MAX629ESA+T

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-pow­ ered applications. The MAX629 is available in an 8-pin SO package. The MAX629 low-power, boost DC-DC converter provides either positive or negative output voltages up to ±28V from a wide range of input voltages. It is designed primarily for use in low-power, high-voltage applications such as LCD biasing and set-top box varactor tuning. The MAX629’s unique control scheme provides high efficiency and a wide range of output voltages with only 80μA quiescent supply current, making it ideal for battery-powered applications. The internal N-channel DMOS switch has a pin-programmable current limit (250mA and 500mA), allowing optimization of output current and component size.

Applications

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

Key features

• 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