Is it possible to detect if a charger in plugged in, and disable (or completely disconnect) any of the remaining circuit? an image of a thing

This image from Detecting When a USB Device Is Plugged In For Status LED provides an interesting idea to light up an LED when it is charging, but it uses way too many components for my use case.

I'm using a LiPo battery attached to a microUSB charging circuit. Assume that the non-battery circuit consist of a single op-amp. How would I disconnect or lower the power voltage beneath usability for the op-amp when the circuit is plugged in, without draining the actual battery charging part of the circuit?

Is the only option to use a mechanical switch?

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    \$\begingroup\$ Yeah, the only option is to use a mechanical switch. There has been absolutely zero technological development since 1907. \$\endgroup\$ – Harry Svensson Dec 8 '17 at 2:35
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    \$\begingroup\$ So far, I have read your question 3 times. I don't quite understand your setup. Can you draw a diagram or picture of some kind? Do you basically just want to turn off the op-amp when 5V is present? That is pretty easy, but we would need to see what else is connected to the op-amp. \$\endgroup\$ – mkeith Dec 8 '17 at 3:23
  • \$\begingroup\$ I hope you do not neglect the safety of overcharging current or voltage in your attempt to simplify the design. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Dec 8 '17 at 4:34
  • \$\begingroup\$ BTW what purpose is R4 ?and does CMP1 work at the 5V rail input? and where is your OCP? \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Dec 8 '17 at 4:44

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