5V 3A Power Supply for USB Devices


This is 5V 3A power supply to drive two USB based devices simultaneously. This power supply is design around LM2576-5.0 switching regulator IC and the main reasons to choose this IC is its low parts count, small heat sink requirements and its inbuilt current limit protection feature.

They specially design this power supply to work with development boards / single board computer (SBC) platforms such as Raspberry Pi, Banana Pi,BeagleBone, etc.

This power supply can also be used to provide power to USB OTG peripherals over USB Y cables.They test this setup and got successful results with Huawei Ascend P6 mobile phone.

The schematic of this power supply is based on sample circuit explained in LM2576 datasheet. In this power supply the most difficult part to obtain is 100?H inductor.

The 100?H inductor used in  prototype is built around King magnestic  toroidal core (Part No: N20x12x8). The core which they used is covered with plastic jacket for mounting purposes, but that “mounting unit” is not mandatory for PCB design. Dimensions of the toroidal core are illustrated in above diagram.They  wind 50 turns of 1.045mm Ø insulated copper wire on this core and we got 102.4?H reading with is coil.

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