MAX1522/MAX1523/MAX1524,pdf (S

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 offtime
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.