Sofirn C8 Quick Review

$11 for a SST-40 + FET flashlight? Interesting. :slight_smile:

Stacking FETs (no, they are not “MOSFets” these days) is not, In my opinion, an avenue worth pursuing.

The one being talked about here looks like a very good one. Each of the two FETs inside has under 18 mOhm on resistance, and whilst each is rated at 8A continuous, data is provided to four times that.

So the original dual package should be quite happy to at least 16A continuous. Dissipating no more than 2.3 watts at that current. Dropping 0.144 volts maximum.Which if properly laid out on a footprint with lots of copper plane, is well within spec. (Case temperature de-rating allows about 65C at that power)

Nevermind these numbers, this dual FET package will have, datasheet, passing 16A, under 9 milliohms resistance. I would suggest looking elsewhere to improve the overall resistance in the current path before worrying about the FET.

All you get by stacking on another one is a (theoretical) halving of Rds on. From maybe 9 to 4.5 milli Ohms. Vanishing returns, and very little more thermal dissipation in a stacked configuration.

Then again, I confidently expect it will carry on working at much higher current levels and temperatures, except that it is off the published datasheet.

Little buggers at the factory trying to hide the component markings?

It was curious for me to see the C8F advertised with XP-G2 emitters inside, to find these user samples here with XP-G3 units and overcurrent problems. Usually happens when non-knowledgeable people takes the decisions.

A spring de-bypass or two would help for XP-G3 (and Nichia 219B/C) emitters.

Cheers ^:)

Tom Tom, the Si9926CD datasheet lists a maximum of 8A per package. The thermal resistance is too high and the little FET bugger will end up like a roasted burger. I'd stack another package just because of reliability.

Cheers ^:)

$9.06 for a TA13 at Banggood only leaves me $1.94 to get an SST-40 on copper DTP star.

Stacking another one on top will make almost no difference to thermal dissipation. You would have to lay them out on separate bits of the PCB, for the heat to be conducted through the leads into separate areas the PCB where it gets dissipated.

We are agreed, this little package would be toasted without any decent thermal path into the board. Stacking another one on top won’t improve anything there.

I think the two FETs inside the one package are quite capable of handling the current, and the power. And the PCB, presumably so.

The rest is over to you, if you think e.g. reducing from 9 to 4.5 milliohms is of any consequence…

$8.99 on e-bay.
$2.09 for SST-40 when buying 1, $1.6 when buying 10.
These are on stars, though I don’t know if they are DTP. Most likely not copper…but if it’s DTP I would stick with it for such cheap light. If it’s not DTP then this light won’t be nearly as cheap….

Agro, these are DTP mounted emitters: “thermoelectric separated” search at FastTech

The boards these leds are mounted over:

  1. https://www.fasttech.com/products/1611/10017569/3741400-20mm-copper-base-plate-for-cree-led-emitters
  2. https://www.fasttech.com/products/1611/10017569/6222100-20mm-copper-base-plate-for-cree-xm-l2-xhp50-led

I believe both boards are DTP, only from different providers. Hope FastTech were more clear with their product descriptions.

Reflow the cheapie on one of these boards, or buy a ready-to-go SST-40 on custom KDLight copper star at Kaidomain.

Cheers ^:)

I can recommend those with experience. First fried two cheap SST-40 with poor star/MCPCP. Then ordered those and they handle amps at least up to 5.5A in my setup. Edit: Someone told me that he drives those at 8A.

“according Cissy from Sofirn driver is direct driven.” That I updated today and I measured tailcap amps of C8A: I got with freshly charged NCR18650GA after some spread 6.10A @ High. Have anybody measured amps with different/ better batteries from any other model (or same) of those C8:s?

Edit: Peak was around 6.3A.

Edit2: Now there is in add that driver is direct drive.

Edit3: Led gasket have been chanced but only for XP 3.5mm footprint leds:

C8F,Cissy told me will have a upgrade model, with 3 groups and DTP MCPCB, :heart_eyes:

Just talked in other matter with Cissy from Sofirn. She asked me something, I answered but maybe here are also people that could say their opinions. It’s about new C8F. There are two kind of driver groups and Cissy asked which one would be better. I quote Cissys message straight here and do tell what you think.

