QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 447 2-PHASE DUAL OUTPUT POWER SUPPLY LTC3728EUH DESCRIPTION Demonstration circuit 447 is a step-down converter featuring the LTC3728EUH regulator. The PolyPhaseTM dual output controller LTC3728EUH drives two high current synchronous buck converters. Input is 5V–14V, output 1 is 2.5V with loads up to 13A and output 2 is 1.8V with loads up to 13A. For applications with input voltage less than 5V, DC447 includes a circuit footprint on the bottom side to provide a 5V bias power supply. Design files for this circuit board are available. Call the LTC factory. Table 1. Performance Summary PARAMETER CONDITION VALUE Minimum Input Voltage 5V Maximum Input Voltage 14V VOUT1 VIN = 5V to 14V, IOUT1 = 0A to 13A 2.5V VOUT2 VIN = 5V to 14V, IOUT1 = 0A to 13A 1.8V Nominal Switching Frequency 450kHz QUICK START PROCEDURE Demonstration circuit 447 is easy to set up to evaluate the performance of the LTC3728EUH. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: 3. With the power off, connect the input 5V–14V (rec- NOTE: When measuring the input or output voltage rip- 4. Increase the load at VOUT1 to 13A. With a 12V input, ple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly across the input or output and ground terminals. See Figure 2 for proper scope probe technique. the input current should be less than 3.5A. Slowly decrease the input voltage to 5V. At 5V input voltage, the input current should be less than 8A. 1. Before powering up, place the jumpers as shown in Figure 1. 2. Connect the loads at VOUT1 and VOUT2. Set the load current to 0A. ommended 12V) power supply to VIN and GND. VOUT1 should be within 2.5V ±0.1V and VOUT2 should be 1.8V ±0.1V. 5. Decrease the load at VOUT1 to 0A. Increase the input voltage to 12V. 6. Increase the load on VOUT2 to 13A. With a 12V input, the input current should be less than 2.5A. Slowly decrease the input voltage to 5V. At 5V input, the input current should be less than 6A. 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 447 2-PHASE DUAL OUTPUT POWER SUPPLY – + + + – – – – + LOAD – + + + + – – + LOAD GND Figure 1. Proper Measurement Equipment Setup VIN – Figure 2. Scope Probe Placement for Measuring Input or Output Ripple 2 5 VO1SEN E5 VO1SEN PG E1 PG 4 2 1 E4 5VBIAS 5VBIAS C9 33PF 5 1 6 R11 15K C14 1000PF C16 33PF 100K 7 R23 OPT 8 9 2 BM. P.S. C.C.M 1 3 R20 JP2 FCB C21 0.01UF C15 0.01UF 2 R25 OPT OFF 1 R24 OPT C66 OPT R14 20.5K 1% 11 C20 R13 26.1K 1% 12 1000PF R18 10 C19 180PF PLLIN VIN BG1 FCB EXTVCC ITH1 INTVCC SGND PGND 3.3VOUT BG2 BOOST2 ITH2 VOSENSE2 SW2 SENSE2- TG2 SENSE2+ RUN/SS2 LTC3728EUH 4 1 D1 B320A 4 D VOUT1 VOUT1 C4 C69 180UF 4V 7343 J1 VOUT1 2.5V@13A C27 1UF 0603 + J6 GND 2 1 2 3 24 D2 CMDSH-3 1 2 23 22 VIN 21 C10 1UF 0603 20 19 C8 4.7UF 10V 0805 VIN C7 1UF 16V 0805 C24 C25 4.7UF 4.7UF 25V 25V 1210 1210 18 17 1 C17 0.1UF 15 14 2 D3 CMDSH-3 4 4 4 D4 B320A 4 13 R17 10 J3 VIN C12 C13 +C11 4.7UF 4.7UF 56UF,25V 25V 25V OSCON 1210 1210 Q3 Si7860DP Q7 OPT Q8 OPT Q4 Si7856DP R15 0.003 2512 L2 1.3UH 5V-14V J4 GND VOUT2 C VOUT2 C28 + C22 1UF 0603 C70 220UF 2.5V J5 VOUT2 1.8V@13A J2 GND R28 10 C23 0.1UF JP3 RUN/SS2 INTVCC E3 FREQSET R3 0.003 2512 2 4 JP1 RUN/SS1 ON 3 3 BOOST1 C5 0.1UF 25 4 1 SYNC C6 1000PF VOSENSE1 4 1 2 3 R10 15K SW1 26 5 6 7 8 OFF 2 SENSE1- L1 1.3UH 27 1 2 3 1 TG1 1 2 3 31 PG SENSE1+ 1 2 3 1000PF RUN/SS1 Q2 Si7856DP 5 6 7 8 20K 30 Q6 OPT 1 2 3 2 R6 C3 1% R7 11.8K ON 3 OPT Q5 OPT 5 6 7 8 C1 0.1UF C65 Q1 Si7860DP 5 6 7 8 R8 10 5 6 7 8 R4 30K R16 1M >5VIN 1 2 3 28 C31 OPT C JP4 U1 R27 1 R9 1M <5VIN 5 6 7 8 R2 10 C26 1UF 0603 OPT L1 & L2= SUMIDA CDEP105-1R3MC-50 1 2 3 R1 10 INPUT SEL. 3 5 6 7 8 C2 180PF 1 5 6 7 8 R26 10 R5 43.2K 1% 2 R19 100K D SYNC E2 3 INTVCC VO2SEN E6 +C32 7343 OPTIONAL BIAS CIRCUIT OPTIONAL DISTRIBUTED CA PS C33 1210 C34 1210 C35 1210 C36 1210 C37 1210 C38 1210 C39 1210 C40 1210 C41 1210 L3 4.7UH VIN C42 1210 >5VIN 3 +C43 7343 C44 1210 C45 1210 C46 1210 C47 1210 C48 1210 C49 1210 C50 1210 C51 1210 C52 1210 B TOKO, FSLM2520-4R7 D5 CMDSH-3 U2 <5VIN 1 5 JP5 BIAS INPUT VOUT1 NOTES: UNLESS OTHERWISE SPECIFIED 2 VIN B 4 3 C30 10UF 10V 1206 C53 + C67 1210 7343 VIN SW 1 2 SD FB GND 2 LT1613 SOT23-5 5VBIAS 1 C29 10UF 10V 1206 5VBIAS R21 37.4K R22 12.1K 1. ALL RESISTORS ARE IN OHMS, 0603. A 2. R23=R24=R25=0 OHM WILL B E ASSEMBLED ONLY IF TWO OUTPUTS ARE TIED TOGETHER FOR HIGH CURRENT OUTPUT. VOUT2 CONTRACT NO. +C54 7343 3. INSTALL SHUN TS ON JP1-JP5 PIN 2 AND 3. IF VIN<5V, INST ALL SHUNTS ON JP4 AND JP5 PIN 1 AND 2. C55 1210 C56 1210 C57 1210 C58 1210 C59 1210 C60 1210 C61 1210 C62 1210 C63 1210 C64 + C68 1210 7343 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 TECHNOLOGY Fax: (408)434-0507 LTC Confi dential-For Customer Use Only APPROVALS DRAWN: KIM T. CHECKED: TITLE: APPROVED: ENGINEER: WEI C. DESIGNER: 2-PHASE DUAL OUTPUT PO WER SUPPLY SIZE A DATE: 5 4 3 2 DWG NO. REV DC447A-1 * LTC37 28EUH Friday, August 02, 2002 SHEET 1 1 A OF 1 A