公开(公告)号：US20180307265A1

公开(公告)日：2018-10-25

申请号：US15926598

申请日：2018-03-20

Applicant: Cirrus Logic International Semiconductor Ltd.

Inventor： Bruce E. DUEWER ,  Brad Allan LAMBERT ,  Michael A. KOST ,  Marc J. KOBAYASHI ,  David HISKY ,  Vitaliy KULIKOV

IPC: G06F1/10 ,  G06F1/12 ,  G06F1/32 ,  G06F13/38

Abstract: A device may include an input for receiving information communicated from a host to the device and a controller configured to recover a device reference clock on the device, the device reference clock proportional to a host reference clock of the host, when clock signaling from the host to the device is unavailable. The controller may recover the device reference clock by measuring a ratio between the host reference clock and the device reference clock of the device by monitoring, with the device, host start-of-frame markers communicated from the host to the device via the input, creating a recovered reference clock based on the measured ratio, and creating local start-of-frame markers that are phase locked with the host start-of-frame markers based on the recovered reference clock.A method for generating a not-yet (NYET) signal in a recovered reference system for recovering a device reference clock on a device, wherein the NYET signal indicates that the device is not yet ready for transition into a low power mode, in order to improve a quality of a recovered reference clock representative of a host reference clock of a host communicatively coupled to the device, may be provided. The method may include detecting receipt of start-of-frame markers from the host to the device, responsive to detecting receipt of the markers, determining whether a condition for NYET generation is being met, responsive to the condition for NYET generation being met, generating the NYET signal to cause the host to continue generating the markers, and responsive to the condition for NYET generation not being met, causing the device to generate an acknowledge signal for transition of the device into the low power mode.