led driving problem..
led driving problem..
(OP)
hi all,
in my circuit i need to drive and switch 100 (if it is not enough, may be 1000)led. and i need 20-30 mA for each led. i think that i can drive them serial, parallel or serial-parallel mixed with power transistors. and my driving signal is PWM signal. because of this, i must not only drive the leds but also switch them. but i ever design such a circuit before. so i need help about led driving circuit.
thanks for sharing your time..
Best Regards,
Oguz Dokuyucu
od@postaci.com
in my circuit i need to drive and switch 100 (if it is not enough, may be 1000)led. and i need 20-30 mA for each led. i think that i can drive them serial, parallel or serial-parallel mixed with power transistors. and my driving signal is PWM signal. because of this, i must not only drive the leds but also switch them. but i ever design such a circuit before. so i need help about led driving circuit.
thanks for sharing your time..
Best Regards,
Oguz Dokuyucu
od@postaci.com





RE: led driving problem..
I remember a similar question in here before so try a search.
RE: led driving problem..
What is the forward voltage spec of your LED's? Also dictates what you do regarding driving your LED's.
At what frequency were you planning to switch your LED's on and off?
What kind of power transistor were you planning to use: MOSFET, BJT, etc...? You might find a number of ordinary BJT's is sufficient, depending on the current for which each transistor is responsible.
Do you have access to an oscilloscope? An oscilloscope is always handy for determining what is REALLY going on.
RE: led driving problem..
i can use three different powerfull switching equipment. These are TIP122 NPN Darlington Transistor(100V 5A), IRF830 TMOS Power FET(500V 4.5A) and TIP3055 Power Transistor(100V 15A). i will connect 10 led serially. and then connect 10 parallel group (each group exist 10 serial led). what kind of circiut i can use to switch transistor. i think that i drive darlington tr. at first and then fet with this. i am waiting for your advices..
Oguz Dokuyucu
od@postaci.com