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Maxim > Design Support > Technical Documents > Application Notes > Power-Supply Circuits > APP 947
Keywords: dual-output power supply, wallcube, switchmode regulator, linear regulator, sitching regulator,
switchmode DC-DC converter, boost controller
APPLICATION NOTE 947
Extend Battery Life with Dual Power Supply for
Wallcube/Battery-Powered Systems
By: Budge Ing
Jan 31, 2002
Abstract: To save battery life, a dual-output power supply draws battery power only when the AC
wallcube source is not present. Featuring the MAX1705 step-up DC-DC converter and either the
MAX1524 boost controller or MAX608 step-up DC-DC controller, this dual-output power supply needs no
extra diodes or MOSFETs to automatically switch input sources and maintain 5V and 3.3V outputs.
The primary concern for power management in portable equipment is to prolong battery life by
eliminating unnecessary energy consumption. The dual-output power supply of Figure 1 supports this
objective while maintaining regulated 5V and 3.3V outputs for as long as the battery or AC-wallcube
voltage (or both) are present.
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