Uninterruptable-supply


Posted on Aug 5, 2012

This circuit provides a continuous supply of regulated + 5 V, with automatic switch-over between line power and battery backup. When the line-powered input voltage is a + 5 V, it provides 4A V to the MAX630 and trickle charges the battery, If the line-powered input falls below the battery voltage, the 3.6 V battery supplies power to the MAX630, which boosts the battery voltage up to +5 V, thus maintaining a continuous supply to the uninterruptable +5 V bus. Since the +5 V output is always supplied through the MAX630, there are no power spikes or glitches during power transfer.


Uninterruptable-supply
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The MAX630"s low-battery detector monitors the line-powered + 5 V, and -the LBD output can be used to shut down unnecessary sections of the system during power failures. Alternatively, the low-battery detector could monitor the NiCad battery voltage and provide warning of power loss when the battery is nearly discharged. Unlike battery backup systems that use 9-V batteries, this circuit does not need +12 or +15 V to recharge the battery, Consequently, it can be used to provide + 5 V backup on modules or circuit cards which only have 5 V available.




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