“Switch: one side switch

  1. 3 groups modes

One click enter group1 : Low- mid-high

Double click enter group2: LL-Low-mid-high

Three click enter group3: firefly-LL-Low-mid-high

In any groups when light on, double click enter hidden mode:strobe-SOS-bike -strobe. three click enter turbo mode 1950 Lumens

2. 3 groups modes:

Turn on enter group 1: low-mid- high

When light on, four times quick press switch to change groups, cycle from group1- group2-group3-group4

In any groups when light on, double click enter hidden mode:strobe-SOS-bike -strobe. three click enter turbo mode 1950 Lumens”

And like Jackie said above C8F is coming with DTP MCPCB because of problems with heat.

3-D photo of C8F to come:

One group with high only please! :smiley:

I voted for plan B if need be. No one’s going to remember to click 3× just to light it up from off. Best to just set it and forget it.

But doubleclick-to-blinky is just evil. Rather doubleclick-to-turbo or something, instead.

If the µC is flashable, maybe some other eswitch-enabled UI could be stuffed into it.

Unfortunately, it says something if a UI is unwieldy enough to have to replace it with something else.

Just sent this to Tracy:

Agree with Lightbringer with regards to the triple and doble click function swap.

Cheers ^:)

Cissy/ Sofirn needs help to decide from 2 groups. She gives everyone who respond to this query 2$ discount QR code from at least 15$ purchase from Sofirn AE shop. I sent it via PM to all who gives their opinion which group would be better.

Copy of what Cissy said about double click after I asked could it be modified:

“Double click to turbo 1950Lm and three click to strobe-SOS-bike-strobe.”

And also assumption from Cissy: “also may use 3 pieces XPL instead of XPG3”

:smiling_imp: may it burn?

I vote plan 2 now when it’s only 3 groups you can switch between.
It’s easier for “normal” people to get right.
Double click for turbo should be standardized.
3 fast clicks for strobe…
Changing groups should atleast be 5 fast clicks so it don’t accidently change group instead of putting on the strobe to blind an attacker or whatever strobe is used for.
If I was in that situation and I panic and try to put on the strobe and accidently changed mode instead of getting the strobe I think I would have gotten more panic.
If i just did a double click when panic I think ~2000 lumens would still blind the attacker.

How do animals react on high lumen strobe when attacking?
Should I strobe an attacking bear, wolf and such animals?

Just curious…

Edit: damn bad English

Does this Sofirn driver have any hidden turbo?
It says 86%PWM at high, can’t find any info about any turbo.
I guess it’s the driver that’s in the Sofirns right now?
No thermal stepdown?

Link:https://m.aliexpress.com/item/32834504322.html

Sofirn New C8A C8F C8T Driver 2 Groups Circuit Board Anti-reverse LED Driver Chip mode memory

Size:Diameter 16.8mm

Protection:Reverse polarity protection, low voltage protection, Memory mode function

Input voltage: 2.8-4.2V;

​Current: Directly-drive

Suit for : Cree XM-L ; XP-L, XP-G

2 Groups:
Group 1:Low 5%PWM> Mid 30%PWM > High 86%PWM,Double click strobe 86%PWM.
Group 2 :Moonlight > Low 5% PWM> Mid 30%PWM > High 86%PWM> SOS 86%PWM,Double click strobe 86%PWM

Low voltage protection: Yes. The light is automatically turns off when the voltage is lower than 2.8 volts. The signal is that the light slowly flashes for 1 minutes

Group Set Operation: When on, 3 click continuously, the light flash 2 times and then automatically goes to next mode group.

Edit the link.

Hmm. It says this above the text I wrote in the other post.

Specifics
Voltage 2.6-8.4V
Brand Name Sofirn
Usage for flashlight
Certification CE

Not right?
Is it only 1 cell driver as the text under this text says?

Size:Diameter 16.8mm

Protection:Reverse polarity protection, low voltage protection, Memory mode function

Input voltage: 2.8-4.2V;

​Current: Directly-drive

I hate when sellers give 2 different descriptions on the same item.
Only makes me not buy it.