Patent ID: 9529376
Filing Date: 2016-12-27
CPC Classification: G01R,G05F

Claim Text:
1. An electric power detection system comprising: a detection resistor provided in an electric power supply path leading to a monitor object; an integration part including a capacitive element and charging the capacitive element by a charge current corresponding to a detection current, which corresponds to a current flowing in the detection resistor; a comparison part for outputting a detection signal, which changes based on an integration value corresponding to a charge voltage of the capacitive element, the detection signal changing to a first signal level and a second signal level when the integration value becomes greater than a predetermined first reference value and less than a predetermined second reference value, respectively; a discharge part for discharging the capacitive element and stopping discharge of the capacitive element, while the detection signal is at the predetermined first signal level and at the predetermined second signal level, respectively; an electric power control part for determining an estimation value of electric power for the monitor object based on a result of counting edges, at which a signal level of the detection signal changes; and a voltage division part for producing, as a reference voltage, a division voltage by dividing a voltage of a monitor object side of the detection resistor by plural resistors, wherein the integration part includes a current conversion resistor and an operational amplifier, which has an inverting input terminal, a non-inverting input terminal and an output terminal, the capacitive element is connected between the inverting input terminal and the output terminal, the inverting input terminal is connected to an electric power supply side of the detection resistor through the current conversion resistor to receive a voltage, which is produced at one end of the detection resistor connected to the inverting input terminal, without being divided when the capacitive element is charged, the non-inverting input terminal is connected to receive the reference voltage corresponding to the voltage of the monitor object side of the detection resistor, and the voltage division part generates the reference voltage to be greater than an offset voltage of the operational amplifier.