Fan-Speed Regulators

Abstract: Temperature-based fan control is a necessity in a growing number of systems, both to reduce system noise and to improve fan reliability. When fan control is augmented by fan-speed monitoring, a speed-control loop can be implemented that is independent of manufacturing variances and wear on the fan. In addition, a fan that is about to fail can be identified so that it can be replaced before it fails. This document discusses the operation of the MAX6650 and MAX6651, two fan controllers with linear closed-loop fan speed control.