Version 4 SHEET 1 3516 680 WIRE -160 -96 -880 -96 WIRE 112 -96 -160 -96 WIRE 256 -96 112 -96 WIRE 528 -96 256 -96 WIRE 672 -96 528 -96 WIRE 976 -96 672 -96 WIRE 1120 -96 976 -96 WIRE 1376 -96 1120 -96 WIRE 1520 -96 1376 -96 WIRE 1728 -96 1520 -96 WIRE 1872 -96 1728 -96 WIRE 2096 -96 1872 -96 WIRE 2240 -96 2096 -96 WIRE 2640 -96 2240 -96 WIRE -304 -48 -432 -48 WIRE -304 0 -304 -48 WIRE 112 0 112 -96 WIRE 528 0 528 -96 WIRE 976 0 976 -96 WIRE 1376 0 1376 -96 WIRE 1728 0 1728 -96 WIRE 2096 0 2096 -96 WIRE -160 96 -160 -96 WIRE 256 96 256 -96 WIRE 672 96 672 -96 WIRE 1120 96 1120 -96 WIRE 1520 96 1520 -96 WIRE 1872 96 1872 -96 WIRE 2240 96 2240 -96 WIRE 2640 96 2640 -96 WIRE -304 144 -304 80 WIRE -256 144 -304 144 WIRE -224 144 -256 144 WIRE 112 144 112 80 WIRE 160 144 112 144 WIRE 192 144 160 144 WIRE 528 144 528 80 WIRE 576 144 528 144 WIRE 608 144 576 144 WIRE 976 144 976 80 WIRE 1024 144 976 144 WIRE 1056 144 1024 144 WIRE 1376 144 1376 80 WIRE 1424 144 1376 144 WIRE 1456 144 1424 144 WIRE 1728 144 1728 80 WIRE 1776 144 1728 144 WIRE 1808 144 1776 144 WIRE 2096 144 2096 80 WIRE 2144 144 2096 144 WIRE 2176 144 2144 144 WIRE 2528 144 2448 144 WIRE 2576 144 2528 144 WIRE 1728 208 1728 144 WIRE 2096 208 2096 144 WIRE 112 224 112 144 WIRE 528 224 528 144 WIRE 2192 240 2128 240 WIRE 2240 240 2240 192 WIRE 2240 240 2192 240 WIRE 2640 256 2640 192 WIRE -160 272 -160 192 WIRE 256 272 256 192 WIRE 256 272 176 272 WIRE 672 272 672 192 WIRE 1120 272 1120 192 WIRE 1520 272 1520 192 WIRE 1872 272 1872 192 WIRE 1680 288 1680 272 WIRE 1728 288 1680 288 WIRE 1776 288 1776 272 WIRE 1776 288 1728 288 WIRE -432 304 -432 -48 WIRE -304 304 -304 144 WIRE -160 304 -160 272 WIRE 256 304 256 272 WIRE 672 304 672 272 WIRE 1120 304 1120 272 WIRE 1520 304 1520 272 WIRE 1872 304 1872 272 WIRE 2240 304 2240 240 WIRE 2640 304 2640 256 WIRE -1312 320 -1312 272 WIRE -880 320 -880 -96 WIRE 976 320 976 144 WIRE 2448 320 2448 144 WIRE 528 352 528 288 WIRE 1376 352 1376 144 WIRE 1728 352 1728 288 WIRE -1312 464 -1312 400 WIRE -880 464 -880 400 WIRE -880 464 -1312 464 WIRE -432 464 -432 384 WIRE -432 464 -880 464 WIRE -304 464 -304 384 WIRE -304 464 -432 464 WIRE -160 464 -160 384 WIRE -160 464 -304 464 WIRE 112 464 112 320 WIRE 112 464 -160 464 WIRE 256 464 256 384 WIRE 256 464 112 464 WIRE 528 464 528 416 WIRE 528 464 256 464 WIRE 672 464 672 384 WIRE 672 464 528 464 WIRE 976 464 976 384 WIRE 976 464 672 464 WIRE 1120 464 1120 384 WIRE 1120 464 976 464 WIRE 1376 464 1376 416 WIRE 1376 464 1120 464 WIRE 1520 464 