QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1320A HIGH POWER DENSITY STEP-DOWN CONVERTER LTCC3608/9EWKG DESCRIPTION Demonstration circuit 1320A is a high power density step-down DC/DC converter featuring LTC3608EWKG/LTC3609EWKG high current, high input voltage monolithic DC/DC step-down converter. The input voltage of the demo board is from 5V to 20V for DC1320A-A with LTC3608EWKG and 5V to 28V for DC1320A-B with LTC3609EWKG. The output voltage is jumper-selectable 1.5V/1.8V/2.5V/3.3V@8A. The converter provides the main output with high efficiency, high power density and fast transient based on constant on-time valley current mode control. Table 1. The converter can be configured for discontinuous or forced continuous operation at light load. The converter switching frequency is compensated for variations in Vin and Vout. The LTC3608/9EWKG is in a compact 7mm X 8mm QFN package. Design files for this circuit board are available. Call the LTC factory. , LTC and LT are registered trademarks of Linear Technology Corporation. Performance Summary (TA = 25°C) PARAMETER CONDITION Input Voltage Typical VALUE 5V-20V for DC1320A-A 5V-28V for DC1320A-B Output Voltage VOUT IOUT = 0A to 8A 1.5V/1.8V/2.5V/3.3V ± 2% VIN = 5V-20V (DC1320A-A) 8A VIN = 5V-28V (DC1320A-B) 8A Vin=5V-28V , Vout=1.5V/1.8V/2.5V/3.3V, Iout=0-8A 500kHz-700kHz VIN = 5V, VOUT1 = 1.8V, IOUT1 = 8A 89% Typical VIN = 12V, VOUT1 = 1.8V, IOUT1 = 8A 87.5% Typical VIN = 20V, VOUT1 = 1.8V, IOUT1 = 8A 85.5% Typical VIN = 5V, VOUT2 = 1.8V, IOUT2 = 8A 87.5% Typical VIN = 12V, VOUT1 = 1.8V, IOUT1 = 8A 83.2% Typical VIN = 24V, VOUT1 = 1.8V, IOUT1 = 8A 82.2% Typical Maximum Output Current Nominal switching frequency DC1320A-A Full Load Efficiency DC1320A-B 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1320A HIGH POWER DENSITY STEP-DOWN CONVERTER QUICK START PROCEDURE Demonstration circuit 1320 is easy to set up to evaluate the performance of the LTC3608/9EWKG. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: ground lead on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly across the Vin or Vout and GND terminals. See Figure 2 for proper scope probe technique. NOTE: When measuring the input or output vol- tage ripple, care must be taken to avoid a long NOTE: If there is no output, temporarily dis1. With power off, connect the input power supply to VIN and GND. Connect the load between VOUT1, VOUT2 and GND. Preset the load current at 0A (minimum). Refer to Figure 1 for correct test set up. The RUN/SS1 and RUN/SS2 jumpers should be at “on” position. 2. Turn on the input power. NOTE: Make sure that the input voltage does not exceed 20V for A-A and 28V for A-B. 3. Check for the proper output voltages: Vout=1.8V, +/-2% connect the load to make sure that the load is not set too high. 4. Once the proper output voltages are estab- lished, adjust the loads within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters. 5. The output voltage can be programmed to other voltages 1.5V/2.5V/3.3V by selecting jumper. The output voltage deviations should be within +/- 2% of nominal voltages. 6. Typical efficiency curves are shown in Figure 3, Figure 4 and Figure 5. 2 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1320A HIGH POWER DENSITY STEP-DOWN CONVERTER Figure 1. Proper Measurement Equipment Setup GND VIN Figure 2. Measuring Input or Output Ripple 3 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1320A HIGH POWER DENSITY STEP-DOWN CONVERTER Figure 3. Typical Supply Efficiency vs Load Current of DC1320A-A at Vin=5V Figure 4. Typical Supply Efficiency vs Load Current of DC1320A-A at Vin=12V Figure 5. Typical Supply Efficiency vs Load Current of DC1320A-A at Vin=20V 4 RPG INTVCC CIN1 + [1] R26 RTH 100pF CMDHS-3 SDM10K45 VOUT 6A MAX 9V - 32V -B CIN1 100uF, 50V 150uF, 35V JP8 3 2 1 INTVCC FCB 8A MAX D1 CCM DCM [1] VOUT 10uF, 50V 10uF, 35V CIN2, CIN3 0.1uF C8 [1] R23 18 17 16 13 12 11 SW 8 1,2,3,4,5,6,7,48, 49,50,51,53, 52 CBst 0.22uF 1500pF 12K Cth OPT OPT PVIN CIN7 CIN6 D1 Cthp VIN 10K R27 0.1uF CSS 5V - 20V [1] JP7 3 2 1M R24 OPT OPT INTVCC CIN5 CIN4 -A INTVCC OFF ON 1 CIN3 [1] RUN/SS CIN2 [1] ASSY E4 E3 100K E2 J2 J1 E1 [1] [1] SGND PGOOD VIN- GND VIN VIN+ U1 U1 [1] LTC3608 R30 162K 1% LTC3609EWKGHV LTC3608EWKG ITH VRNG PGOOD VON RUN/SS BOOST SW PVIN F CB 19 ION 22 PGN D 40 35.7K OPT R26 SVIN 34,35,36, 37,38,39, L1 VFB 23 29 30 31 32 28 25 24 21 9 4.7 W 1.5uH L1 [1] OPT C12 10 60.4K 1% (Opt) R21 13.7K 1% 3.3V C6 19.1K 1% JP5 JP4 2.5V 30.1K 1% R20 R19 1.5V 1.8V R16 40.2K 1% JP2 JP3 R29 SVIN R28 C10 OPT 4.7uF 10V OPT COUT4 C9 0.47uF 50V 1 R25 VOUT VIN VISAHY IHLP2525CZ-01 C7 INTVCC 33,41,42,43, 44,45,46,55, 47 SW R31 OPT VOUT SELECT 3.3 W 1.0uH R23 SVIN INTVCC INTVCC NC NC NC NC NC SW EXTVCC SGN D 27 10,14,15, 20,26,54, VIN OPT COUT3 VOUT COUT6 22uF 6.3V COUT2 100uF 6.3V OPT C11 COUT1 100uF 6.3V J6 VOUT E9 E8 J3 J4 E7 EXTVCC VO- GND VOUT [1] VO+ J5 IOSTEP 10m V/A E10 IOSTEP_CLK R1 10K C2 1uF 10V DYNAMIC LOAD CIRCUIT 0.010 1% R2 1 C13 Q1 1uF SUD50N03-09P-E3 10V COUT5 22uF 6.3V 3 2 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1320A HIGH POWER DENSITY STEP-DOWN CONVERTER 5