DEMO MANUAL DC2438A LTM2894 7.5kVRMS Isolated USB Data Transceiver Description Demonstration circuit 2438A is an isolated USB data transceiver featuring the LTM(R)2894. The demo circuit features an EMI optimized circuit configuration, including an isolated DC-DC converter, and printed circuit board layout. All components for data signaling and isolation are integrated into the LTM2894 using LTC's isolator Module(R) technology. The demo circuit operates from a supply on VCC and/or VBUS. The DC-DC converter generates an unregulated isolated output voltage on VCC2 and regulated 5V for USB communication on VBUS2. Design files for this circuit board are available at http://www.linear.com/demo/DC2438A L, LT, LTC, LTM, Linear Technology, Module and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Performance Summary Specifications are at TA = 25C SYMBOL PARAMETER CONDITIONS VCC MIN TYP MAX Operating Supply Range (Isolated Power Input) 4.4 6 45 V VBUS Operating Supply Range (USB Bus Power Input) 4.4 5 5.5 V VCC2 Input Operating Range (DC-DC Off) VCC Input Operating Range (DC-DC On) Output Voltage 6 4.4 45 7.5 V V V V VBUS = 4.4V, ICC2 = 200mA VCC = 6V, ICC2 = 500mA 5.5 5.5 UNITS tLDR Low Speed Data Rate 1.5 Mbps tFDR Full Speed Data Rate 12 Mbps VIORM Maximum Working Insulation Voltage GND to GND2 Common Mode Transient Immunity 1414 1000 VDC VRMS 50 kV/s Operating Principles The LTM2894 demo board includes an isolated DC-DC converter delivering power to VCC2 at approximately 6V from the input supply VCC and/or VBUS. Isolation is maintained by the separation of GND and GND2 where significant operating voltages and transients can exist without affecting the operation of the LTM2894. The logic side is enabled upon connection of a USB cable via the LTM2894 ON pin. All logic side signals are referenced to the logic supply pin VLO. The LTM2894 has two power supply inputs, VCC and VBUS. For applications requiring more than 200mA from VCC2, VCC must be connected to an external supply of 6V to 7V. VBUS may be connected to USB bus power to enable data communication. If the isolated DC-DC converter is not needed then VCC2 may be driven by an external voltage. Upstream USB signaling is controlled by the bidirectional pins D1+ and D1-. A 1.5k pull-up resistor is automatically configured dependent upon the connected downstream peripheral device. For full speed operation a 1.5k pull-up is asserted on D1+, for low speed mode on D1-. The downstream USB data pins, D2+ and D2-, each have integrated 15k pull-down resistors. dc2438af 1 DEMO MANUAL DC2438A Operating Principles 1. Board/ground plane size has been minimized. This reduces the dipole antenna formed between the logic side and isolated side ground planes. 2. Top signal routing and ground floods have been optimized to reduce signal loops, minimizing differential mode radiation. 3. The DC-DC converter uses a cascaded transformer arrangement, where the first transformer's isolated side center tap is connected to logic side ground. This effectively returns all common mode currents generated by the switching converter edge rate and transformer parasitic capacitance. EMI performance is shown in Figure 1, measured using a gigahertz transverse electromagnetic (GTEM) cell and method detailed in IEC 61000-4-20, "Testing and Measurement Techniques - Emission and Immunity Testing in Transverse Electromagnetic Waveguides". 