Version 3 SHEET 1 904 704 WIRE 4 116 4 136 WIRE 4 116 -44 116 WIRE -196 148 -196 116 WIRE -80 152 -80 144 WIRE -80 128 -80 116 WIRE -80 116 -176 116 WIRE -44 116 -44 156 WIRE -44 116 -80 116 WIRE -44 156 -32 156 WIRE -16 216 -16 224 WIRE -16 224 24 224 WIRE 24 224 24 216 WIRE 24 224 24 232 WIRE -48 256 -48 236 WIRE -48 220 -48 196 WIRE -48 196 -32 196 WIRE 40 176 68 176 WIRE 180 184 216 184 WIRE 40 196 48 196 WIRE 48 196 48 248 WIRE 48 248 112 248 WIRE 144 248 144 232 WIRE 48 272 48 280 WIRE 48 280 132 280 WIRE 144 280 216 280 WIRE 132 280 144 280 WIRE 132 288 132 280 WIRE 48 248 48 256 WIRE 216 184 252 184 WIRE -176 116 -196 116 WIRE -196 168 -196 188 WIRE 48 156 40 156 WIRE 144 184 164 184 WIRE 144 184 144 212 WIRE 144 156 48 156 WIRE 4 116 144 116 WIRE 68 196 68 176 WIRE 144 160 144 156 WIRE 144 176 144 184 WIRE 144 272 144 280 WIRE 132 248 144 248 WIRE 144 248 144 252 WIRE 252 184 252 212 WIRE 252 280 252 228 WIRE 216 184 216 216 WIRE 216 232 216 280 WIRE 216 280 252 280 WIRE 144 116 144 124 WIRE 144 144 144 156 WIRE 108 440 68 440 WIRE 68 440 68 416 WIRE 68 416 68 392 WIRE 68 392 104 392 WIRE 104 392 120 384 WIRE 68 440 68 456 WIRE 120 392 168 392 WIRE 120 416 148 416 WIRE 148 416 148 440 WIRE 148 440 128 440 WIRE 168 440 148 440 WIRE 188 392 216 392 WIRE 216 392 216 440 WIRE 216 440 188 440 WIRE 216 440 240 440 WIRE 68 416 104 416 WIRE 104 416 120 408 WIRE -224 32 312 32 WIRE 312 32 312 492 WIRE 312 492 -224 492 WIRE -224 32 -224 492 FLAG -80 152 GND FLAG 24 232 GND FLAG -48 256 GND FLAG 132 288 GND FLAG 216 184 Out FLAG -176 116 Batt FLAG -196 188 GND FLAG 48 196 Ifb FLAG 48 156 Sw FLAG 68 196 GND FLAG 68 456 GND SYMBOL ind 140 208 R0 WINDOW 0 9 10 Left 0 WINDOW 3 9 20 Left 0 SYMATTR InstName L2 SYMATTR Value 22U SYMBOL ind 140 120 R0 WINDOW 0 9 10 Left 0 WINDOW 3 9 20 Left 0 SYMATTR InstName L1 SYMATTR Value 22U SYMBOL POWERPRODUCTS\LT1512 4 176 R0 WINDOW 0 2 -44 Left 0 WINDOW 3 0 10 Center 0 SYMATTR InstName U1 SYMATTR Value LT1512 SYMATTR Value2 LT1512 SYMATTR SpiceModel LT1512.sub SYMBOL cap 140 160 R0 WINDOW 0 6 2 Left 0 WINDOW 3 6 16 Left 0 SYMATTR InstName C4 SYMATTR Value 1U SYMBOL schottky 164 188 R270 WINDOW 0 8 8 Left 0 WINDOW 3 0 8 Right 0 SYMATTR InstName D1 SYMATTR Value MBRS130L SYMBOL VOLTAGE -196 144 R0 WINDOW 0 6 4 Left 0 WINDOW 3 6 26 Left 0 WINDOW 39 6 34 Left 0 WINDOW 123 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value PULSE(0 4.8 0 100u 4.5m 3.5m) SYMATTR SpiceLine Rser=100m SYMBOL cap -84 128 R0 WINDOW 0 6 2 Left 0 WINDOW 3 6 16 Left 0 SYMATTR InstName C1 SYMATTR Value 10U SYMBOL cap -44 236 R180 WINDOW 0 6 16 Left 0 WINDOW 3 6 2 Left 0 SYMATTR InstName C2 SYMATTR Value 0.22U SYMBOL RES 136 244 R90 WINDOW 0 0 14 Right 0 WINDOW 3 8 14 Left 0 SYMATTR InstName R1 SYMATTR Value 27 SYMBOL cap 44 256 R0 WINDOW 0 6 2 Left 0 WINDOW 3 6 16 Left 0 SYMATTR InstName C3 SYMATTR Value 0.22U SYMBOL res 140 248 R0 WINDOW 0 9 10 Left 0 WINDOW 3 9 19 Left 0 SYMATTR InstName R2 SYMATTR Value 0.26 SYMBOL LED 248 212 R0 WINDOW 0 6 0 Left 0 WINDOW 3 6 18 Left 0 SYMATTR InstName D2 SYMATTR Value Luxeon1 SYMBOL cap 212 216 R0 WINDOW 0 6 2 Left 0 WINDOW 3 6 16 Left 0 SYMATTR InstName C5 SYMATTR Value 68U SYMBOL res 164 396 R270 WINDOW 0 8 14 Left 0 WINDOW 3 0 14 Right 0 SYMATTR InstName R2b SYMATTR Value 0.47 SYMBOL res 164 444 R270 WINDOW 0 8 14 Left 0 WINDOW 3 0 14 Right 0 SYMATTR InstName R2c SYMATTR Value 0.6 SYMBOL res 104 444 R270 WINDOW 0 8 14 Left 0 WINDOW 3 0 14 Right 0 SYMATTR InstName R2a SYMATTR Value 1.2 text -208 462 Left 0 !.tran 7m text -196 72 Left 0 ;LT 1512 regulating into LED load, Vout target = max, current limit 350mA (set by R2) text -204 378 Left 0 ;78% efficient at nominal 4.8V (measured) text -208 472 Left 0 !.save dialogbox v(batt) i(v1) v(out) i(d2) v(ifb) v(sw) text 44 306 Left 0 ;Measured current = 0.92/R2 [V(R2) is nominally 100mV, text 46 318 Left 0 ;122mV in simulation], so simulation will show >350mA text -196 54 Left 0 ;LT1512-A circuit; constant-current SEPIC, as built 2002.12.20 text 234 428 Left 0 ;To L2 text 46 348 Left 0 ;Possible sense resistor switching. Note that there is a text 46 360 Left 0 ;permanent connection from L2 to Gnd at all times. text 184 474 Left 0 ;Mike Cowlishaw, January 2003 text -202 302 Left 0 ;Circuit as built uses 3 combinations of the text -202 312 Left 0 ;sense resistor switching, giving: text -194 360 Left 0 ;R2=1.80ohm, I(D2)=54mA, approx 35 hours text -194 342 Left 0 ;R2=0.60ohm, I(D2)=159mA, 13.2 hours text -194 326 Left 0 ;R2=0.26ohm, I(D2)=348mA, 5.6 hours text -196 84 Left 0 ;V1 (Battery): 2.7V to 10V (could be higher with suitable passives; uncalculated)