MAX1681

19-1247; Rev 0; 7/97 125mA, Frequency-Selectable, Switched-Capacitor Voltage Converters _______________General Description The MAX1680/MAX1681 inductorless switched-capacitor voltage converters either invert an input voltage of +2.0V to +5.5V or double it while supplying up to 125mA output current. They have a selectable-frequency option that allows the use of small capacitors: 4.7µF (MAX1680), 1µF (MAX1681). With their high output current capability, these charge-pump devices are suitable replacements for inductor-based regulators, which require more expensive external components and additional board space. The devices’ equivalent output resistance (typically 3.5Ω) allows them to deliver as much as 125mA with only a 440mV drop. A shutdown feature reduces quiescent current to less than 1µA. The MAX1680/MAX1681 are available in 8-pin SO packages. For devices that deliver up to 50mA in smaller µMAX packages, refer to the MAX860/MAX861 data sheet. ____________________________Features o Selectable Switching Frequencies: 125kHz/250kHz (MAX1680) 500kHz/1MHz (MAX1681) o Allow Use of Small Capacitors (1µF for the MAX1681) o 125mA Output Current o 3.5Ω Output Impedance o 1µA Logic-Controlled Shutdown o Configurable as Voltage Inverters or Doublers o +2.0V to +5.5V Input Voltage Range o Available in 8-Pin SO Packages o 90% Efficiency MAX1680/MAX1681 ________________________Applications Local Negative Supplies Interface Power Supplies Op-Amp Power Supplies MOSFET Bias _____________...