YX8018B Component Identification and Symbol

componentsidentificationterminology

I am trying to fix some solar lamps, that contain pretty much only a handful of electrical components:

enter image description here

  • A switch
  • a solar panel
  • a 1.2 V AAA batery
  • an LED
  • a resistor (inside its "home" it measures ca 45 mOhm, it's labeled in Red-brown-violet-Silver [210 MOhm?!])

and then a little black 4-legged thingy labeled

  • yx8018b av7n1

While I could find replacement parts under the part number "yx8018", I have no idea what the item is called and how to note it down in the accompanying sketch – an if there is a difference between XY8018 and YX8018B.

Best Answer

Although I can't answer the details about the variations of the YX8018 (with or without a B suffix) it is a solar LED driver, similar to the YX8050 whose output waveform I captured in a previous answer.

The datasheet for the YX8018 shows a sample schematic like this:

extract from YX8018 datasheet

The inductor (marked "L" in the schematic), required for the boost converter inside this IC, is what you have misidentified as a 270 MOhm resistor. In fact, it is a 220 µH inductor - that is why it measures as such a low resistance.

This additional photo supplied from comments, shows two of the inductors: The "loose" one on the left side of the photo shows the red, red, brown, silver colour bands more clearly than the one still soldered to the PCB on the right side:

photo showing two of the inductors - one loose on the left side, one still soldered to the PCB on the right side

Different inductor values are used to change the LED current, as described in the datasheet's table:

inductor values and LED currents from YX8018 datasheet

I have no idea what the item is called

Solar LED driver.

and how to note it down in the accompanying sketch

See the schematic sample above. There is no specific standardized symbol - so use a rectangle as shown with the part-number on it.

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