A B C D E L3 (Opt.) D25 (Opt.) T1 PA0808 L1 0.68uH 4 3 3 C67 4.7uF 25V VA R4 10 1 +VOUT 4 11 E1 C2 3.3uF 50V 1210 C3 3.3uF 50V 1210 C4 3.3uF 50V 1210 1 5 10 C5 3.3uF 50V 1210 R13 0 1206 9 +Vout E3 L2 22uH R79 3.3K 3 4 12V/4.2A 8 1 11 Q27C 2 R94 147 1% R93 147 1% A 2 1 3 FS/SYNC 3 MODE 16 SG VCC 1 11 10 IS+ C10 (Opt.) R9 (Opt.) 5 9 ITH 4 R69 0 R68 27.4K C75 47pF 2 R46 619 C79 1.0nF C76 (Opt.) C77 10uF C8 470pF D6 4.3V MMSZ4687T1 6 4 1 2 VSB B LTC CONFIDENTIAL - FOR CUSTOMER USE ONLY LINEAR TECHNOLOGY CORPORATION -VOUT Customer Notice R92 47K 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. -VOUT 3 Q37 MMBT2907A FB/PH R41 11.8K Q36 MBT3946DW1T1 5 3 R91 10.0K 1 C82 82pF R66 100K +VOUT SS 1 C9 0.22uF 2 2 VCC SG VCC -VOUT R90 7.50K R7 47K Q34 2N7002 -VOUT Q27 FCX491 VIN R89 374 1 RUN/SS C78 4.7nF 1 1 PGND SS C30 2.2nF 250V 2 D3 22V MMSZ5251BS 6 U2 LTC3726EGN R63 90.9K 3 2 12 PT5 SLP PT- IS- 14 SW PT+ 5 C7 (Opt.) 3 1 R56 100 SG 7 8 R61 100 R87 0 R86 261K 15 6 4 13 C73 470pF D29 PT1N4148WS 2 1 1 C81 10pF R76 470 1206 VSB R83 (Opt.) 2 IS 3 -VOUT VSW Q27C -Vout E4 -VOUT C71 1uF 1 C6 (Opt.) 4 FS/IN- 6 9 T2 PA0297 C72 0.1uF GND C29 33nF 10 7 NDRV SSFLT PGND ULVO 2 R88 47pF D2 1N4148WS Q26 FMMT619 2 3 C70 1nF U1 LTC3725EMSE FB/IN+ 1 VSLMT 1 C24 4.7uF VCC 2 R22 28.7K C55 470pF GATE 3 2 Rb 162K R18 147K 8 R55 100 1% R84 0 R58 5.1K 10K D4 4.7V MMSZ5230BS R54 100 1% R2 86.6 1/4W 1 Ra Q32 FMMT718 3 2 FG Q28 FMMT38C D28 MMSZ5236BS 7.5V VCC R85 (Opt.) R6 10K CUT 68uF 16V R50 0.010 1W C69 150pF 200V R1 86.6 1/4W + C80 C31 (Opt.) 1210 2 R48 .010 1W C33 22uF 16V Q12 Si7450DP R51 86.6 1/4W 2 3 Q6 MMBFJ201 3 Q14 Si7852DP C1 1.5nF 100V VA Q11 (Opt.) C27 2.2nF 3 R52 86.6 1/4W C66 1nF 100V R3 100 VSW 2 1 R49 0 7 1 E2 Q8 Si7852DP 2 1 GND -Vin 6 8 +Vin 9V-36V VIN D1 (Opt.) C D 1630 McCARTHY BLVD. MILPITAS, CA. 95035 408-432-1900 408-434-0507 FAX Title LTC3725EMSE, LTC3726EGN 9V-36Vin Forward Converter Size Document Number Rev Demo Circuit 1174A-B Date: Wednesday, August 12, 2009 Sheet E 1 A of 1 1