Electrical – Help identifying a SOP-18 IC (labels removed) by reverse engineered circuit


I have a SOP-18 IC (0.65mm pin pitch) which I need to identify. It seems the vendor removed the labels on top of the IC, so I need your help.

The IC is usually connected to a bunch of LEDs and two pins are connected to an epoxy blob (I guess a MCU). I assume the IC is some kind of shift register or LED driver, but I would like to know which one exactly. Based on the number of pins and location of the GND and VCC pin I could also assume it's a PIC MCU, but just for controlling LEDs, that would be an overkill imho…

On the bottom side of the IC, there are some codes: "T6AL7CFF0074-2" and "VO8"

Attached I have pictures of the IC top and a schematic how to IC is connected on the PCB. Under the IC on the PCB there was the code "8A21" printed on the silkscreen.

I hope you can help me to identify this part.

Reverse engineered circuit
Photo of the IC

Best Answer

2 pins coming from an MCU sounds like a serial link; since the IC has 10 parallel outputs, this smells like a serial to parallel shift register.

The 10kΩ resistor is probably used to set the current that the IC allows each LED to sink into Pin 1–3, 6–10, 17–18.

This sounds like one of the relatively popular LED drivers out there; for example, starchip SCT2016, though that has 16 output channels.

The fact that there's no marking on the package might mean you simply can't buy that chip: might be a one-off run in some old wafer fab.

If the marking was actually scraped off: this surely hasn't happened because someone tried to hide trade secrets from their competitors (this LED driver's job is so obvious that this wouldn't help, at all), but probably because these are counterfeits of some large IC manufacturer's design and they couldn't have imported the device with the counterfeits claiming they were the real deal.

I tried to look through the LED drivers over at octoparts.com and filtered for ICs with 18 pins – link – but none of these even remotely have a comparable pinout to yours. Since Octopart only list major distributor inventory (ie. none of the "small chinese company with 2 engineers that runs wafers on the cheapest technology that written-off wafer fabs offer"), it's pretty unlikely you'll be able to find a chip that's 100% compatible to yours.