ID this 8041 SOT23-5 please - Page 1
Forum section: electronics / beginners

author: cybermaus
author_rank: Frequent Contributor
timestamp: July 19, 2023, 10:16:10 am
content: This chip is on a DAB+ radio, in the vincinity of the LCD and the core DAB+ moduleI did find some 8041 SOT23-5 chips. One is an OpAmp, and one is aboost driver.However, there is no coil anywhere, and pin 4 is, as mentioned NC rather than the needed HIGH for ENThe white stripe is the silkscreen, and there is no conductor below it. I scratched all through it, and no copper to be found.I am not very up to speed with LCD, but remind me, there is no need for a boosted high voltage to LCD right? The battery is already 4xAA, so at least 4V at all times.I really wonder why either LCD or DAB module would need higher voltages, but again, I am not too familiar with LCD drivers. And no coil anywhere visible (I guess one could be hiding under the LCDBut forthe OpAmp, well, the pin 4 = NC is equally weird. Also the Diode would more point to some boost/buck stuff.

author: m k
author_rank: Super Contributor
timestamp: July 23, 2023, 07:22:00 pm
content: One hint was 4.1V regulator with on/off.Maybe it's just a switch.

author: inse
author_rank: Super Contributor
timestamp: July 23, 2023, 07:46:51 pm
content: I wonder what the fat diode D18 is for.Does the radio also have a external supply?What voltage do you measure at the pads now?Check if there is more than one „grounded“ pin.

author: cybermaus
author_rank: Frequent Contributor
timestamp: July 23, 2023, 08:22:55 pm
content: Quote from: inse on July 23, 2023, 07:46:51 pmThere is no extra grounded pins, I specifically measured that. All pins seem to have either a resistance or a P-N level to ground (measured in diode mode with red to ground)The radio does have an external supply, but that whole secions, with coils and regulators is on a completely different part of the board.I did not measure current voltages. Not because I did not think of it, but it is a bit hard. Basically, I need to remove several daughterboards (including the one with the power secion) to get this one into few.Yes, D18 is a typical buck/boost diode, if only I could see a coil connected.....Quote from: m k on July 23, 2023, 07:22:00 pmNot sure I quite follow what you mean here. No one mentioned a 4.1V regulator yet, nor did I see one.If it is the op-amp I guess it could be just a switch. Or did you find some other 8041 sheet somewhere?Anyway, I ordered some 8041 boost regulators, unless someone comes up with better suggestions, I'll solder it in and see what happens.

author: inse
author_rank: Super Contributor
timestamp: July 24, 2023, 08:21:44 am
content: Are any interesting components on the other side of the PCB?

author: cybermaus
author_rank: Frequent Contributor
timestamp: July 24, 2023, 08:46:47 am
content: Most of the direct opposite side is covered with a soldered multi-pin LCD module obscured with a plastic shroud/spacer.It could hide some components, but I think to low for a proper coil unless if it was really low profile.

author: tooki
author_rank: Super Contributor
timestamp: July 24, 2023, 09:55:03 am
content: My gut feeling is that 8041 is a date code (the014th day of either2008 or2018 ) and that the letters are the actual product identifier.Never mind: a quick web search for “8041 sot-23-5” brought up this as the first result:http://www.micro-bridge.com/data/ESMT/EMP8041.pdfI think that’s your most likely candidate. Its pinout matches your photos.We don’t know whether it’s the 5V or 3.3V version, though I’d guess the latter to be more likely these days.Quote from: cybermaus on July 19, 2023, 10:16:10 amYou don’t mention what kind of LCD it is. Basic segment LCDs (like in calculators) don’t need any high voltages, though they might need negative ones. Character LCDs (like the common 1602 type) sometimes need a negative voltage on the contrast pin, especially for extra-large versions or types with extended temperature range, or for 3.3V operation (there’s often a footprint for a 7661 charge pump on the PCB to support those scenarios). TFTs require numerous positive and negative voltages, so the driver ICs built into the display modules typically contain integrated charge pumps to generate them all.LCDs don’t use much current, so you don’t really see boost/buck/buck-boost converters used for them, hence why you’re finding no inductors. For the tiny currents involved, charge pumps (switched-capacitor converters) are simpler, often happy with tiny capacitors built into the driver IC.

