DEMO MANUAL DC1832A LT3995 60V, 3A, 2MHz Step-Down Switching Regulator with 2.7µA Quiescent Current Description Demonstration circuit 1832A is a monolithic step-down DC/DC switching regulator featuring the LT3995. The LT3995 is a compact, high efficiency monolithic step-down switching regulator that consumes only 2.7μA of quiescent current. The demo circuit is designed for 3.3V, 3A output from a 4.3V to 60V input. The switching frequency can be programmed either via oscillator resistor or external clock up to 2MHz. To synchronize to an external clock, move JP2 to SYNC and apply the external clock to the SYNC turret. The RT resistor (R5) should be chosen to set the LT3995 internal switching frequency at least 20% below the lowest synchronization input frequency. Low ripple Burst Mode® operation increases the efficiency at the light load while keeping the output ripple below 15mV. The SYNC pin on the demo board is grounded by default by setting JP2 at RT FREQ for low ripple Burst Mode operation. Figure 1 shows the demo board efficiency at 12V input voltage. The LT3995 is in shutdown when the EN pin is low and active when the pin is high. The threshold of the EN pin is accurate at 1.02V with 60mV of hysteresis. Users can populate R7 and R8 to provide a programmable under The demo board has an EMI filter installed. The EMI performance of the demo board at 12V input voltage is shown on Figure 2. The limit in Figure 2 is EN55022 Class B. The figure shows the circuit passes the test with a wide margin. To use the EMI filter, the input should be tied to VEMI not VIN. The LT3995 data sheet gives a complete description of the part, operation and application information. The data sheet must be read in conjunction with this demo manual for demo circuit 1832A. The LT3995 is assembled in a 16lead plastic MSOP package with an exposed pad for low thermal resistance. Proper board layout is essential for both proper operation and maximum thermal performance. See the data sheet sections for details. Design files for this circuit board are available at http://www.linear.com/demo L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. 70 85 60 10dB/DIV LOG, REF 70.00dBµV 90 80 EFFICIENCY (%) voltage lockout. A low dropout voltage of 500mV is maintained when the input voltage drops below the programmed output voltage. During a short-circuit fault, the LT3995 has current limit foldback to limit the power dissipation. 75 70 65 60 55 50 45 40 TRACE 1 PASS 50 40 30 20 10 0 –10 –20 0 0.5 1.5 2 1 LOAD CURRENT (A) 3 2.5 dc1832a F01 –30 START 150kHz RES BW (CISPR) 9kHz VBW 62kHz STOP 30.00 MHz SWEEP 717ms (6637pts) dc1832a F02 Figure 1. LT3995 Efficiency vs Load Current, 12VIN to 3.3VOUT Efficiency Figure 2. LT3995 Demo Board EMI Performance (Switching Frequency = 300kHz, VIN = 12V) dc1832af 1 DEMO MANUAL DC1832A Performance Summary PARAMETER Specifications are at TA = 25°C CONDITIONS Guaranteed Minimum Input Voltage VALUE 4.3V Maximum Input Voltage 60V Output Voltage VOUT VIN = 4.3V ~ 60V 3.275V ± 3% Switching Frequency RT = 182k 300kHz ± 20% Guaranteed Maximum Output Current IOUT VIN = 4.3V ~ 60V 3A Typical Efficiency VIN = 12V, IOUT = 3A 82.2% Typical Output Voltage Ripple VIN = 12V, IOUT = 3A 11mV Quick Start Procedure Demonstration circuit 1832A is easy to set up to evaluate the performance of the LT3995. Refer to Figure 3 for proper measurement equipment setup and use the following procedure. NOTE. When measuring the input or output voltage ripple, 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 VIN or VOUT and GND terminals. See Figure 4 for the proper scope technique. 1. Place JP1 on the ON position. 2. Place JP2 on the RT FREQ position. 3. With power off, connect the input power supply to VIN and GND. Make sure that the input voltage does not exceed 60V. 4. With power off, connect load from VOUT to GND. 5. Turn on the power at the input. 6. Check for the proper output voltage (3.3V). NOTE. If there is no output, temporarily disconnect the load to make sure that the load is not set too high or is shorted. 