Re: Driving large numbers of LEDs

On Fri, 16 May 2008 17:58:44 +0000, Guy Macon
<http://www.guymacon.com/> wrote:




John Larkin wrote:

How about three cheap (MeanWell are good) constant-voltage offline
switchers? LEDs aren't zero-impedance loads (some people run them
constant-voltage!) so aren't all that pickey. You could add a
current-sense resistor somewhere in each bank and have a uP measure
that and fake out the remote-sense inputs of the supply to servo the
current.

We buy a nice 150 watt MeanWell, all approved, emi filtered, PFC
switcher for under $40.

That looks quite promising. With uC control of the current
instead of just PWM, I can even add temerature compensation.

Now nobody flame me if this is a stupid idea, but it occured
to me that I could maks a simple switcher where I build up the
field in an inductor and then let it discharge into a string
of LEDs. Just an idea; I haven't worked out the details.

Like this?
http://www.supertex.com/pdf/datasheets/HV9910B.pdf

Also..Supertex has some other LED driving goodies too..


D from BC
British Columbia
Canada
.

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