| 摘要 |
PURPOSE:To obtain a rotation detecting circuit requiring no external resistance other than ICs by automatically setting the most appropriate detection resistance value selectively to match a step motor when a battery is closed or when reset is released with a logic variation of the resistance value of the detection resistance made pssible in a certain range. CONSTITUTION:If it is possible to incorporate a resistance in a range or 30kOMEGA- 15kOMEGA in the production process of ICs, the resistance value of the detection resistance can be set by stages at an interval of 2kOMEGA from 0kOMEGA to 30kOMEGA in relation with signals at control terminals S1, S2, S3 and S4. Level of detection resistance is varied by steps in a section A' to select proper value according to a detection pulse for setting the detection resistance. Then, a pulse is outputted at another output terminal Pi1 to perform the same automatic setting of a detection resistance. After the setting of the detection resistance by a detection pulse at the output terminal Psn, the operation proceeds to the subsequent section A''. As long as the automatic setting is incomplete, the same operation is repeated to complete it. |
