| 摘要 |
PURPOSE:To prevent oscillation and to perform measurement stably and accurately by applying an input voltage larger than a specific value to an IC with an inverting function initially, and lowering the voltage to the specific value thereafter. CONSTITUTION:This invented potential supply circuit is controlled by a CPU which is not shown in a figure, and data in BCD representation corresponding to the power potential VDD and high logical level input signal potential VIH of the IC are supplied to data converting circuits 42 and 43 through a bus line 41. Those are stored in latch circuits 44 and 45 with latch pulses L1 and L2 from the CPU and then supplied to D/A converting circuits 47 and 49 through gate circuits 46 and 48 respectively. The output of the gate circuit 46 is supplied to the D/A converter 49 through the other gate circuit 50, and those gate circuits are controlled by G1-G3; and the outputs of DC power amplifiers 51 and 52 are applied to a power terminal and an input signal terminal at timing shown in a figure. Thus, measurement is performed without preventing oscillation originating from a capacitor, etc.
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