5 4 3 PGOOD2 E2 INTVCC VFB2 RUN2 RUN2 VRNG2 VRNG1 1 R3 OPT ON 1 R4 OPT 3 R6 OPT C1 OPT ECO REV __ DESCRIPTION 2 APPROVED PRODUCTION MIKE S. DATE 5-11-11 RUN2 RUN1 2 OFF REVISION HISTORY NOTE: EXTERNALLY TIE THE DTR1 PIN TO THE DTR2 PIN IF THE TRANSIENT DETECT CIRCUIT IS USED R1 OPT VIN JP1 RUN2 2 OPTIONAL COMPONENTS FOR SINGLE OUTPUT, DUAL PHASE OPERATION E1 R7 OPT D D E3 TRK/SS2 0 R9 4 TRK/SS2 INTVCC INTVCC R21 C7 220pF * 6 VRNG2 7 R23 10K R24 1 JP3 MODE 5 C6 47pF R26 * 8 * FCM 2 SYNC 9 3 C 10 DCM 4 11 FSW = 300kHz R29 E8 R30 PLLIN R28 137K 12 * VRNG1 * 13 C11 47pF R31 E9 CLKOUT 14 C12 330pF * 15 VOUT2 TRK/SS1 16 C14 0.01uF R37 TRK/SS1 OPT R39 0 17 C15 OPT R40 10K R44 OPT ON R45 * S1+ 18 C16 * 19 TG2 TRACK/SS2 SW2 ITH2 BG2 VRNG2 DRVCC2 PHASEMD EXTVCC MODE/PLLIN INTVCC CLKOUT PGND SGND VIN RT DRVCC1 VRNG1 BG1 ITH1 SW1 TRACK/SS1 TG1 VOUTSENSE1+ BOOST1 VOUTSENSE1- PGOOD1 SENSE1+ RUN1 SENSE1- S1- DTR1 34 32 EXTVCC 31 4 R25 2.2 28 RJK0330DPB Q4 4 RJK0305DPB Q1 4 * VO2+ J3 RS2 * R20 2512 * * + COUT6 COUT7 100uF 6.3V 1206 COUT8 100uF 6.3V 1206 330uF 2.5V 7343-D15T + COUT5 330uF 2.5V 7343-D15T GND VO2- S1+ R32 C13 0.1uF R38 100K D1 L1 SW1 CMDSH-3 INTVCC 4 * RJK0330DPB Q2 4 * OPT Q6 R36 * 21 R48 0 R34 * VOUT1 J5 RS1 * 2512 + COUT2 COUT3 100uF 6.3V 1206 COUT4 100uF 6.3V 1206 330uF 2.5V 7343-D15T 330uF 2.5V 7343-D15T J6 GND S1- INTVCC R42 10 DCR SENSE FILTER / DIVIDER FOR PHASE 1 R43 10 R47 OPT E11 VO1_SNS+ B VO1_SNSC17 OPT E14 OPTIONAL COUT RUN1 VOUT1 J7 LOAD STEP CIRCUIT #1 E15 1 VOUT2 5 4 3 2 EXTVCC LOAD STEP CIRCUIT #2 1 VOUT1 ONLY ADD FOOTPRINTS ON SOLDERMASK, DO NOT SHOW IN SCHEMATIC. VOUT2 J8 VOUT1 5 4 3 2 R50 OPT 3 VOUT1 1.2V / 15A + COUT1 E12 RUN1 PGOOD1 J4 E7 2 OFF VOUT2 1.5V / 15A CIN3 10uF 35V 1210 OPT Q5 4 25 20 E6 VOUT2 R19 R27 2.2 26 22 VIN- * C C10 0.1uF R350 E5 DCR SENSE FILTER / DIVIDER FOR PHASE 2 27 23 GND OPT Q8 C8 4.7uF 16V 0805 C9 INTVCC 1uF 24 J2 S2- 30 29 L2 SW2 33 CIN6 OPT 1210 S2+ R18 D2 CMDSH-3 CIN7 (OPT) 1210 1 2 3 C4 0.1uF 35 5 5 R160 CIN8 (OPT) 1210 CIN5 10uF 35V 1210 NOTE: TIE SGND PIN TO PGND PAD UNDERNEATH IC. R49 OPT 1 B * R46 10K VIN JP4 RUN1 R41 LTC3838EFE 39 E10 TRK/SS1 U1 VFB2 36 4 5 4 BOOST2 4 CIN4 10uF 35V 1210 OPT Q7 VIN 4.5V - 26V + 1 2 3 S2+ C5 0.01uF SENSE2+ RJK0305DPB Q3 5 3 PGOOD2 R12 100K 37 CIN1 100uF 100uF 35V 35V 35HV100M 35HV100M +CIN2 1 2 3 * SENSE2- 38 5 * RUN2 1 2 3 60 DEG C3 DTR2 1 2 3 R15 R17 10K 2 5 * 1 2 3 S2- R14 5 1 R13 15K VFB2 2 3 J1 INTVCC 1 90 DEG VIN R55 0 C2 OPT 120 DEG VIN+ INTVCC 1 2 3 JP2 PHASMD CLKOUT R11 0 5 R10 OPT INTVCC OPT 1 2 3 R8 PGND E4 TRK/SS2 E19 LOAD STEP 10mV / A 5% DUTY CYCLE MAX C18 1uF Q9 SUD50N03-12P 1 E17 LOAD STEP 10mV / A 5% DUTY CYCLE MAX 2 EXTVCC 2 E16 Q10 SUD50N03-12P 1 PULSE1 + COUT13 E18 OPT 7343-D15T PULSE2 + COUT14 OPT 7343-D15T R51 10K E22 IOSTEP1+ NOTES: UNLESS OTHERWISE SPECIFIED A R53 0.01 2010 E23 1. ALL RESISTORS ARE IN OHMS, 0603. ALL CAPACITORS ARE IN MICROFARADS, 0603. IOSTEP1- 3 3 GND E20 GND R52 10K E24 IOSTEP2+ VOUT2 E21 GND + R54 0.01 2010 E25 IOSTEP2- COUT15 OPT 7343-D15T + COUT16 OPT 7343-D15T 2. INSTALL SHUNTS ON JUMPERS AS SHOWN. ASSY -A (DCR SENSE) -B (RSENSE) L1,L2 Vishay IHLP4040DZ-01 0.56uH WURTH 7443330068(0.68uH) A C16, C3 R32, R18 0.1uF 1000pF 4.02K OPT R34,R19 11K OPT R36,R20 R41,R45, R14,R15, 0 OPT OPT 10 CUSTOMER NOTICE RS1, RS2 0.000 Ohm 2512 0.0025 Ohm 2512 R29,R24 R30,R26 OPT 0 0 OPT R31 R21 17.4K 20K 40.2K 45.3K APPROVALS LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES. VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APP ENG. APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. TECHNOLOGY HZ MIKE S. TITLE: SCHEMATIC WIDE INPUT RANGE, HIGH EFFICIENCY DUAL STEP-DOWN DC-DC CONVERTER SIZE THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. 5 4 3 2 N/A SCALE = NONE 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 www.linear.com Fax: (408)434-0507 LTC Confidential-For Customer Use Only DATE: IC NO. REV. LTC3838EFE 2 DEMO CIRCUIT 1626A Wednesday, October 19, 2011 1 SHEET 1 OF 1