9Amp buck converter help

[jezdec]

I`m looking at this driver "Ampere from PCB Components" and I have one dummy question:
Input voltage for Ampere is specified from 7V to 25V.
And now what is the optimal input voltage to drive single SST 90, because I believe the output voltage can`t be higher
than 3.8V....am I right?

 

[jezdec]

I`m looking at this driver "Ampere from PCB Components" and I have one dummy question:
Input voltage for Ampere is specified from 7V to 25V.
And now what is the optimal input voltage to drive single SST 90, because I believe the output voltage can`t be higher
than 3.8V....am I right?

Maybe I have asked this wrong....:whistle:
Since input voltage for Ampere is specified from 7 to 25 Volts my question is:
In case of driving single SST 90 from Ampere the input voltage can be from 7 to 25 volts,
and if I connect triple SST 90 (in series) input voltage can also be from 7 to 25 volts??

A little help....please:confused:

 

[Mr Happy]

The phrase "Ampere from PCB Components" is unfortunately not of any help in locating the driver you are describing.

However, a buck converter must have a higher input voltage than the required output voltage. So if your three SST-90's in series have a combined voltage requirement of 11.4 V, then the input voltage must be higher than 11.4 V, perhaps with an extra margin too. You can only find out the details by looking at the data sheet and performance specifications for the driver.

 

[jezdec]

The phrase "Ampere from PCB Components" is unfortunately not of any help in locating the driver you are describing.

However, a buck converter must have a higher input voltage than the required output voltage. So if your three SST-90's in series have a combined voltage requirement of 11.4 V, then the input voltage must be higher than 11.4 V, perhaps with an extra margin too. You can only find out the details by looking at the data sheet and performance specifications for the driver.

Sorry...you can find Ampere here: http://pcb-components.de/

In the data sheet is specified, that input voltage is from 7 to 25 volts and voltage drop is 2V.
And this is just what I can`t understand....the voltage must be at least 2 volts higher than input V for LED or multiple LEDS....OK this I understand,
but max. input voltage can be up to 25 volts nomether if I drive single SST 90 (3.7V) or triple SST 90 (11.1V)????

 

[Mr Happy]

but max. input voltage can be up to 25 volts nomether if I drive single SST 90 (3.7V) or triple SST 90 (11.1V)????

It would appear so. It would be best to ask them directly if you want confirmation.

 

[moderator007]

If the driver will do 9amps then the forward voltage of a sst-90 at 9amps is 3.87v from the datasheet. 3.87v X 3 = 11.61v forward voltage for the series wired leds. The driver needs 2v over the forward voltage so 13.61v would be the absolute lowest voltage the driver will work at. Considering voltage sage of batteries I would try to get a battery source of 18v or higher. The higher the voltage you run the less current the driver will draw from the batteries. 4 IMR 18650's should work but 5 would be better. Usually with buck drivers the more voltage the driver has to step down the less efficient it is. But this doesn't always hold true. As Mr.Happy said you may want to contact them and get some more info.

 

[jezdec]

I just got a reply from "PCB Components" and it says:

"Yes, theoretical the max. voltage can be up to 25V for single SST90, but its not recomended because of efficient."

So the nominal voltage for singe SST 90 is somewhere around 8-12V, and for triple SST 90 from 15 to 20V.