US 8,796,880 B2Granted

Variable adapter ID circuit

AssigneeHewlett-Packard Development Company, L.P.

InventorsRobert C Brooks, Patrick L Ferguson, Robert S Wright

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Abstract

A first resistance (125) within a power supply (110) can be connected to a power supply output (120). A variable resistance (130) can be serially coupled with the first resistance, thereby providing a first intermediate voltage at a point (115) disposed between the first resistance and the variable resistance. The variable resistance can be at a maximum in the absence of an expansion device (140) and at less than maximum in the presence of an expansion device. The first intermediate voltage and a second intermediate voltage (145) can be introduced to a comparator (150). The comparator can provide an output signal (170) when the first intermediate voltage exceeds the second intermediate voltage. The comparator output signal can be used to confirm the power supply capacity to power an external device (180) and to enable one or more external device functions.

Claims15

Dependent claims

A system comprising:

a power supply (110) having a power input (115) and a power output (120);
a first circuit comprising:
a first resistance (125) disposed in, on, or about the power supply, operatively coupled in series with a variable resistance (130);
wherein the first resistance is operably connected to the power output of the power supply;
wherein a first intermediate voltage exists at a point (135) disposed between the first and the variable resistances;
wherein the variable resistance is at a maximum value in the absence of an expansion device (140);
wherein the variable resistance is at less than maximum value in the presence of an expansion device;
a second intermediate voltage (145), wherein the second intermediate voltage comprises a fixed voltage signal;
a comparator (150) comprising:
a first signal input (155) comprising the first intermediate voltage;
a second signal input (160) comprising the second intermediate voltage;
and
a signal output (165);
wherein the comparator signal output comprises:
a binary high signal (170) if the first signal input voltage exceeds the second signal input voltage;
and
a binary low signal if the second signal input voltage equals or exceeds the first signal input voltage;
and
an external device (180) having a signal input (185);
wherein the comparator signal output is operatively connected to the external device signal input;
wherein, when the comparator output signal comprises a binary high signal, one or more external device functions are enabled;
and
wherein, when the comparator output signal comprises a binary low signal, one or more external device functions are disabled.

20 more elements

A system for detecting the presence of an expansion device, comprising:

a power supply (110) having a power input (115) and a power output (120);
a first circuit comprising:
a first resistance (125) disposed in, on, or about the power supply, coupled in series with a variable resistance (130) having a first intermediate voltage at a point (135) disposed between the first and the variable resistance, wherein the variable resistance comprises:
a second resistance (210) coupled in parallel with a third resistance (220) having a serially connected switching device (230);
wherein the switching device is closed in the presence of an expansion device (140) to form the first circuit;
wherein the switching device is open in the absence of an expansion device to form the first circuit;
wherein the switching device (230) halts current flow through the third resistance in the absence of an expansion device (140);
and
wherein the switching device permits current flow through the third resistance in the presence of the expansion device (140);
a second circuit (300) comprising:
a fourth resistance (310) operatively coupled in series with a fifth resistance (320), having a second intermediate voltage at a point (315) disposed between the fourth and fifth resistances;
a comparator (150) having a first signal input (155), a second signal input 160), and a signal output (165);
wherein the first intermediate voltage is operatively connected to the first signal input;
wherein the second intermediate voltage is operatively connected to the second signal input;
wherein the comparator output signal (170) comprises a binary high signal if the first signal input exceeds the second signal input;
and
wherein the comparator output signal comprises a binary low signal if the second signal input equals or exceeds the first signal input;
and
an external device (180) having at least one signal input (185);
wherein the comparator output signal is operatively connected to the at least one signal input;
and
wherein, when the comparator output signal comprises a binary high signal, one or more external device features are enabled;
and
wherein, when the comparator output signal comprises a binary low signal, one or more external device features are disabled.

21 more elements

A method for detecting one or more expansion devices (140);

comprising:
operably connecting a power supply (110) output (120) to an external device (180);
passing at least a portion of the power supply output through a first circuit comprising a first resistance (125) and a variable resistance (130) operably connected in series;
measuring a first intermediate voltage at a point (115) disposed between the first resistance and the variable resistance;
passing at least a portion of the power supply output through a second circuit comprising a fourth resistance (310) and a fifth resistance (320) operably connected in series;
measuring a second intermediate voltage at a point (315) disposed between the fourth resistance and the fifth resistance;
comparing the first intermediate voltage with the second intermediate voltage using a comparator (150);
and
enabling one or more external device features when the first intermediate voltage exceeds second intermediate voltage.

6 more elements

Dependencies are inferred from the claim text.