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Renesas Singapore - Knowledgebase

What is Chattering?

Latest Updated:08/01/2005


What is Chattering?


This is a phenomenon whereby a manual switch repeatedly turns on and off in a short time because of vibration of the contact.
This may cause malfunctioning of reset input and counter input.
Usually, chattering is eliminated by a combination of an RC circuit and a Schmitt trigger buffer.

The diode shown in the circuit example below is to discharge the capacitor so that the absolute maximum rating of the buffer input is not exceeded when the power is turned off.
When using a capacitor with a high capacitance and low ESR, a current-limiting resistor is required between the diode and the capacitor for protection. Limit the current using a resistor with a low enough resistance value to obtain a voltage corresponding to a low level when the switch is switched on but still protect the buffer.

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