Hello, I am using the LMC555 to generate pulses with fixed duty cycle, 50% and 5Hz. The pulse is given to CPLD as clock. However it happens, although not frequently, that short (4us) before the rising edge of 555 output one positive pulse shows. The duration is approximately 100ns. This pulse triggers the flip-flops of cpld, generating wrong signals.
The circuit is all the same as in datasheet, except that only 100nF decoupling capacitor is used, where one extra 1uF elco is recommended. Could that possibly be the problem? Layout is designed as recommended. And since it only happens once in hours, and is critical, I would like to figure out the exact reason why this happens to be 100% sure that the circuit operates without problem for a very long time. If this short pulse cannot be eliminated then the other circuits will have troubles :(
Thank you!