This small IC puzzles me, as I can't find any datasheet and even get an idea what it is. "C21SC" and "P134" are printed on top of it (it's SOIC8 package, if I am not mistaken):

enter image description here

Googling produced no results except for links for buying on alibaba.com. Can anyone recognize what it really is?

UPDATE: Can it be this - 24C21 - 2-Wire Serial EEPROM?

  • \$\begingroup\$ What is the context? Was the part removed from a circuit board? If so what are the surrounding components, can you post of picture of the surroundings? Many smaller ICs do not have part numbers printed on them, only a package code which would not be uniquely identifiable without context. \$\endgroup\$ – Zuofu Oct 6 '13 at 17:45
  • \$\begingroup\$ Unfortunately, the context is lost. My guess is it is some kind of memory, maybe with i2c capability. \$\endgroup\$ – Roman Susi Oct 6 '13 at 17:51

I have a similar component excepting the package, which is DIP-8.

Indeed it is 24C21 (mine is 24LC21 and marked as LC21) and it is an I2C memory designed for computer monitors, to store the EDID.

It has 1 kbyte.

It is direcly connected to pins 12 and 15 of VGA connector and may have a read-only or transmit mode, because its content shouldn't change.

Even though it is designed for monitors, you can use it in any circuit, as long as you connect it via I2C bus.

  • 2
    \$\begingroup\$ Let me add that this sort of numbering is conventional for small surface mount parts. Knowing this will help you find the translation lists. \$\endgroup\$ – gbarry May 2 '14 at 20:24

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