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.