Simple SOT23 Boost Controllers

The MAX1522/MAX1523/MAX1524 are simple, compact boost controllers designed for a wide range of DC-DC conversion topologies, including step-up, SEPIC, and flyback applications. They are for applications where extremely low cost and small size are top priorities. These devices are designed specifically to provide a simple application circuit and minimize the size and number of external components, making them ideal for PDAs, digital cameras, and other low-cost consumer electronics applications.

These devices use a unique fixed on-time, minimum off-time architecture, which provides excellent efficiency over a wide-range of input/output voltage combinations and load currents. The fixed on-time is pin selectable to either 0.5µs (50% max duty cycle) or 3µs (85% max duty cycle), permitting optimization of external component size and ease of design for a wide range of output voltages.

The MAX1522/MAX1523 operate from a +2.5V to +5.5V input voltage range and are capable of generating a wide range of outputs. The MAX1524 is intended for bootstrapped operation, permitting startup with lower input voltage. All devices have internal soft-start and short-circuit protection to prevent excessive switching current during startup and under output fault conditions. The MAX1522/MAX1524 have a latched fault mode, which shuts down the controller when a short-circuit event occurs, whereas the MAX1523 reenters soft-start mode during output fault conditions. The MAX1522/MAX1523/MAX1524 are available in a space-saving 6-pin SOT23 package.

Applications

* Industrial +24V and +28V Power Supplies * LCD Bias Supplies * Low-Cost Battery-Powered Applications * Low-Cost, High-Current, or High-Voltage Boost Conversion * Low-Cost, Multi-Output Flyback Converters * SEPIC Converters

* Simple, Flexible Application Circuit

* 2-Cell NiMH or Alkaline Operation (MAX1524)

* Low Quiescent Current (25µA typ)

* Output Fault Protection and Soft-Start

* High Efficiency Over 1000:1 IOUT Range

* Pin-Selectable Maximum Duty Factor

* Micropower Shutdown Mode

* Small 6-Pin SOT23 Package

* No Current-Sense Resistor