Post Date : Nov 09, 2023 / Last updated : Dec 08, 2023

Release delay function

The release delay function of voltage detector is a function that does not output a release signal immediately after the monitoring voltage reaches the release voltage, but outputs it after a certain period of time has passed.

This delay time is called release delay time. There are products for which release delay time is set in IC and products for which release delay time can be externally adjusted using an external capacitor.

Products for which delay time is internally set
Products for which delay time can be externally adjusted

Why is the release delay time required?

Immediately after startup of power supply, the voltage may not be stabilized due to ringing, etc.

In such a case, if you use a voltage detector without release delay function, the output of voltage detector may repeat "H" and "L" in the area where the power supply voltage fluctuates. This repetition of "H" and "L" may lead to malfunction of following MCU.

In order to prevent such malfunction, the release delay function (release delay time) is required so that a release signal is output after the power supply voltage gets stabilized.

The followings are typical example of power supply line instability other than startup of power supply.

  • When turning ON/OFF a mechanical switch (chattering of mechanical switches)
  • When the impedance of power supply line is large / wiring is long
  • Chattering when batteries are inserted or mounted