Behind the Scenes of the DEFCON 18 Badge - Grand Idea Studio
Behind the Scenes of the DEFCON 18 Badge - Grand Idea Studio
Behind the Scenes of the DEFCON 18 Badge - Grand Idea Studio
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R3 1kSeamless Power SwitchingVBATTD2Q1FDN340PVCCD5#TXLED3V3OUTMMDL914T1G22131412417C160.1uFCBUS0CBUS1CBUS2CBUS3CBUS4VCCIO3V3OUTDCDRIGNDGNDGNDAGNDCBattery Switchover• P-channel MOSFET on by default via R4•10When USB plugged in, 3V3OUT (FT232) goes HIGH12•14MOSFET turns <strong>of</strong>f and battery is isolated from circuit• Body diode <strong>of</strong> MOSFET prevents battery from gettingreverse fed by 3V3OUT (small nA leakage is OK)• Voltage drop across D5 causes VCC to be lower forUSB-powered (2.7V) than battery powered W4 (3V) Jumper• Higher forward voltage (Vf) -> lower reverseW5leakage Jumper(Vr)VCCVCCR41kVCCW6JumperTMSP2DNP2468135791113JTAG PortMolex 15-91-2140 fVCC
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