ADM00433

MCP16301 High-Performance Low-Noise 5V Output Buck Converter Evaluation Board User’s Guide  2012-2013 Microchip Technology Inc. DS50002063B Note the following details of the code protection feature on Microchip devices: • Microchip products meet the specification contained in their particular Microchip Data Sheet. • Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions. • There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data Sheets. 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Trademarks The Microchip name and logo, the Microchip logo, dsPIC, FlashFlex, KEELOQ, KEELOQ logo, MPLAB, PIC, PICmicro, PICSTART, PIC32 logo, rfPIC, SST, SST Logo, SuperFlash and UNI/O are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. FilterLab, Hampshire, HI-TECH C, Linear Active Thermistor, MTP, SEEVAL and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A. Silicon Storage Technology is a registered trademark of Microchip Technology Inc. in other countries. Analog-for-the-Digital Age, Application Maestro, BodyCom, chipKIT, chipKIT logo, CodeGuard, dsPICDEM, dsPICDEM.net, dsPICworks, dsSPEAK, ECAN, ECONOMONITOR, FanSense, HI-TIDE, In-Circuit Serial Programming, ICSP, Mindi, MiWi, MPASM, MPF, MPLAB Certified logo, MPLIB, MPLINK, mTouch, Omniscient Code Generation, PICC, PICC-18, PICDEM, PICDEM.net, PICkit, PICtail, REAL ICE, rfLAB, Select Mode, SQI, Serial Quad I/O, Total Endurance, TSHARC, UniWinDriver, WiperLock, ZENA and Z-Scale are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. GestIC and ULPP are registered trademarks of Microchip Technology Germany II GmbH & Co. KG, a subsidiary of Microchip Technology Inc., in other countries. All other trademarks mentioned herein are property of their respective companies. © 2012-2013, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper. ISBN: 978-1-62077-420-5 QUALITY MANAGEMENT SYSTEM CERTIFIED BY DNV == ISO/TS 16949 == DS50002063B-page 2 Microchip received ISO/TS-16949:2009 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California and India. The Company’s quality system processes and procedures are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001:2000 certified.  2012-2013 Microchip Technology Inc. Object of Declaration: MCP16301 High-Performance Low-Noise 5V Output Buck Converter Evaluation Board User’s Guide  2012-2013 Microchip Technology Inc. DS50002063B-page 3 MCP16301 HIGH-PERFORMANCE LOW-NOISE 5V BUCK CONVERTER EVALUATION BOARD USER’S GUIDE Table of Contents Preface ........................................................................................................................... 5 Introduction............................................................................................................ 5 Document Layout .................................................................................................. 5 Conventions Used in this Guide ............................................................................ 6 Recommended Reading........................................................................................ 7 The Microchip Web Site ........................................................................................ 7 Customer Support ................................................................................................. 7 Document Revision History ................................................................................... 7 Chapter 1. Product Overview 1.1 Introduction ..................................................................................................... 9 1.2 MCP16301 Short Overview ............................................................................ 9 1.3 What Is the MCP16301 High Performance Low Noise 5V Buck Converter Evaluation Board? .................................................................................. 11 1.4 MCP16301 High Performance Low Noise 5V Buck Converter Evaluation Board Kit Contents ................................................................ 11 Chapter 2. Installation and Operation 2.1 Introduction ................................................................................................... 13 2.2 Getting Started ............................................................................................. 14 Appendix A. Schematic and Layouts A.1 Introduction .................................................................................................. 21 A.2 Board – Schematic ....................................................................................... 22 A.3 Board – Top Silk And Copper ...................................................................... 23 A.4 Board – Mid Inner Layer 1 ........................................................................... 24 A.5 Board – Mid Inner Layer 2 ........................................................................... 25 A.6 Board – Bottom Copper and Pads ............................................................... 26 Appendix B. Bill of Materials (BOM).......................................................................... 27 Worldwide Sales and Service .................................................................................... 