CONTROL SYSTEMS FOR REDUCING CURRENT TRANSIENTS

• US 20160091960A1
• Filed: 09/29/2014
• Published: 03/31/2016
• Est. Priority Date: 09/29/2014
• Status: Abandoned Application

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: ISMAIL, James S., HARDELL, David A., COX, Keith, ECKERT, Karen S.
• Application Number:
  US14/500,393
• Publication Number:
  US 20160091960A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C
• CPC Class Codes: G06F 1/28 Supervision thereof, e.g. detecting power-supply failure by out of limits supervision
• CPC Class Codes: G06F 1/3206 Monitoring of events, devices or parameters that trigger a change in power modality
• CPC Class Codes: G06F 1/324 by lowering clock frequency
• CPC Class Codes: G06F 1/3296 by lowering the supply or operating voltage
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A method, apparatus, and system for reducing current transients of a power supply are disclosed. Specifically, the embodiments discussed herein include a control system configured to throttle a processor of a computing device when the current demanded by the processor from the power supply exceeds a reference current value. Throttling can include reducing or limiting the performance state that the processor can be operable in. Additionally, the control system can be operated according to multiple time domains, allowing the sampling of an input current to be performed at a higher rate than a rate at which analysis on the sampled input current is performed. The processor can remain throttled depending on a delayed release filter, which determines when a processor can return to a performance state that was previously removed.

Claims

1. A controller used to reduce a frequency and/or a peak current value of a transient current induced by an input current supplied, by a power supply, to a computing system having at least one processor, the controller comprising:

an input current filter operable at a first frequency and arranged to sample the input current; and

a control effort generator coupled to the input current filter, the control effort operable at a second frequency that is less than the first frequency and configured to use a sampled input current to provide a control effort signal to the at least one processor to reduce the frequency and/or the peak current value of the transient current by throttling the at least one processor thereby reducing a performance state of the at least one processor.

2. The controller of claim 1, wherein the first frequency and the second frequency are tunable for reducing the frequency and/or the peak current value.

3. The controller of claim 1, wherein the control effort generator comprises:

a limiter configured to limit a magnitude of the control effort signal.

4. The controller of claim 1, wherein the control effort generator comprises:

a release filter configured to slow a decay of the control effort signal.

5. The controller of claim 1, wherein the control effort signal is based on a difference between the sampled input current and a reference signal corresponding to a peak current threshold of the power supply.

6. The controller of claim 5, wherein the control effort generator is configured to provide the reference signal corresponding to a power specification for a particular power supply.

7. The controller of claim 5, wherein the reference signal is encoded as updatable firmware in the power supply.

8. The controller of claim 1, wherein the input current filter is a one-sided filter that filters the input current when the input current decreases with respect to a previous current sample.

9. The controller of claim 8, wherein the input current is unfiltered by the input current filter when the input current increases with respect to the previous current sample.

10. The controller of claim 1, wherein the at least one processor includes a central processing unit (CPU) and a graphics processing unit (GPU), and the computing system includes a memory storing a hysteresis table configured to provide an order for throttling the CPU and the GPU.

11. The controller of claim 10, wherein the hysteresis table is further configured to cause a CPU performance state to be removed before removing a GPU performance state.

12. A system for temporarily reducing a current demand of at least one processor, the system comprising:

a sample generator configured to;

sample an input current according to a first time domain, and

output a current sample from a sample buffer of the sample generator according to a second time domain; and

a process limiter operatively coupled to the sample generator and configured to provide a control effort signal according to a signal delay to limit an activity of the at least one processor and delay an increase in the activity of the at least one processor.

13. The system of claim 12, wherein the control effort signal is provided when an error signal reaches an error threshold, wherein the error signal is calculated based on the current sample and a reference current value.

14. The system of claim 13, further comprising:

a compensator configured to integrate one or more error values to generate the error signal, wherein the errors values are based on a difference between the current sample and the reference current value.

15. The system of claim 12, wherein the sample generator is further configured to filter the input current when the input current decreases relative to a previous sampled input current.

16. A method for temporarily limiting a power consumption of a processor in response to an increased current demand of the processor from a power supply, the method comprising:

receiving a sampled input current from a sample storage configured to;

include an input and output contemporaneously operable at different frequencies,

sample an input current, between the processor and power supply, and

output the sampled input current for comparison to a reference value associated with the power supply; and

limiting the power consumption of the processor when the sampled input current reaches at least the reference value.

17. The method of claim 16, wherein limiting the power consumption of the processor includes temporarily reducing a performance state of the processor according to a performance limit and based on the sampled input current.

18. The method of claim 17, further comprising:

returning a previous performance state to the processor after a subsequent sampled input current is determined to be less than the reference value.

19. The method of claim 16, wherein receiving the sampled input current from the sample storage includes receiving a most recent sampled input current from a plurality of input current samples.

20. The method of claim 16, further comprising:

comparing the sampled input current to the reference value to generate an error signal, and

evaluating a trend of multiple error signals over multiple iterations of the comparing.