DEMO MANUAL DC1897B LTC3605A 20V, 5A Monolithic Synchronous Step-Down Regulator DESCRIPTION Demonstration circuit 1897 is a step-down converter, using the LTC®3605A monolithic synchronous buck regulator. The DC1897B has a maximum input voltage of 20V, and is capable of delivering up to 5A of output current at a minimum input voltage of 4V. The output voltage of the DC1897B can be set as low as 0.6V, the reference voltage of the LTC3605A. At low load currents, the DC1897B operates in discontinuous mode, and during shutdown, it consumes 11µA of quiescent current typically. The DC1897B can achieve efficiency over 90%. The LTC3605A has phase-lock-loop circuits, allowing high current multiphase operation of several DC1897Bs in parallel. The DC1897B can also track another voltage with the LTC3605A track function. Because of the high switching frequency of the LTC3605A, which is programmable up to 4MHz, the DC1897B uses low profile surface mount components. All these features make the DC1897B an ideal circuit for use in industrial applications and distributed power systems Design files for this circuit board are available at http://www.linear.com/demo L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. PERFORMANCE SUMMARY Table 1. Performance Summary PARAMETER CONDITIONS VALUE Input Voltage Range 4V to 20V Output Voltage Range 0.6V to 5V Run/Shutdown GND = Shutdown VIN = Run Output Voltage Regulation VIN = 4V to 20V, IOUT = 0A to 5A VIN = 4.7V to 20V, IOUT = 0A to 5A VIN = 6.4V to 20V, IOUT = 0A to 5A 2.5V ±2% Typical (2.45V to 2.55V) 3.3V ±2% Typical (3.234V to 3.366V) 5V ±2% Typical (4.9V to 5.1V) Typical Output Ripple Voltage VIN = 12V, VOUT = 2.5V IOUT = 5A (20MHz BW) <20mVP-P Discontinuous Mode VIN = 12V, VOUT = 2.5V VIN = 12V, VOUT = 3.3V VIN = 12V, VOUT = 5V IOUT < 1.25A IOUT < 1.45A IOUT < 1.65A Phase Phase = INTVCC Phase = GND Phase = Floating 180° Out-of-Phase: 2 Phase 120° Out-of-Phase: 3 Phase 90° Out-of-Phase: 4 Phase Nominal Switching Frequency RT = 162k 1MHz ±20% Table 2. Jumper Description JUMPER FUNCTION RANGE/SETTING (DEFAULT) JP1 Output Voltage Setting 2.5V JP5 Phase Mode (PHMODE): 180 Degrees Out-of-Phase (DOP) – 2 Phase, 120 DOP – 3 Phase, or 90 DOP – 4 Phase (2 PHASE) – 3 PHASE – 4 PHASE JP6 Mode: Forced Continuous Mode (FCM) or Discontinuous Mode (DCM) (FCM) – DCM JP7 Run (ON) – OFF dc1897bf 1 DEMO MANUAL DC1897B QUICK START PROCEDURE Demonstration Circuit 1897 is easy to set up to evaluate the performance of the LTC3605A. For proper measurement equipment configuration, set up the circuit according to the diagram in Figure 1. Before proceeding to test, check that the shunts are inserted into these positions: the 2.5V output voltage header JP1, the 180° out-of-phase (2-PHASE) position of the phase mode (PHMODE) header JP5, the forced continuous mode (FCM) position of mode header JP6, and the on position of run header JP7. 