ID this 8041 SOT23-5 please

[cybermaus]

This chip is on a DAB+ radio, in the vincinity of the LCD and the core DAB+ module

I did find some 8041 SOT23-5 chips. One is an OpAmp, and one is a boost driver.
However, there is no coil anywhere, and pin 4 is, as mentioned NC rather than the needed HIGH for EN
The 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 LCD

But for the OpAmp, well, the pin 4 = NC is equally weird. Also the Diode would more point to some boost/buck stuff.

[m k]

One hint was 4.1V regulator with on/off.
Maybe it's just a switch.

[inse]

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.

[cybermaus]

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.

There 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.....

One hint was 4.1V regulator with on/off.
Maybe it's just a switch.

Not 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.

[inse]

Are any interesting components on the other side of the PCB?

[cybermaus]

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.

[tooki]

My gut feeling is that 8041 is a date code (the 014th day of either 2008 or 2018 ) 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.pdf

I 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.

This chip is on a DAB+ radio, in the vincinity of the LCD and the core DAB+ module

I did find some 8041 SOT23-5 chips. One is an OpAmp, and one is a boost driver.
However, there is no coil anywhere, and pin 4 is, as mentioned NC rather than the needed HIGH for EN
The 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 LCD

You 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.

[cybermaus]

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.pdf

Oh, 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 4

It 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.

[m k]

One hint was 4.1V regulator with on/off.
Maybe it's just a switch.

Not 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.

It 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.

[tooki]

One hint was 4.1V regulator with on/off.
Maybe it's just a switch.

Not 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.

It was a google hint.

You wrote “one hint was…”. 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?!?

[m k]

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.

[cybermaus]

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.

[m k]

Better that way.
Then D18 connection is also much more rational.

[cybermaus]

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.

[m k]

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.

[tooki]

It was from the not so distant past when I wrote it.

But you hadn't given the hint yet at all, so you can't refer back to something that never happened... 

[tooki]

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.

Yeah, 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.