the ultimate LED regulator or close enough

[[email protected]]

I live on a boat and an always delt with electrical efficiancy. And its time to upgrade from my super bright LED to some of these new 3 and 5 watt leds.
The ulimate dc dc buck bost swiching regulator
input 3 to 18 vdc
output regulated 2.3 vdc to 13.8 vdc
regulated current 3A
regulated 10% duty @ 10khz 10A
both pwm and 100%duty
I would like to be able to Run the light with as little energy as possible. I'm thinking 4 leds, 2 parralel and 2 serries.
When I start looking for possible reglators I am overwhelmed.
Any helping ideas. I have basic soldering and electronic skills.
Thank you Wiley

 

[miso]

I'd search for a dedicated chip for the task.

That said, you really don't want to parallel LEDs. Only the cheap ass
Chinese designs do that. Every diode is a little different, and you will
get current hogging if you parallel them.

I would avoid the buck-boost. Pick a scheme and live with it. My
preference would be a discontinuous conduction boost. Keep it simple. A
LED can deal with ripple fine since the eye will average out anything
over a few hundred Hertz.

If you put enough LEDs in series so that you always need a boost
converter, the design becomes very easy with off the shelf chips. What
is normally done to make a LED driver is to send the boost inductor
output (via blocking diode) to the string of LEDs, and then put a
resistor from the LED string to ground. Then set up the voltage sense
pin of the boost chip so that it senses the voltage across this
resistor. By regulating the voltage across the resistor, you have
effectively regulated the current in the LED string. The inductor flies
back to whatever voltage is appropriate.

I recall Micrel made some cheap chip to do this, and LTC made a better
though more expensive one. If for some reason the diode string is
broken, the inductor voltage will fly high enough to damage the driver
transistor. Some chips protect for this, and some don't.

But any basic boost converter circuit can be made to do this. The longer
the string of LEDs, the less you have to worry about the loss of power
in the sense resistor.

 

[[email protected]]

I'd search for a dedicated chip for the task.



That said, you really don't want to parallel LEDs. Only the cheap ass

Chinese designs do that. Every diode is a little different, and you will

get current hogging if you parallel them.



I would avoid the buck-boost. Pick a scheme and live with it. My

preference would be a discontinuous conduction boost. Keep it simple. A

LED can deal with ripple fine since the eye will average out anything

over a few hundred Hertz.



If you put enough LEDs in series so that you always need a boost

converter, the design becomes very easy with off the shelf chips. What

is normally done to make a LED driver is to send the boost inductor

output (via blocking diode) to the string of LEDs, and then put a

resistor from the LED string to ground. Then set up the voltage sense

pin of the boost chip so that it senses the voltage across this

resistor. By regulating the voltage across the resistor, you have

effectively regulated the current in the LED string. The inductor flies

back to whatever voltage is appropriate.



I recall Micrel made some cheap chip to do this, and LTC made a better

though more expensive one. If for some reason the diode string is

broken, the inductor voltage will fly high enough to damage the driver

transistor. Some chips protect for this, and some don't.



But any basic boost converter circuit can be made to do this. The longer

the string of LEDs, the less you have to worry about the loss of power

in the sense resistor.

 

[[email protected]]

I live on a boat and an always delt with electrical efficiancy. And its time to upgrade from my super bright LED to some of these new 3 and 5 watt leds.

The ulimate dc dc buck bost swiching regulator

input 3 to 18 vdc

output regulated 2.3 vdc to 13.8 vdc

regulated current 3A

regulated 10% duty @ 10khz 10A

both pwm and 100%duty

I would like to be able to Run the light with as little energy as possible. I'm thinking 4 leds, 2 parralel and 2 serries.

When I start looking for possible reglators I am overwhelmed.

Any helping ideas. I have basic soldering and electronic skills.

Thank you Wiley

This is to Miso
Miso thank you very much. I'll look up the info you gave me. I've been driving fork lift for the last 6 years and lost touch with my hoby of electronics. I was rased in Yokohama Japan from 1965 to 1973, 10 years old to 18. Love the sushi. Achihbara (Spelling) in Tokyo is incredible for electronis of all types.
Thanks again Wiley