Electricity: power supply or regulation systems – Input level responsive
Reexamination Certificate
1999-07-30
2001-04-17
Han, Jessica (Department: 2838)
Electricity: power supply or regulation systems
Input level responsive
C363S049000, C323S267000
Reexamination Certificate
active
06218821
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to computer storage systems and, more particularly, to high performance controllers for disk array systems. The controllers incorporate marginable power supplies and power-up bypass circuits for testability, high reliability and controlled operation during power-up.
BACKGROUND OF THE INVENTION
Computer storage systems for high capacity, on-line applications are well known. Such systems use arrays of disk devices to provide a large storage capacity. To alleviate the delays inherent in accessing information in the disk array, a large capacity system cache memory is typically utilized. Controllers known as back end directors or disk adaptors control transfer of data from the system cache memory to the disk array and from the disk array to the system cache memory. Each back end director may control several disk devices, each typically comprising a hard disk drive. Controllers known as front end directors or host adaptors control transfer of data from the system cache memory to a host computer and from the host computer to the system cache memory. A system may include one or more front end directors and one or more back end directors.
The front end directors and the back end directors perform all functions associated with transfer of data between the host computer and the system cache memory and between the system cache memory and the disk array. The directors control cache read operations and execute replacement algorithms for replacing cache data in the event of a cache miss. The directors control writing of data from the cache to the disk array and may execute a prefetch algorithm for transferring data from the disk devices to the system cache memory in response to sequential data access patterns. The directors also execute diagnostic and maintenance routines. In general, the directors incorporate a high degree of intelligence.
Current computer storage systems are characterized by high performance and high reliability. Nonetheless, as the performance of the host computers which operate with the computer storage systems increases, it is necessary to provide computer storage systems having enhanced performance. In particular, operating speeds must be increased as the operating speeds of host computers increase. Furthermore, as the cost of computer memory decreases and program complexity increases, the volumes of data transferred increase. Because computer storage systems are frequently used in highly critical applications, reliability is an important consideration. The storage systems must remain operational, even when certain components and subsystems fail. Accordingly, the storage systems may incorporate redundant hardware and are extensively tested. Because the performance of computer storage systems is determined to a significant degree by the performance of the controllers, there is a need for very high performance, high reliability controllers for computer storage systems.
SUMMARY OF THE INVENTION
According to a first aspect of the invention, apparatus comprises a power supply for generating a first supply voltage that is variable within a first range, and an electronic circuit that is powered by the first supply voltage. The electronic circuit comprises a converter for converting the first supply voltage to a second supply voltage and a control circuit responsive to variations of the first supply voltage for controlling the converter such that the second supply voltage is maintained within a second range.
The control circuit may include a reference voltage source for generating a reference voltage and a voltage comparator for generating a trim voltage for controlling the converter in response to a difference between the first supply voltage and the reference voltage. The first range may be greater than the second range.
According to a second aspect of the invention, an electronic circuit is provided. The electronic circuit is powered by a first supply voltage that is variable within a first range. The electronic circuit comprises a converter for converting the first supply voltage to a second supply voltage, and a control circuit responsive to variations of the first supply voltage for controlling the converter such that the second supply voltage is maintained within a second range.
According to a third aspect of the invention, power supply apparatus comprises a power supply for generating a first supply voltage, and a bypass circuit for controlling the first supply voltage during power-up. The bypass circuit comprises a sensing circuit for comparing the first supply voltage and the second supply voltage and generating a control signal in response to a difference between the first and second power supply voltages, a control circuit responsive to the control signal for controlling the first supply voltage, and a reset circuit for enabling the control circuit during power-up and for inhibiting the control circuit during normal operation. The control circuit may comprise at least two FETs connected in series. The reset circuit preferably enables the FETs during power-up and inhibits the FETs during normal operation, independent of the control signal. The power supply may include a DC-DC converter which is inhibited during at least a portion of the power-up.
The bypass circuit may further comprise a test circuit for detecting a shorted condition of each of the FETs. The bypass circuit may further include means for simulating a shorted FET in response to a test signal.
According to a fourth aspect of the invention, a method is provided for controlling a supply voltage. The method comprises the steps of generating a first supply voltage that is variable within a first range, converting the first supply voltage to a second supply voltage using a DC-DC converter, and controlling the DC-DC converter such that the second supply voltage is maintained within a second range in response to variations of the first supply voltage.
According to a fifth aspect of the invention, a method is provided for controlling a supply voltage. The method comprises the steps of generating a first supply voltage, comparing the first supply voltage and a second supply voltage and generating a control signal in response to a difference between the first and second supply voltages, controlling the first supply voltage in response to the control signal during power-up, and enabling the control circuit during power-up and inhibiting the control circuit during normal operation.
REFERENCES:
patent: 3725740 (1973-04-01), Kuster
patent: 4847546 (1989-07-01), Bobier et al.
patent: 5332960 (1994-07-01), Kudoh
patent: 5659208 (1997-08-01), Kimble et al.
patent: 5847549 (1998-12-01), Dodson, III
EMC Corporation
Han Jessica
Wolf Greenfield & Sacks P.C.
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