SST-90 True CC Driver 10 Amps Hi/Lo Mode

Hi CPF,

I was not online for a while since I`m really busy with my job (which is BTW designing DCDC converters for LED backlights). But the SST-90 seems to be worth it to spend some of my rare spare time

Developing a driver for a 9 Amps (or in case of the CST-90 13.5 Amps) LED is a challenging task especially when it should fit in a flashlight tube. Even the little resistance of 10 Milliohm results at 10 Amps in a power loss of 1 Watt which has to be dissipated. Not to mention the transition and charging losses of the MOSFET which preponderant at high switching frequencies (which are necessary to keep the inductor small).

Keeping that in mind I developed a synchronous rectified buck-driver.


Some facts:

- Designed to drive one SST-90 with Vf<6V (driving two LEDs with a low Vf should be also possible)

- Diameter 26.2mm / 1.030" (fitting a MAG C tube!!!)

- Input voltage 5.8-16 V (can be driven of 2-3 LiIon`s in series, one SLA or 6 NiMh`s)

- Output current 0-10 Amps

- Efficiency hopefully >95% (Efficiency was my main concern. 5% loss still means 2 Watts of dissipation. Less efficiency won`t be possible to handle in a flashlight tube)

- Low voltage cut-off 5.8V (to protect the cells if driven by 2 unprotected LiIons and prevent excessive dissipation in the MOSFETs cuz of low gate voltage)

- 2 current level control by a simple switch like the MAG switch (Low level adjustable by potentiometer on the PCB, High level fixed to 10 Amps)

- Optional control modes:
potentiometer can be desoldered and the PCB is prepared to solder a wired potentiometer on for stepless current control
PWM input is prepared on the pcb. It needs to be pulled down (e.b. µC open-drain output). Max. frequency tbd. but definately below 500Hz.


I am gonna order the PCBs for the first five prototypes tomorrow. The parts I have already. This is gonna be fun


Any questions?

EDIT:

yes! when can I get one?

sector_cleared said:

Any questions?

Click to expand...

Are you going to be making a production run, and if so, when can I list it?

Shouldn't this be in the electronics forum?

Wow! :twothumbs

Keep us updated, where do I sign up for one?

How does this integrate with the stock Maglite switch?

Looking for testers?

Sounds like it could be seriously awesome. Good stuff!

It's much interesting..
We need tests, pics, specs, etc...

I know nothing (well, next to nothing, at best) about CC drivers, so forgive me if this is a stupid question, but you mentioned a potentiometer to adjust the output current. Do you have an estimate of the output current range?

I'm in!

If you make these available for sale I would like to take one of the first 5!

Email or PM me for the first available, or pre-order!

I've been trying to find a high current driver for SST-90 to run off a 12v lead-acid battery (13.7v max.)

John F

I'm in for at least one, maybe more, depending upon price.

Please let me know.

in for at least two

fawesome, I'm in for one also:twothumbs

It's good that you designed it so small, but I think this emitter will have problems with heat in a D size light so I doubt that many people will be using a C size light as a host. I'm already trying to determine what power level I will be able to run it continuously. My guess is about 15 watts, which means around 5 amps.

Sounds very interesting but I think you should also provide a 5A for the SST-50 and it would even be better if the output level could be set by the modder.
In case you are looking for testers I'm living nearby...

Would it be possible to disable the low voltage cutoff? I'd like to run 4 high capacity NiMh cells, so low voltage would be ~3.6v or just go direct drive.

I'm laughing at the way this "innovation" thread has instantly turned into a sales thread without any coaxing from the OP (who has not replied since his original post, by the way).

It's no wonder that happend. People have been starving for a real CC driver for the SST-90 and now at first glimpse of one, we're all salivating.

Having said that, as the first to reply with interest, I'm calling dibs on the first available unit, whether it be a prototype for testing or a rev 1.0 unit for sale. :naughty:

JohnF said:

Email or PM me for the first available, or pre-order!

I've been trying to find a high current driver for SST-90 to run off a 12v lead-acid battery (13.7v max.)

John F

Click to expand...

Me too, but I got a bigger problem, since I get the current from the stator(YX178 Madass), I'm stuck with 18.7V max.(E.G. 13.7V from the stator plus 5V from the alternate current).

Mister, could you raise the maximum input voltage to 19V?

Could the driver accept the 19v input voltage without burning?

How much for 10 drivers?

[email protected]

Hello cpf,

I was able to order the PCBs yesterday but I think it won`t arrive before the christmas holidays start

@all: I ordered for the first 5 prototypes. It will take me at least 2 weeks to finish and test the drivers. If everything turns out well I want to do a production run.

@Hack on wheels: This driver is designed to work with the Mag stock switch. The cycle is OFF-LOW-HIGH-OFF. The low lvl is easily adjustable by the onboard potentiometer. The high lvl is full blast :naughty:

I will write more and answer the other questions later. My breakfast break is over :thumbsdow

I'll have 2 of each please

Hey, I better jump in.

I'll take one!!