DEMO MANUAL DC1973A LT8697 USB 5V 2.5A Output, 42V Input Synchronous Buck with Cable Drop Compensation Description Demonstration circuit 1973A is a USB 5V 2.5A output, 42V input synchronous buck with cable drop compensation featuring the LT®8697. The LT8697 is a compact, high efficiency, high speed synchronous monolithic step-down switching regulator designed to power 5V USB applications. Top and bottom power switches, compensation components and other necessary circuits are inside of the LT8697 to minimize external components and simplify design. A precise output voltage and programmable cable drop compensation maintain accurate 5V regulation at the USB socket at the end of a long cable. When probing the board, pay attention to GND and C_GND. On the demonstration board, they are connected together by default through R13 so a user can connect the ground clip of a probe to C_GND. However, if a user wants to evaluate an actual cable, the cable will replace R4 and R13. The copper between pads of R13 should be cut open. In this case, C_GND is no longer the same as GND. A differential measurement is needed to probe across the point of load. The demonstration board also includes a USB socket. With the proper configuration of jumpers X1, X2, X3 and X4, the USB can be configured for different applications. See Table 1 for configurations. The circuit runs at 2MHz to minimize external components size and to avoid AM band. The demo board has an EMI filter installed. The conducted EMI performance of the board is shown on Figure 2. The figure shows the circuit passes the EN55022 Class B with a wide margin. A 500mA onboard step load can also be activated to evaluate the load transient response of the circuit. To active the step load, simply set jumper X5 to V+. When the load current is being drawn from VCABLE, the load current is limited by the current limit of the LT8697 or by 5.8V limit at VOUT, whichever comes first. The rated load current of the demonstration circuit is set at 2.1A, enough for all USB applications. If higher voltage or higher current is needed at VCABLE, refer to application examples on the data sheet. If VCABLE is not connected to any load, VOUT can be used to power up a load. VSYS can also be used to supply a small load. Design files for this circuit board are available at http://www.linear.com/demo/DC1973A The LT8697 data sheet gives a complete description of the part, operation and application information. The data sheet must be read in conjunction with this quick start guide for demo circuit 1973A. 