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 2 for proper scope probe measurement technique. With the DC1897B set up according to the proper measurement configuration and equipment in Figure 1, apply 6.3V at VIN (do not increase VIN over the rated maximum supply voltage of 20V, or the part may be damaged). Measure VOUT; it should read 2.5V (If desired, the quiescent current of the circuit can be monitored now by swapping the shunt in header JP7 into the OFF position). The output voltage should be regulating. Measure VOUT—it should measure 2.5V ±2% (2.45V to 2.55V). Vary the input voltage from 4V to 20V and adjust the load current from 0 to 5A. VOUT should regulate around 2.5V ±3% (2.425V to 2.575V). Measure the output ripple voltage—it should measure less than 30mV AC. Observe the voltage waveform at the switch pins (the other side of the inductor from the output). Verify the switching frequency is between 800kHz and 1.2MHz (t = 1.25ns and 833ns), and that the switch node waveform is rectangular in shape. Change the shunt position on the MODE header from FCM to DCM (discontinuous mode). Set the input voltage to 12V and the output current to any current less than 1A. Observe the discontinuous mode of operation at the switch node, and measure the output ripple voltage. It should measure less than 100mV AC. Insert the JP7 shunt into the OFF position and move the shunt in the 2.5V output JP1 header into any of the two remaining output voltage option headers: 3.3V (JP2) or 5V (JP3). Just as in the 2.5V VOUT test, the output voltage should read VOUT ±1% tolerance under static line and load conditions and ±1% tolerance under dynamic line and load conditions (±2% total). Also, the circuit operation in discontinuous mode will be the same. When finished, turn off the circuit by inserting the shunt in header JP7 into the OFF position. dc1897bf 2 DEMO MANUAL DC1897B QUICK START PROCEDURE Figure 1. Proper Equipment Measurement Setup Figure 2. Measuring Input or Output Ripple dc1897bf 3 DEMO MANUAL DC1897B QUICK START PROCEDURE Normal Switching Frequency and Output Ripple Voltage Waveforms VIN = 12V, VOUT = 5V, IOUT = 5A, fSW = 1MHz Trace 1: Switch Voltage (5V/Div) Trace 2: Output Ripple Voltage (20mV/Div AC) Figure 3. Switch Node and Output Ripple Voltage Waveforms Load Step Response Waveforms VIN = 12V, VOUT = 5V, 5A Load Step (0A to 5A) Forced Continuous Mode, fSW = 1MHz Trace 2: Output Voltage (200mV/Div AC) Trace 4: Output Current (2A/Div) Figure 4. Load Step Response Load Step Response Waveforms Load Step Response Waveforms VIN = 12V, VOUT = 2.5V, 5A Load Step (0A to 5A) Forced Continuous Mode, fSW = 1MHz Trace 2: Output Voltage (100mV/Div AC) Trace 4: Output Current (2A/Div) VIN = 12V, VOUT = 3.3V, 5A Load Step (0A to 5A) Forced Continuous Mode, fSW = 1MHz Trace 2: Output Voltage (100mV/Div AC) Trace 4: Output Current (2A/Div) Figure 5. Load Step Response Figure 6. Load Step Response dc1897bf 4 DEMO MANUAL DC1897B QUICK START PROCEDURE 2-Phase Dual Output Waveforms VIN = 12V, VOUT1 = 2.5V, IOUT1 = 5A, VOUT2 = 3.3V, IOUT2 = 5A, fSW = 1MHz Trace 1: VOUT1 Switch Voltage (10V/Div) Trace 4: L1 Ripple Current (5A/Div) Trace 3: VOUT2 Switch Voltage (10V/Div) Trace 2: L2 Ripple Current (5A/Div) Figure 7. Switch Node Voltage and Inductor Ripple Current Waveforms of Two Circuits Operating 180° Out-of-Phase Circuit Efficiency VIN = 12V Discontinuous Mode, fSW = 1MHz Figure 8. Efficiency Graph dc1897bf 5 DEMO MANUAL DC1897B PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 1 C1 CAP, 0805 2.2µF 20% 10V X5R AVX 0805ZD225MAT2A 2 2 C2, C3 CAP, 1210 22µF 20% 