I'm trying to understand why with this very easy schematic, I got with my multimeter:

  • 5.2V between the 5V pin of the USB breakout and GND: OK
  • 0V between the GND of the LDO and the GND of the USB breakout: OK
  • 0.9V between the output pin of the LDO and the GND: I do not have 3.3V.

How can I solve this problem? I have tried with both capacitors like in the test schematic of the datasheet but same issue.

Schematic with LE33CZ 3.3V regulator

Ref: LE33CZ

  • \$\begingroup\$ Type of capacitor matter. Should b tantalum. Overwise output oscillating. \$\endgroup\$
    – user263983
    Commented Apr 3, 2021 at 21:10
  • \$\begingroup\$ Already tested with capacitors but I got the same issue \$\endgroup\$
    – Artex
    Commented Apr 3, 2021 at 21:19

1 Answer 1


You appear to have connected the regulator incorrectly.

From the datasheet:

enter image description here

You have 5V from the USB adapter going to pin 1. That's "Vout" according to the datsheet.

Connect your yellow wire to the right most pin of the regulator instead of the left most pin.

  • \$\begingroup\$ Are you sure ? For me my LDO is on the other side, so I plugged the yellow on the right pin \$\endgroup\$
    – Artex
    Commented Apr 3, 2021 at 21:18
  • 2
    \$\begingroup\$ The datasheet shows the regulator from the bottom. \$\endgroup\$
    – JRE
    Commented Apr 3, 2021 at 21:20
  • \$\begingroup\$ Yeah, I missed it at first but see the diagram says that the TO-92 model is viewed from the bottom so definitely reevaluate as JRE says and make sure you are plugging in to the input pin. \$\endgroup\$
    – jakob
    Commented Apr 3, 2021 at 21:23
  • \$\begingroup\$ Thanks you a lot JRE !! \$\endgroup\$
    – Artex
    Commented Apr 3, 2021 at 23:40

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