4/5A step-down converters are efficient at light loads

April 01, 2014 // By Graham Prophet
A light-load efficiency improvement algorithm ensures the AP6550 and AP6540 synchronous DC-DC buck converters from Diodes Incorporated achieve an efficiency as high as 96% delivering continuous load currents of 4A and 5A, respectively.

Current mode control produces a fast transient response and simple loop stabilisation, ensuring line and load regulation in distributed point-of-load power management applications. By operating at higher fixed switching frequencies of 500 kHz and 750 kHz, these highly integrated converters are also able to help shrink circuit footprints by minimising the size of external inductive and capacitive components. The 500 kHz 4A-rated AP65402 and 5A-rated AP65502 provide an adjustable output voltage range of 0.925V to 16V, while the 750 kHz parts, AP65403 and AP65503, offer a higher range of 2.5V to 16V.

An operating voltage range of 4.75V to 17V means the converters are suited for both 5V and 12V bus system design and all devices tolerate a transient peak voltage of up to 7A. Component packaging is the industry-standard exposed pad SO-8EP, with pin-outs identical throughout the product family.

The converters integrate a broad range of protection features, including thermal shutdown, under-voltage lockout, over-voltage and current-limit protection. A capacitor programmed soft-start function is also provided to control inrush current and output voltage overshoot. They are priced at $0.65 (10,000) pieces.

Diodes Inc.; www.diodes.com