CD74HC123: CMOS logic retriggerable monostable multivibrator with reset

JEAN LUC MONTET

Part Number: CD74HC123

Hi,

on a sample of one of our designs, we use the 2 monostables of a same package with the same couple of RC (665k and 10uF) respectively. We expected a 3s pulse width.

With one of them we obtain a pulse width of 1.8s and 2.5s with the second one...

We cheked R and C values which are OK. C is of tantalum technology.

May you have an explanation or tracks to lead to determine the reason why for such a difference ?

Thanks in advance for your answer.

Best Regards,

JL MONTET

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 256740 points

The current through the resistor must be much larger than the capacitor's leakage current. The datasheet shows only resistor values up to 200 kΩ. Consider ceramic or film capacitors.

0 JEAN LUC MONTET over 1 year ago in reply to Clemens Ladisch

Prodigy 10 points

Thanks for your answer that helps us. I'm going to consider more precisely C characteristics. I will keep you advised

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CD74HC123: CMOS logic retriggerable monostable multivibrator with reset