I need it ASAP...any body ?
I need it bad like the n00bs say.

I don't need it ASAP, I was just messing with you guys.

To cut short, I just want to test LED back lights of LCD TV's.
Right now I have a 60VDC variable SMPS. I need one to carry around. So it needs to be battery powered.
Input can be a 3.7V li-on. One, two or three cells is not a problem. So input can be 3.7V or 7.4V or 11.1V.
LED string voltage varies from 20V to 200V ( sometimes a bit more than 200V. 200V is the max I saw so far).
Current needs to be at least 500mA.
Basically a battery powered DC to DC converter that can handle 500mA and variable from 20V to 250V or so.
Load regulation does not need to be strict as all I need is to check the LED string for couple of seconds.

I am looking for ideas on how to design this kinda circuit.
The battery can be chosen as li-on comes in different capacities.

So, please throw in some suggestions.
Thank you

 

Hello,

When you say 200 Volts and 500 mA, you are talking about 100 Watts.
Do you expect the battery to deliver this + the extra losses of the conversion?

Bertus

 

I know that.
It's not continues.
Just for a few seconds to check the LEDs for a visual inspection.
If a LED not working, strip won't light, if shorted, a simple glance can tell.
I believe polymer can supply that much surge with a couple of cells in series or parallel.

By the way, 500mA is the worst case. I have tested strings at 40V at around 100mA quite easily.
500mA is the worst case target.

Actually it should be a CC device that can control current around a few mA to 500mA with a max voltage of around 250VDC

 

What about buying one ???

 

What about buying one ???

Point me to one

 

Point me to one

Take most any cheap and tiny automotive power inverter of 100 - 120 watts that plugs directly into a power port socket and just modify the HV DC stage feedback loop to run at the ~200 volts you need rather than the typical 150 170 they run at.

Strip it down to a bare circuit board and remove the output H bridge components and mount it in a a small projects box with some lipo cells and there you go. portable self contained ~200 VDC source.

You've been pointed, now start walking.

 

Take most any cheap and tiny automotive power inverter of 100 - 120 watts that plugs directly into a power port socket and just modify the HV DC stage feedback loop to run at the ~200 volts you need rather than the typical 150 170 they run at.

Strip it down to a bare circuit board and remove the output H bridge components and mount it in a a small projects box with some lipo cells and there you go. portable self contained ~200 VDC source.

You've been pointed, now start walking.

Hey...tht's not a bad idea at all. Me likeeee....!
Best part is me got a couple lying around