28  2012-2013 Microchip Technology Inc. DS50002063B-page 4 MCP16301 HIGH-PERFORMANCE LOW-NOISE 5V BUCK CONVERTER EVALUATION BOARD USER’S GUIDE Preface NOTICE TO CUSTOMERS All documentation becomes dated, and this manual is no exception. Microchip tools and documentation are constantly evolving to meet customer needs, so some actual dialogs and/or tool descriptions may differ from those in this document. Please refer to our web site (www.microchip.com) to obtain the latest documentation available. Documents are identified with a “DS” number. This number is located on the bottom of each page, in front of the page number. The numbering convention for the DS number is “DSXXXXXA”, where “XXXXX” is the document number and “A” is the revision level of the document. For the most up-to-date information on development tools, see the MPLAB® IDE online help. Select the Help menu, and then Topics to open a list of available online help files. INTRODUCTION This chapter contains general information that will be useful to know before using the MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board. Items discussed in this chapter include: • • • • • • Document Layout Conventions Used in this Guide Recommended Reading The Microchip Web Site Customer Support Document Revision History DOCUMENT LAYOUT This document describes how to use the MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board as a development tool to emulate and debug firmware on a target board. The manual layout is as follows: • Chapter 1. “Product Overview” – Important information about the MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board • Chapter 2. “Installation and Operation” – Includes instructions on how to get started with the MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board and a description of the user’s guide • Appendix A. “Schematic and Layouts” – Shows the schematic and layout diagrams for the MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board • Appendix B. “Bill of Materials (BOM)” – Lists the parts used to build the MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board  2012-2013 Microchip Technology Inc. DS50002063B-page 5 MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board User’s Guide CONVENTIONS USED IN THIS GUIDE This manual uses the following documentation conventions: DOCUMENTATION CONVENTIONS Description Arial font: Italic characters Initial caps Quotes Underlined, italic text with right angle bracket Bold characters N‘Rnnnn Text in angle brackets < > Courier New font: Plain Courier New Represents Examples Referenced books Emphasized text A window A dialog A menu selection A field name in a window or dialog A menu path MPLAB® IDE User’s Guide ...is the only compiler... the Output window the Settings dialog select Enable Programmer “Save project before build” A dialog button A tab A number in verilog format, where N is the total number of digits, R is the radix and n is a digit. A key on the keyboard Click OK Click the Power tab 4‘b0010, 2‘hF1 Italic Courier New Sample source code Filenames File paths Keywords Command-line options Bit values Constants A variable argument Square brackets [ ] Optional arguments Curly brackets and pipe character: { | } Ellipses... Choice of mutually exclusive arguments; an OR selection Replaces repeated text Represents code supplied by user DS50002063B-page 6 File>Save Press , #define START autoexec.bat c:\mcc18\h _asm, _endasm, static -Opa+, -Opa0, 1 0xFF, ‘A’ file.o, where file can be any valid filename mcc18 [options] file [options] errorlevel {0|1} var_name [, var_name...] void main (void) { ... }  2012-2013 Microchip Technology Inc. Preface RECOMMENDED READING This user's guide describes how to use the MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board. Other useful documents are listed below. The following Microchip documents are available and recommended as supplemental reference resources. • MCP16301 Data Sheet – “High-Voltage Input Integrated Switch Step-Down Regulator” (DS25004) • MCP16301 High-Voltage Buck-Boost Demo Board User’s Guide (DS52020) • MCP16301 High-Voltage Buck Converter 600 mA Demo Board User’s Guide (DS51978) THE MICROCHIP WEB SITE Microchip provides online support via our web site at www.microchip.com. This web site is used as a means to make files and information easily available to customers. Accessible by using your favorite Internet browser, the web site contains the following information: • Product Support – Data sheets and errata, application notes and sample programs, design resources, user’s guides and hardware support documents, latest software releases and archived software • General Technical Support – Frequently Asked Questions (FAQs), technical support requests, online discussion groups, Microchip consultant program member listing • Business of Microchip – Product selector and ordering guides, latest Microchip press releases, listing of seminars and events, listings of Microchip sales offices, distributors and factory representatives CUSTOMER SUPPORT Users of Microchip products can receive assistance through several channels: • • • • Distributor or Representative Local Sales Office Field Application Engineer (FAE) Technical Support Customers should contact their distributor, representative or field application engineer (FAE) for support. Local sales offices are also available to help customers. A listing of sales offices and locations is included in the back of this document. Technical support is available through the web site at: http://www.microchip.com/support. DOCUMENT REVISION HISTORY Revision B (August 2013) • Updated the board layout in Figure 2-2. • Updated the A.3 “Board – Top Silk And Copper” and A.6 “Board – Bottom Copper and Pads” layouts in Appendix A. “Schematic and Layouts”. • Updated Appendix B. “Bill of Materials (BOM)”. Revision A (June 2012) • Initial Release of this Document.  