Developer --> Technical Publications
PATHHardware Documentation > PowerBook G3 Series 1999

RAM SO-DIMM Electrical Limits

Each RAM SO-DIMM must not exceed the following maximum current limits on the +3 V supply:

Active
1.2 A (8 devices at 150 mA each)
Sleep
6 mA per bank

The maximum current specified for active operation generally rules out the use of 4-bit-wide SDRAM devices in a RAM expansion card. Such a card would have 16 such devices, and the 1.2 A maximum current would allow only about 75 mA per device. To stay within the current limits, RAM expansion cards should use only 8-bit or 16-bit SDRAM devices.

The restriction on sleep current is required not only to maximize the battery life but to meet the limitations of the backup battery during hot swapping of the main battery.

© 1999 Apple Computer, Inc. – (Last Updated 29 April 99)