Buck converters achieve high efficiency under both light and full-load conditions

Diodes Inc have introduced the AP3401 and AP3428 DC-DC step-down converters that are capable of driving loads up to 1A with excellent line and load-regulation provided by a constant-frequency PWM control that requires no external compensation and so minimises component count and material costs. Developed to meet the demands of set-top boxes, TVs, routers, Wi-Fi modules and security systems, these buck converters feature low power consumption and highly-efficient light-load operation. The devices operate from an input voltage between 2.5V and 5.5V, making them well-suited for use with a single Li+/Li-polymer cell, multiple Alkaline/NiMH cells and other power sources; they also 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 the benefit of integrated ultra-low RDS(ON) MOSFETs and the ability to operate at 100% duty cycle with a switching frequency up to 1.5MHz. The AP3401 also features a power-good output. An integrated soft-start reduces start-up current spikes to avoid system damage when switching power on or off. Other features for protection of the IC and system include over-current, under-voltage lockout and over-temperature with thermal shutdown. The device’s DFN2020 package with exposed pads provides the power handling capability needed for thermally demanding consumer applications.