This is a ATX12VO Standard compatible +5VSB to +12VSB Converter Circuit. It is based around the FP6296 chip which is a current mode boost DC-DC converter. This board enables older power supplies which output 12V, 5V, 3V Rails to be compatible with the new ATX12VO Standard. This board features a universal design and is compatible with Power Supplies from any lineup of any manufacturer. Please refer to your PSU output pinout and ATX12VO Connector pinout to route the connecting wires for the connector cable properly. This board only converts the +5VSB rail to +12VSB rail as needed in ATX12VO standard.
This board is expected to go inline in the PSU to ATX12VO motherboard connector cable and be sleeved, which would make it look similar to the above cable.
This board features an extremely small form factor of 16.8mm x 17.3mm so that it can be easily incorporated inline in a sleeved ATX12VO Motherboard Connector cable. The compact size of the board and dense arrangement of components make it highly resilient to bending or breakage while attempting to cable manage or route ATX12VO Motherboard Connector cable in a tight PC case. The small form factor also ensures the flexibility of the cable is not compromised when installed inline. The larger the inline circuit board, the lesser the flexibility. Reduced flexibility of cable can result in difficulty in cable management or unsatisfactory results in cable management.
PCB Front View
PCB Back View
Proceed to place the diode and inductor on the back, these are held in place via the adhesive. Then place the front smd components and reflow solder the entire assembly. Thread in the cables from the back and solder onto the front side, ensure enough solder flows to make a solid connection through the plated through hole and solder flows across to the exposed contact on the back side. Please note that +12V and GND terminals are pretty close, ensure the terminals are not bridged during soldering.
It is to be noted that +5VSB commences at the PSU Connector end and terminates at this board while +12VSB originates at this board and continues to the ATX12VO Motherboard Connector. +12V and GND wires are to run across the cable from the PSU connector end to the motherboard connector end and the +12V and GND connections for this board may use wires spliced in with the +12V and GND wires running across the cable or have dedicated wires run through the PSU connector end to the +12V and GND terminals of this board. The inline circuit assembly maybe encapsulated with a heatshrink for better isolation. It can then be bundled together with the other wires running across the cable and be sleeved together.
This board prioritises small form factor above all else and as such will have a performance penalty as opposed to the reference layout which uses a two layer design with single sided component layout spread out over a much larger area with global ground net on bottom layer.
Mounting the magnetic component (Inductor) directly on the otherside of the controller introduces significant noise and coupling. As such a 4 layer PCB is required for isolation which is achieved by flooding ground in the middle two copper layers as well as underneath the inductor on the bottom layer. This should provide significant shielding to signal lines and the throughly stitched ground planes should ensure low impedance across ground net. This minimises the magnetic effect but does not completely isolate it, as such a nominal coil whine is to be expected. This design uses all smd components to reduce noise bleed and isolate switching noise to ensure minimal noise characteristics on output line.
The reference design might be cheaper as it utilises 2 layers as opposed to 4 layers in this design, but the cost difference should be negligible on a per unit basis when panelized due to the smaller board footprint in this design which would net more boards from a similar sized panel. Thorough use of vias in this design is necessary for proper signal integrity even though it might increase expense. Thick signal traces are used wherever necessary to minimise the inductive effect of the tracks for high frequency signals. Ceramic Capacitors with low ESR must be used. MLCC X5R and X7R Series are recommended.
Although I am pretty confident the board should work, you might still wish to have the board verified by a professional. I am not particularly confident about the values of C4 and C10.
Couldn't find a proper model for Inductor L1 and Diodes D1 and D2, so they are missing on the PCB views.
This project was made with Kicad 7.0 . Generate gerbers as per specification from the fab of your choice.
This board has not been printed and tested physically to verify functionality. I do not assume any liability for the materials, information and opinions provided on, or available through, this project. I disclaim any liability for injury, death or damages resulting from the use thereof. Modify or work on it at your own risk.
All PCB design files and hardware are released under the Creative Commons Attribution Share Alike 4.0 license.
Commercial Usage strictly disallowed.