# US 9,436,203 B2 · Method and apparatus for regulator control > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,436,203 B2 - Document ID: US9436203B2 - Status: Granted - Kind: B2 - Application number: 14/048,189 - Filed: 2013-10-08 - Published: 2014-04-10 - Granted: 2016-09-06 - Earliest claimed: 2012-10-08 - Assignees: Marvell World Trade Ltd. - Applicants: Marvell World Trade Ltd. - Inventors: Reuven Ecker; Ido Bourstein - Web page: https://patentgrep.com/patent/US9436203B2 ## CPC - G05F 3/02: Regulating voltage or current - G05F 3/08: wherein the variable is DC - G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES ## Abstract Aspects of the disclosure provide an integrated circuit (IC) chip that includes a feedback control circuit and a detecting circuit. The feedback control circuit is configured to govern a feedback signal to a first regulator that regulates a first power supply to the IC chip based on the feedback signal. The feedback control circuit is powered at least partially by a second power supply. The detecting circuit is configured to detect a power down of the second power supply, and to cause the feedback control circuit to be disengaged from the feedback signal in response to the power down. ## Claims ### Claim 1 An integrated circuit (IC) chip, comprising: a feedback control circuit configured to govern a feedback signal to a first regulator that regulates a first power supply to the IC chip based on the feedback signal, the feedback control circuit being powered at least partially by a second power supply; and a detecting circuit configure to detect a power down of the second power supply, and to cause the feedback control circuit to be disengaged from the feedback signal in response to the power down. ### Claim 2 (depends on 1) The IC chip of claim 1, further comprising: a circuit configured to provide the feedback signal based on the first power supply when the feedback control circuit is disengaged from the feedback signal. ### Claim 3 (depends on 1) The IC chip of claim 1, wherein the feedback control circuit comprises: a driving circuit configured to be powered by the second power supply to drive the feedback signal for regulating the feedback signal; and an enable/disable circuit configured to disable the feedback driving circuit in response to the power down of the second power supply in order to disengage the feedback control circuit from the feedback signal. ### Claim 4 (depends on 3) The IC chip of claim 3, wherein the feedback control circuit further comprises: a feedback generation circuit configured to determine an adjustment to the first power supply. ### Claim 5 (depends on 4) The IC chip of claim 4, wherein the feedback generation circuit is configured to gradually change the adjustment to zero in response to the power down of the second power supply. ### Claim 6 (depends on 5) The IC chip of claim 5, wherein the feedback generation circuit is configured to gradually change the adjustment to zero before the enable/disable circuit disables the feedback driving circuit. ### Claim 7 (depends on 3) The IC chip of claim 3, wherein the driving circuit is configured to have a higher output impedance than a passive circuit in response to the power down of the second power supply and to be disengaged from the feedback signal. ### Claim 8 (depends on 1) The IC chip of claim 1, wherein the first power supply provides power to digital circuitry in the IC chip and the second power supply provides power to analog circuitry in the IC chip. ### Claim 9 A method, comprising: detecting a power down of a second power supply that at least partially powers a feedback control circuit, the feedback control circuit adjusting a feedback signal to a regulator that regulates a first power supply based on the feedback signal; and causing the feedback control circuit to be disengaged from the feedback signal in response to the power down of the second power supply. ### Claim 10 (depends on 9) The method of claim 9, further comprising: providing the feedback signal via a circuit based on the first power supply when the feedback control circuit is disengaged from the feedback signal. ### Claim 11 (depends on 9) The method of claim 9, wherein causing the feedback control circuit to be disengaged from the feedback signal in response to the power down of the second power supply further comprises: driving the feedback signal based on the second power supply for regulating the feedback signal; and disabling the driving of the feedback signal in response to the power down of the second power supply in order to disengage the feedback control circuit from the feedback signal. ### Claim 12 (depends on 11) The method of claim 11, wherein driving the feedback signal based on the second power supply for regulating the feedback signal further comprises: determining an adjustment to the first power supply; and generating the feedback signal based on the first power supply and the adjustment. ### Claim 13 (depends on 12) The method of claim 12, further comprising: gradually changing the adjustment to zero in response to the power down of the second power supply. ### Claim 14 (depends on 13) The method of claim 13, wherein gradually changing the adjustment to zero before disabling the driving of the feedback signal based on the second power supply. ### Claim 15 (depends on 11) The method of claim 11, further comprising: entering a high output impedance state to be disengaged from the feedback signal. ### Claim 16 A system, comprising: a first regulator configured to provide a first power supply based on a feedback signal; a second regulator configured to provide a second power supply; and an integrated circuit (IC) chip configured to operate based on the first power supply and the second power supply, the IC chip comprising: a feedback control circuit configured to govern the feedback signal to the first regulator, the feedback control circuit being powered at least partially by the second power supply; and a detecting circuit configure to detect a power down of the second power supply, and to cause the feedback control circuit to be disengaged from the feedback signal in response to the power down. ### Claim 17 (depends on 16) The system of claim 16, further comprising: a circuit configured to provide the feedback signal based on the first power supply when the feedback control circuit is disengaged from the feedback signal. ### Claim 18 (depends on 16) The system of claim 16, wherein the feedback control circuit comprises: a driving circuit configured to be powered by the second power supply to drive the feedback signal; and an enable/disable circuit configured to disable the driving circuit in response to the power down of the second power supply in order to disengage the feedback control circuit from the feedback signal. ### Claim 19 (depends on 18) The system of claim 18, wherein the feedback control circuit further comprises: a feedback generation circuit configured to determine an adjustment to the first power supply, and generate the feedback signal based on the first power supply and the adjustment. ### Claim 20 (depends on 19) The system of claim 19, wherein the feedback generation circuit is configured to gradually change the adjustment to zero in response to the power down of the second power supply.