High Power LED Driver Circuit Help..

[Ubergeek63]

i think i may have found a circuit ideal for the job.

Google Image Result for https://gifpdf.ic-on-line.cn/0185/yb1682_440151800001.gif

would anyone know what i would have to do to change the output to 20v@2a??

how should you NOT use that chip... let me count the ways...

1) you should not use the example circuit since it requires a current limit resistor to wash out the tolerances to the tune of 4V (20% of 20V) of headroom to wash out component tolerances time your 2A load: you would need an 8W resistor...

2) you should not use a lower headroom voltage since as the LEDs heat up their voltages go down causing burn out as they begin to draw more than their rated current.

3) you should not, though it would work better then the previous 2 options, put the LEDs in place of the voltage sense resistor since that would still leave the reference voltage resistor at 1.2V times 2A or 2.5W

I could probably come up with more... but the HV9910 has none of those problems since ti was designed as a current source for power LEDs.

 

[Ubergeek63]

i think i may have found a circuit ideal for the job.

Google Image Result for https://gifpdf.ic-on-line.cn/0185/yb1682_440151800001.gif

would anyone know what i would have to do to change the output to 20v@2a??

what do you plan on using as a source? the AC rail, a separate power supply, or a battery?

 

[keny]

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[cobra1]

what do you plan on using as a source? the AC rail, a separate power supply, or a battery?

i was planning on using a 240v ac, the power will come from a battery pack, fed through a 240v inverter.

 

[Ubergeek63]

i was planning on using a 240v ac, the power will come from a battery pack, fed through a 240v inverter.

backup? if not then why are you going though 3 power power conversions?