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. dc1973af 1 DEMO MANUAL DC1973A Description Figure 1. LT8697 Demo Circuit EMI Performance, Switching Frequency = 2MHz Table 1. Configure X1 – X4 for Different USB Applications X1 X2 X3 X4 J3 Do Not Care Do Not Care Do Not Care OPEN Not in USE OPEN OPEN SHORT SET USB - DCP D+ D- OPEN SET USB - APPLE 2.1A dc1973af 2 DEMO MANUAL DC1973A Performance Summary SYMBOL PARAMETER VIN Input Supply Range Specifications are at TA = 25°C CONDITIONS MIN TYP 6 VOUT Output Voltage 4.8 Max IOUT Maximum Output Current 2.1 fSW Switching Frequency 1.9 EFE Efficiency at DC IOUT = 2.1A, Measured at VOUT 5 MAX UNITS 42 V 5.2 V A 2 91 2.05 MHz % Quick Start Procedure Demonstration circuit 1973A is easy to set up to evaluate the performance of the LT8697. Refer to Figure 2 and Figure 3 for proper measurement equipment setup and follow the procedure below: 1.With power off, connect the input power supply to VIN and GND. 2.With power off, connect the load to VCABLE and C_GND. 3.Set X1 to X5 to OPEN positions. 4.Turn on the power at the input. 5.Carefully evaluate other design parameters as needed. 6.If a USB device is to be connected to J3, use Table 1 as a guide to set X1 to X4 for different USB applications. The total current provided at J3 and VCABLE should not exceed 2.1A. 7.Set X5 to V+ if a quick transient test is desirable. The load step applied to VCABLE is 500mA. Again, make sure the total load current does not exceed 2.1A during the test. dc1973af 3 DEMO MANUAL DC1973A Quick Start Procedure Figure 2. Proper Measurement Equipment Setup Figure 2. Measure Output Ripple dc1973af 4 DEMO MANUAL DC1973A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Cap., X7R 4.7µF 50V 10% 1206 TAIYO YUDEN, UMK316BJ475KL-T Required Circuit Components 1 1 C2 2 1 C3 Cap., X5R 0.22µF 16V 10% 0603 TAIYO YUDEN, EMK107BJ224KA-T 3 2 C4, C25 Cap., X7R 47µF 10V 10% 1210 MURATA, GRM32ER71A476KE15L 4 1 C5 Cap., X5R 0.1µF 16V 10% 0402 AVX, 0402YD104KAT2A 5 1 C6 Cap., X7R 1µF 25V 10% 0603 MURATA, GRM188R71E105KA12L 6 1 C13 Cap., X7R 1nF 25V 10% 0402 TDK, C1005X7R1E102K 7 1 R1 Res., Chip 1M 0.06W 1% 0402 VISHAY, CRCW04021M00FKED 8 1 R3 Res., 0.02Ω 0.25W 1% 1206 VISHAY, WSL1206R0200FEA 9 1 R4 Res., Sense, 0.3Ω 2W 1% 0830 SUSUMU, RL7520WT-R30-F 10 2 R6, R22 Res., Chip 100k 0.06W 5% 0402 VISHAY, CRCW0402100KJNED 11 1 R7 Res., Chip 12.4k 0.1W 1% 0603 VISHAY, CRCW060312K4FKEA 12 1 R8 Res., Chip 49.9k 0.06W 1% 0402 VISHAY, CRCW040249K9FKED 13 1 R9 Res., Chip 10k 0.06W 5% 0402 VISHAY, CRCW040210K0JNED 14 1 R10 Res., Chip 16.5k 0.1W 1% 0603 VISHAY, CRCW060316K5FKEA 15 1 U1 I.C., Switching Reg. QFN(24) (UDD) 3MMX5MM LINEAR TECH., LT8697EUDD#PBF Cap., Alum 22µF 63V 25% SUN ELECT., 63CE22BS Additional Demo Board Circuit Components 1 1 C1 2 1 C7 Cap., X7R 4.7µF 50V 10% 1206 MURATA, GRM31CR71H475KA12L 3 1 C8 Cap., X7R 4.7µF 50V 10% 1206 TAIYO YUDEN, UMK316BJ475KL-T 4 0 C9 (OPT) Cap., 1206 5 1 C10 Cap., X7R 0.1µF 25V 10% 0603 TDK, C1608X7R1E104K 6 2 C11, C12 Cap., X7R 1µF 25V 10% 0805 TDK, C2012X7R1E105K 7 1 C14 Cap., X7R 2.2nF 10V 10% 0603 AVX 0603ZC222KAT2A 8 3 C15-C17 Cap., X7R 0.1µF 50V 10% 0402 TDK, C1005X7R1H104K 9 1 FB1 Ferrite Bead, 0805 TDK, MPZ2012S221AT 10 1 L1 Inductor, 3.3µH