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Board Level Hardware Description
1
!
Caution
About the Battery
1-18
VMEbus +5V STDBY pin and the secondary source may be the
onboard battery. If the system source should fail or the board is
removed from the chassis, the onboard battery takes over. Refer to
Chapter 2 for the jumper configurations.
For proper operation of the SRAM, some jumper
combination must be installed on the respective Backup
Power Source Select Header (J14). If one of the jumpers
is used to select the battery, the battery must be installed
on the MVME162LX. The SRAM may malfunction if
inputs to the DS1210S are left unconnected.
The SRAM is controlled by the MC2chip, and the access time is
programmable. Refer to the MC2chip description in the
MVME162LX Embedded Controller Programmer's Reference Guide for
more detail.
The power source for the onboard SRAM is a RAYOVAC FB1225
battery with two BR1225-type lithium cells which is socketed for
easy removal and replacement. 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 lithium
battery supplied on the MVME162LX should provide at least two
years of backup time with the board powered off and with an
ambient temperature of 40
board is powered on half of the time), the battery lifetime is four
years. At lower ambient temperatures, the backup time is greatly
extended.
When a board is stored, the battery should be disconnected to
prolong battery life. This is especially important at high ambient
temperatures. The MVME162LX is shipped with the batteries
disconnected (i.e., with VMEbus +5V standby voltage selected as
both primary and secondary power source). If you intend to use the
°
C. If the power-on duty cycle is 50% (the
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