DS1248 datasheet(7/21 Pages) DALLAS

7 / 21 page

DS1248/DS1248P

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BATTERY LONGEVITY

The DS1248 has a lithium power source that is designed to provide energy for clock activity and clock

and RAM data retention when the VCC supply is not present. The capability of this internal power supply

is sufficient to power the DS1248 continuously for the life of the equipment in which it is installed. For

specification purposes, the life expectancy is 10 years at +25

°C with the internal clock oscillator running

in the absence of VCC power. Each DS1248 is shipped from Dallas Semiconductor with its lithium energy

source disconnected, guaranteeing full energy capacity. When VCC is first applied at a level greater than

VPF, the lithium energy source is enabled for battery-backup operation. Actual life expectancy of the

DS1248 will be much longer than 10 years since no lithium battery energy is consumed when VCC is

present.

CLOCK ACCURACY (DIP MODULE)

The DS1248 is guaranteed to keep time accuracy to within

±1 minute per month at +25°C. The clock is

calibrated at the factory by Dallas Semiconductor using special calibration nonvolatile tuning elements

and does not require additional calibration. For this reason, methods of field clock calibration are not

available and not necessary.

CLOCK ACCURACY (POWERCAP MODULE)

The DS1248P and DS9034PCX are each individually tested for accuracy. Once mounted together, the

module will typically keep time accuracy to within

±1.53 minutes per month (35ppm) at +25°C.

DS1248 Datasheet(PDF) 7 Page - Dallas Semiconductor