Hello,
I am trying to figure out a simple way to power this DC/DC LED Driver (AL8843) with 120vac without having to use a separate AC/DC converter. I am NOT very advanced in electrical circuit design, however, I love to build things. I will be using the circuit to power some Cree XP-L LED Stars
https://www.ledsupply.com/leds/cree-xlamp-xp-l-high-density-led-star

I have included the data sheet for the specs on the LED driver and evaluation board for the schematic. Some basic info on the chip is:
Wide Input Voltage Range: 4.5V to 40V
Output Current up to 3A
Internal 40V NDMOS Switch
Typical 4% Output Current Accuracy
Single Pin for On/Off and Brightness Control by DC Voltage or PWM Signal
Recommended Analog Dimming Range: 10% to 100%
Soft-Start
High Efficiency (Up to 97%)
LED Short Protection
Inherent Open-Circuit LED Protection
Over Temperature Protection (OTP)
Up to 1MHz Switching Frequency

Would a bridge rectifier work for this? Other options?? I am trying to save space and come up with a design with all components on one board. I am using the AL8843EV1 evaluation board as a basis for the led driver circuit. Just need to figure out a way to power it. I have successfully built a similar design that uses batteries to power an AL8861 LED driver which works great, thanks to some help from forum members here!. Any advice would be greatly appreciated! Thanks for helping me out!

 

All too often simple ways to do things are inherently unsafe. The safe way to do this is with a 1:1 isolation transformer and a bridge rectifier. In North America this would be followed by DC-DC converter with a 170 Volt input.

 

Thanks for the reply! I was hoping for something a little less bulky and expensive! I could always use something like this:
https://www.mouser.com/ProductDetail/MEAN-WELL/EPS-120-24?qs=Kh9WxvXxjWnnDbjQEBerRg==
or a laptop power supply. Just was hoping for a simple and safe design that isn't as large as a smps. I'm pretty sure LED's don't require AS much filtering as an smps has. Thought maybe a simple bridge rectifier or something else may work.
Any other ideas? Thanks!

 

I guess I may have violated forum rules by asking this question. I apologize!! Post can be deleted by a moderator please. Thanks!

 

Consider for a bit that ALMOST ALL Mains voltage to DC switcher supplies INCLUDE that AC to DC converter, AND an isolation transformer. BUT the isolation transformer operates at a much higher frequency where it can be a whole lot smaller.
So there is a totally safe, adequately isolated scheme.
Look at those five-volt 1.5 amp cell phone chargers, many of which are isolated and that are not much over a single cubic inch inside their thick plastic insulating package.
My cautions are a few: First, as has been repeated by those who know, is that designing a decent switch-mode power supply is a serious challenge, and second: is that there is a whole lot of really poor quality junk for sale on line. But there are also a few totally honest, high integrity, and willing to provide information on their products, sellers around. AND there are some folks to be found in these forums who can provide better advice on who to trust than I can.

 

The safest way is to use an ac/dc converter (120VAC to 12VDC/24VDC) for the AL8843. Keeps it simple, safe, and avoids any nasty shocks.

 

The MOUSER catalog listed devices should work. A big caution is that adequate heat sinking is needed for the LEDs. AND, consider that if it will not be subject to anybody touching the LED or it's heat sinks, isolation may not be needed.

 

Any other ideas?

Line voltage + novice = disaster. Just buy something.

 

The specifications list the MAXIMUM forward voltage as 2.95 volts. So FIVE of these in series fed from a 12 volt , on amp, supply will work well. It does not need to be an LED rated supply, just one able to deliver adequate current at the sensible voltage.
UNDERSTAND that an LED will work very well at less than the maximum voltage and current, and last MUCH longer.