DEMO MANUAL DC1480A LTC3865EUH-1 Dual 5A Synchronous Buck Converter with Pin Selectable Outputs DESCRIPTION Demonstration circuit 1480A is a dual output synchronous buck DC/DC converter featuring the LTC®3865EUH-1. The input voltage range is from 4.5V to 14V. The outputs are 3.3V/5A and 1.8V/5A. Each output voltage can be precisely programmed to a preset value within 1% error with the VID pins. The demo board uses a high density, two sided drop-in layout. The package of LTC3865EUH-1 is a small, low thermal impedance 5mm × 5mm 32-Lead QFN. The light load operation mode of the converter is determined with the MODE/PLLIN pin. Use JP1 jumper to select Burst Mode® operation, pulse-skipping mode or forced continuous mode operation. Switching frequency is preset at about 500kHz. This frequency can be modified by changing R5 value at the FREQ pin. The converter can also be externally synchronized from 250kHz to 770kHz through MODE/PLLIN pin (SYNC terminal on the board). To shut down a channel, force its RUN pin below 1.2V (Jumper: OFF). The power good output (PGOOD1 or PGOOG2 terminal) is low when that channel output exceeds ±10% regulation window. Design files for this circuit board are available at http://www.linear.com/demo L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. PERFORMANCE SUMMARY PARAMETER (TA = 25°C) CONDITION Input Voltage Range VALUE 4.5V to 14V Output Voltage, VOUT1 VIN = 4.5V to 14V, IOUT1 = 0A to 5A 3.3V ±1% Output Voltage, VOUT2 VIN = 4.5V to 14V, IOUT2 = 0A to 5A 1.8V ±1% Maximum Output Current, IOUT1 VIN = 4.5V to 14V, VOUT1 = 3.3V 5A Maximum Output Current, IOUT2 VIN = 4.5V to 14V, VOUT2 = 1.8V 5A Typical Full Load Efficiency, Channel 1 VIN = 12V, VOUT1 = 3.3V, IOUT1 = 5A 91.6% Typical Full Load Efficiency, Channel 2 VIN = 12V, VOUT2 = 1.8V, IOUT2 = 5A 86.6% Typical Switching Frequency 500kHz dc1480af 1 DEMO MANUAL DC1480A QUICK START PROCEDURE Demonstration circuit 1480A is easy to set up to evaluate the performance of the LTC3865EUH-1. Refer to Figure 1 for the proper measurement equipment setup and follow the procedure below: 5.Once the proper output voltages are established, adjust the loads within the operating range and observe the output voltage regulation, ripple voltage and other parameters. Jumper positions: 6.If necessary, change the resistor options on VID pins for other output voltages according to Table 1. JP1 (MODE): PS Note 1. When measuring the output or input voltage ripple, do not use the long ground lead on the oscilloscope probe. See Figure 2 for the proper scope probe technique. Short, stiff leads need to be soldered to the (+) and (–) terminals of an output capacitor. The probe’s ground ring needs to touch the (–) lead and the probe tip needs to touch the (+) lead. Note 2. To accurately measure the output voltages and efficiency, measure VOUT1 and VOUT2 on output capacitors COUT2 and COUT4 directly. JP2, JP3 (RUN1/RUN2): ON 1.With power off, connect the input power supply to VIN (4.5V to 14V) and GND (input return). 