56nm is an "older technology"? Sure, it is not even close to the latest for high-end processors, but it was the state-of-the-art in 2006 and I would think it would be way overkill for small mostly analog ASICs. On Thu, Nov 1, 2018 at 3:43 PM Harrison Cooper wrote: > It would not surprise me if this was a custom ASIC, OsRAM is a huge > company, and already doing ASIC's for other products, and if they are usi= ng > a older technology...say 56nm for this, this chip would be pennies. > > -----Original Message----- > From: piclist-bounces@mit.edu On Behalf Of John > Coppens > Sent: Thursday, November 01, 2018 7:58 AM > To: piclist@mit.edu > Subject: [EE] Unknown LED current regulator > > Hello all. > > I've been really surprised at the variations of the circuitry inside LED > bulb replacements. A while ago, I bought a couple of bulbs ('Great > Value'-brand, a local Walmart product), which started showing failing aft= er > just a couple of weeks. Opening them up showed that they were fed by just= a > (linear) series regulator. So much for green energy. > > Now I acquired a couple of OSRAM bulbs, and opened one up just to > investigate. It did have a switching current regulator, but it used a 4-p= in > chip for which I could not find any data. In fact, I didn't find _any_ > 4-pin current regulator IC. > > I've attached the circuit. I suspect the 1.8 Ohm resistor to be the > current-determining component. Strange is the (I suspect) transformer whi= ch > is actually across the LEDs (I'm not positive about it's internal > connections. I measure 10 Ohm across two pins, 14k across two other pins, > but without unsoldering). 12 LEDs (I suspect triplets) are connected > between + and -. > > Does anyone have an idea which IC this could be? It's marked 9938F and > S1C01X. No logo as far as I can detect. > > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .