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Functional Description
4
4-8
provide an early warning to avoid data loss. Because the DS1210S
may block the second access, the software should do at least two
accesses before relying on the data.
Optionally, the MVME177 provides jumpers that allow the power
source of the DS1210S to connect to the VMEbus +5 V STDBY pin
or the onboard battery.
The optional power source for the SRAM is a socketed Sanyo
CR2430 battery. A small capacitor is provided to allow the battery
to be quickly replaced without data loss.
The lifetime of the battery is very dependent on the ambient
temperature of the board and the power-on duty cycle. The FB1225
and CR2430 lithium batteries should provide at least two years of
backup time with the board powered off and the board at 40û C. If
the power-on duty cycle is 50% (the board is powered on half of the
time), the battery lifetime is four years. At lower ambient
temperatures the backup time is greatly extended and may
approach the shelf life of the battery.
When a board is stored, if the battery is present, it should be
disconnected to prolong battery life. This is especially important at
high ambient temperatures. MVME177 boards with battery backup
are shipped with the batteries disconnected.
The power leads from the battery are exposed on the solder side of
the board, therefore the board should not be placed on a conductive
surface or stored in a conductive bag unless the battery is removed.
Note
Lithium batteries incorporate inflammable materials
such as lithium and organic solvents. If lithium
batteries are mistreated or handled incorrectly, they
may burst open and ignite, possibly resulting in injury
and/or fire. When dealing with lithium batteries,
carefully follow the precautions listed below in order to
prevent accidents:
Do not short circuit
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