Convoy 17/22 mm SST40 Driver temperature protection removal

kinhcan55 · 2019-12-02T22:56:43.000Z

Yokiamy:

Maybe this thread helps, driver might be sonewhat different though

【convoy】SFT40 5000K back in stock (sufficient) - #1810 by Yokiamy

The M3 has different driver, I’m not sure I find it correctly =((

kinhcan55 · 2019-12-02T23:04:58.000Z

I think i found it =D

EasyB · 2019-12-02T23:52:10.000Z

Good info. I just ordered a few of these and I’m sure I will do this mod.

These drivers with the stepped modes look like constant current linear mode FET drivers like led4power’s. Is the other ‘ramping’ driver from convoy mentioned above also this type of driver? The description and UI seem strange. Is the current limited to 8A?

jacc · 2020-04-17T14:25:57.000Z

Barkuti:

Satan@103TFS:

@Barkuti what do you think if I just bypass “5mΩ” with the wire to run XHP50.2 3V I’m not sure if it a good ideal.

If you do that the driver won’t be able to regulate at all. This means no ramping and no modes. I haven’t tried it, though.

You still need to tweak the sense resistor stack value for it to work. You could try an R004 on top, it could work well or it may not. Add some heatsinking to the thing in such a case, as you’ll be above the maximum power rating for single 1206 resistors (a couple stacked one doesn’t changes this significantly). A good mound of thermal glue above sense resistor and MOSFET could help.

oweban:

… I assume R010?

So what I’m understanding is that more resistance = higher amperage… Now to work out the right number to hit ~7.5A
…

If the driver uses R010 for 6A this means sense voltage is V_sense = R × I = 10mΩ × 6A = 60mV. If you want to add 1.5A, you need R_extra = V / I = 60mV / 1.5A = 40mΩ or an R040 in parallel with the existing R010.

I have not measured how that driver behaves actually but if you really want to be sure to hit 7.5A, add some more conductance is my advice. I’d look for an R030, which would raise the maximum current to 8A theorerical (6A + 2A), albeit it would leave the actual figure in close proximity to 7.5A effective due to MOSFET heating, imho.

Hi Barkuti & folks,

Can I ask, where is the sense resistor on this board to be sure?

aliexpress.com

2.07€ 69% OFF|22Mm Driver Voor SST40 ,4 Modi 0.1% 3% 30% 100%, max Huidige...

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I have ordered the 20mm board 6A version which I supposed is the same as the 17mm/22mm one. Would you be so kind to show me where it is? thanks

PiercingTheDarkness · 2020-04-17T14:34:53.000Z

Look at your link picture and it clearly shows R010

Barkuti · 2020-04-17T14:41:11.000Z

jacc:

…

Can I ask, where is the sense resistor on this board to be sure?

https://www.aliexpress.com/item/33024197621.html

…

The sense resistor is that big R010 chip resistor onboard, down there in this photo:

That looks to be 2010 imperial size.

jacc · 2020-04-18T04:12:32.000Z

Thanks for the reply, Guess what? I have bought the 1210 sizes and its on its way! Haha, I read it off other threads of the similar driver but in a 17mm size I think?

Since 2010 size is 5mm x 2.5mm and 1210 is 3.5mm x 2.5mm, I suppose this allows me to join two resistors serially to lower the output (which was my main objective anyway).

I actually do see another R010 on the board, at the left side of the 10pin IC. Could that be the sense resistor as well? Regs

Barkuti:

jacc:

…
Can I ask, where is the sense resistor on this board to be sure?
https://www.aliexpress.com/item/33024197621.html
…

The sense resistor is that big R010 chip resistor onboard, down there in this photo:

That looks to be 2010 imperial size.

oweban · 2020-04-18T04:16:28.000Z

The sense resistor is the small black one at the very right of the board in that pic; “north east” of the MCU

jacc · 2020-04-18T05:46:33.000Z

oweban:

The sense resistor is the small black one at the very right of the board in that pic; “north east” of the MCU

Oh thanks for the double confirmation. Looks like I will be having a tough time trying to fit 1210 resistors there

PiercingTheDarkness · 2020-04-18T05:49:06.000Z

oweban:

The sense resistor is the small black one at the very right of the board in that pic; “north east” of the MCU

I don’t think you’re correct. Barkuti has modified these boards before so I’d be more inclined to trust his answer

oweban · 2020-04-18T05:51:38.000Z

Oops sorry I was thinking about the thermal resistor. Brain dead lately.