2012-2013 Microchip Technology Inc. DS50002063B-page 7 MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board User’s Guide NOTES: DS50002063B-page 8  2012-2013 Microchip Technology Inc. MCP16301 HIGH-PERFORMANCE LOW-NOISE 5V BUCK CONVERTER EVALUATION BOARD USER’S GUIDE Chapter 1. Product Overview 1.1 INTRODUCTION This chapter provides an overview of the MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board and covers the following topics: • MCP16301 Short Overview • What Is the MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board? • MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board Kit Contents 1.2 MCP16301 SHORT OVERVIEW The MCP16301 device is a highly integrated, high-efficiency, fixed frequency, step-down DC-DC converter in a popular 6-pin SOT-23 package, that operates from input voltage sources up to 30V. Integrated features include a high-side switch, fixed frequency peak current mode control, internal compensation, peak current limit and overtemperature protection. All control system components necessary for stable operation over the entire device operating range are integrated. High-converter efficiency is achieved by integrating the current-limited, low-resistance, high-speed N-Channel MOSFET and associated drive circuitry. High-switching frequency minimizes the size of the external filtering components, resulting in a small solution size. The MCP16301 is a high-input voltage step-down regulator, capable of supplying a maximum of 600 mA to a regulated output voltage from 2.0V to 15V. An integrated precise 0.8V reference combined with an external resistor divider sets the desired converter output voltage. The internal reference voltage rate of rise is controlled during startup, minimizing the output voltage overshoot and the inrush current. The internally trimmed 500 kHz oscillator provides a fixed frequency, while the peak current mode control architecture varies the duty cycle for output voltage regulation. An internal floating driver is used to turn the high side integrated N-Channel MOSFET on and off. The power for this driver is derived from an external boost capacitor whose energy is supplied from a fixed voltage ranging between 3.0V and 5.5V, typically the output voltage of the converter. For applications with 5.5V < VOUT < 15V and VIN < 30V, an alternative boost supply must be used (from input derived, output derived or an auxiliary system voltage). For more information and examples, see the MCP16301 data sheet. The EN input is used to enable and disable the device. If disabled, the MCP16301 device consumes 7 µA (typical) from the input. An integrated Under Voltage Lockout (UVLO) prevents the converter from starting until the input voltage is high enough for normal operation. The converter will typically start at 3.5V and operate down to 3.0V. An overtemperature protection limits the silicon die temperature to +150°C by turning the converter off. The normal switching resumes at +120°C.  2012-2013 Microchip Technology Inc. DS50002063B-page 9 MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board User’s Guide 1N4448 VIN 4.5V To 30V CBOOST L1 100 nF 15 µH BOOST SW VIN CIN 22 µF VOUT 3.3V @ 600 mA 40V Schottky Diode EN COUT 22 µF 31.2 K VFB GND FIGURE 1-1: 1.2.1 • • • • • • • • • • • • • • • DS50002063B-page 10 10 K Typical MCP16301 3.3V OUT Application. MCP16301 Features Up to 96% Typical Efficiency Input Voltage Range: 4.0V to 30V Output Voltage Range: 2.0V to 15V 2% Output Voltage Accuracy 600 mA Output Current Quiescent Current (Switching Mode, No Load): 2 mA Typical Quiescent Current (Shutdown, EN = 0): 7 µA Typical 500 kHz Fixed Frequency Peak Current Mode Control Internal Compensation Internal Soft-Start Cycle-by-Cycle Peak Current Limit Undervoltage Lockout (UVLO): 3.5V to Start, 3.0V to Stop Overtemperature Protection Package type: SOT-23-6  2012-2013 Microchip Technology Inc. Product Overview 1.3 WHAT IS THE MCP16301 HIGH-PERFORMANCE LOW-NOISE 5V BUCK CONVERTER EVALUATION BOARD? The MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board is designed to operate from a 6V to 30V input and regulate the output to 5V, while delivering a maximum 600 mA of load current. The evaluation board is optimized for a high-efficiency and low-output noise and ripple, especially at 12V Input and 100 mA load current. Because the MCP16301 is switching fast to achieve high efficiency, high-frequency noise is generated and may affect some RF systems. This evaluation board demonstrates a low-noise, high-performance design. RBOOST CBOOST 82R BOOST BOOST Diode 100 nF L 22 µH VOUT = 5V SW CIN 22 µF VIN EN CSnubber 120 pF RSnubber 4R7 MCP16301 VIN = 12V Input RT 52k3 COUT FB GND 22 µF RB 10k FIGURE 1-2: MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board Block Diagram. 