Choice of Circuit Parameter outside 555 Monostable Work Mode

Published:2011/7/5 0:03:00 Author:Zoey | Keyword: Choice, Circuit Parameter, 555 Monostable Work Mode | From:SeekIC

Basic relationshipbetween monostable model timingand timing network RaC has been shown in picture 2-3.As RaC’s time constant has various mixes, and operation of the circuit is relevant to property of load, trigger level and voltage controlled. Following factors should be taken into consideration to guarantee normal operation of the monostable circuit. 1 Choose a proper value of the time resistance Ra The minimum value of RaC can be set only if the discharge tube won’t be broken and the maximum value of RaC is determined by threshold current on the comparator A1. 2 Choose a proper value of time capacitance The minimum value of shall be 100pf or a little bit larger and the maximum value is determined by the leakage current of the capacitor. 3 Driving power Driving power of 555 is mainly determined by the current property of transistor P6 and Na. 4 Take sensitive loads into consideration 5 Set an accurate time and controllable voltage V If value of RaC has been set, output pulse width is determined by Vc/VDD. Changing the ratio Vc/VDD to make up the changes arose by capacitance of capacitor, we can set an accurate time.



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