2.Connect the load #1 between VOUT1 and GND (Initial load: no load); connect the load #2 between VOUT2 and GND (Initial load: no load). OUTPUT VOLTAGE PROGRAMMING 3.Connect the DVMs to the input and outputs. The output voltages of both channels can be programmed to preset values. There are two VID pins for each channel: VID11, VID12 for VOUT1, and VID21, VID22 for VOUT2. See Table 1 for details. 4. Turn on the input power supply and check for the proper output voltages. With current VID pin setting, VOUT1 should be 3.3V ±1%; VOUT2 should be 1.8V ±1%. Table 1. Output Voltage Programming VID11/VID21 VID12/VID22 VOUT1/VOUT2 (V) INTVCC INTVCC 5V (VIN ≥ 5V) INTVCC FLOAT 3.3V INTVCC GND 2.5V FLOAT INTVCC 1.8V FLOAT FLOAT 0.6 or External Divider FLOAT GND 1.5V GND INTVCC 1.2V GND FLOAT 1V GND GND 1.1V dc1480af 2 DEMO MANUAL DC1480A QUICK START PROCEDURE Rail Tracking Demonstration circuit 1480A is configured for independent turn-on of VOUT1 and VOUT2. The ramp rate for VOUT1 is determined by the TRK/SS1 cap at C6 and the ramp rate for VOUT2 is determined by the TRK/SS2 capacitor at C14. This board can be modified on the bench to allow VOUT1 to track an external signal. It can also be modified to allow VOUT2 to track VOUT1 or to allow VOUT2 to track an external signal. Tables 2 and 3 cover the rail tracking options for each rail. Table 2. VOUT1 Tracking Options (3.3V) TRACK1 DIVIDER CONFIGURATION R7 R9 0Ω Not Stuffed 0.1µF 45.3kΩ 10kΩ Not Stuffed Soft-Start without Tracking (Original Board) External Coincident Tracking TRK/SS1 CAPACITOR C6 Table 3. VOUT2 Tracking Options (1.8V) TRACK2 DIVIDER TRK/SS2 CAPACITOR CONFIGURATION R15 R14 R17 C14 Soft-Start without Tracking (Original Board) 0Ω Not Stuffed Not Stuffed 0.1µF 0Ω 20kΩ 10kΩ Not Stuffed 20kΩ Not Stuffed 10kΩ Not Stuffed Coincident Tracking to VOUT1 (3.3V) External Coincident Tracking + + VOUT1 IIN VIN SUPPLY + + A V + – V VIN – V – + VOUT2 VOUT1 LOAD IOUT1 A A IOUT2 + + – – VOUT2 LOAD + Figure 1. Proper Measurement Equipment Setup dc1480af 3 DEMO MANUAL DC1480A QUICK START PROCEDURE + VOUT COUT – GND 1480a F02 100 100 90 90 80 80 70 CCM PS BM 60 50 40 30 20 10 0 0.01 70 50 40 30 10 10 1480a F03 Figure 3. Efficiency vs Load Current (VIN = 12V, VOUT1 = 3.3V, 500kHz) CCM PS BM 60 20 VIN = 12V VOUT = 3.3V ILOAD = 5A MAX 0.1 1 LOAD CURRENT (A) EFFICIENCY (%) EFFICIENCY (%) Figure 2. Measuring Output Voltage Ripple 0 0.01 VIN = 12V VOUT = 1.8V ILOAD = 5A MAX 0.1 1 LOAD CURRENT (A) 10 1480a F04 Figure 4. Efficiency vs Load Current (VIN = 12V, VOUT2 = 1.8V, 