Version 4.1 SHEET 1 2208 680 WIRE 176 -144 144 -144 WIRE 288 -144 256 -144 WIRE 288 -128 288 -144 WIRE 144 16 144 -144 WIRE -80 64 -192 64 WIRE 64 64 -80 64 WIRE 192 64 160 64 WIRE 288 64 288 -48 WIRE 288 64 272 64 WIRE 336 64 288 64 WIRE 464 64 336 64 WIRE 592 64 544 64 WIRE 640 64 592 64 WIRE 720 64 640 64 WIRE 336 96 336 64 WIRE -192 128 -192 64 WIRE 592 128 592 64 WIRE 720 128 720 64 WIRE 336 208 336 176 WIRE -192 336 -192 208 WIRE 336 336 336 272 WIRE 336 336 -192 336 WIRE 448 336 336 336 WIRE 592 336 592 192 WIRE 592 336 448 336 WIRE 720 336 720 208 WIRE 720 336 592 336 WIRE 448 384 448 336 FLAG 448 384 0 FLAG 288 -144 pwm_duty FLAG 288 64 source FLAG 640 64 output FLAG -80 64 Vin SYMBOL voltage -192 112 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 WINDOW 3 24 44 Left 2 SYMATTR Value 10 SYMATTR InstName V1 SYMBOL ind 448 48 M90 WINDOW 0 5 56 VBottom 2 WINDOW 3 32 56 VTop 2 WINDOW 39 60 56 VTop 2 SYMATTR InstName L1 SYMATTR Value 47µ SYMATTR SpiceLine Rser=0.1R SYMBOL cap 576 128 R0 WINDOW 39 24 84 Left 2 SYMATTR SpiceLine Rser=0.1 SYMATTR InstName C1 SYMATTR Value 100µ SYMBOL res 704 112 R0 SYMATTR InstName R1 SYMATTR Value 1R SYMBOL diode 352 272 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D1 SYMATTR Value MBRB2545CT SYMBOL voltage 288 -144 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 WINDOW 3 -120 113 Left 2 SYMATTR Value PULSE(0 5 0 10n 10n 5u 10u) SYMATTR InstName V2 SYMBOL nmos 64 16 M90 SYMATTR InstName M1 SYMATTR Value Si7336ADP SYMBOL res 272 -160 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R2 SYMATTR Value 10R SYMBOL res 288 48 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R3 SYMATTR Value 5m SYMBOL res 320 80 R0 SYMATTR InstName R4 SYMATTR Value 5m TEXT -192 424 Left 2 !.tran 0 10m 0 10n TEXT -152 -416 Left 5 ;Simplest SMPS, Buck, open loop (no feedback) TEXT -136 -360 Left 2 ;As this is the simplest form of SMPS with no feedback Variations in the input voltage or the load will affect the DC output voltage\nPWM is Pulse width Modulation\nthe advantage of this type of power supply over a linear power supply is efficiency.\nthe disadvantage is noise, it generates noise every time it switches. TEXT 360 -152 Left 2 ;(control) TEXT 960 8 Left 2 ;click on run\nthen click on the "Vin" net to plot it\nthen click on the "pwm_duty" net to plot it.\nyou will have to zoom the time axis to see the waveforms.\nclick on the plot window, then on plot settings/add plot pane.\nthen click on "Vsource" to plot it.\nnote that that this node goes to Vin when the switch is on, and to 0V-diode drop when its off.\nclick on the plot window, then on plot settings/add plot pane.\nthen click on "L1" to plot its current.\nclick on the plot window, then on plot settings/add plot pane.\nthen click on "D1" and "M1" to show how the inductor current switches between these two components\nclick on the plot window, then on plot settings/add plot pane.\nthen click on the "Vout" net to plot it.\n \nnote that there is a high freq (no I don't mean HF) between D1 and M1, \nthis can be stopped by using components called snubbers, but thats beyond the scope of this simple circuit. TEXT 952 -32 Left 4 ;Instructions