System for suppressing power transients when connecting a disk drive in an operating raid system

• US 5,587,685 A
• Filed: 11/22/1995
• Issued: 12/24/1996
• Est. Priority Date: 10/31/1994
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Johansson, Christopher W.
• Primary Examiner(s): Callahan, Timothy P.
• Assistant Examiner(s): Wells, Kenneth B.
• Application Number:
  US08/562,263
• Time in Patent Office: 398 Days
• Field of Search: 327/545, 327/546, 327/551, 327/552, 327/379, 327/380, 327/384, 327/385, 361/58, 361/18, 361/90, 361/91, 361/101, 361/110, 361/111, 361/43, 323/901, 323/908
• US Class Current: 327/546
• CPC Class Codes: G11B 33/126 Arrangements for providing electrical connections, e.g. connectors, cables, switches
• CPC Class Codes: H02J 1/001 Hot plugging or unplugging of load or power modules to or from power distribution networks
• CPC Class Codes: H02J 1/06 Two-wire systems
• CPC Class Codes: H03K 17/163 Soft switching
• CPC Class Codes: H03K 17/693 Switching arrangements with several input- or output-terminals, e.g. multiplexers, distributors logic circuits H03K19/00; code converters H03M5/00, H03M7/00
• CPC Class Codes: Y10S 323/908 Inrush current limiters

Abstract

Individual devices of a redundant array of independent devices (RAID) are coupled to an electrical power supply. For devices having widely varying load impedances, such as disks, incident with the coupling of electrical power thereto, the replacement or addition of a device in the system, while the system is in operation, causes unacceptable power transients in the power supply. To minimize such power transients, a transient suppression circuit is employed to isolate the load impedance of the device from the power supply. Isolation is achieved in the transient suppression circuit by employing an active circuit element, such as a MOSFET power transistor, as the power coupler. A capacitor controlled voltage divider circuit, incident with the coupling of electrical power thereto, couples a time varying gate voltage, which changes as a function of the rate of charge of the capacitor, to the MOSFET power transistor. This slowly increases MOSFET conduction, thereby providing controlled conductive coupling of the electrical load of the device to the power supply.

Claims

1. A system of control for electrically interconnected discrete devices, comprising:

a. an electrical power supply having at least a first and a second voltage terminal;

b. a plurality of discrete devices connected to said electrical power supply;

c. a device controller for electrically controlling said discrete devices in a predetermined functional relationship;

d. at least a first and second transient suppression circuit (TSC) coupled to at least one of said plurality of discrete devices, for suppressing transient currents, said first TSC comprising a first active circuit element, and said second TSC comprising a second active circuit element, and each said active circuit element having an output terminal connected to said at least one discrete device and having an active circuit element input;

e. said first transient suppression circuit further comprising a first capacitor and voltage divider circuit for generating a time varying voltage signal input to said first active circuit element to control conduction of said first active circuit element;

f. said second transient suppression circuit further comprising a second capacitor and voltage divider circuit for generating a time varying voltage signal input to said second active circuit element to control conduction of said second active circuit element; and

,

g. connector means for coupling one of said power supply voltage terminals to said first active circuit element input and to said first and second capacitor and voltage divider circuits, and the other of said power supply voltage terminals to said second active circuit element input, and wherein said connector means include, a plurality of pin connectors each having a substantially similar length.

2. The system according to claim 1, in which:

said active circuit elements are power transistors.

3. The system according to claim 2, in which:

a. said power transistors are a first P-Channel MOSFET power transistor and a second N-channel MOSFET power transistor.

4. The system according to claim 1, in which:

a. said first active circuit element is a power transistor having a source, a drain and a gate, said drain being connected to said first active circuit element output terminal, said source being connected to said power supply first voltage terminal by said connector means;

b. said first voltage divider circuit comprises at least two series connected resistors having an intermediate tap connected to said first power transistor gate, said connector means connecting said first voltage divider circuit to said power supply first voltage terminal; and

c. at least a first capacitor of said first capacitor and voltage divider circuit being connected to said intermediate tap of said first voltage divider circuit and having a charging rate controlled by one of said resistors of said first voltage divider circuit.

