Has anyone modded a H1-A boost driver?

The H1-A, from the datasheet, can only go up to 12.6V, so not really suitable for a 4S emitter like the XHP35.

It could, however, fully drive in series triples (3S) providing up to 2.5A of output without much trouble, but seems to be MCU-gimped to ≈7.3V. Crap.

Cheers ^:)

Just a note on LVP of these boards.

H1-A maintains regulated output until input voltage hits 3V, at which point it begins to taper the output down as to maintain the 3V on the input, it cuts off somewhere below 100mA on the output, once input can no longer hold 3V.

H2-C in 1S mode begins its taper around 3.2V, but does allow the input to keep dropping until it hits 3V then it will cut off, output is somewhere below 50mA by this point.

H2-C in 2S mode is similar, but it will begin tapering around 5.8V, slowly allowing the input to drop until 5.7V where it cuts off.

More info! Pulled the inductors off today. They didn’t scratch off the chip numbers but rather covered them in some sort of epoxy, with careful scraping I was able to find that H1-A is indeed a TPS61088 chip (S61088A is visible marking).

H2-C is a different chip which is marked I believe MPFE 3429 839 on its 3 lines. The “P” could be a “B” and the “F” could be an “E”, very hard to tell with the epoxy residue. My searches haven’t found the chip, but it must be some sort of external switch boost controller. The switch used is an AON6718 MOSFET.

Both drivers use a Microchip PIC 12F683 MCU.

Also, more good news on H1-A. It is NOT MCU capped in its output voltage. Using the TI datasheet I swapped the high side FB resistor from a stock 47K and successfully boosted the voltage higher. A 62K resistor yielded 9.05V and a 75K resistor yielded 10.72V, so somewhere around 70K will be perfect for a 3S emitter setup. UI still fully in tact, but the sense resistor will need to be changed to limit the input to 10A or less to avoid burning out the switches inside the TPS61088 IC, as they are only rated for 10A.

I did not try, but I believe if a zener is placed across the MCU power rail 2S battery input should be possible for the 3S emitter setup, but LVP likely won’t function properly.

The resistor that needs to be changed to modify the output voltage can actually be seen in the picture on Post #2 of this thread.

If you look at the top photo, on the left side of the board you see 4 resistors, the R025 sense resistor, an upside down 123 (12K) resistor, and 2 473 (47K) resistors. The one to change is the 473 located next to and in the same orientation as the 123 resistor.

I ordered one of the new FX70 boost drivers from KD today as well, so that will be next to be tested once it arrives.

Good work. I ordered an H1-A about a month ago, finally shipped.

May as well repost the pictures here

Still pretty much in the dark on how these work so please be nice about correcting my misunderstandings.
If the inductor is saturated you can:
A) increase inductance
B) increase switching frequency
Either of which will increase circuit resistance/lower efficiency
A larger inductor(thicker wire)of the same inductance will have lower resistance and higher current rating
The switch ic has a min/max frequency sometimes controlled by an external capacitor
One needs to verify that the main diode and sense resistor(s) can handle an increase in current and/or voltage and also that input and output capacitors are rated for an increase in input/output voltage
Switching regulators have voltage spikes on the output that can fry emitters below maximum led current.
Power handling of sense resistors is indicated by size but caps are frequently unmarked and more often than not of lowest quality needed for operation within spec. Better quality parts can sometimes make the difference between a driver working/not working.

Thanks a lot for the research on maximum open circuit voltage for the H1-A. Opens up the possibility for nice fully regulated triples, PWM free too. Output power is about right, I'd reduce the output current to ≈2.5A, which I believe is more than enough for compact single cell flashlights with 3S emitters. Definitively a winner.

Did you meant a KX70?

Cheers

RBD, you are basically correct. I did not spend a whole lot of time looking through the datasheet on switch frequency, but my money would be on a larger inductor to keep efficiency up and heat down with this driver. That said, the stock hardware seems to perform fairly well, perfectly suited to smaller lights where you won’t be able to hold max output for long due to heat anyhow.

If using in a larger light, swapping the inductor for a larger unit of the same inductance, and ensuring good contact of the ground ring to the flashlight body, would probably allow the continuous use of high mode on a single cell given the 10A switch limit.

Barkuti, yes you are correct, I did mean KX70 driver. The new 4A boost driver for XHP70. Hoping we can push to 5 or 6 amps, will have to see.

Not one to leave well enough alone, I decided to finish setting up an H1-A for 3S emitter operation. Mods are a 75K FB resistor and an R030 sense resistor.

OCV is 10.75V

Low:
Input - 3.70V 0.032A
Output - 9.60V 0.010A
Efficiency - 81%

Mid:
Input - 3.65V 0.696A
Output - 9.61V 0.238A
Efficiency - 90%

High:
Input - 3.53V 2.348A
Output - 9.64V 0.805A
Efficiency - 94%

Turbo:
Input - 3.15V 8.670A
Output 9.77V 2.410A
Efficiency - 86%

Overall I am very happy with these results since it is fully regulated PWM free output with good 3.0V LVP. Sure we can probably hot rod better output with 3 parallel emitters and a FET driver, but really this is more output than most triple hosts can handle for very long anyhow heat wise.

Nice to see it working as expected.

Related: #566 post in KD (kaidomain): Deals and new products thread

Cheers ^:)

Great write up in that thread, and thanks for that picture that clarifies which resistor to modify output voltage. I took a bunch of photos of both boards after I removed the inductors, just need to upload them somewhere since Google hosting is a pain these days.

No clue as to the ratings of the ceramic caps on the board per RBD’s concerns, but it is functioning as expected at least. Thankfully ceramic caps won’t go bang when over volted like electrolytic, they just lose capacitance.

I really want to try to get this driver into an S2+ triple setup. For under $11 shipped, this board is a big winner in my book.

Awesome news. Thanks for the experimentation Jensen567. Now does anyone have a host suggestion for a triple setup and the 20mm driver?

I think it will fit in an S2+ if the driver pocket in the pill is opened up and the driver is soldered directly to the pill. I was looking this afternoon as I want to do this myself. The idea of a fully regulated triple is very appealing.

I’m playing around with modding the H2-C driver. Stock it was putting out right around 1.4A to an XHP35. Then I put a 0.007ohm resistor (length of wire I measured) in parallel with the 2 stacked R100 resistors.

Input at driver:
3.54V 13A

Output:
14.15V 2.4A

For about 74% efficiency. But it only outputs this for several seconds before it starts to blink the output. Next mode down was ~1.8A. The inductor gets hot, but it’s not burning in the seconds before the output starts to blink at around 2-3Hz. Any idea what the blinking indicates? This is all preliminary testing as I plan to get a lower resistance inductor.

Also, I turned up the input voltage to ~2s levels on my power supply, and saw momentarily 3.5A to the LED before I disconnected it. Any idea why this might be? I’m not sure if it would was just a transient high current and I don’t want to try this again for fear of breaking my LED. Thanks for any help.

Bad, verrry bad EasyB. Don't game that way with the sense resistor stack, been there done that (Sir Magical Smoke appeared  onstage).

Around four millimeters of AWG37 (≈⅛ of an AWG28) thinner than hair wire has about those 7mΩ of resistance, and certainly nowhere near the amount of mass and cooling ability to handle the massive amount of electrical power who supposedly should cross through it. Of course, then you can have the “cool” idea of coiling a thicker wire, effectively setting an inductor in parallel with the sense resistors, and then you'll soon start smelling funny and hearing humming noises around the stuff… please stop now before you break your driver.

Using a proper sense resistor stack and 2S battery input for the H2-C should allow you to drive an XHP35 (probably) to 2.5A with little or no issues.

Take care.

Originally posted on Fri, 06/02/2017 - 20:01; little fixup.

Oops, I meant to make a 0.07ohm wire, not 0.007ohm. :blush:

(12cm of 22AWG solid copper wire has 0.007ohm, measured by measuring the voltage drop with a known current through it)

If you are talking about the KX70 i also ordered this driver few days ago and i am thinking if it is possible to bump the current a little bit, somewhere in the 4.5-5A range.

I plan to use it with XHP50.2 led and according to the test that djozz did the led needs 6.3V for 4A up to 6.5V for 5A current.

Please post your findings if you do this test on the driver.

I replaced all the sense resistors with a piece of wire with 28mOhms, which should result in ~2.4A output. The wire is 0.025” diameter solid copper and 50cm long. It’s not coiled so shouldn’t have significant inductance. I get the same results as above, around 2.4A with 1s input but still ~3.5A with 2s input. Is this a symptom of a component being operated out of spec? like the inductor being saturated or something?

I switched back to the two R100 stacked resistors and the driver behaves as it should; 1.4A with 1s or 2s input.

Well, the odd behavior I’m seeing does indeed have something to do with the wire sense resistors I made. I made a 50mOhm section of wire and the driver did not behave the same as with the 2 stacked R100 resistors. I guess I’ll just wait until I get the proper sized resistors.

Yeah a wire that long, even not coiled up will present a fair bit of parasitic inductance to the circuit which could certainly cause the strange behaviors you see.

I will play around with the H2-C a little more when I get a chance, now that I know it is an external switch we can push past the 10A input limit of H1-A. The switch should be good for around 15A, though the stock inductor isn’t.

Using 2S input levels should prove to be very good on H2-C based on my initial test. I bet we can get around 2.5A output safely using 2S input and the stock inductor, as barkuti said. Which could make one heck of a light using XHP35 HI.

I will be sure to post KX70 results when I get the driver. Just got my tracking number a few days ago. I may make a new thread for all the KD boost drivers to document everything. I am also hoping for around 5A output with modifications, the inductor may need changing for that though, as it doesn’t look much bigger than the ones used on the H1-A and H2-C from the pictures.

Just a quick question:
20mm ( Dia. ) x 7.5mm (Thickness)(including all component)


Is that with the spring?
Could anyone measure the hight of only the components on the inner side please?


I plan on getting an MT-G2 into my F13 and I need to make the pill thicker - but I need to know how thick I can make it.


Thanks!