Abstract: A power management circuit is provided for a data storage device that is adapted for communicating with a host via an interface circuit. The power management circuit is responsive to a utilization of a control circuit of the data storage device, determined independently of the communication between the data storage device and the host, in providing a supply power to the data storage device. A method is provided comprising connecting a data storage device with a host via an interface circuit; sending data transfer commands from the host to the interface circuit; and monitoring the utilization of a control circuit of the data storage device in terms of the rate at which commands are processed by the control circuit for use in selectively providing a supply power to the data storage device.