Buck converters increase efficiency at light loads

The AP6550 and AP6540's current mode control produces a fast transient response and simple loop stabilisation, ensuring dependable line and load regulation in distributed point-of-load power management applications. By operating at higher fixed switching frequencies of 500 and 750kHz, the converters are also able to help shrink circuit footprints by minimising the size of external inductive and capacitive components. The 500kHz 4A-rated AP65402 and 5A-rated AP65502 provide an adjustable output voltage range of 0.925 to 16V, while the 750kHz parts, the AP65403 and AP65503, offer a higher range of 2.5 to 16V. A wide operating voltage range of 4.75 to 17V means the converters are suited for both 5 and 12V bus system design and all devices tolerate a transient peak voltage of up to 7A. To help increase circuit reliability, the buck converters integrate a 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.