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Boost Battery Output Voltage to extend Backup Power Availability at System Power Input

IP.com Disclosure Number: IPCOM000032873D
Original Publication Date: 2004-Nov-17
Included in the Prior Art Database: 2004-Nov-17
Document File: 2 page(s) / 550K

Publishing Venue

IBM

Abstract

In systems that require non-volatile data to be battery backed the general method is to provide a battery and battery charger function. The batteries become connected to the load (non-volatile data) when the normal power supply loses AC input, either intentionally or accidentally. Once connected, the batteries are drained by the load to a point when the battery voltage decays beyond a useful voltage level, at which point they become ineffective and the load loses it battery power. It is important to note that the battery system generally continues to have some remaining charge but whose output voltage is below the acceptable input voltage of the load, generally received by a voltage regulator. A method and apparatus is needed to take advantage of this remaining (useless) battery charge. This disclosure provides for a Battery Boost function which senses when the batteries are discharged to such a state and then boosts the battery voltage to a usable voltage level which in turn can be used to power the load.

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Boost Battery Output Voltage to extend Backup Power Availability at System Power Input

Disclosed is a system which provides for extended
usage of batteries once they have been discharged whereby the
battery backed load no longer can recognize or use the incoming
battery voltage level. Figure 1 illustrates a system in which
a load, e.g. non-volatile memory device, is normally powered by
a power supply and auxilliary battery system, consisting of a
battery charger and batteries. A Battery Boost function is
implemented to provide power to the load once the
batteries are sufficiently discharged.

Referring to Figure 2, at time T1 the power/battery system
receives AC input provides a voltage, Vps, which results in
voltage of Vload to the load. This is generally defined as
normal operation. At time T2 the Power Supply loses AC input
voltage and the battery system takes over and generates voltage
Vbat which in turn results in voltage Vload to the load. During
time interval T2 to T3 the batteries are providing power to the
load and are being discharged. At time T3 the battery voltage
Vbat is sufficiently low that the voltage regulator used to
regulate voltage to the load can no longer sustain regulation and
would normally result in the non-volatile data in the load
becoming volatile and losing data/information. However, the
Battery Boost function is designed to sense this threshold point
and begin boosting the significantly low battery voltage to a
usable level of Vboost, resulting in a volt...