Patent ID: 7902806
Filing Date: 2011-03-08
Classification: H05B,Y02B

Abstract:
1. A load control unit that generates a driving control signal whose level is changed by a prescribed frequency and duty in accordance with a driving instruction signal at a prescribed level corresponding to a fixed input from a driving instruction unit so as to control the supply of an electric power to a load from a battery in accordance with a pulse-width modulation control by the driving control signal, the load control unit comprising: a reference voltage generating unit that generates a reference voltage of a triangle wave on the basis of the voltage of the battery; a first charging/discharging unit that charges and discharges to generate the triangle wave at a constant current proportional to the voltage of the battery; a second charging/discharging unit connected in series to the first charging/discharging unit to charge and discharge in reverse to the charge and discharge of the first charging/discharging unit; a first comparing unit that compares the voltage of the first charging/discharging unit with the reference voltage and switches between the charge and discharge of the first charging/discharging unit so as to generate the triangle wave; and a second comparing unit that compares a divided voltage obtained by resistively dividing the voltage of the battery with the voltage of the triangle wave generated by the first comparing unit so as to generate a PWM pulse for driving the load, wherein the ratio of capacities between the first and second charging/discharging units approximates to the ratio of resistances for obtaining the divided voltage.