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Browse Prior Art Database

Battery Back-Up Memory System

IP.com Disclosure Number: IPCOM000102408D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 88K

Publishing Venue

IBM

Related People

Niijima, H: AUTHOR [+4]

Abstract

A battery back-up memory system is described which is suitable for portable computers. The memory system comprises of semiconductor memory devices, a battery for total operation of the portable computer, a DC-DC converter only for data back-up of the semiconductor memory devices and a memory control circuit. The data in the semiconductor memory devices can be backed up by the current supplied by the battery for normal operation of the portable computer through the DC-DC converter used only for the memory back up. Low power battery back-up of the memory devices can be realized without an extra battery for memory data back-up.

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Battery

Back-Up Memory System

       A battery back-up memory system is described which is
suitable for portable computers. The memory system comprises of
semiconductor memory devices, a battery for total operation of the
portable computer, a DC-DC converter only for data back-up of the
semiconductor memory devices and a memory control circuit. The data
in the semiconductor memory devices can be backed up by the current
supplied by the battery for normal operation of the portable computer
through the DC-DC converter used only for the memory back up. Low
power battery back-up of the memory devices can be realized without
an extra battery for memory data back-up.

      Data processing systems, including semiconductor memories, such
as DRAM or SRAM, require electric current from the power supply to
back-up the stored data. It is useful to have a battery for this
operation without any other power source. This requires a data
back-up mode in which the semiconductor memory data is backed up by a
battery, the necessary current for the data back-up being supplied by
the battery through a voltage conversion circuit.

      In conventional data processing systems using a battery as
power source, an extra battery (usually secondary battery) is also
used for data back-up of the semiconductor memory. However, the size
of the battery for data back-up has to be large for long data back-up
time.  Another problem is the short back-up time due to the back-up
battery being not fully charged up. As shown in Fig. 1, the power
source battery supplies the current necessary for the operation of
data processing system through a DC-DC converter. The DC-DC converter
is used to compensate the voltage change of the power source battery
due to the discharge.

      In the bat...