Apologies everyone, barkuti is right. I’ve done the mod on those sense resistors myself.

PiercingTheDarkness · 2020-04-18T06:19:52.000Z

Anyone know which component is the thermal resistor on the 17mm driver of post #6? (bottom picture). There’s two components within the drawn cicle

Barkuti · 2020-04-18T06:39:46.000Z

The upper one Funtastic. I could also say the rightmost one, and so it is valid for both top (∅22 mm) and bottom (∅17 mm) driver pictures.

PiercingTheDarkness · 2020-04-18T06:49:32.000Z

Barkuti:

The upper one Funtastic. I could also say the rightmost one, and so it is valid for both top (∅22 mm) and bottom (∅17 mm) driver pictures.

Awesome, many thanks

jacc · 2020-04-18T10:26:15.000Z

20mm driver: 2.07€ 69% OFF|20mm Fahrer für SST40 ,4 modi 0.1% 3% 30% 100%, max strom ausgang 6000mA, Temperatur schutz management innen|Taschenlampen| - AliExpress
AON 7220 Mosfet: AON7220, AON7220 Datasheet, AON7220 PDF - Alpha & Omega Semiconductors

Strange though, when looking into the datasheet of the MOSFET, it seems like the big R010 resistor is connected to the Source terminal of the MOSFET (the first 3 pins of the MOSFET are tied together). The Gate pin on the other hand is not connected to the R010, it goes under the MOSFET (or under) to another location. We can see that all the remaining pins on the right side of the MOSFET (4 pins) are connected together as the Drain terminal, which means the datasheet is correct to the MOSFET used here.

I m not good at electronics. Does the Gate terminal connect to the “sense resistor” to bias the Vgs?

oweban:

Oops sorry I was thinking about the thermal resistor. Brain dead lately.

Apologies everyone, barkuti is right. I’ve done the mod on those sense resistors myself.

polarweis · 2020-04-18T10:49:55.000Z

Can i just remove the temp thingy with a soldering iron? Do i need to bridge something after removing it?

icpart · 2020-04-18T10:52:12.000Z

jacc:

20mm driver: 2.07€ 69% OFF|20mm Fahrer für SST40 ,4 modi 0.1% 3% 30% 100%, max strom ausgang 6000mA, Temperatur schutz management innen|Taschenlampen| - AliExpress
AON 7220 Mosfet: AON7220, AON7220 Datasheet, AON7220 PDF - Alpha & Omega Semiconductors

Strange though, when looking into the datasheet of the MOSFET, it seems like the big R010 resistor is connected to the Source terminal of the MOSFET (the first 3 pins of the MOSFET are tied together). The Gate pin on the other hand is not connected to the R010, it goes under the MOSFET (or under) to another location. We can see that all the remaining pins on the right side of the MOSFET (4 pins) are connected together as the Drain terminal, which means the datasheet is correct to the MOSFET used here.

I m not good at electronics. Does the Gate terminal connect to the “sense resistor” to bias the Vgs?

oweban:

Oops sorry I was thinking about the thermal resistor. Brain dead lately.

Apologies everyone, barkuti is right. I’ve done the mod on those sense resistors myself.

Yes sense resistor is connected to the source, the linear driver is exact the same as typical Electronic load circuit Simple Electronic DC Load - Codrey Electronics

Yokiamy · 2020-04-18T20:07:14.000Z

polarweis:

Can i just remove the temp thingy with a soldering iron? Do i need to bridge something after removing it?

1 Yes you can
2 No do dont

pennzy · 2020-12-07T18:45:03.000Z

Can step down be eliminated from a Sofirn C8F, 18650 version? I know it is a long shot asking but WTH. The three minute timer really isn’t needed. Not on high anyway. Maybe turbo.

Sirstinky · 2020-12-07T19:55:52.000Z

I think that stepdown is in the firmware on the driver. You’d need to figure out how to change the firmware.