4 1 11 8 +VT1 5 2 SW0 10 C3 1000pF 250V C18 0.1uF 50V R9 (Opt.) TP4 7 EN/Shdn 6 IN R39 57.6K C29 (Opt.) R62 10K R29 33K U1 LT1952EGN-1 ROSC1 115K 2.5VR R59 13.3K C30 100pF R46 22.1K R56 309K C28 1uF 16V RCS1 0.018 VFB R40 2.2K 1 Comp 2 3 OUT Sout 16 FB=1.23V Vin 15 Rosc Out 14 4 Sync PGND 13 5 SS/MaxDC Delay 12 6 Vr=2.5V OC 11 7 SD/Vsec Isense 10 8 GND Blank 9 VU1 D11 BAT760 1 CU1 0.1uF 50V 2 C14 100pF R5 57.6K R41 0 R12 910 R15 39K 3 OUT 1 6 3 R21 10K 2 5 3 4 U5 LT4430ES6 SYNC C16 0.22uF 10V R25 820 C13 0.33uF C12 0.1uF R44 220K VAUX R14 10K VAUX R13 47 1 Q20B 5 R6 10K C42 2200pF 250VAC T2 PA1323 PULSE ENG. R2 Opt. 1 SW1 1 VCC OPTO 6 2 GND COMP 5 3 OC FB 4 C4 2200pF C6 (Opt.) C9 1uF 16V R22 4.12K 1 CS+ 8 SYNC 2 CS- TIMER 7 3 CG GND 6 4 VCC FG 5 R20 38.3K 1% 2 C23 470pF R17 10 Q21A PBSS4140DPN FG Q21B 5 +VO1 VU1 R23 100K C31 47pF Q8A Opt. OUT Q9 Opt. R42 Opt. C SYNC U3 LTC3900CS8 Option 2 R26 22.1K Q19 2N7002 1 C1 0.33uF R53 Opt. R10 Opt. B C34 Opt. 2 GDO CS 5 R47 169K VAUX2 Q8B 3 R7 (Opt.) 2 4 2.5VR R36 (Opt.) C40 0.01uF 1 5 2 R18 270 R48 10 C27 220pF C19 100pF 6 C17 (Opt.) CG 1 Q5 BC857BF R60 30.1K CS R49 332K C11 (Opt.) U2 HCPL-M453 C26 10uF, 16V R4 22K C7 0.1uF 2.5VR R11 100 R16 10 D8 (Opt.) 3 FB VU1 Q1 Si7450DP 2 SGND R19 2.2 C2 1uF 16V Q20A PBSS4140DPN 2 4 2 3 4 R51 (Opt.) R52 0 +VS 8 5 1 B 9 Vin U4 LTC4441MSE TP5 VFB 1 DrVcc Rblank 1 R31 (Opt.) D5 (Opt.) J2 VAUX 3 2 Ext. Sync Blank 3 2 C C10 220pF 2 VU1 D -Vout 3 D2 BAS516 D4 (Opt.) 10 1 R55 53.6 OUT 2 J1 TP2 Q11 (Opt.) 1 TP1 CSYS + 470uF 6.3V UCC PXE CO5 (Opt.) CO1 (Opt.) 2 11 OUT PGND GND 1 VAUX2 1 2 2 GDO CO2 CO3 CO4 Q16 Q17 Q18 HAT2165H D3 (Opt.) C8 (Opt.) +VO1 100uF 6.3V TDK Q13 CG Q14 Q15 HAT2165H T1 Pulse PA0950 2 -Vin D6 PDZ12B FG 7 1 4 1 C21 0.1uF L1 .65uH PA1382.650 5 2 4 1 SW1 6 3 D1 BAS516 CIN1 CIN5 (Opt.) 2 6 Q6 PZTA42 R32 82K 1 D10 Opt. 2 CIN2 CIN3 CIN4 3 1 2.2uF 100V TDK D R8 82K 1206 +Vout +3.3V at 50A 1 4 2 Isolation Boundary 4 TP3 D7 BAS516 R3 10 3 Q7 PBSS4350Z 4 3 2 6 R50 Opt. 1 6 R1 (Opt.) 2 1 +VS 1 R54 0 2 +VT1 1 VU1 +Vin 36V-75V 3 4 5 1 R58 39.2K 2 GDO R24 2.2 GDO CS Q2 Si7450DP 5 RCS2 0.018 R33 1K R34 220K +VS 1 SW0 R27 Opt. R35 22K CS Q3 Opt. C24 1000pF R45 806 U6 LTC3803ES6 ITH/RUN G 6 2 GND 5 4 VFB R30 10K VIN SNS 1 R37 10K 4 C25 1uF 16V 3 R57 (Opt.) D16 BAS516 4 2 C20 2.2uF 10V D17 BAS516 Q10 FDC2512 R43 100 VAUX 1 5 R38 2.2 1 3 RCS4 Opt. T3 PA1546 8 C5 0.1uF 100V 1206 Optional Circuit SW0 A D15 BAS516 2 D9 PDZ5.1B 2 2 R28 2.2 R61 4.7 1 C15 47pF Linear Technology Has Made A Best Effort To Design A Circuit That Meets Customer-Supplied Specifications; However, It Remains The Customer's Responsibility To Verify Proper And Reliable Operation In The Actual Application. Component Substitution And Printed Circuit Board Layout May Significantly Affect Circuit Performance Or Reliability. Contact Linear Technology Applications Engineering For Assistance. This Circuit Is Proprietary To Linear Technology And Supplied For Use With Linear Technology Parts. LINEAR TECHNOLOGY CORPORATION 1630 McCARTHY BLVD. MILPITAS, CA. 95035 408-432-1900 408-434-0507 FAX 7 RCS3 0.1 1206 VU1 Customer Notice C22 2.2uF 10V Title 2 LTC CONFIDENTIAL - FOR CUSTOMER USE ONLY 48Vin to 3.3V, 50A Isolated DC/DC Converter Size Document Number Date: Wednesday, October 12, 2005 Rev DEMO CIRCUIT 677A Sheet 1 1 of 1 A