Version 4 SHEET 1 1800 960 WIRE 528 -80 288 -80 WIRE 688 -80 528 -80 WIRE 1088 -80 688 -80 WIRE 288 -48 288 -80 WIRE 528 -32 528 -80 WIRE 992 -32 816 -32 WIRE 1392 -32 1056 -32 WIRE 816 16 816 -32 WIRE 864 16 816 16 WIRE 976 16 928 16 WIRE 688 64 688 -80 WIRE 816 64 816 16 WIRE 288 112 288 32 WIRE 384 112 288 112 WIRE 528 112 528 48 WIRE 528 112 464 112 WIRE 560 112 528 112 WIRE 976 112 976 16 WIRE 976 112 944 112 WIRE 1088 112 1088 -80 WIRE 288 128 288 112 WIRE 304 192 288 192 WIRE 464 192 384 192 WIRE 560 192 528 192 WIRE 1040 192 944 192 WIRE 400 272 384 272 WIRE 560 272 528 272 WIRE 976 272 976 176 WIRE 976 272 944 272 WIRE 1088 272 1088 208 WIRE 1088 272 976 272 WIRE 1136 272 1088 272 WIRE 1168 272 1136 272 WIRE 1280 272 1248 272 WIRE 1296 272 1280 272 WIRE 1392 272 1392 -32 WIRE 1392 272 1376 272 WIRE 1424 272 1392 272 WIRE 1536 272 1424 272 WIRE 1424 288 1424 272 WIRE 1536 288 1536 272 WIRE 1136 320 1136 272 WIRE 288 352 288 192 WIRE 320 352 288 352 WIRE 528 352 528 272 WIRE 528 352 400 352 WIRE 560 352 528 352 WIRE 1040 352 944 352 WIRE 1424 384 1424 352 WIRE 1536 384 1536 368 WIRE 464 432 400 432 WIRE 560 432 544 432 WIRE 1088 432 1088 368 WIRE 1088 432 944 432 WIRE 1136 432 1136 384 WIRE 1136 432 1088 432 WIRE 400 448 400 432 WIRE 1088 448 1088 432 WIRE 560 512 528 512 WIRE 1280 512 1280 272 WIRE 1280 512 944 512 WIRE 400 528 400 512 WIRE 752 576 752 560 WIRE 288 608 288 352 WIRE 528 608 528 512 WIRE 528 608 288 608 WIRE 1392 608 1392 272 WIRE 1392 608 528 608 FLAG 1088 448 0 FLAG 400 528 0 FLAG 752 576 0 FLAG 384 272 0 FLAG 1424 384 0 FLAG 1536 384 0 FLAG 288 128 0 FLAG 1536 272 OUT FLAG 288 -80 IN SYMBOL PowerProducts\\LT3800 752 304 R0 SYMATTR InstName U1 SYMBOL nmos 1040 112 R0 SYMATTR InstName Q1 SYMATTR Value Si4850EY SYMBOL nmos 1040 272 R0 WINDOW 0 -2 31 Right 2 WINDOW 3 38 104 Right 2 SYMATTR InstName Q2 SYMATTR Value Si4470DY SYMBOL cap 960 112 R0 SYMATTR InstName C1 SYMATTR Value 1µ SYMBOL res 512 -48 R0 SYMATTR InstName R1 SYMATTR Value 1Meg SYMBOL res 560 416 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R2 SYMATTR Value 82.5K SYMBOL cap 384 448 R0 SYMATTR InstName C2 SYMATTR Value 680p SYMBOL schottky 1120 384 M180 WINDOW 0 24 72 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D1 SYMATTR Value MBRS1100 SYMATTR Description Diode SYMATTR Type diode SYMBOL ind 1152 288 R270 WINDOW 0 32 56 VTop 2 WINDOW 3 5 56 VBottom 2 SYMATTR InstName L1 SYMATTR Value 15µ SYMATTR SpiceLine Rpar=2K SYMBOL res 1280 256 M90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R3 SYMATTR Value 1.25 SYMBOL res 496 256 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R4 SYMATTR Value 20K SYMBOL res 416 336 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R5 SYMATTR Value 1R SYMBOL res 400 176 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R6 SYMATTR Value 200K SYMBOL cap 528 176 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C3 SYMATTR Value 1500p SYMBOL cap 1408 288 R0 SYMATTR InstName C4 SYMATTR Value 270µ SYMBOL voltage 288 -64 R0 WINDOW 3 25 101 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value 55 SYMATTR InstName V1 SYMBOL diode 1056 -48 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName D2 SYMATTR Value 1N4148 SYMBOL res 480 96 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R7 SYMATTR Value 82.5K SYMBOL diode 864 32 R270 WINDOW 0 32 32 VTop 2 WINDOW 3 0 32 VBottom 2 SYMATTR InstName D3 SYMATTR Value 1N4148 SYMBOL res 1520 272 R0 SYMATTR InstName Rload SYMATTR Value 40R TEXT 1128 560 Left 2 !.tran 10m startup TEXT 872 -144 Center 2 ;LT3800 - High-Voltage Synchronous Current Mode Step-Down Controller\nInput: 20V to 55V Output: 12V @ 6.25A TEXT 216 624 Left 2 ;Note:\n If the simulation model is not found please update with the "Sync Release" command from the "Tools" menu.\n It remains the customer's responsibility to verify proper and reliable operation in the actual application.\n Component substitution and printed circuit board layout may significantly affect circuit performance or reliability\n Contact your local sales representative for assistance. This circuit is distributed to customers only for use with LTC parts\n Copyright © 2006 Linear Technology Inc. All rights reserved.