125mA, Frequency-Selectable, Switched-Capacitor Voltage Converters

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.

Applications

* Interface Power Supplies * Local Negative Supplies * MOSFET Bias * Op-Amp Power Supplies

* Selectable Switching Frequencies:

* 125kHz/250kHz (MAX1680)

* 500kHz/1MHz (MAX1681)

* Allow Use of Small Capacitors (1µF for the MAX1681)

* 125mA Output Current

* 3.5Ω Output Impedance

* 1µA Logic-Controlled Shutdown

* Configurable as Voltage Inverters or Doublers

* +2.0V to +5.5V Input Voltage Range

* Available in 8-Pin SO Packages

* 90% Efficiency