XHP70.2 at full power of 30W through two channels.

svitlo · 2019-01-31T18:50:13.000Z

BlueSwordM:

Wouldn’t it just be better to use a 12V MCPCB instead?

Not.
When powered from 6 …. 12V of two or three lithium cells, the best is 6V version.
If you have 4 lithium power, then the 12V version is better.

BlueSwordM · 2019-01-31T18:52:20.000Z

Oh it’s a 2 channel buck driver!

That’s very smart IMO.

svitlo · 2019-01-31T19:04:18.000Z

BlueSwordM:

Oh it’s a 2 channel buck driver!

That’s very smart IMO.

Yes, you can use modern step-down synchronous drivers with integrated power elements.
And if you need a very cheap way, you can use inexpensive сhinese drivers such as qx9920 and others.

EasyB · 2019-01-31T20:05:50.000Z

I don’t think I understand the benefit of a 2 channel buck driver. Does this mean it has 2 sets of components like inductor and FET? Is there really a size advantage to using two 2.4A-capable drivers versus one 4.8A-capable driver?

svitlo · 2019-01-31T20:25:59.000Z

There is a benefit.
Verified
With a current of 2.4 A, inexpensive, small-sized power elements can be used. The load on the elements is distributed evenly. At a current of 4.8A, special measures are needed to remove heat from the power elements, which leads to an increase in size and price.

Try to make a driver for a 4.8A LED.
Then you will understand

tundraotto · 2019-01-31T21:13:52.000Z

Yes - this is definitely a good idea!

Lexel · 2019-01-31T21:24:35.000Z

the MCPCB you use is pretty useless
with 2 seperate buck circuits you can simply run a normal 6V MCPCB and connect the 2 buck in parallel

if the Buck chips support synchronisation you can 180° phase shift them

MF01 4S—>3S simple connect both outputs in parallel to the MCPCB

Original driver has 4 2S—>6S boost converters in parallel but is still a lot less efficient

mattheww1950 · 2019-02-01T00:28:34.000Z

svitlo:

There is a benefit.
Verified
With a current of 2.4 A, inexpensive, small-sized power elements can be used. The load on the elements is distributed evenly. At a current of 4.8A, special measures are needed to remove heat from the power elements, which leads to an increase in size and price.

Try to make a driver for a 4.8A LED.
Then you will understand

One of the less obvious benefits is the fact that the losses are proportional to the current squared. As a result, it is very likely that a pair of 2.4 amp drivers will have smaller losses than a single 4.8 amp driver.
2 x 2.4 x 2.4=11.52
4.8 x 4.8 =23.4
So such a ‘twin’ driver would in theory have only about half the losses of a single larger driver. Less heat, less wasted energy, longer run time.

EasyB · 2019-02-01T00:47:19.000Z

mattheww1950:

svitlo:

There is a benefit.
Verified
With a current of 2.4 A, inexpensive, small-sized power elements can be used. The load on the elements is distributed evenly. At a current of 4.8A, special measures are needed to remove heat from the power elements, which leads to an increase in size and price.

Try to make a driver for a 4.8A LED.
Then you will understand

One of the less obvious benefits is the fact that the losses are proportional to the current squared. As a result, it is very likely that a pair of 2.4 amp drivers will have smaller losses than a single 4.8 amp driver.
2 x 2.4 x 2.4=11.52
4.8 x 4.8 =23.4
So such a ‘twin’ driver would in theory have only about half the losses of a single larger driver. Less heat, less wasted energy, longer run time.

Well that is assuming two identical circuits with identical resistance components. Of course more large inductors and FETs is better but we don’t have unlimited space.

It sounds like heat dissipation is improved with multiple small components compared with single larger components, possibly because of the higher surface area to volume ratio of the small components.

clientequator · 2019-02-01T03:20:21.000Z

This driver I see on mountain electronic do 5.5A output as bucking driver in 17mm size!

http://www.mtnelectronics.com/index.php?route=product/product&path=67_115&product_id=554

It say it can take 5-18V input and work for 3, 6 and 12V led.

For heating, I believe usually the led is the main heat element, not the driver, so usually flashlight overheat first because of led not driver?

LouieAtienza · 2019-02-01T04:56:32.000Z

Lexel:

the MCPCB you use is pretty useless
with 2 seperate buck circuits you can simply run a normal 6V MCPCB and connect the 2 buck in parallel

if the Buck chips support synchronisation you can 180° phase shift them

MF01 4S—>3S simple connect both outputs in parallel to the MCPCB

Original driver has 4 2S—>6S boost converters in parallel but is still a lot less efficient

It’s amazing you post this because I had just recently proposed this thought to someone earlier, and this helps confirm my thought.

Hoop · 2019-02-01T05:06:18.000Z

Lexel:

the MCPCB you use is pretty useless

It looks like it’s DTP, in which case, not useless.

Thanks for sharing this idea svitlo!

LouieAtienza · 2019-02-01T05:16:48.000Z

There may be other advantages to a MCPCB like this… for a mounted light, you could make the light “directional” by dimming one channel and brightening the other - like for a stationary vehicle light that still “turns” with the vehicle, or “points” up or down with the terrain… possibly with a cross fader or stacked pot.

svitlo · 2019-02-01T05:29:13.000Z

clientequator:

This driver I see on mountain electronic do 5.5A output as bucking driver in 17mm size!

http://www.mtnelectronics.com/index.php?route=product/product&path=67_115&product_id=554

It say it can take 5-18V input and work for 3, 6 and 12V led.

For heating, I believe usually the led is the main heat element, not the driver, so usually flashlight overheat first because of led not driver?

This driver is implemented on MAX16820
I tried these drivers. At 5A, they work only for a very short time. All power elements are very hot.
In this version of 17mm, this driver can be operated with currents up to 2.5A

svitlo · 2019-02-01T05:56:14.000Z

Lexel:

the MCPCB you use is pretty useless
with 2 seperate buck circuits you can simply run a normal 6V MCPCB and connect the 2 buck in parallel

if the Buck chips support synchronisation you can 180° phase shift them

In my version do not use specialized chips with the ability to synchronize. No need to shift the phase 180 ° .
I used two simple non-complex Buck drivers. Project price matters

moderator007 · 2019-02-01T06:10:34.000Z

I have master and slaved two buck drivers together before and tied the outputs. It doubled the power out and doubled the current draw. Both ran in a reasonable range.
It worked like a charm and both where controlled using one mcu. No reason why they couldn’t be used on a single designed board if the host had the room.

Nicolicous · 2019-02-01T06:24:45.000Z

Where to buy your driver svitlo?

Scallywag · 2019-02-01T14:09:46.000Z

I want to use the two channels to strobe each half of the XHP70.2 alternately. I'd say, something like 10 Hz, and less than 50% duty cycle, 180° out of phase.

Even more fun if you use two separate strobe frequencies

Lexel · 2019-02-01T14:43:05.000Z

LouieAtienza:

There may be other advantages to a MCPCB like this… for a mounted light, you could make the light “directional” by dimming one channel and brightening the other - like for a stationary vehicle light that still “turns” with the vehicle, or “points” up or down with the terrain… possibly with a cross fader or stacked pot.

think about the thermal stresss in the LED if only one side heating up, also would affect the beam negatively, your directional idea would not work like you think, you can make that with 2 indipendant LEDs and optics
there is no benefit of such a MCPCB it generates only disadvantages

svitlo · 2019-02-01T22:17:46.000Z

Nicolicous:

Where to buy your driver svitlo?

Buying one driver does not make sense.
It needs to be bought with a LED.
Available XHP70.2 90CRI 2channels