| 摘要 |
PURPOSE:To attain a bumpless action and to improve the reliability for maintenance of functions in a mode A by switching a mode M to the mode A after detecting that the deviation between input and output signals is set within a prescribed voltage range. CONSTITUTION:An input signal S1 and an output SMout of a D/A converting circuit are supplied to a subtraction circuit 231 for subtraction between voltages V1 and V2 of signals. Thus a deviation (V1-V2) is supplied to comparators 232 and 233 and compared with reference voltages (e) and (-e) respectively, and these comparison outputs are supplied to an AND gate 235. The gate 235 sends a signal of logic H to an AND gate 236 when the deviation (V1-V2) is set within a prescribed voltage range + or -e. Thus the conditions are satisfied and an H signal is delivered to an FF237. The FF237 delivers an A mode switch control signal of a logic H when a clock S6 is supplied and then an output selecting circuit 22 is switched to an A mode output terminal. |
