Electronic Design

Inductorless DC-DC Converter Targets Portables

With greater than 90% efficiency, the FAN5660 inductorless dc-dc converter will find its way into portable applications and system voltage conversions. Using only two capacitors, the charge pump's 100-mA output replaces switching regulators, thereby eliminating inductors and their associated cost and electromagnetic interference (EMI). The FAN5660 inverts a 1.5- to 5.5-V input to a corresponding -1.5- to -5.5-V output. This converter can split or double a full load (5.0-V input voltage) of a power supply or battery, providing 2.25 V in splitter mode and 9.5 V in doubler mode. Because the FAN5660 does not require an external diode in voltage doubler mode, it occupies less pc-board area. Equipped with an on-board oscillator circuit, the charge pump provides more flexibility when selecting appropriate operating frequencies. When the low, 5-kHz operating frequency is selected, a low quiescent current will result. A smaller capacitor can be used at the higher, 50-kHz operating frequency. Its 90%-plus efficiency at full load is achieved with an operating current of just 120 µA. The FAN5660 comes in a space-saving eight-lead small-outline IC package. In 1000-unit quantities, it costs $1.61 each.

Fairchild Semiconductor International
www.fairchildsemi.com; (888) 522-5372

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