user manual

Functional Description

MVME162IG/D2 1-13

Caution

For proper operation of the SRAM, some jumper

combination must be installed on the Backup Power Source

Select Header (J20). If one of the jumpers is used to select

the battery, the battery must be installed on the MVME162.

The SRAM may malfunction if inputs to the DS1210S are

left unconnected.

The SRAM is controlled by the MCchip, and the access time is programmable.

Refer to the MCchip description in the MVME162 Embedded Controller

Programmer’s Reference Guide for more detail.

About the Battery

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

MVME162 should provide at least two years of backup time with the board

powered off and with an ambient temperature of 40° 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, the battery should be disconnected to prolong battery

life. This is especially important at high ambient temperatures. The MVME162

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 battery as a power source, whether primary or secondary, it is

necessary to reconfigure the jumpers on J20 before installing the module. Refer

to SRAM Backup Power Source Select Header J20 in Chapter 2 for available

jumper configurations.

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.