HarryN
Flashlight Enthusiast
Hi, I usually either buy regulators as needed or use a resistor to knock down the current flow for LED use, but I thought it would be fun to try to actually build one from scratch. This seemed like as good of place to post this as any.
I have never actually built a working circuit that contained more than a battery, diode, resistor and LED, so this will be a real test for me.
Constant current drivers require a bit more finess, so I thought I would start with a constant voltage one instead. I realize that they are some very sophisticated ones out there (Alan B versions) - this is just a simple version as a learning experience and for use in a project light I am thinking about. There is nothing "intelligent" or programmable in this project - think on/ off - maybe some dimming.
I am targeting a fairly wide voltage input range (about 5 - 30 volts) and approx 4 amps or so output at 3.3 volts. This is in the range where you can just about "cheat" and run a power LED direct drive. :naughty:
There are an amazing number of companies that offer controller chips - so it is almost a daunting task to pick from them all. I looked mostly at IRC (irf.com), TI, ON Semi, and National. They all have advantages, and I mostly wanted very simple and few parts, so I ended up at National. I don't know if it is the "best" decision, just a decision.
The main values their product brought to the table are
- 4.5 V to 42 volt input
- 5 amp output
- adjustable voltage output
- Built in mosfet (the on / off large power transistor)
- Very few parts needed to build (at least in theory)
- A very strong web design center that does all of the calculations and part selection for you.
I have never actually built a working circuit that contained more than a battery, diode, resistor and LED, so this will be a real test for me.
Constant current drivers require a bit more finess, so I thought I would start with a constant voltage one instead. I realize that they are some very sophisticated ones out there (Alan B versions) - this is just a simple version as a learning experience and for use in a project light I am thinking about. There is nothing "intelligent" or programmable in this project - think on/ off - maybe some dimming.
I am targeting a fairly wide voltage input range (about 5 - 30 volts) and approx 4 amps or so output at 3.3 volts. This is in the range where you can just about "cheat" and run a power LED direct drive. :naughty:
There are an amazing number of companies that offer controller chips - so it is almost a daunting task to pick from them all. I looked mostly at IRC (irf.com), TI, ON Semi, and National. They all have advantages, and I mostly wanted very simple and few parts, so I ended up at National. I don't know if it is the "best" decision, just a decision.
The main values their product brought to the table are
- 4.5 V to 42 volt input
- 5 amp output
- adjustable voltage output
- Built in mosfet (the on / off large power transistor)
- Very few parts needed to build (at least in theory)
- A very strong web design center that does all of the calculations and part selection for you.
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