25V X7R MURATA GRM32ER61E226ME15L 3 1 C4 CAP, 0603 0.1µF 20% 25V X7R AVX 06033C104MAT2A 4 2 C5, C12 CAP, 1206 47µF 20% 10V X5R TAIYO YUDEN LMK316BJ476ML-T 5 1 C6 CAP, 0402 220pF 20% 50V C0G AVX 04025A221MAT2A 6 1 C7 CAP, 0402 10pF 20% 50V C0G AVX 04025A100MAT2A 7 1 C8 CAP, 0402 100pF 20% 50V C0G AVX 04025A101MAT2A 8 1 D1 DIODE, CMDSH-3, SOD-323 CENTRAL SEMI. CMDSH-3TR 9 1 L1 IND 1.0µH VISHAY IHLP2525CZER1R0M01 10 1 R1 RES, 0402 162k 1% 1/16W VISHAY, CRCW0402162KFKED 11 1 R2 RES, 0402 10k 1% 1/16W VISHAY CRCW040210K0FKED 12 1 R3 RES, 0402 14k 1% 1/16W VISHAY CRCW040214K0FKED 13 1 R4 RES, 0402 3.16k 1% 1/16W VISHAY CRCW04023K16FKED 14 1 R13 RES, 0402 0Ω JUMPER VISHAY CRCW04020000Z0ED 15 1 U1 IC, QFN24 LINEAR TECHNOLOGY, LTC3605AEUF Additional Demo Board Circuit Components 1 2 C9, C15 CAP, 0603 0.1µF 20% 25V X7R AVX 06033C104MAT2A 2 1 C10 CAP, 7343 22µF 20% 35V TANT AVX TPSY226M035R 3 0 C11 CAP, 1206 OPTION OPTION 4 0 C13, C14 CAP, 1812 22µF 20% 25V X7R OPTION TDK C4532X7R1E226M OPTION 5 1 R5 RES, 0402 2.21k 1% 1/16W VISHAY CRCW04022K21FKED 6 1 R6 RES, 0402 1.37k 1% 1/16W VISHAY CRCW04021K37FKED 7 0 R7, R12 RES, 0402 OPTION OPTION 8 4 R8, R10, R14, R15 RES, 0402 100k 5% 1/16W VISHAY CRCW0402100KJNED 9 1 R9 RES, 0402 150k 5% 1/16W VISHAY CRCW0402150KJNED 11 1 R11 RES, 0402 10Ω 5% 1/16W VISHAY CRCW040210R0JNED Hardware—For Demo Board Only 1 9 E1-E9 TURRET MIIL-MAX 2501-2-00-80-00-00-07-0 2 4 JP1, JP2, JP3, JP4 HEADER, SINGLE ROW, 2-PIN, 2mm SULLINS, NRPN021PAEN-RC 3 1 JP5 HEADER, 3-PIN, DBL ROW 2mm SULLINS, NRPN03PAEN-RC 4 1 JP6 HEADER, 2mm DBL ROW (2X2) 4-PIN SULLINS, NRPN022PAEN-RC 5 1 JP7 HEADER, 2mm, 3-PIN SULLINS, NRPN031PAEN-RC 6 4 JP1, JP5-JP7 SHUNT, 2mm SAMTEC 2SN-BK-G dc1897bf 6 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. [1] NOTES: GND PGOOD JP7 3 2 1 4 PHASE E8 R10 100K TRACK C9 0.1uF 25V C6 220pF 14K R3 DCM (DISCONTINUOUS MODE) R9 150K VIN 2 PHASE 3 PHASE R8 100K C7 10pF C10 IS AN OPTIONAL CAPACITOR. IT IS INSERTED ON THE DC1897A TO DAMPEN THE (POSSIBLE) RINGING VOLTAGE DUE TO THE LONG INPUT LEADS. ON A NORMAL, TYPICAL PCB, WITH SHORT TRACES, THE CAPACITOR IS NOT NEEDED. E6 E5 OFF ON RUN 4 3 6 5 JP5 4 3 PHMODE 1 2 E3 E1 FCM (FORCED CONTINUOUS MODE) R15 100K JP6 2 1 MODE 100K R14 CLKIN CLKOUT R1 162K 6 5 4 3 2 1 C1 2.2uF 10V ITH TRACK FB MODE PHMODE RT U1 LTC3605AEUF INTVCC 24 CLKIN RUN 7 23 CLKOUT PGOOD 8 22 9 SW SW SW SW PVIN PVIN D1 CMDSH-3 SGND 21 INTVCC 0 R13 L1 1uH C2 22uF 25V C4 0.1uF 25V 13 14 15 16 17 18 C15 0.1uF 25V R11 10 10 VOUT 19 PGND 20 BOOST SW 11 SVIN SW 12 R12 OPT PGND 25 C8 100pF C3 22uF 25V 1 REV 5V JP3 R6 1.37K C12 47uF 6.3V 1206 TECHNOLOGY GND OPT. JP4 R7 OPT. E9 C11 47uF 6.3V OPT GND E7 VOUT 2.5V / 3.3V / 5V@5A E4 E2 4V to 20V VIN 1 LTC3605AEUF DEMO CIRCUIT 1897B 11/07/13 10:52:40 N/A TOM G. APPROVED 1 1 Vout SELECT 3.3V JP2 R5 2.21K C5 47uF 6.3V 1206 C14 + C10 [1] 22uF 22uF 25V 35V OPT VIN DATE 11/01/13 5A MONOLITHIC SYNCHRONOUS BUCK REGULATOR REVISION HISTORY PRODUCTION DESCRIPTION 2.5V JP1 R4 3.16K R2 10.0K C13 22uF 25V OPT ECO DEMO MANUAL DC1897B SCHEMATIC DIAGRAM dc1897bf 7 DEMO MANUAL DC1897B 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 dc1897bf 8 Linear Technology Corporation LT 1213 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2013