5 4 Vu1 Q4 BCX55 2 Isolation Boundary R3 10 1 1 2 C1 0.1uF 50V 1 2 1 6 Fg 2 11 14 C4 0.1uF 6.3V SS 4 Sync PGND 13 5 SS/MaxDC Delay 12 R11 13.3K 6 Vr=2.5V OC 11 7 SD/Vsec Isense 10 Blank 9 8 GND R17 340K +Vb C14 100pF R9 169K R12 910 SS 2 D5 PMEG4005 1 C 6 D6 (Opt.) D7 (Opt.) R14 0.015 R13 47 Sout R18 22.1K C7 (Opt.) T2 Q4470-B COILCRAFT C10 220pF C17 100pF R20 45.3K ** D4 BAT760 C5 4700pF R15 39K R21 1.3M 1206 C3 Q7B 5 C11 0.47uF 16V 1 6 2 5 3 4 B U3 PS2801-1 R24 0 Vfb R10 1K 4 1 3 2 R30 1.2K D8 PDZ7.5B R16 4.7K R22 270 5 R25 0 3 Vdd 2 Fg 16 3 Cg -Sync 15 Pgnd Vaux 14 4 GND Icomp 13 5 Opto +Isns 12 6 Vcomp -Isns 11 7 Marg PwrOK 10 8 Vfb=1.233V C13 47pF Q6 BC847BF 3 2 C16 0.1uF X7R Sync R28 56K R32 150K OVP C9 0.1uF 9 B +Vo1 R27 38K R31 12.4K LINEAR TECHNOLOGY CORPORATION 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. 4 C8 1uF 16V X5R 1 Vaux Customer Notice * To Enable Buffer Change R33 to 10 ohm Fg U2 LTC1698EGN R23 1.5K LTC CONFIDENTIAL - FOR CUSTOMER USE ONLY ** Install 0 ohm Resistor Instead Cg C12 15nF C15 2200pF 250V A Vaux Q5 BCX55 3 Sync R19 560 Vu1 C6 0.22uF 25V X7R 1 Out CU1 10uF 16V 2 Rosc R6 2.2 1 3 -Vout TP6 Q1 PHM21NQ15T 4 Vin R33 0 +5V at 20A TP5 3 FB=1.23V 15 Comp + CO2 (Opt.) 1 R8 115K 16 3 C * Sout 2 C2 680pF Q3 HAT2165H TP3 CSYS 470uF 6.3V POSCAP 2 U1 LT1952EGN 1 Q8 BC857BF 1 Vu1 5 2 R5 33K Vu1 1 Sout R7 22K 2 Vfb Q7A PBSS4140DPN Q2 HAT2165H T1 PA0491.003 2 TP4 Cg D TP2 CO1 100uF 6.3V TDK X5R 10 8 +Vin D3 BZX384-C12 -Vin +Vout 7 2 36V to 72V D1 PDZ18B R4 82K 3 CIN1 CIN2 2.2uF 100V X7R TDK D D2 BAS516 1 1 TP1 +Vo1 L1 1.5uH CDEP147NP-1R5MC-95 1 R2 47K 1206 2 +Vin 1 1 +Vb R1 0 2 2 +Vin 3 2 1630 McCARTHY BLVD. MILPITAS, CA. 95035 408-432-1900 408-434-0507 FAX Title A 48Vin to 5Vout @ 20A Converter Size Document Number Date: Monday, November 15, 2004 DEMO 759A LT1952EGN, LTC1698EGN Sheet 1 1 of 1 Rev