COILCRAFT, XAL5030-332MEC 11 1 L2 Inductor, 4.7µH VISHAY, IHLP2020BZER4R7M01 DIODES INC., ZXMN3A14FTA 12 1 Q1 Power Mosfet, SOT23 13 0 R2, R14 (OPT) Res., 0402 14 2 R5, R23 Res., Power, 18Ω, 1W, 1% 2512 SUSUMU, CPA2512Q18R0FS-T10 dc1973af 5 DEMO MANUAL DC1973A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER VISHAY, CRCW12060000Z0EA 15 1 R11 Res., Chip, 0Ω, 0.25W, 1206 16 0 R13 Res., Chip, 1206 17 1 R15 Res., Chip, 75k, 0.1W, 1% 0603 VISHAY, CRCW060375K0FKEA 18 1 R16 Res., Chip, 43.2k, 0.1W, 1% 0603 VISHAY, CRCW060343K2FKEA 19 2 R17, R18 Res., Chip, 49.9k, 0.1W, 1% 0603 VISHAY, CRCW060349K9FKEA 20 1 R19 Res., Chip, 10k, 0.1W, 5% 0603 VISHAY, CRCW060310K0JNEA 21 1 R20 Res., Chip, 2M, 0.1W, 1% 0603 VISHAY, CRCW06032M00FKEA 22 2 R21, R24 Res., Chip, 2Ω, 0.25W, 5% 1206 VISHAY, CRCW12062R00JNEA 23 1 U2 I.C., Oscillator, TSOT-23-S5 LINEAR TECH., LT6900CS5#PBF Turret, Testpoint MILL-MAX, 2501-2-00-80-00-00-07-0 Hardware: For Demo Board Only 1 13 E1-E13 2 4 E15-E18 Testpoint, Turret, 0.061" MILL-MAX, 2308-2-00-80-00-00-07-0 3 5 X1-X5 Headers, Sgl. Row 3 Pins 2mm Ctrs. SULLINS, NRPN031PAEN-RC 4 5 xX1-xX5 Shunt, 2mm Ctrs. SAMTEC, 2SN-BK-G 5 1 J3 USB, Right Angle, Receptacle CnC TECH LLC, 1002-001-01000 6 4 MH1-MH4 Stand-Off, Nylon 0.375" KEYSTONE, 8832(SNAP ON) dc1973af 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. A B C D GND E2 ICTRL RCBL GND SYNC 5 E10 E8 E6 E4 C15 0.1µF 50V R22 100k R7 12.4k 0603 4.7µH C8 4.7µF 50V 1206 L2 + C6 1µF 25V 0603 INTVCC C1 22µF 63V SUNCON 63CE22BS 1. ALL RESISTORS ARE 0402. ALL CAPACITORS ARE 0402. NOTES: UNLESS OTHERWISE SPECIFIED 100k R6 FB1 C7 4.7uF 50V 1206 INTVCC C16 0.1µF 50V VIN 4 C5 0.1µF OPT R2 C2 4.7µF 50V 1206 R1 1M R20 2M 0603 R10 16.5k (2MHz) 0603 C17 0.1µF 50V 3 8 7 3 2 17 24 23 1 4 6 5 SET PGND PGND RT TR/SS INTVCC ICTRL RCBL SYNC EN/UV VIN VIN 2 VSYS OUT USB5V PG SYS ISN ISP SW SW SW X5 5 10k 0603 R19 20 19 18 22 21 15 14 13 16 3 C14 2.2nF 0603 U2 LTC6900CS5 V+ OPEN 3 BST U1 LT8697EUDD N/C E1 N/C 9 GND 25 N/C 11 N/C 12 VIN 6V - 42V 4 1 C3 0.22µF 16V 0603 L1 R5 18 2512 R21 2 1206 R23 18 2512 R24 2 1206 Q1 ZXMN3A14F VCABLE R14 OPT 49.9k R8 3.3µH C4 XAL5030-332MEC 47µF 10V 1210 3 2 R18 49.9k 0603 R16 43.2k 0603 C25 47µF 10V 1210 2 R17 49.9k 0603 OPEN DX2 3 1 SHORT R4 E15 VCABLE 1 2 X3 DATA- DATA+ 1 2 3 4 C12 1µF 25V 0805 C11 1µF 25V 0805 1 E11 E9 E7 E5 E3 VCABLE C10 E13 0.1µF 25V 0603 E12 USB 1 2 3 4 J3 0.3 2W 0830 C-GND GND R13 OPT 1206 E17 E18 VCABLE VOUT E16 OPEN OPEN SET 3 1 X4 0.02 1206 R3 VSYS X1 OPEN D+ 3 1 10k 1nF C9 OPT 10V 1206 R9 C13 R15 75k 0603 0 1206 R11 2 2 10 1 V+ GND 2 2 2 3 1 DIV 4 3 1 5 PG GND VOUT 5.xV / 2.1A C_GND VCABLE 5V / 2.1A GND VSYS 5.xV / 0.1A A B C D DEMO MANUAL DC1973A Schematic Diagram dc1973af 7 DEMO MANUAL DC1973A 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 dc1973af 8 Linear Technology Corporation LT 0713 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2013