500kHz) dc1480af 4 DEMO MANUAL DC1480A PARTS LIST ITEM QUANTITY REFERENCE-DESCRIPTION DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 1 CIN1 Cap, Alum 39µF 16V 20% OSCON-C6 OSCON 16SVP39M 2 2 CIN3, CIN2 Cap, X5R 10µF 16V 20% 1206 Taiyo Yuden EMK316BJ106ML 3 2 COUT1, COUT3 Cap, X5R 10µF 6.3V 10% 1206 Taiyo Yuden JMK316BJ106KL-T 4 2 COUT2, COUT4 Cap, POSCAP 220µF 4V 20% Sanyo 4TPE220MF 5 4 C1, C5, C10, C15 Cap, X7R 1000pF 50V 10% 0603 AVX 06035C102KAT1A 6 5 C3, C6, C7, C12, C14 Cap, X7R 0.1µF 25V 10% 0603 AVX 06033C104KAT2A 7 2 C4,C13 Cap, X5R 1µF 6.3V 10% 0603 Taiyo Yuden JMK107BJ105KA-T 8 1 C8 Cap, X5R 4.7µF 16V 20% 0805 Taiyo Yuden EMK212BJ475MG 9 1 C9 Cap, NPO 220pF 25V 10% 0603 AVX 06033A221KAT2A 10 1 C11 Cap, X7R 470pF 50V 5% 0603 AVX 06035C471JAT1A 11 1 C16 Cap, X5R 1µF 16V 20% 0805 Taiyo Yuden EMK212BJ105MG 12 2 D1, D2 Schottky Diode, 30V CMDSH-3 Central Semi. CMDSH-3TR 13 2 L1, L2 Inductor, 2.2µH IHLP-2525CZ-01 Vishay IHLP-2525CZERM01 2R2uH 14 2 Q2, Q1 Dual MOSFET N-Channel, 30V Siliconix Vishay Si4816BDY 15 2 RS1, RS2 Res, LRC 0.006 0.25W 5% 1206 IRC LRF1206-01-R006-J 16 3 R1, R33, R38 Res, Chip 10k 0.06W 5% 0603 Vishay CRCW060310K0JNEA 17 7 R2, R6, R7, R11, R15, R16, R21 Res, Chip 0Ω 1/16W 1A 0603 Vishay CRCW06030000Z0EA 18 4 R3, R4, R18, R20 Res, Chip 100 0.06W 5% 0603 Vishay CRCW0603100RJNEA 19 1 R5 Res, Chip 162k 0.06W 1% 0603 Vishay CRCW0603162KFKEA 20 1 R8 Res, Chip 2.2 0.06W 5% 0603 Vishay CRCW06032R20JNEA 21 1 R10 Res, Chip 24.9k 0.06W 1% 0603 Vishay CRCW060324K9FKEA 22 1 R13 Res, Chip 15k 0.06W 5% 0603 Vishay CRCW060315K0JNEA 23 2 R19, R22 Res, Chip 100k 0.06W 5% 0603 Vishay CRCW0603100KJNEA 24 1 U1 IC, Voltage Regulator QFN (32) (UH) 5mm × 5mm Linear Technology LTC3865EUH-1 Additional Circuit Components 1 2 CIN5,CIN4 Cap, 0805 2 1 C2 Cap, 0603 3 2 Q3, Q4 (SyncFet) N-Channel, Dual 4 20 R9, R12, R14, R17, R23, R24 R25, R26, R27, R28, R29, R30, R31 R32, R34, R35, R36, R37, R39, R40 Res, 0603 Fairchild FDS6982AS Hardware Demo Board Only 1 17 2 E1, E2, E3 ,E4, E5, E6, E7, E8, E9, E10 Turret, Testpoint 0.094” Mill Max 2501-2-00-80-00-00-07-0 E11, E12, E13, E14, E15, E16, E17 3 1 JP1 Headers, 4 Pins 2mm Ctrs. Samtec TMM-104-02-L-S 4 2 JP2, JP3 Headers, 3 Pins 2mm Ctrs. Samtec TMM-103-02-L-S 5 3 XJP1, XJP2, XJP3 Shunt, 2mm Ctrs. Samtec 2SN-BK-G 6 4 MH1 to MH4 Stand-Off, Nylon 0.25” Tall Keystone, 8831(Snap On) 7 1 FAB, 1480A_ Rev0 Demo Circuit 1480A 8 2 Stencil 1480A Stencil #1480A dc1480af 5 DEMO MANUAL DC1480A SCHEMATIC DIAGRAM dc1480af 6 DEMO MANUAL DC1480A SCHEMATIC DIAGRAM dc1480af 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. 7 DEMO MANUAL DC1480A 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 dc1480af 8 Linear Technology Corporation LT 1010 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2010