Electronics Overview 02/12/2008 Lecture 8 1 diode bridge Winter 2012 UCSD: Physics 121; 2012 2 Winter 2012 UCSD: Physics 121; 2012 3 € 1CIdt∫ € 1Xtot=1X1+1X2+1X3+ …Winter 2012 UCSD: Physics 121; 2012 4 1 2 3 R1 R2 V VoutElectronics Overview 02/12/2008 Lecture 8 2 Winter 2012 UCSD: Physics 121; 2012 5 V R Winter 2012 UCSD: Physics 121; 2012 6 A B A’ CT B’ AC input AC output Winter 2012 UCSD: Physics 121; 2012 7 V I V I V I V I 0.6 V plain resistor diode idealized diode WAY idealized diode no current flows current flows the direction the arrow points in the diode symbol is the direction that current will flow acts just like a wire (will support arbitrary current) provided that voltage is positive Winter 2012 UCSD: Physics 121; 2012 8 p-type n-typeElectronics Overview 02/12/2008 Lecture 8 3 Winter 2012 UCSD: Physics 121; 2012 9 Winter 2012 UCSD: Physics 121; 2012 10 AC source load input voltage voltage seen by load diode only conducts when input voltage is positive Winter 2012 UCSD: Physics 121; 2012 11 A C B D AC source load input voltage voltage seen by load B & C conduct A & D conduct Winter 2012 UCSD: Physics 121; 2012 12 A C B D AC source + load - load voltages seen by loads can buy pre-packaged diode bridgesElectronics Overview 02/12/2008 Lecture 8 4 Winter 2012 UCSD: Physics 121; 2012 13 A C B D AC source load capacitor Winter 2012 UCSD: Physics 121; 2012 14 R C V Winter 2012 UCSD: Physics 121; 2012 15 1 2 3 R1 R2 Vin Vout Rload Winter 2012 UCSD: Physics 121; 2012 16 R1 Z Vin Vout = Vz Rload zener voltage high slope is what makes the zener a decent voltage regulatorElectronics Overview 02/12/2008 Lecture 8 5 Winter 2012 UCSD: Physics 121; 2012 17 note zeners Winter 2012 UCSD: Physics 121; 2012 18 beware that housing is not always ground Winter 2012 UCSD: Physics 121; 2012 19 B C E B E C npn pnp Winter 2012 UCSD: Physics 121; 2012 20 out Rc Rb in Vcc B C EElectronics Overview 02/12/2008 Lecture 8 6 Winter 2012 UCSD: Physics 121; 2012 21 out Rc Rb in Vcc Winter 2012 UCSD: Physics 121; 2012 22 out R in Vcc Winter 2012 UCSD: Physics 121; 2012 23 Vreg Rload Vz Vin Rz Z Vin Winter 2012 UCSD: Physics 121; 2012 24Electronics Overview 02/12/2008 Lecture 8 7 Winter 2012 UCSD: Physics 121; 2012 25 from: http://www.maxim-ic.com/appnotes.cfm/appnote_number/4087 The FET switch is turned off or on in a pulse-width-modulation (PWM) scheme, the duty cycle of which determines the ratio of Vout to Vin Winter 2012 UCSD: Physics 121; 2012 26 Winter 2012 UCSD: Physics 121; 2012 27 FET Inductor Current Supply Current Capacitor Current Output Voltage (ripple exag.) Winter 2012 UCSD: Physics 121; 2012 28Electronics Overview 02/12/2008 Lecture 8 8 Winter 2012 UCSD: Physics 121; 2012 29 Winter 2012 UCSD: Physics 121; 2012 30 R ωL Z Zr Zi 1/ωC real axis imag. axis Winter 2012 UCSD: Physics 121; 2012 31 C L input output Winter 2012 UCSD: Physics 121; 2012 32Electronics Overview 02/12/2008 Lecture 8 9 Winter 2012 UCSD: Physics 121; 2012 33 Winter 2012 UCSD: Physics 121; 2012 34 Winter 2012 UCSD: Physics 121; 2012 35 Winter 2012 UCSD: Physics 121; 2012