1520 384 WIRE 1520 464 1376 464 WIRE 1728 464 1728 416 WIRE 1728 464 1520 464 WIRE 1872 464 1872 384 WIRE 1872 464 1728 464 WIRE 2096 464 2096 272 WIRE 2096 464 1872 464 WIRE 2240 464 2240 384 WIRE 2240 464 2096 464 WIRE 2448 464 2448 400 WIRE 2448 464 2240 464 WIRE 2640 464 2640 384 WIRE 2640 464 2448 464 WIRE -880 512 -880 464 FLAG -880 512 0 FLAG -880 -96 VS FLAG 256 272 Sense2 FLAG 672 272 Sense3 FLAG 1120 272 Sense4 FLAG 1520 272 Sense5 FLAG 1872 272 Sense6 FLAG 2640 256 Sense8 FLAG 160 144 Base2 FLAG 576 144 Base3 FLAG 1024 144 Base4 FLAG 1424 144 Base5 FLAG 1776 144 Base6 FLAG 2528 144 Base8 FLAG -1312 272 VR FLAG -160 272 Sense1 FLAG -256 144 Base1 FLAG 2192 240 Sense7 FLAG 2144 144 Base7 SYMBOL npn 192 96 R0 SYMATTR InstName Q21 SYMATTR Value BC846B SYMBOL npn 176 224 M0 SYMATTR InstName Q22 SYMATTR Value BC846B SYMBOL res 240 288 R0 SYMATTR InstName Rshunt2 SYMATTR Value 63.97 SYMBOL res 96 -16 R0 SYMATTR InstName Rbias2 SYMATTR Value 10k SYMBOL voltage -880 304 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value PULSE(8 32 0 10 1 1 12) SYMBOL npn 608 96 R0 SYMATTR InstName Q31 SYMATTR Value BC846B SYMBOL res 656 288 R0 SYMATTR InstName Rshunt3 SYMATTR Value 53.43 SYMBOL res 512 -16 R0 SYMATTR InstName Rbias3 SYMATTR Value 10k SYMBOL diode 512 224 R0 SYMATTR InstName D31 SYMATTR Value BAV99 SYMBOL diode 512 352 R0 SYMATTR InstName D32 SYMATTR Value BAV99 SYMBOL npn 1056 96 R0 SYMATTR InstName Q41 SYMATTR Value BC846B SYMBOL res 1104 288 R0 SYMATTR InstName Rshunt4 SYMATTR Value 116.51 SYMBOL res 960 -16 R0 SYMATTR InstName Rbias4 SYMATTR Value 10k SYMBOL LED 960 320 R0 WINDOW 3 19 72 Left 2 SYMATTR Value SML-A12U8T SYMATTR InstName D41 SYMATTR Description Diode SYMATTR Type diode SYMBOL npn 1456 96 R0 SYMATTR InstName Q51 SYMATTR Value BC846B SYMBOL res 1504 288 R0 SYMATTR InstName Rshunt5 SYMATTR Value 544.31 SYMBOL res 1360 -16 R0 SYMATTR InstName Rbias5 SYMATTR Value 10k SYMBOL zener 1392 416 R180 WINDOW 0 24 64 Left 2 WINDOW 3 19 2 Left 2 SYMATTR InstName D51 SYMATTR Value BZX84C6V2LT116 SYMATTR Description Diode SYMATTR Type diode SYMBOL npn 1808 96 R0 SYMATTR InstName Q61 SYMATTR Value BC846B SYMBOL res 1856 288 R0 SYMATTR InstName Rshunt6 SYMATTR Value 122.54 SYMBOL res 1712 -16 R0 SYMATTR InstName Rbias6 SYMATTR Value 10k SYMBOL References\\LT1004-1.2 1728 384 R0 SYMATTR InstName U61 SYMBOL voltage 2448 304 R0 WINDOW 3 23 96 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 23 120 Left 2 SYMATTR Value 3.3V SYMATTR SpiceLine Rser=100 SYMATTR InstName