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I am making a UPS for a WiFi router. My goal is to get 12V uninterrupted power at the DC jack J2.

The buck converter XL4015 is used to charge the 18650 battery pack (2S or 3S) and boost converter XL6019 is used to boost the battery pack voltage to 12V.

Condition-1: When the AC mains is available

  1. The power from the DC adapter (J1) is fed directly to the output jack (J2) through a Schottky diode (D1).
  2. The battery pack is charged by XL4015 converter.

Condition-2: When the AC mains is not available

The battery pack should feed power to the boost converter through the P-MOSFET (IRF4095). The boost converter boosts the voltage to 12V and feeds it to output jack J2 through the Schottky diode (D2)

Will this circuit meet my objectives? Any changes for improvement in the MOSFET switching circuit are highly appreciated.

Schematic

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  • \$\begingroup\$ Google isn't giving me any hits for XL4019. Do you mean XL6019? How much current can your 12V power supply deliver, and how much does the router need? \$\endgroup\$
    – Bruce Abbott
    Commented Jun 29, 2021 at 4:48
  • \$\begingroup\$ @BruceAbbott it's the XL4015. xlsemi.com/datasheet/XL4015%20datasheet.pdf on the left and XL6019 on the right. The image is a bit blurry. \$\endgroup\$
    – tobalt
    Commented Jun 29, 2021 at 6:22
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    \$\begingroup\$ Judging by the size of components used you're looking at several amps of current being switched (correct me if I'm wrong), so the Schottky diodes will dissipate maybe up to 1W which seems like a waste. Have you considered the switching being done by a power multiplexer instead to cut dissipation losses in the Schottky diodes ? \$\endgroup\$
    – citizen
    Commented Jun 29, 2021 at 9:54
  • \$\begingroup\$ It would seem much simpler to just use the two DC-DC converters, replace the mosfet with wire and not have the diode at all. \$\endgroup\$
    – Jasen Слава Україні
    Commented Jun 29, 2021 at 12:42

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