5. The system according to claim 1, in which:

a. said second active circuit element is a power transistor having a source, a drain and a gate, said drain being connected to said power supply second voltage terminal by said connector means, said source being connected to said second active circuit output terminal;

b. said second voltage divider circuit comprises at least two series connected resistors having an intermediate tap connected to said second power transistor gate;

c. at least a second capacitor of said second capacitor and voltage divider circuit connected to said, intermediate tap of said second voltage divider circuit and having a charging rate controlled by one of said resisters of said second voltage divider circuit; and

d. said second voltage divider circuit is connected to said power supply first voltage terminal by said connector means.

6. A system of electrically interconnected discrete devises having means for connecting or disconnecting one of said discrete device to the system while the system is in operation, comprising:

a. an electrical power supply having a first and second voltage terminal;

b. a plurality of discrete devises connected to said electrical power supply;

c. a devise controller for electrially controlling said discrete devises in a predetermined functional relationship;

d. a first voltage P-channel MOSFET active circuit element for coupling electrical power from said power supply first voltage terminal to said one of said discrete devises and a second lower voltage N-channel MOSFET active circuit element for coupling electrical power from said supply second voltage terminal to said one of said discrete devices.

e. a first voltage divider and capacitor circuit for producing a first control signal whose amplitude changes with time, initiated when electrical power is coupled to said first voltage divider and capacitor circuit, said first control signal for initiating time varying conduction of said first voltage P-channel MOSFET for a predetermined interval of time;

f. a second voltage divider and capacitor circuit for producing a second control signal whose amplitude changes with time, initiated when electrical power is coupled to said first voltage divider and capacitor circuit, for initiating time varying conduction of said second lower voltage N-channel MOSFET for a predetermined interval of time; and

,

g. an electrical connector for coupling said first voltage P-channel MOSFET, and said first and second voltage divider and compacitor circuits to said electrical power supply first voltage terminal, and said second voltage N-channel MOSFET to said electrical power supply second terminal, said electrical connector having pin connectors of substantially similar length.

7. A system for suppressing power transients when electrically connecting a discrete device to a power supply, comprising:

a. an electrical power supply having a plurality of voltage terminals with at least two of the voltage terminals having a different voltage;

b. a plurality of transient suppression circuits (TSCs) coupled to the discrete device for suppressing transient currents, each TSC comprising, respectively;

i. an active circuit element having an input and output terminal, the output terminal being connected to the discrete device; and

,

ii. a capacitor and voltage divider circuit for generating a time varying voltage signal to control conduction of the active circuit element; and

,

c. connector means having a plurality of similar length pin connectors for coupling the power supply to the TSCs, and wherein;

i. a first one of the voltage terminals is coupled to;

the active circuit element input terminal and the capacitor and voltage divider circuit of a first one of the TSCs, and the capacitor and voltage divider circuit of a second one of the TSCs; and

,

ii. a second one of the voltage terminals is coupled to the active circuit element input terminal of the second one of the TSCs.

8. A system for suppressing power transients when electrically connecting a first discrete device to a power supply that is electrically interconnected with at least a second discrete device, comprising:

a. an electrical power supply having a plurality of voltage terminals for providing at least two different voltages;

b. a plurality of transient suppression circuits (TSCs), each TSC including a capacitor and voltage divider circuit coupled to an active circuit element to control conduction of the active circuit element, and each active circuit element having an input and output terminal, the output terminal being connectable to the first discrete device; and

,

c. connector means having similar length connector pins, for connecting the power supply to the TSCs, and wherein the capacitor and voltage divider circuits of a first and second TSC of the plurality of TSCs, and the active circuit element input terminal of the first TSC, are further coupled to a first one of the voltage terminals via the connector means, and the active circuit element input terminal of the second TSC is coupled to a second one of the voltage terminals via the connector means.