |