Has anyone modded a H1-A boost driver?

Thanks Jensen567

from that datasheet:

OK, I edited my above post to note that the H2-C results are inaccurate. I still don’t know exactly what was going on, but after forcing the output to 9V it works normally again. New results!

H2-C Stock

Input 3.58V 2.48A outputs 12.03V 0.66A, efficiency 89%

Input 3.43V 5.60A outputs 12.06V 1.39A, efficiency 87%

H2-C with 2x R100 replaced with 2x R075

Input 3.52V 3.44A outputs 12.04V 0.90A, efficiency 89%

Input 3.24V 8.72A outputs 12.09V 1.90A, efficiency 81%

Input 7.01V 3.60A outputs 12.09V 1.93A, efficiency 92%

I now like both of these drivers quite a bit! I did not have time to take temps this test, and the readings are taken before the step down. Step down is also gradual over 30 seconds or so, not abrupt. It Also appears like using a 2S input with H2-C will result in a much better efficiency (not surprising at all). It still doesn’t like driving below 10.5V or so without losing UI.

Just to note, I used 2x R075 resistors as opposed to 3x R100 resistors because with the R100 setup my bench supply hit the 10.1A current limit, so I wanted to bring it below that.

With 1S input on H2-C I think around 2A output is about the best we can do, with 2S input I think we can push it further as the driver did not heat up nearly as fast.

Is the H1-A able to output 12V with 6V input? Or will that just fry it? I want a XHP35 in my L2, but I haven’t found a suitable driver yet (takes a 20mm)

I don’t think it would fry it, but it wouldn’t output 13V either. In post 47 of this thread EasyB linked to Tjhosan who got the H2-C to fit into an L2, might be worth asking him.

According to the datasheet the boost converter certainly has the ability. Whether or not the other components are up to it is the question. See my previous post concerning setting output voltage as well as the Datasheet

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)