60 50 CISPR 22 CLASS B LIMIT 40 AMPLITUDE (dBV/m) The demo circuit has been designed and optimized for low RF emissions. EMI mitigation techniques used include the following: 30 20 10 0 -10 -20 -30 DC2438A DETECTOR = PEAK-HOLD RBW = 120kHz, VBW = 300kHz SWEEP TIME = 680ms # OF SWEEPS 10 # OF POINTS = 501 0 100 200 300 400 500 600 700 800 900 1000 FREQUENCY (MHz) DC2438a F01 Figure 1. DC2438A Radiated Emissions Quick Start Procedure Demonstration circuit 2438A is easy to set up and evaluate the performance of the LTM2894. Refer to Figure 2 for proper measurement equipment setup and follow the procedure below. NOTE: When measuring the input or output voltage ripple or high speed signals, care must be taken to avoid a long ground lead on the oscilloscope probe. 2. Connect USB cable from computer to input side (J1) of the demo board. 3. Connect computer mouse, low speed device, or USB memory stick, typically high speed device, to output side (J2) of demo board. 4. Verify proper operation of mouse or memory stick. 1. Connect external power supply to VCC and GND if greater than 200mA is required from VCC2 or VBUS2. Figure 2. Demo Board Setup dc2438af 2 DEMO MANUAL DC2438A Quick Start Procedure Figure 3. Layer 1 Top Layer Figure 4. Layer 2 Bottom Layer dc2438af 3 DEMO MANUAL DC2438A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER IC, LTM2894IY LINEAR LTM2894IY#PBF Required Circuit Components 1 1 U1 Hardware: For Demo Board Only 2 1 C1 Cap, Tantalum 4.7F 10% 2312 50V AVX TAJC475K050RNJ 3 1 C2 Cap, Ceramic 180pF 5% 0603 100V C0G AVX 06031A181JAT2A 4 2 C3, C6 Cap, Ceramic 4.7F 10% 1210 50V X7R AVX 12105C475KAT2A 5 2 C4, C5 Cap, Ceramic 47pF 5% 0603 100V C0G AVX 06031A470JAT2A 6 1 C7 Cap, Ceramic 22nF 10% 0603 25V X7R AVX 06033C223KAT2A 7 1 C8 Cap, Ceramic 1nF 10% 0603 50V X7R AVX 06035C102KAT2A 8 1 C9 Cap, Ceramic 10nF 10% 0603 50V X7R AVX 06035C103KAT2A 9 1 C10 Cap, Ceramic 10F 10% 0805 10V X7R Murata GRM21BR71A106KE51L 10 4 D1 to D4 Diode, Schottky, 80V 500mA SOD123 Diodes Inc. MBR0580S1-7 11 1 J1 USB RECEPTACLE TYPE B Wurth Elektronik 61400416121 12 1 J2 USB RECEPTACLE TYPE A Wurth Elektronik 61400416021 13 4 JP1 to JP4 Header, Loop 1x2 0.2 Aavid 125700D00000G 14 1 L1 Inducotr, 10H 1008 0.5 0.25A Wurth Elektronik 74479888310 15 3 R1, R6, R7 Resistor, 100k 1% 0603 Vishay CRCW0603100KFKEA 16 1 R2 Resistor, 464k 1% 0603 Vishay CRCW0603464KFKEA 17 1 R3 Resistor, 28k 1% 0603 Vishay CRCW060328K0FKEA 18 1 R4 Resistor, 49.9k 1% 0603 Vishay CRCW060349K9FKEA 19 1 R5 Resistor, 39 1% 0805 Vishay CRCW080539R0FKEA 20 2 R8, R9 Resistor, 249 1% 0805 Vishay CRCW0805249RFKEA 21 1 TR1 Transformer, 2.5kV 1:1.1 Wurth Elektronik 760390012 22 1 TR2 Transformer, 5kV 1:1.7 Wurth Elektronik 750313769 23 1 U2 IC, 1A, 1MHz, Push-Pull DC-DC Driver LINEAR LT3999IMSE#PBF 24 1 U3 IC, 45V VIN, Low Noise, 500mA LDO LINEAR LT3065IDD-5#PBF dc2438af 4 DEMO MANUAL DC2438A Schematic Diagram dc2438af 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 DC2438A 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 (c) 2004, Linear Technology Corporation dc2438af 6 Linear Technology Corporation LT 0316 * PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear.com (c) LINEAR TECHNOLOGY CORPORATION 2016