50mA, Frequency-Selectable, Switched-Capacitor Voltage Converters

Description

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The MAX860/MAX861 charge-pump voltage converters invert input voltages ranging from +1.5V to +5.5V, or double input voltages ranging from +2.5V to +5.5V. Because of their high switching frequencies, these devices use only two small, low-cost capacitors. Their 50mA output makes switching regulators unnecessary, eliminating inductors and their associated cost, size, and EMI. Greater than 90% efficiency over most of the load-current range, combined with a typical operating current of only 200µA (MAX860), provides ideal performance for both battery-powered and board-level voltage-conversion applications.

A frequency-control (FC) pin provides three switching-frequencies to optimize capacitor size and quiescent current and to prevent interference with sensitive circuitry. Each device has a unique set of three available frequencies. A shutdown (active-low SHDN) pin reduces current consumption to less than 1µA. The MAX860/MAX861 are suitable for use in applications where the ICL7660 and MAX660's switching frequencies are too low. The MAX860/MAX861 are available in 8-pin µMAX^® and SO packages.

Key Features

• 8-Pin, 1.11mm High µMAX Package
• Invert or Double the Input Supply Voltage
• Three Selectable Switching Frequencies
• High Frequency Reduces Capacitor Size
• 87% Efficiency at 50mA
• 200µA Quiescent Current (MAX860)
• 1µA Shutdown Supply Current
• 600mV Voltage Drop at 50mA Load
• 12Ω Output Resistance

Applications/Uses

• Handheld Instruments (PDAs, Palmtops)
• Interface Power Supplies
• Medical Instruments
• Operational Amplifier Power Supplies
• Portable Computing