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I'm trying to ensure a minimal Vin to solar powered (incl. battery ) ESP8266 project.

When battery voltage drops under a certain value , MCU enters an undefined state, which prevents it from wakening again when voltage is as needed ( tried both with 3v3 unregulated input and 5v regulated ).

My question is - is there a way to use a Zener Diode ( in some combination or else ), to ensure that when voltage drops under 3.0v or 4.5v ( as an example ), a cut-off will occur, preventing entering this state ?

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  • \$\begingroup\$ Use a comparator plus hysteresis for UVLO (under voltage lock out). \$\endgroup\$
    – Andy aka
    Feb 21, 2020 at 9:05
  • \$\begingroup\$ can you send any link for such ? \$\endgroup\$
    – guyd
    Feb 21, 2020 at 9:09

1 Answer 1

Reset to default
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You you can use a ultra low power voltage monitoring IC. This IC or similar IC will keep the MCU at reset state even down till 0.7 V of \$V_{IN}\$ .

enter image description here

As soon as the Voltage drops below the internal reference, the MCU will be held under reset. This will make sure that MCU will work normally when the input voltage is back in its valid range.

enter image description here

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  • \$\begingroup\$ Great! Can you share any ref link to start with ? \$\endgroup\$
    – guyd
    Feb 21, 2020 at 9:30
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    \$\begingroup\$ ti.com/product/TLV803 but this is just one example. there are similar products from Analog, Maxim.. \$\endgroup\$
    – User323693
    Feb 21, 2020 at 10:55

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