1 2 3 4 5 6 7 8 REVISION HISTORY INTVCC ECO VIN REV 2 R2 20.0K 1% JP2 1 2 3 4 JP1 MODE PS R1 OPT RUN1 1 2 3 ON BM OFF INTVCC C1 OPT DATE JIAN L. 4-13-10 JP3 R3 OPT 90 DEG 60 DEG R4 10K A A E1 R5 0 CLKOUT VIN R9 127K 1% R8 10 E3 1 R7 10 VIN C3 1nF S1- S1+ ITEMP1 R29 0 31 R32 OPT R33 10 VOUT1 COUT2 10uF 6.3V 6 7 4 BG1 R19 2.2 Q1A Si4816BDY VIN 25 E6 + COUT5 OPT. VOUT1 3.3V / 5A C8 1uF 6.3V E7 EXTVCC 23 C13 1uF 35V C14 4.7uF 10V 22 21 VIN BG2 R24 0 TG2 D2 CMDSH-3 INTVCC CIN3 4.7uF 50V R26 OPT C17 0.1uF 1 TG2 Q2B Si4816BDY L2 2.2uH R28 OPT RS2 0.005 1206 VOUT2 TDK RLF7030-2R2M COUT4 10uF 6.3V R30 OPT INTVCC 4 + COUT3 220uF 4V E9 + COUT6 OPT. VOUT2 2.5V / 5A C19 1uF 6.3V Q2A Si4816BDY E10 GND 2 3 C R37 10 INTVCC R38 10 E13 DIFFP R41 100K 1% OPTIONAL JUMPERS FOR SINGLE OUTPUT / DUAL PHASE OPERATION VIN TEMPERATURE COMPENSATION NETWORK FOR DCR SENSING R43 OPT ITEMP1 R44 OPT ITH1 R40 OPT ITEMP2 Q3A OPT FDS698SAS ITH2 R45 OPT D C22 OPT R46 OPT C23 OPT TG1 R48 OPT 1 R51 OPT RN2 OPT 3 Q3B OPT R49 OPT Q4B OPT FDS698SAS BG1 RUN2 CIN5 OPT CUSTOMER NOTICE 4 SW2 2 BG2 2 THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. 1 2 3 4 CONTRACT NO. LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A APPROVALS CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HZ HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES. VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL JIAN LI ENG. APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. FDS698SAS 1 RUN1 RN1 OPT 1 TRK/SS2 TG2 7 8 R50 OPT TRK/SS1 2 SW1 2 VFB2 Q4A OPT FDS698SAS 4 R47 OPT VFB1 VIN CIN4 OPT 5 6 PGOOD2 3 PGOOD1 E16 INTVCC 7 8 E15 ILIM1 1 PGOOD2 VO2_SNS+ R39 OPT 5 6 PGOOD1 VO2_SNS- E14 R42 100K 1% B GND INTVCC 24 E11 E12 GND 2 3 26 C21 1uF GND + COUT1 220uF 4V S1- 27 R36 OPT EXTVCC E4 28 ILIM2 R34 10 VIN 4.5V 25V RS1 0.005 R16 OPT 5 INTVCC 8 32 CLKOUT SW1 33 34 FREQ PHSASMD 35 36 38 39 37 ITEMP2 ITEMP1 MODE/PLLIN 29 R35 OPT R31 OPT R13 OPT TDK RLF7030-2R2M RUN2 C20 OPT L1 2.2uH 1206 D1 CMDSH-3 SW2 1 2 3 EXTVCC BOOST2 R17 0 5 ON R25 63.4K 1% Q1B Si4816BDY 6 7 R27 OPT JP4 RUN2 OFF SGND VIN C18 OPT PGND2 DIFFP 41 C16 0.1uF BG2 SENSE2- SW2 R23 OPT 40 SENSE2+ 10 E8 EXTVCC 30 20 9 TK/SS2 NC 8 S2- INTVCC 19 S2+ VIN ITH2 PGOOD2 C15 1nF VFB2 18 TRK/SS2 7 17 6 PGOOD1 R22 0 ITH2 16 R20 OPT C12 OPT C11 1500pF 5 BG1 ILIM2 R21 23.2K 1% VFB2 PGND1 15 C10 150pF BOOST1 SGND 1 C4 0.1uF TG1 TG1 VFB1 4 R18 20.0K ILIM1 3 B 14 VFB1 ITH1 RUN2 2 13 ITH1 TK/SS1 RUN1 1 TRK/SS1 C9 OPT VOUT1 SENSE1- C7 68pF SENSE1+ R14 29.4K 1% R15 20.0K DIFFOUT C6 1nF DIFFN C5 0.1uF U1 LTC3855EUJ 12 R12 OPT TRK/SS2 R11 OPT SW1 E5 11 TRK/SS1 CIN2 4.7uF 50V 8 ITEMP2 R10 0 CIN1 + 22uF 35V 2 R6 91K S1+ C2 OPT S2+ E2 CLKOUT S2- PLLIN C APPROVED PHASMD 120 DEG 1 2 3 4 RUN1 FCM DESCRIPTION PRODUCTION 5 6 TECHNOLOGY 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 Fax: (408)434-0507 LTC Confidential-For Customer Use Only TITLE: SCHEMATIC DUAL OUTPUT SYNCHRONOUS BUCK CONVERTER SIZE IC NO. A DATE: Tuesday, January 17, 2012 7 REV LTC3855EUJ DEMO CIRCUIT 1586A 2 SHEET 8 1 OF 1 D A B C D