I reflowed the driver, but it seems dead any test I can do?
when I turn it on a current of about 6mA flows
I tested all parts to have continuity to the other parts and it seems all right
I get 1.3V from ground to LED+
and 0.56V over the LED
read the TI datasheet is says that the power safe mode pin must not be open, it has 3 pads so I have to solder bridge one?
H1-A and H2-C in 17mm
Oh I’m so sorry, I forgot to to write it down and tell you! You have to solder bridge the middle pad to one of the outer ones. It must not be left open. Do NOT short out all 3 pads. There’s a small “E” of enable, and a “D” for disable power save mode. You can look at the datasheet to learn a bit more about the two modes.
It’s there for better efficiency at low currents. Since your running it at 1.4A, short the middle one with the “D” next to it (I think it could have a bit higher efficiency). You can enable it if you want, but I would only activate it if I’m under 150mA.
Edit: The 6mA is mostly because of the OpAmp quiescent current. It’s about 4.6mA typically.
Yeah I did solder the bridge, but still no output for the LED
Added C8 nothing changed
Checked the Buck chip for all connections and its fine
could you troubleshoot this driver if I send you 3 of them?
I can troubleshoot them if you want, here are some pictures of the board and the schematic. Could you check all the traces? The pictures help you which pads are connected, check them for continuity. Could you make some photos of your boards as well? Link: https://imgur.com/a/315u7
If someone finds a mistake, please tell me.
Note: the one airwaire (coloured yellow) is there because Eagle won’t let me create polygons without something in it with the same signal. I placed a pad there on the bottom layer, so this one airwire can be ignored.
In the schematic, the pad on the input is called Bat-, it should be Bat+.
I measured the board the connections from the buck/Boost driver to the other parts are all like the board design
and no shorts between two pins of the buck converter measured
I build now all 3 drivers and test if one works
And just leave C8 open. Wait, is there a 206 resistor on R1? That is 20 mega ohm. You need 20 milli ohm there.
Was about to comment, R1 looks like sense resistor so I think 20m was 20 milliohm, 206 is 20 megaohm, so would make sense if no light with 20 meg in series with the emitter.
OK it makes sense was a bit wondering about 20MOhms but I thought with C8 some kind of protection for the OPAmp
but as I had no layout I thought it is 20MOhms
Shoki you may have a 0,02Ohms 0603 resistor that you can send me 3?
or I add there some 0.02mm² wire of a certain length
I got here only 3 0.1Ohms 0805 resistors in my box
I think I got some dead Klarus XT11 Drivers I may salvage a few 0.05Ohm 0805 resistors
and a small zip lock filled with stripped driver parts I may find some small resistors
I currently don’t have, but I can order some, wanted to make a mouser order this weekend for the new MP3431 board anyway. If you want I can buy some 20mOhm resistors and send them to you.
Do you have higher resistor values in the milli ohm region, just to check if the board works?
The 0.02mm² wire won’t work, 1.4A through that is a bit too much (50mA is the maximum current for that size). For now, maybe a 0.1Ohms 0805 resistor fits. Just to make sure it works (and it should put out around 300mA). I can order some resistors for you, no problem.
And with 20MOhm, you were driving an LED with around 1.5nA :laughing:
after looking on my dead drivers and an old motherboard I found suitable resistors
0.1+0.05+0.05 parallel are 0.2
and a way oversized 0.02 one
If you can solder the three resistors on top of each other, go for it. Let me know if you then still need 3 0.02Ohm resistors.
OK I stacked resistors on 2 drivers one without and one with C8 both do not light up
Ok found it I soldered positive to the wrong side of the spring pad on the one without capacitor
I get 1.65A on the one without capacitor
so I have to reduce R2?
To get less current, the gain of the Opamp has to be increased. So R2 has to be higher, or R3 needs to be lower.
stacked a 19.1k Ohms on R3 so I get 1.48A that seems OK for 1.4A UV emitter
if you do a order from Mouser or digikey soon could you get me 3 0603 0.02Ohms resistors?
Good to know. And the other driver with C8?
does not work even with removed capacitor, I think a contact of the boost converter is not connected
the 3. with only a 0.1Ohms resistor and capacitor works, at reduced current
Was that a driver you powered on without shorting out two pads at first? Or have you tried the now working one without shorting the pads as well? Maybe the IC is toast because you tried it without shorting the pads at first.
OK, the 3rd one works as expected.
I inspected it with magnification glass and it looked like the IC had no connection to the inductor on the side where it is hidden behind C1
I used very little paste on the outer pins of the IC to do no shorts there
OK reflowed it with a bit paste and now it works
this driver does spot on 1.41A, probably a lot variation on this 3 stacked sense resitors