Fault tolerant bus for highly available storage enclosure
First Claim
1. A backplane apparatus comprising:
- a common bus comprising a plurality of signal lines, each signal line of the common bus having a current limiting element of impedance RA d.c. coupled to a first supply level; and
isolation circuitry for electrically coupling each of the plurality of signal lines of the common bus to a corresponding plurality of signal lines of an electronic device to enable communication between the common bus and the electronic device through the isolation circuitry, the isolation circuitry having an impedance RD, wherein (RA+RD)≧
3.3KΩ
, wherein RD≦
25KΩ
.
2 Assignments
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Accused Products
Abstract
A backplane apparatus for an electronic device enclosure includes a common bus comprising a plurality of signal lines, each signal line having a current limiting element, RA. Isolation circuitry is provided for electrically coupling each of the plurality of signal lines of the common bus to a corresponding plurality of signal lines of the electronic device to enable signal communication between the common bus and the electronic device through the isolation circuitry. In one embodiment, the backplane apparatus further comprises connectors to enable removably attaching the electronic devices such as disk drives. In one embodiment, the isolation circuitry coupling each signal line of the common bus to the connector comprises an inline resistor, RD. The isolation circuitry associated with some of the signal lines may include pull up resistors. The values of RA and RD are selected to ensure that the common bus meets pre-determined current and voltage requirements so that the common bus can change states even if one or more of the devices fail by shorting to ground.
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Citations
17 Claims
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1. A backplane apparatus comprising:
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a common bus comprising a plurality of signal lines, each signal line of the common bus having a current limiting element of impedance RA d.c. coupled to a first supply level; and
isolation circuitry for electrically coupling each of the plurality of signal lines of the common bus to a corresponding plurality of signal lines of an electronic device to enable communication between the common bus and the electronic device through the isolation circuitry, the isolation circuitry having an impedance RD, wherein (RA+RD)≧
3.3KΩ
, wherein RD≦
25KΩ
. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A backplane apparatus comprising:
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a common bus comprising a plurality of signal lines, each signal line having first terminal of an associated first current limiting element d.c. coupled to a first supply level, the first current limiting element of impedance RA;
isolation circuitry electrically coupling each of the plurality of signal lines of the common bus to a plurality of electronic devices, each device having a corresponding plurality of signal lines to enable communication of signals between the common bus and the plurality of electronic devices; and
switching circuitry for each signal line of the common bus, wherein each switching circuitry selectively couples a second terminal of the associated first current limiting element to a second supply level to select a logic level of the associated signal line. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification