Adaptive COT Buck Converter Handles Fast-Changing Loads
Diodes Incorporated has introduced a synchronous buck converter designed to optimize transient response in low-voltage TV and monitor applications. Based on an adaptive constant on-time (COT) control algorithm, the 650kHz, 5A-rated, AP65550 quickly reacts to rapid changes in load conditions, guaranteeing a minimal drop in output voltage. The COT control scheme handles wide input/ output voltage ratios and provides low external component count. The internal proprietary circuit enables the device to drive low ESR output capacitors, such as SPCAP or POSCAP and ultralow ESR ceramic capacitors. Discontinuous current mode allows AP65550 maintain high efficiency at light load conditions.
Managing wide variations in input/output voltage ratios, the device control algorithm also helps minimize external component count and enables the use of both low and ultra-low equivalent series resistance capacitors. The converter is available in the SO-8EP package and suitable for 5V, 9V and 12V bus systems, due to its stable 4.5V to 18V operating voltage range.
The buck converter’s automatic light-load efficiency-improvement feature ensures seamless transition between continuous conduction mode at higher loads and discontinuous conduction mode at lighter loads. This helps designers comply with low power consumption regulations and achieves operating efficiencies as high as 92%.
To protect downstream components from damage and premature aging, the converter integrates a complete suite of protection features, including under-voltage lockout, thermal shutdown, over-current protection and programmable soft-start.
