| 摘要 |
PURPOSE:To use parts in common and decrease the number of parts and to improve reliability, by selecting a specific output among respective outputs of reference voltage adjustment parts connected to a buffer on the basis of a specifying signal. CONSTITUTION:A voltage for a reference voltage developed across the voltage standardizing diode 12 in a reference voltage generation part 1 is led out, as it is, by the operational amplifier 21 of the buffer 2 and applied to reference voltage adjusting parts 31-3n, where it is adjusted by potention meters VR to requested voltages. The outputs of the adjustment parts 31-3n are applied to the photocouplers 71-73 of a reference voltage switching part 7 to output only a reference voltage applied to a photodetecting element corresponding to a light emitting element specified by a reference voltage selection signal SS to the buffer 5. The reference voltage applied to the buffer 5 is outputted, as it is, from an operational amplification part 51. Thus, the circuit part is used in common and unified, so the constitution is simplified. |
