| 摘要 |
PURPOSE:To reduce remarkably current consumption at standby by providing a demodulated input detecting means so as to make a current of a circuit not in operation nearly zero at the input without a demodulated signal. CONSTITUTION:When a signal to be demodulated from input terminals 4, 5 is inputted and the input signal level exceeds a prescribed level at first, signal to be a demodulated input detection circuit 21 outputs a signal 123 going to 'H' and returning to 'L' at the leading of a signal 122. While the signal 123 is at 'H', that is, at the reading, a power current required for the operation flows to an analog processing circuit 1, a digital processing circuit 2 and an oscillation circuit 3 to apply normal reading. Thus, while the signal 123 is at 'L', that is, at the standby, the power current not required for the analog processing circuit 1, the digital processing circuit 2 and the oscillation circuit 3 is lost and the current is reduced to the required minimum power current.
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