28V, Low-Power, High-Voltage, Boost or Inverting DC-DC Converter

The MAX629 low-power DC-DC converter features an internal N-channel MOSFET switch and programmable current limiting. It is designed to supply positive or negative bias voltages up to ±28V from input voltages in the 0.8V to VOUT range, and can be configured for boost, flyback, and SEPIC topologies.

The MAX629's current-limited pulse-frequency-modulation (PFM) control scheme provides high efficiency over a wide range of load conditions. An internal, 0.5A N-channel MOSFET switch reduces the total part count, and a high switching frequency (up to 300kHz) allows for tiny surface-mount magnetics.

The MAX629's combination of low supply current, logic-controlled shutdown, small package, and tiny external components makes it an extremely compact and efficient high-voltage biasing solution that's ideal for battery-powered applications. The MAX629 is available in an 8-pin SO package.

Applications

* 2-Cell and 3-Cell Battery-Powered Applications * High-Efficiency DC-DC Boost Converters * Palmtop Computers * Positive or Negative LCD Bias Generators * Varactor Tuning Diode Bias

* Internal, 500mA, 28V N-Channel Switch (No External FET Required)

* Generates Positive or Negative Output Voltages

* 80µA Supply Current

* 1µA Max Shutdown Current

* Up to 300kHz Switching Frequency

* Adjustable Current Limit Allows Use of Small, Inexpensive Inductors

* 8-Pin SO Package