Buck and Boost Drivers, Testing, Modding, and Discussion (Pic Heavy)

Another little question: Jensen567 I see you boosted H1-A driving current up to 3.75A (R025 + R100 = R020), do you believe it could be reasonable to pump it up a little bit higher? Like for example R025 + R050 = <R017 (4.5A, 16.67mΩ) or maybe R025 + R100 + 2(R330) = <R018 (≈4.2A, ≈17.84mΩ).

I wonder if heat could be a problem.

Cheers ^:)

This is the only real info I’ve found on modding the H1-A sense resistor for increased current. What size is the resistor? I’m looking to order some R100s and very unfamiliar with SMD resistor sizing. So exactly what kind of resistor should I be ordering? Will 1206 1% SMD 0.1 Ohm work?

Measured mine: slightly above 3mm in lenght and about half of that in width, I guess that means it is a 1206 imperial.

Cheers ^:)

Did someone noticed the H1-A's layout is somewhat different from what is show in the product pictures?

I was yesterday playing with one of them and somehow messed up with the capacitors by the inductor's lead, lost one of them and the other is damaged I believe (don't ask me how that could happen, but it gave me reason to send a m@r@n where he belongs). Measured such capacitance (2x capacitors) in a brand new driver and got ≈120µF which is a lot. Gotta have to measure another unit I have at hand unpackaged. Biggest 3.5 × 2.8mm size 16V SMD caps I've found on AliExpress are 47µF each.

May someone confirm such capacitance stack size?

Cheers :-)

According to the above picture the capacitor stack I messed up is at the left side of the inductor. As previously said, I measure either ≈120µF or ≈50µF for that stack. I know this sounds weird but…

Bought these 16V 47µF tantalum capacitors to fix it. They're polarized, this means likely it is that the non-polarized capacitors I am replacing probably were 2x 22µF units.

Mmm, this means just one would do.

Cheers ^:)

Tantalum caps have higher ESR, so there is good chance they will release some smoke.

Ah tantalum caps.

The bane of many Macbooks since 3 generations.

You mean increased blow up chance?

Well, if that is so I'll install capacitors on both PCB “slots” and hope for the best (even if this means capacitance is gonna be about twice).

Cheers :-)

KD has changed some things on the H1-A. Mainly resistor values.
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I have read along Jensen567 following all your mods, thanks for posting by the way.
What I’m trying to achieve is about 12v out at about 2 amps driving a triple series Seoul Viosys UV emitters.

I reflowed the leds on to a series 20mm board encase you are wonder about that link.
The R1 resistor is now a 01D (factory) 100k (at least I think its R1) so I assumed the driver works around the 12.6v limit now. So I hooked ever thing up on my power supply and bam the driver works with the series triple Seoul but I can only get about 500 ma output. I thought the sense resistor determined the output current. I had not changed it and was going to limit the power supply current to keep from damaging the emitters, just testing.
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I haven’t changed anything on the board yet, looking for advice as what I do need to change on this new revised board. I also want to change the LVP to 2.75v but I would like to get close with output working first. Any advice is appreciated.
Datasheet here: http://www.ti.com/lit/ds/symlink/tps61088.pdf

Now that we're here…

Repaired my driver. Ended up buying ceramic capacitors, a size bigger :-) but made them fit. Bought 'em of 22µF capacity and my guess was right.

I noticed the differences moderator007 describe too.

Cheers :-)

I just fired this thing back up again, this time I hooked up a second meter to monitor voltage to the emitter. I got 11.25V to the emitter’s and at .971ma of current across the emitter. The input voltage was at 4.1V and about 3.25 amps in.
I’m thinking maybe the 100k resistor is still to small to get to the 12.6V limit. 120k or 150k might get there.

Jennsen, while deciding on which 1s boost driver I want to use in my Convoy L6 I saw all your posts regarding the KX70 driver from kaidomain. Thanks a lot for all that data! I also want to do your ldo+cap mod.

What current rating does the 2.8V LDO need? I found some with 150mA for example.

I want to have a max of 4A. The ldo mod shouldn’t change that? What I don’t understand is how your ldo mod changes the lower modes?

From what I see and fathom here, LVP condition is when voltage at pin 3 goes down to 1.5V. If so, replacing R11 with an 8KΩ resistor results in 2.7V LVP, or changing R12 by a 12KΩ one does 2.75V LVP.

However…

For the love of God, may someone point out what/where are the 10KΩ “01C” resistors pertaining to the MCU's pin 3 battery input divider? Seems like that 01C below the MCU in the picture could be R12, but where the @#$% is R11? May someone confirm? I can't figure out if something else has changed from here, may have to peek at my drivers.

Cheers ^:)

There on the other side of the driver next to the spring. It took me a little while to trace them down. :wink:
If you trace pin 3 to the battery side of the driver there they will be with a small capacitor.
I can take a pic if needed, it will just be awhile before i can get free.

R2 is below the capacitor and R1 is below R2, with the trace running to the spring. That hole with a trace above the right side of the capacitor is pin 3 from the other side.
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I can’t remember exactly what value I changed it to but the first time I changed the divider value the driver would run down to 2.4V on a bench power supply but at a very low current. So the boost IC will work at a lower than rated voltage.

I believe you meant “R12 is below the capacitor and R11 is below R12, with the trace running to the spring”.

Thanks, this means the divider is now set with 100KΩ resistors, and much easier to access. Thank O:) God.

Cheers ^:)

Yeah in the schematic R11 and R12. Usually in a voltage divider there labeled R1 and R2. You got it figured out though. :smiley: Being on the battery side of the driver does make it very convenient :+1:

It looks like an Attiny programmed for the GT should plug right in place of the PIC with the right adapter board.

The ones in this thread will not work. here is the LD-29 MCU pinout (eg how to put your ATtiny13A in there...)

Are there more boards around here somewhere?

Where does the switch connect to?

What's wrong with PIC microcontrollers?

PIC microcontrollers are widespread among lots of great drivers. The existing disregard against these microcontrollers is odd to me, it is sort of like swimming against the tide. Porting the high level language code among them should not be hard.

Cheers ^:)