Version 4
SHEET 1 1252 680
WIRE 48 112 -16 112
WIRE 416 112 368 112
WIRE 528 112 496 112
WIRE 592 112 528 112
WIRE 528 128 528 112
WIRE -16 144 -16 112
WIRE 528 208 528 192
WIRE -16 240 -16 224
WIRE 48 288 -16 288
WIRE -16 320 -16 288
WIRE -16 416 -16 400
FLAG -16 240 0
FLAG -16 416 0
FLAG 48 288 pwm
IOPIN 48 288 Out
FLAG 48 112 ramp
FLAG 528 208 0
FLAG 368 112 pwm
FLAG 592 112 test
SYMBOL voltage -16 128 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value PULSE(0 20 0 100u 1p 0 100u)
SYMBOL bv -16 304 R0
SYMATTR InstName B1
SYMATTR Value V=if(V(ramp)< int(time*10+1),3.3,0) tripdv=1m tripdt=1n
SYMBOL res 400 128 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R1
SYMATTR Value 10k
SYMBOL cap 512 128 R0
SYMATTR InstName C1
SYMATTR Value 1µ IC=0
TEXT -16 -32 Left 2 !.tran 0 2 0 1u
TEXT -16 0 Left 2 !.options plotwinsize=0
TEXT 72 448 Left 2 ;Replace time*10 with time*1 for 1sec/step