| 摘要 |
PROBLEM TO BE SOLVED: To apply constant voltage and keep supply current from a power source constant by connecting the power source to a power source input terminal through a constant-current element, and connecting the constant current element. SOLUTION: With the power source input terminal D of a circuit block, a power source 1 is connected through a constant current source 2, and the cathode side of a Zener diode 3 whose anode side is grounded is connected, where the supply current from the power source 1 becomes constant. Consuming current I1 of the circuit block changes with operating conditions of the circuit block. The current I2 flowing through the Zener diode 3 changes with change of the current I1 so that a total of the current I1 and the current I2 may be current I0 supplied from the power source 1 by the constant-current source 2. Reversed bias is applied to the Zener diode 3 and, therefore, applying voltage to the circuit block is clamped so as to be constant voltage. It is thus possible to apply constant voltage and keep the supply voltage from the power source constant. |
