Transparent SMD IC Identification

Discussion in 'General Electronics Chat' started by accepttheownage, Jun 1, 2011.

  1. accepttheownage

    Thread Starter New Member

    May 7, 2010
    I am having no luck identifying the IC in the following picture:

    It seems like some kind of optical sensor, which makes sense considering it came from a laser printer board which also contains a IR laser. I am hoping to repurpose the chip as an optical sensor, but I have no idea where to start as far as the pinout goes. Unfortunately there are no markings on the chip either. Anyone have any experience with these chips?
  2. kubeek


    Sep 20, 2005
    Maybe if you could do a better macro of the chips then you could tell which pin is what. Like this I can only guess that the bottom middle pin is ground and the top second from left is probably the anode of the photodiode and input to some shaping circuit, which leaves one power pin and two other i/os.
  3. Barnaby Walters


    Mar 2, 2011
    Hmm… How great to be able to see inside! Perhaps the fact that many of the pins are N/C could help you track it down?

  4. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    Just guessing here, but the sensor chip looks to have only ground and one output wire. It could be just a light sensor.

    Then why would a simple light sensor need such a complex chip? And why so few wires to the chip?

    It could be a light to frequency converter, there are plenty on google. These output a calibrated frequency based on the level of light. A google search for "light to frequency sensor 10pin SOIC" found some 8pin ones but a quick search did not reveal any 10pin ones.

    Hovever it did show up some companies like TAOS that make light to freq, light to voltage and light to digital ICs, it is quite likely one of those types so you could search all those options for any 10pin SOIC packagae device.

    Looking at your phot the top left pin (10) seems to have a large track so it could be the Vin pin and Vin regulator. Maybe it's the output but I guess Vin.

    For output I guess pin1 and gnd seems obviously pin3.

    You could power it up with 10mA current limited +3.3v supply on pin 10 and see if any of the other pins have an output. 10mA into any pin is unlikely to blow it... ;)
    Last edited: Jun 1, 2011
  5. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    Cool picture.

    I would guess the device on the left is an op amp and the right side is the sensor. The sensor would have a "back contact" to the large metal pad under it, and that pad is connected to the bottom center pin which also gets a wire bond from the op amp.

    Hard to tell from the picture how the devices are attached. It sort of looks like silver conductive epoxy as I get the impression there is a "lump" of this stuff around the parts. However, if it is dead flat then these are eutectic attach, similar to solder but can use several metals amongst those one is gold.

    How infinite is your source of these IC's? Digikey has 13,862 of a TPS852(T) for under a buck each, and they WILL order more if they run out.