DS1742-85 MAXIM [Maxim Integrated Products], DS1742-85 Datasheet - Page 6

• Manufacturer Part Number: DS1742-85
• Description: Y2KC Nonvolatile Timekeeping RAMwww.
• Manufacturer: MAXIM [Maxim Integrated Products]

DS1742
BATTERY LONGEVITY
The DS1742 has a lithium power source that is designed to provide energy for clock activity,
and clock and RAM data retention when the V
supply is not present. The capability of this
CC
internal power supply is sufficient to power the DS1742 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 V
power. Each DS1742 is
CC
shipped from Dallas Semiconductor with its lithium energy source disconnected, guaranteeing
full energy capacity. When V
is first applied at a level greater than V
, the lithium energy
CC
PF
source is enabled for battery backup operation. Actual life expectancy of the DS1742 will be
much longer than 10 years since no lithium battery energy is consumed when V
is present.
CC
BATTERY MONITOR
The DS1742 constantly monitors the battery voltage of the internal battery. The Battery Flag bit
(bit 7) of the day register is used to indicate the voltage level range of the battery. This bit is not
writable and should always be a 1 when read. If a 0 is ever present, an exhausted lithium
energy source is indicated and both the contents of the RTC and RAM are questionable.
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