Patent ID: 7737688

Claim:
A magnetic field detecting apparatus comprising: a magnetic field detecting unit, energized in response to a potential level of an input signal and outputting any one of two signals having different potential levels from each other in response to a peripheral magnetic field; an energizing control unit, producing a periodic energizing control signal indicative of timing at which said magnetic field detecting unit is energized by employing a clock signal and another signal obtained by frequency-dividing or frequency-multiplying said clock signal, the energizing control unit supplying said produced energizing control signal to said magnetic field detecting unit; a first inverting unit, inverting the potential level of the output signal of said magnetic field detecting unit; and an energizing time period control unit, supplying a time period control signal to said energizing control unit, said time period control signal controlling the time period of said energizing control signal in response to the potential level of the output signal of said magnetic field detecting unit and the potential level of the signal obtained by inverting the potential level of said output signal by said first inverting unit; wherein said energizing time period control unit supplies any one of two pieces of said energizing control signals whose durations and time periods are different from each other, during which said magnetic field detecting unit is not energized, in response to the potential level of said time period control signal supplied from said energizing time period control unit.