High voltage floating current sense amplifier
AssigneeIntersil Americas Inc.
InventorEric M. Solic
Life of this patent
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Abstract
A high voltage floating current sense amplifier circuit, including first and second resistive devices and a floating amplifier circuit, that senses current through a current sense device coupled between an output node and a battery node each referenced to a common node. The battery node couples to a positive terminal of a removable battery. The floating amplifier circuit drives a proportional current through the first resistor in order to maintain voltage across the first resistive device at approximately the same voltage as that across the current sense device. The second resistive device has a first end coupled to the common node and a second end coupled to receive the proportional current for developing a sense voltage indicative of current through the current sense device.
Claims12
A high voltage floating current sense amplifier circuit for sensing current through a current sense device coupled between an output node and a battery node each referenced to a common node, the battery node for coupling to a positive terminal of a removable battery, said high voltage floating current sense amplifier circuit comprising:
- a first resistive device having a first end coupled to the output node and a second end;
- a floating amplifier circuit, coupled to said second end of said first resistive device and for coupling to the battery node, that drives a proportional current through said first resistive device in order to maintain voltage at said second end of said first resistive device at approximately the same voltage as the battery node;
- and
- a second resistive device having a first end coupled to said common node and a second end coupled to receive said proportional current for developing a sense voltage indicative of current through said current sense device.
A power circuit, comprising:
- a switching regulator that provides power current to an output node having up to a maximum voltage level relative to a common node having a reference voltage level;
- a current sense device having a first end coupled to said output node and a second end coupled to a battery node, said battery node for coupling to a positive terminal of a removable battery that couples between said battery and common nodes;
- a floating high voltage current sense amplifier circuit that develops a sense current that is proportional to current through said current sense device for voltages of said output node;
- and
- a first resistive device having a first end coupled to said common node and a second end coupled to said floating high voltage current sense amplifier circuit that receives said sense current and that develops a current sense output voltage.
A method of sensing current through a current sense device for higher voltages up to a maximum voltage level, the current sense device coupled between an output node and a battery node that couples to the high side of a removable battery, said method comprising:
- coupling a first end of a first resistive device to the output node;
- providing a floating differential amplifier that floats with the battery node;
- driving a P-channel device coupled to a second end of the first resistive device with the floating amplifier to maintain voltage across the first resistive device substantially equal to voltage across the current sense device to develop a proportional current through the first resistive device;
- and
- applying the proportional current to a second resistive device to develop a current sense output voltage.
Dependencies are inferred from the claim text.