Step-Up/Down DC-DC Converter in QSOP Package

The MAX1672 integrates a step-up DC-DC converter with a linear regulator to provide step-up/down voltage conversion. This device provides a constant output voltage for inputs that vary above and below the output voltage. It has a 1.8V to 11V input range and a preset 3.3V or 5V output. The output can also be set from 1.25V to 5.5V using two resistors. Typical efficiency is 85%.

The MAX1672's step-up/linear-regulator configuration permits the use of a single, physically smaller inductor than can be used with competing SEPIC and flyback configurations. Switch current is also selectable, permitting the use of smaller inductors in low-current applications. The linear regulator also acts as a filter to reduce output ripple voltage.

The MAX1672 has a low 85µA quiescent supply current, which is further reduced to 0.1µA in logic-controlled shutdown. The output voltage is disconnected from the input in shutdown. The MAX1672 also has a PGI/PGO-bar low-battery detector.

The MAX1672 comes in a 16-pin QSOP package (same size as a standard 8-pin SO). For a larger device that delivers more output current, refer to the MAX710/MAX711. The preassembled MAX1672 evaluation kit is available to speed designs.

Applications

* 2-Cell to 4-Cell AA Alkaline Handheld Equipment * 3.3V and Other Low-Voltage Systems * Battery-Powered Devices * Digital Cameras * Single-Cell, Lithium-Powered Portable Devices with AC Input Adapters

* Step-Up/Down Voltage Conversion

* 1.8V to 11V Input Range

* 3.3V/5V or Adjustable Output Voltage Range

* Output Current:

* 300mA at 5V (VIN > 2.5V)

* 150mA at 5V (VIN > 1.8V)

* Smaller Inductor than SEPIC and Flybacks

* Load Disconnects from Input in Shutdown

* Supply Current from Battery:

* 85µA (No-Load)

* 0.1µA (Shutdown)

* PGI/PGO-bar Low-Battery Comparator

* 16-Pin QSOP Package (Same Footprint as 8-pin SO)

* No External FETs Required

* Thermal and Short-Circuit Protection