Step-down regulators provide extremely fast line and load transient response

Exar's 1A, 3A, 5A and 8A 40V synchronous step-down regulators in small 5mm x 5mm QFN packages utilize the company’s proprietary constant on-time architecture to provide superior line and load regulation, fast transient response, and stability with ceramic output capacitors. They are available now from Digi-Key. The XR76201, XR76203, XR76205, and XR76208 are synchronous step-down regulators combining the controller, drivers, bootstrap diode, and MOSFETs in a single package for point-of-load supplies. They have load current ratings of 1A, 3A, 5A and 8A, respectively. A wide 3V to 40V input voltage range allows for single supply operation from industry standard 24V ±10%, 18V to 36V, and rectified 18VAC and 24VAC rails. With a proprietary emulated current mode COT control scheme, they provide extremely fast line and load transient response using ceramic output capacitors. They require no loop compensation, simplifying circuit implementation and reducing overall component count. The control loop also provides 0.05% (XR76201) or 0.07% (XR76203, XR76205, XR76208) load regulation, 0.15% line regulation, and maintains constant operating frequency. A selectable power saving mode allows the user to operate in DCM at light current loads, thereby significantly increasing the converter efficiency.