The AP3401 and AP3428 DC/DC step-down converters drive up to 1A with line- and load-regulation provided by a constant-frequency PWM control that requires no external compensation to minimize component count and material costs.

The low power consumption and efficient light load are designed for set-top boxes, TVs, routers, Wi-Fi modules and security systems. 

They operate from an input voltage between 2.5 and 5.5V, making them suitable for use with a single Li /Li-polymer cell, multiple Alkaline/NiMH cells and other power sources. They deliver an output voltage from 0.6V up to the full input voltage with an output current up to 1A. The high-current and low-dropout threshold performance is achieved with integrated ultra-low RDS(ON) MOSFETs and the ability to operate at 100 per cent duty cycle with a switching frequency up to 1.5MHz. The AP3401 also has a power-good output.

An integrated soft-start reduces start-up current spikes to avoid system damage when switching power on or off. Other protection features are over-current, under-voltage lockout and over-temperature with thermal shutdown. The DFN2020 package has exposed pads for power handling in thermally demanding consumer applications.