High power led matrix connection

[bmandl]

I think I came to a solution. I will use current mirror with aditional bypass transistor, which can whitstand 6A of current in case, no string is connected, so all the current passes throuhgh this transistor. I draw a circuit in LTspice and simulated it and it works. Please, ignore part values, because they are just for a test. Do you think this will work as expected?

 

[KlausST]

Hi,

Yes, in your simulation you don't see how Q3 will explode.

Klaus

 

[bmandl]

Why would Q3 explode?

 

[KlausST]

Hi,

Calculate the max power dissipation....and compare the result with the datasheet rated power dissipation.

Klaus

 

[bmandl]

I would use different transistor.

 

[FvM]

The "different transistor" must be able to dissipate 200 W continuously. No realistic design idea.

 

[bmandl]

I guess, I'll really have to omit the protection and maybe just use some current mirror to equalize currents. I hope that non of the leds dies, or at least just one string.

 

[bmandl]

Exactly how would resistors in each string equalize currents through leds? I am talking about configuration with constant current power supply and multiple parallel strings of series leds with series resistors?
Oh, and btw, how about this circuit for equalization of current?