To provide a technology that can substitutionally measure an arbitrary temperature by arranging a function that can directly measure "a reference voltage that does not depend on a temperature" and " the potential of an element that depends on a temperature", in a temperature monitoring function of a semiconductor device for monitoring a lithium-ion battery.

The semiconductor device for monitoring the lithium-ion battery comprises: a first voltage source 301 having temperature dependency; a second voltage source 302 not having temperature dependency; a temperature detecting comparator 303 connected to the first voltage source 301 at its one input, and connected to the second voltage source 302 at the other input; a first switch 304 connected to the first voltage source 301 at its one terminal; a second switch 305 connected to the second voltage source 302 at the other terminal; and a testing comparator 306 connected to an IDT 211 at its one input, and connected to the other terminal of the first switch 304 and the other terminal of the second switch 305 at its other input.

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