EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: aggo_ee on August 20, 2024, 03:54:37 am
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I am trying to identify an LED driver IC that has had the markings sanded off. It is a L/TQFP-128 package as far as I can tell and from testing with a multimeter each pin is driving a string of 3 or 4 LEDs (depending on colour/forward voltage) and sinking current to turn them on. There are 42 pixels on the PCB with each pixel having 5 different colours for a total of 210 strings of LEDs each IC controlling 105 strings. The single panel has two of these unknown ICs that based on the silkscreen are using a clock, data, latch connection with a series data connection akin to a shift register. I have not had any luck finding any led drivers or shift registers with current control similar to this TB62D612FTG and suspected it may be a microcontroller although assuming each pixel has only one colour active at a time it would still need to be sinking 21 X 20mA (measured) for a total of 420mA which seems far higher than the total current sinking capability of a standard microcontroller.
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If its 3 or 4 LEDs then the open circuit voltage is probably too high for a MCU as well.
There are tons of these type of ICs on LCSC, but, nothing close to 128 pins. https://www.lcsc.com/products/LED-Drivers_583.html (https://www.lcsc.com/products/LED-Drivers_583.html)
Maybe post a photo.
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Unforunately I no longer have the PCB but for my own knowledge wanted to figure out the method they could be using to control 105 strings of LEDs with a single IC. I have some notes of the package pin connections to ground, latch, data etc however even finding the correct topology in a matching package seems to be difficult. Unless I'm missing something the MCU also wouldn't be able to control the current as it would just sink directly to ground.