“DUAL USB HOST/HUB OUTPUT WITH CONSTANT CURRENT LIMIT/PROTECTIONRajkumar Sharma 122 Views moderate Tested
This project has 2 outputs that enable us to power up 2 USB devices simultaneously from an input supply of 12-30V DC. The idea of this project is to have safe power for USB powered devices. The circuit is designed to simplify USB port power delivery based on self-powering 2 port USB HOST/HUB. IC provides two constant current outputs each of 1.1Amp 5V DC, and when any of USB port is overload/short circuit, the fault flag goes from high to low, and the outputs are in constant current mode. The project can be used as a dual-port USB charger in cars or trucks.
The project comprises of two parts, a DC-DC converter, and constant current limit switches. LM2576 IC is used as a DC-DC converter that provides 5V 3Amps from an input supply 12V to 30V DC and FPF2303 chip used as dual-channel load switch, consist of dual, independent, current-limited, slew rate controlled P-channel MOSFET power switches. Slew rated turn-on prevents inrush current from glitching supply.The board provides two jumpers J1 and J2 to enable the outputs. Switch control is accomplished by pulling down the pin ONA/ONB using jumpers. a current limit condition immediately pulls the fault signal pins FLAG-A or FLAG-B low and the part remains in the constant-current mode until the switch current falls below the current limit. The circuit offers current limiting, UVLO, and thermal shutdown protection for each USB port, in the event of an overcurrent condition, the load switch limits the load to the current limit value. The minimum current limit is set to 1.1A. The chip does not turn off the response to an overcurrent condition but remains operating in a constant current mode as long as ONA or ONB are enabled and thermal shutdown or UVLO is not activated.
The project can be controlled using Arduino by interfacing ONA/ONB pins for ON/OFF the output and Flag pins FLAG-A/FLAG-B to check the fault conditions.”