author: cybermaus
author_rank: Frequent Contributor
timestamp: July 24, 2023, 10:02:31 am
content: Quote from: tooki on July 24, 2023, 09:55:03 amOh, nice find. I'll study the implications of this a little better, but off-hand it does look like a better candidate indeed.Especially with the NC pin 4It is a fairly simple gray LCD, reflective plus side-light, but with 5x7 matrix digits rather then segment as well as fixed element indicators.Since I also do not find a lcd driver IC, and it is soldered pins rather then zebra strip, with way to few pins, I would not at all be surprised if I were to desolder it and thus release the shroud/spacer, I would find it is a self contained I2C connected module.

author: m k
author_rank: Super Contributor
timestamp: July 24, 2023, 11:06:01 am
content: Quote from: cybermaus on July 23, 2023, 08:22:55 pmIt was a google hint.Track to D18 is quite thin, but other side is even thinner.So forward then and to one lower layer or is it the area under Q25 text.Q10 could be feedback for IC13 and Q25 an output check.Then Q24 would be a source and Q9 its handler.Just curious, what is the last marking of IC3?Not many can be IC with 3 legs and diode input.If not a transistor marked by a function.

author: tooki
author_rank: Super Contributor
timestamp: July 24, 2023, 12:16:54 pm
content: Quote from: m k on July 24, 2023, 11:06:01 amYou wrote “one hintwas…”. The paste tense suggests you’re referring to some past hint, not offering a new one.Nor does a 4.1V regulator make any sense anyway. That’s not a standard value. And searching for “4.1V regulator with on/off” doesn’t find anything useful anyway, so what were you trying to get at?!?

author: m k
author_rank: Super Contributor
timestamp: July 24, 2023, 06:18:48 pm
content: It was from the not so distant past when I wrote it.Something offered that 80* is a regulator and 4.1V was a guess since it seems to go through a diode first and 41 is suitable.Mouser also has 18 versions, so not totally unheard of.

author: cybermaus
author_rank: Frequent Contributor
timestamp: July 24, 2023, 06:27:36 pm
content: Why indeed, ISL8018 is indeed a 1.8V regulator.So now I see where you were coming from, but checking its pinout and also it is a buck/boost, so no, that is not a likely suspect.For now, I have the 8041 linear 3.0/3.3/5.0 regulator mentioned above as best suspect.Using that pinout, I'll mount some wires, assemble, and measure and test with an external 3.3 supply.

author: m k
author_rank: Super Contributor
timestamp: July 24, 2023, 06:43:05 pm
content: Better that way.Then D18 connection is also much more rational.

author: cybermaus
author_rank: Frequent Contributor
timestamp: July 24, 2023, 06:47:21 pm
content: Well, it is still a huge diode for those tiny traces, and also it is actually in the wrong direction for the linear regulator itself, but maybe it is unrelated, just connected to the same Vsource rail.

author: m k
author_rank: Super Contributor
timestamp: July 25, 2023, 02:48:30 pm
content: If you look under D18 there seem to be more that just pads.So track to IC11 seems to be just a normal small current source.

author: tooki
author_rank: Super Contributor
timestamp: July 25, 2023, 02:52:36 pm
content: Quote from: m k on July 24, 2023, 06:18:48 pmBut you hadn't given the hint yet at all, so you can't refer back to something that never happened...

author: tooki
author_rank: Super Contributor
timestamp: July 25, 2023, 02:57:10 pm
content: Quote from: cybermaus on July 24, 2023, 06:47:21 pmYeah, it's huge, but probably super cheap.It'd be the wrong direction to supply the linear regulator. But not if the same rail is supplying something else. It's going off to that other chip, so maybe it's just generating another voltage.