[Idea/Collab Project] A Badcaps.net ATX PSU!
A little project i am doing for a friend resurfaced my interest in building power supplies. That project is 95% complete now and only needs a few protection components fitted until it's ready to go, but more on that later. It is a boost regulator from 12v, designed to deliver 18-19v for juicing up a car audio amplifier with output ICs rated for 18v, as the power output almost doubles at 18v. And given the output voltage and current (7A peak, 4A+ continuous) it is also perfectly suitable for powering any kind of laptop from a 10.8 to 15v source such as a car battery or PC power supply if that's what you have lying around. 
I could have used a cheap nasty chinese 12v laptop adapter for this job, however i wanted a stable power supply that will not blow up 10 minutes later or put out something silly like 30 volts with no load, the 2 i have tried being beyond disappointing in this regard.
So i spun my own and it ended up quite nice. What makes this special is that it requires NO heatsink, the cooling of the power devices is achieved just through the PCB. To achieve this feat i used synchronous rectification, and i achieved that despite the use of a regular UC3843 controller IC (dedicated sync rectifier controllers are rare and expensive at $4-$5 for a single chip, and you'll still need a separate main controller!). For the boost inductor, i have reused a 3.3v output toroid from an ATX PSU with no modifications required. Enough spoilers, i'll post the whole thing next week.
Since AMD will be finally launching a DDR4 platform next year, i will be building myself a new PC. And i thought, why not start with the power supply? Yes folks, i am thinking of building my own ATX power supply from scratch.
Maybe some of you are interested in something like that as well.
My design guidelines would be as follows:
For a topology, i am thinking of sticking with the tried and true half bridge with BJT switches, but giving it a modern spin with synchronous rectification on the output and independent 3.3v and 5v regulation. Basically a single rail 12v design with the minor rails being downconverted by buck regulators, "just like the big boys". I would like to stick to a modest power rating, say 200 to 500W, as i feel like there are not enough high quality power supplies in the lower power ranges.
I am not going to use active PFC unless someone designs me a drop-in PFC front-end, as i have not done something like that before, and i feel it would overcomplicate this project.
Who's in?
I could have used a cheap nasty chinese 12v laptop adapter for this job, however i wanted a stable power supply that will not blow up 10 minutes later or put out something silly like 30 volts with no load, the 2 i have tried being beyond disappointing in this regard.
So i spun my own and it ended up quite nice. What makes this special is that it requires NO heatsink, the cooling of the power devices is achieved just through the PCB. To achieve this feat i used synchronous rectification, and i achieved that despite the use of a regular UC3843 controller IC (dedicated sync rectifier controllers are rare and expensive at $4-$5 for a single chip, and you'll still need a separate main controller!). For the boost inductor, i have reused a 3.3v output toroid from an ATX PSU with no modifications required. Enough spoilers, i'll post the whole thing next week.
Since AMD will be finally launching a DDR4 platform next year, i will be building myself a new PC. And i thought, why not start with the power supply? Yes folks, i am thinking of building my own ATX power supply from scratch.
Maybe some of you are interested in something like that as well.My design guidelines would be as follows:
- Basic power supply (200-500W scalable)
- Hobbyist friendly (0805 SMD and SOIC as minimum component size)
- Using "jellybean" (widely available) parts
- Recycling as many components as possible (for instance, we could use 5vsb and driver transformers from dead ATX PSUs and MOSFETs from old motherboards for a synchronous rectifier)
- A realistic timeframe (I'd say 6 months to 1 year until 100% design completion and testing)
For a topology, i am thinking of sticking with the tried and true half bridge with BJT switches, but giving it a modern spin with synchronous rectification on the output and independent 3.3v and 5v regulation. Basically a single rail 12v design with the minor rails being downconverted by buck regulators, "just like the big boys". I would like to stick to a modest power rating, say 200 to 500W, as i feel like there are not enough high quality power supplies in the lower power ranges.
I am not going to use active PFC unless someone designs me a drop-in PFC front-end, as i have not done something like that before, and i feel it would overcomplicate this project.
Who's in?