7. Once the proper output voltage is established, adjust the load within the operating ranges and observe the output voltage regulation, ripple voltage, efficiency and other parameters. 8. An external clock can be added to the SYNC terminal when SYNC function is used (JP2 on the SYNC position). Please make sure that the SYNC frequency is at least 20% higher than the set switching frequency. See the data sheet Synchronization section. dc1832af 2 DEMO MANUAL DC1832A Quick Start Procedure Figure 3. Proper Measurement Equipment Setup Figure 4. Measuring Input or Output Ripple dc1832af 3 DEMO MANUAL DC1832A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER CAP., X5R, 47µF, 10V, 20%, 1210 TDK, C3225X5R1A476M Required Circuit Components 1 2 C1, C8 2 1 C2 CAP., X5R, 0.47µF, 25V, 10%, 0603 TDK, C1608X5R1E474M 3 2 C3, C7 CAP., X7R, 2.2µF, 100V, 10%,1210 TDK, C3225X7R2A225M 4 1 C5 CAP., C0G, 10pF, 50V, 10%, 0402 TDK, C1005C0G1H100D 5 1 C6 CAP., X7R, 10nF, 25V, 10%, 0402 TDK, C1005X7R1E103K 6 1 C11 CAP., X5R, 1µF, 10V, 10%, 0603 TDK, C1608X5R1A105K 7 1 C12 CAP., X7R, 0.1µF, 100V, 10%, 0603 MURATA, GRM188R72A104KA35D 8 1 D1 DIODE, PDS360 PowerDi5 DIODE INC., PDS360 9 1 L1 IND, 8.2µH COILCRAFT, XAL6060-822ME 10 1 R1 RES., CHIP, 1.00M, 1/16W, 1%, 0402 NIC, NRC04F1004TRF 11 1 R2 RES., CHIP, 576k, 1/16W, 1%, 0402 NIC, NRC04F5763TRF 12 1 R5 RES., CHIP, 182k, 1/16W, 1%, 0402 NIC, NRC04F1823TRF 13 1 R6 RES., CHIP, 200k, 1/16W, 1%, 0402 NIC, NRC04F2003TRF 14 1 U1 I.C., LT3995EMSE, MSE16 LINEAR TECHNOLOGY, LT3995EMSE Additional Demo Board Circuit Components 1 1 C4 CAP., ALUM., 100µF, 100V, 10% SUN ELECT, 100CE100KXT 2 2 C9, C10 CAP., X7R, 2.2µF, 100V, 10%, 1210 TDK, C3225X7R2A225M 3 1 C13 CAP., HVP SERIES, 33µF, 63V, 20% SUNCON, 63HVP33M 4 1 L2 IND, 1.0µH VISHAY, IHLP-1616BZER1R0M01 5 1 L3 IND, 3.3µH VISHAY, IHLP-2020BZER3R3M01 6 0 R7,R8 RES., 0603 OPT Hardware: For Demo Board Only 1 7 E1, E2, E3, E4, E5, E6, E7 TURRET, 0.094" MILL-MAX, 2501-2-00-80-00-00-07-0 2 2 E8, E9 TESTPOINT, TURRET, 0.061" PBF MILL-MAX, 2308-2-00-80-00-00-07-0 3 2 JP1, JP2 JMP, 1X3-079 SAMTEC, TMM-103-02-L-S 4 2 XJP1, XJP2 SHUNT, 2mm CTRS. SAMTEC, 2SN-BK-G dc1832af 4 EN/UVLO PG GND VIN 4.3V - 60V E5 E6 E4 E3 SUNCON 100CE100KXT 100uF 100V + C4 VIN OFF ON JP1 C3 2.2uF 100V 1210 1 2 3 C7 2.2uF 100V 1210 R8 OPT 0603 R7 OPT 0603 C12 0.1uF 100V 0603 R6 200K C6 10nF 2 13 15 GND VEMI SS EN PG 10 11 VIN 12 VIN VIN E9 E8 8 NC 17 GND SW SW SW RT SYNC FB OUT BOOST C9 2.2uF 100V 1210 9 NC U1 LT3995EMSE R5 182k 1% (300kHz) C2 0.47uF 0603 33uF 63V 63HVP33 + C13 R2 576k 1% R1 1.00M 1% VIN 3 2 1 JP2 E7 E2 C11 E1 1uF 10V 0603 RT FREQ SYNC C8 47uF 10V 1210 SYNC GND VOUT 3.3V / 3A 1. ALL RESISTORS ARE IN OHMS, 0402. ALL CAPACITORS ARE IN MICROFARADS, 0402. C5 10pF C1 47uF 10V 1210 VOUT NOTE: UNLESS OTHERWISE SPECIFIED L3 3.3uH IND-IHLP2020BZ-01 D1 PDS360 1 2 3 L2 1.0uH IND-IHLP1616BZ-01 C10 2.2uF 100V 1210 14 16 1 3 4 5 6 7 L1 8.2uH DEMO MANUAL DC1832A Schematic Diagram dc1832af Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 5 DEMO MANUAL DC1832A DEMONSTRATION BOARD IMPORTANT NOTICE Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions: This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations. If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES. The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or agency certified (FCC, UL, CE, etc.). No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance, customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind. LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive. Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and observe good laboratory practice standards. Common sense is encouraged. This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application engineer. Mailing Address: Linear Technology 1630 McCarthy Blvd. Milpitas, CA 95035 Copyright © 2004, Linear Technology Corporation dc1832af 6 Linear Technology Corporation LT 0513 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2013