FX-30 Driver in series?

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Bruno28
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FX-30 Driver in series?

Hello,

Im creating a little light that will use two XHP-70 6v, and I’m thinking of just using the standard FX-30 Driver for convenience.

My input is 12 volts but it says that the driver can only take 6-8.4v. SO my solution around it would be to use two FX-30 Driver in series, so that my 12v input is shared between the two drivers (6 volts).

Is there any downside to this?

Ive seen people selling the FX-30 Driver with suggested input 6-13v. SO can it handle the 12v input (considering that the battery will sag and lower the voltage) or should I go in series as suggested above?

Rufusbduck
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You could power and switch each of them independently but as far as I know you can’t hook up two buck drivers to the same load. The info is conflicting between 3-9V input and 3cell LVP at 9V. 3-cell input is 12.6V Max so maybe you could drive both LEDs in parallel with one FX-30 from 3 cells but the output would be divided between them.

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

Scott

Jerommel
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http://budgetlightforum.com/node/53101

I had a somewhat similar question.
I just want to know if the FX-30 can handle 9.0 – 12.6 Volts.

Rufusbduck
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Kaidomain FX-30 it depends on which part is a typo, the 5.5-9V input or the 3-cell LVP. I’d be inclined to doubt the input voltage spec or they wouldn’t be mentioning 3-cell LVP.

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

Scott

Jerommel
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From that page:

Quote:
Feature(s):

1. Constant current (Note: For using 2 battery, input voltage need to > VF)

2. Low voltage protection function
By using 3 x batteries: When the voltage is less than 9V, it will drop to Lo mode automatically.
By using 2 x batteries: When the voltage is less than 6V, it will drop to Lo mode automatically.


Feature 1. implies the obvious: with 2 partially discharged cells you will not have full blast.
Feature 2. does explain that it can run on 3 cells, and apparently the driver has 2 LVP thresholds: 6 volts and 9 volts.

I hope it’s true.. Wink

sedstar
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I have done this once, for a power supply project, a long time ago…

the basic project, was for a HAM to make their own 12v powersupply with decent amperage. You were to get 3 computer power supplies, of the type that had adjustable voltages on the diff. “legs” of the comp power supplies.

you basically run the 3 power supplies in series, like cells in a battery. You are only “using” the 5v sections of the power supplies… the basic premise? was that the two following PS’s were going to be “floating ground”. the adjusted-down 4.x volts from PS #1, feeds the GND of the PS #2… which then in turn feeds GND of the third power supply, and then the output is 3x the voltage.

i had never previouisly encountered “floating GND” nor a time that a circuit could operate like that. MANY people i described the project to, would tell me it “doesnt work”, but… i am here to tell you it worked and worked well.

NOTE: i am aware THIS might not be the same situation? I am just relating a time i had a similar project.

i realized though, after that? how many times i heard the phrase “with respect to GND” instead of simply STATING a specific ballpark voltage.

6v WITH RESPECT TO GND… well? what if GND was 6v as well? you could get 12v out… heck, my project tripled it like that.

NOT SAYING this works in this case, as i cant design power supplies, but, I can “follow the plot line” well enough to accomplish a bit here and there… so, using power supplies in series like adding up cell voltages in series? is possible in some cases…

With enough black coffee and cigarettes? all things are possible…

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Rufusbduck
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Yeah, I’ve heard the phrase “you can’t do that” often enough but in the case of drivers with multiple mcu’s in series it doesn’t seem workable. Circuits give me a headache as it is, this sounds like a migraine approaching. Maybe it works better with purely voltage controlled supplies.

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

Scott

Bruno28
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is anyone able to test this driver with 5v input? I might have to use a 2s input but its a LiFePo4 battery that has low voltage cutoff at 2.5v but a max charge voltage of 3.65v.

So with 2s my operating voltages is from 5v to 7.3v. (discharged to charged battery)

sedstar
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if you COULD gett it to start to work? couldnt you just resistor down the supply voltage to the MCU? that would be the only thing that wouldnt like the second stage voltage.

With enough black coffee and cigarettes? all things are possible…

I am currently still shipping… REAL GENUINE CREE xp-g emitters, the classic… brace yourself? as low as 20 cents apiece!! Check out the SALES THREAD, everyone is happy… then PM me

SALES THREAD:
http://budgetlightforum.com/node/52528

if you are into reloading? this is my site… I inherited the remains of what was once arguably the best reloading site on the internet… its the “BLF” of reloading sites…

http://reloadbench.freeforums.net/

if you think night vision would be cool? It IS… this site i am a member of, and its basically the “BLF” of home made scratch-built digital night vision. They are at the leading forefront of advanced DIY for digital night vision, and thats gun mounted or handheld… builds rival and exceed commercial offerings…

http://nightvisionforumuk.com/

Bruno28
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sedstar wrote:
if you COULD gett it to start to work? couldnt you just resistor down the supply voltage to the MCU? that would be the only thing that wouldnt like the second stage voltage.

Not quite sure what you mean?
I have a voltage (5v to 7.3v.) that is in the lower range of functioning from the Driver (6-8v). So I would need to step up so that I can maximise the full range of the battery voltage before the driver cuts out as I will still have a good amount of capacity on the battery that wont be used.

Bruno28
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I have confirmed with Simon from Convoy that the driver can take 12v. So I bought 2 to try out and will go 3s instead of 2s.