V2 SYMBOL npn 2576 96 R0 SYMATTR InstName Q81 SYMATTR Value BC846B SYMBOL res 2624 288 R0 SYMATTR InstName Rshunt8 SYMATTR Value 258.48 SYMBOL voltage -1312 304 R0 WINDOW 3 -146 177 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value PULSE(50 1000 0 10 10 0 20) SYMATTR InstName V3 SYMBOL npn -224 96 R0 SYMATTR InstName Q11 SYMATTR Value BC846B SYMBOL res -176 288 R0 SYMATTR InstName Rshunt1 SYMATTR Value 81.84 SYMBOL res -320 -16 R0 SYMATTR InstName R11 SYMATTR Value 10k SYMBOL res -320 288 R0 SYMATTR InstName R12 SYMATTR Value 1k5 SYMBOL npn 1776 208 R90 WINDOW 0 -2 66 VRight 2 WINDOW 3 -2 -58 VRight 2 SYMATTR InstName Q62 SYMATTR Value BC846B SYMBOL voltage -432 288 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V4 SYMATTR Value 12 SYMBOL npn 2176 96 R0 SYMATTR InstName Q71 SYMATTR Value BC846B SYMBOL res 2224 288 R0 SYMATTR InstName Rshunt7 SYMATTR Value 123.83 SYMBOL res 2080 -16 R0 SYMATTR InstName Rbias7 SYMATTR Value 10k SYMBOL tlv431 2096 240 R0 SYMATTR InstName U1 TEXT 984 536 Left 2 !.tran 10 TEXT -816 88 Left 2 !#.step temp -40 80 10\n.temp 25 TEXT 120 -352 Left 2 ;Plot the collector currents of Qx1 and VS.\nThe shunt resistors have been trimmed to get 10mA at 12V and 25°C.\n \nThis assumes that all used models are accurate, especially over temperature and, especially\nfor the LED, at currents beyond the normal operating conditions.\n \nThis simulation has not been verified in reality. TEXT 2472 448 Left 2 ;µC Port Pin TEXT 1784 -320 Left 2 !.MEASURE I1 FIND Ic(Q11) WHEN V(VS)=12\n.MEASURE I2 FIND Ic(Q21) WHEN V(VS)=12\n.MEASURE I3 FIND Ic(Q31) WHEN V(VS)=12\n.MEASURE I4 FIND Ic(Q41) WHEN V(VS)=12\n.MEASURE I5 FIND Ic(Q51) WHEN V(VS)=12\n.MEASURE I6 FIND Ic(Q61) WHEN V(VS)=12\n.MEASURE I7 FIND Ic(Q71) WHEN V(VS)=12\n.MEASURE I8 FIND Ic(Q81) WHEN V(VS)=12 TEXT 1816 -368 Left 2 ;View error log to see the results TEXT -840 496 Left 2 ;V1 line for ramp testing:\nPULSE(0 32 0 10 1 1 12) TEXT -1552 136 Left 2 !.MEASURE Rshunt FIND V(VR) WHEN Ic(Q71)=10m\n#.OPTION MAXSTEP=100u TEXT -1544 -176 Left 2 ;To find R for a given current:\nSet R=V(VR) as shunt resistor value.\nSet V1 to 12V (!!!)\nSet .MEASURE to the corresponding Ic.\nSet TEMP to 25°C.\nUse MAXSTEP to get better precision.\nView error log to see exact value. TEXT -400 -216 Left 2 ;Added V4 because\nthis circuit does not\nmake sense with an\nunregulated supply. TEXT -1472 -272 Left 3 ;To trim Rshunt TEXT 120 -392 Left 3 ;Eight different constant current sources RECTANGLE Normal -960 544 -1600 -240 2