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Maxim > Design Support > Technical Documents > Application Notes > Amplifier and Comparator Circuits > APP 110
Keywords: DC-DC converter, low load currents, boost converter, Schmitt-trigger NAND gate
APPLICATION NOTE 110
Boost Converter Has High Efficiency at Light
Loads
Jul 09, 1998
Abstract: This design note shows how a boost converter is designed from a quad Schmitt-trigger NAND
gate and the MAX921, a comparator with integrated voltage reference. Consuming only microwatts of
power, this 5V-to-15V boost converter provides low load currents with high efficiency. The efficiency is >
90% for load currents between 1mA and 8mA.
In most DC-DC converters, the normal supply currents do not allow high efficiency at low load currents.
The circuit in Figure 1, however, contains micropower components that enable it to maintain 90%
efficiency for load currents as low as 1mA. IC1 (a quad Schmitt-trigger NAND gate) draws maximum
quiescent currents of only 0.25µA, and IC2 (a combination voltage reference and comparator) draws only
2.5µA.
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