| 摘要 |
PURPOSE:To enable accurate measurement, by providing a bypass circuit in parallel with an analog switching circuit to switch a current. CONSTITUTION:Signals PH1, PH1*, PL2 and PL2* are turned ON with signals PH2, PH2* (signal of inverted PH2), PL1 and PL1* OFF, transistors (Tr) 18, 22, 4 and 5 are turned On simultaneously and diodes of a diode bridge (DB)14 are biased forward by current sources 42 and 43 set for a fixed current. As a result, a DC voltage VIH (high level set voltage) develops at the output of a driver 1 through the DB 14 and applied to a pin connection terminal 36 to drive the pin of an electronic device connected to the terminal 36. Then, when the signals PL1, PL1*, PH2 and PH2* are turned ON with the signals PH1, PH1*, PL2 and PL2* OFF, Trs 16, 20, 7 and 8 are turned ON simultaneously and diodes of a DB 12 are biased forward by current sources 40 and 41. An output changes from the voltage VIH to VIL (low level set voltage) thereby a voltage VIL is outputted.
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