1.4 MCP16301 HIGH-PERFORMANCE LOW-NOISE 5V BUCK CONVERTER EVALUATION BOARD KIT CONTENTS The MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board kit includes: • MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board • Important Information Sheet  2012-2013 Microchip Technology Inc. DS50002063B-page 11 MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board User’s Guide NOTES: DS50002063B-page 12  2012-2013 Microchip Technology Inc. MCP16301 HIGH-PERFORMANCE LOW-NOISE 5V BUCK CONVERTER EVALUATION BOARD USER’S GUIDE Chapter 2. Installation and Operation 2.1 INTRODUCTION The MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board is used to demonstrate a high-voltage input DC-DC converter design, that can deliver high efficiency, while minimizing high-frequency switching noise. The board steps down high-input voltages, up to 30V, to a low-output voltage, having more than 90% efficiency and a minimum of 30 mV output ripple. High-frequency input/output noise generated by the switching converters can reach high-noise levels that interfere with other devices powered from the same source. The high amplitude of high-frequency noise can disturb some RF systems. High efficiency is achieved with the MCP16301 buck converter by switching the integrated N-Channel MOSFET at a high speed. This high speed can cause disturbances to other system components if the high-speed switching edges of the converter are not minimized. The designer must be concerned with: • good PCB layout practice • choosing high-quality shielded inductors and low Equivalent Series Resistance (ESR) capacitors • choosing an RC snubber or a RBOOST resistor to properly limit the speed of the internal N-Channel MOSFET switch (see Figure 1-2). The evaluation board is optimized for 12V Input and 100 mA load. 2.1.1 MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board Features The MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board has the following key features: • • • • • • Input Voltage: 6 to 30V Output Voltage: 5V Output Capability: 600 mA Load Current Output Ripple Plus Noise: 30 mVp-p @ 12V Input and 100 mA Load Low-Radiated Noise Efficiency: Up to 91% @ 12V Input (see Figure 2-1)  2012-2013 Microchip Technology Inc. DS50002063B-page 13 MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board User’s Guide 90 Efficiency (%) 80 70 60 50 40 0 FIGURE 2-1: 2.2 100 200 300 IOUT (mA) 400 500 600 Efficiency vs. Load Current at 12V Input. GETTING STARTED The MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board is fully assembled and tested to evaluate and demonstrate the MCP16301 design. 2.2.1 Power Input and Output Connection 2.2.1.1 POWERING THE MCP16301 HIGH-PERFORMANCE LOW-NOISE 5V BUCK CONVERTER EVALUATION BOARD When the board is ready for evaluation, apply positive input voltage to the VIN terminal and the corresponding return to the ground terminal. The maximum input voltage should not exceed 30V. An electronic load or resistive load can be used for evaluation. The electronic loads attempt to sink current at 0V during startup. A resistive load or constant resistance is recommended for startup evaluation. Connect the positive voltage terminal of the load to the VOUT terminal on the evaluation board, and connect the negative or return side of the load to the ground terminal. Connectors are placed on the bottom side of board: • VIN for positive power • Two grounds for negative power • VOUT connector for output load DS50002063B-page 14  2012-2013 Microchip Technology Inc. Installation and Operation 2.2.2 Board Testing To test the board, follow these steps: 1. Apply the input voltage. 2. An external pull up resistor is connected from VIN to the EN input of the MCP16301. Once the input voltage is greater than 3.5V, the device begins to switch. Apply greater than 6V supply to the input for proper operation. A minimum load is required to regulate the output to 5V. For minimum load requirements (light load conditions), see the device data sheet for detailed information. 3. The measured output voltage should be 5V typical. Adjusting the input voltage and load should not cause the output to vary more than a few mV over the operating range of the converter. 4. Typical conditions for evaluating the board are: 12V input, 100 mA load. Using an oscilloscope, measure the AC ripple of the output without any bandwidth limitation. VOUT ripple plus noise should be approximately 30 mV. To avoid errors, remove the ground lead of the scope probe and measure the output ripple on the output capacitors pads. Use a short wire wrapped around the ground barrel of the probe to touch the capacitor’s ground pad. Note: The VOUT ripple plus noise value varies with the input and output parameters. Additional analysis can be performed by changing the RC snubber and RBOOST resistor values (see Figure 2-1). These additional circuits lower the efficiency, but reduce switching noise. Set 12V Power Supply FIGURE 2-2: Circuit. V-Meter R MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board Setup  2012-2013 Microchip Technology Inc. DS50002063B-page 15 MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board User’s Guide 2.2.3 How Does the MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board Work? The MCP16301 integrates a low resistance N-Channel MOSFET (typically 460 m). A high-side or floating supply is needed to drive the gate of the N-Channel MOSFET above the input voltage (to turn it on). The evaluation board uses the 5V output voltage to charge the boost capacitor (CBOOST), while the inductor current flows, clamping the SW node to a diode drop below ground. Prior to start up, there is no inductor current, so an internal precharge circuit charges the boost cap up to a minimum threshold. Once CBOOST is charged, the N-Channel MOSFET can be turned on, ramping current into the inductor. The BOOST diode is used to provide a charging path for the CBOOST capacitor, while current is flowing through the inductor. The two sense resistors (RT and RB in Figure 2-1) set the output (VOUT) at 5.0V according to the following equation: EQUATION 2-1: V OUT R TOP = R BOT   ------------- – 1 V FB where VFB = 0.8V is the reference voltage of the FB pin. The transconductance error amplifier gain is controlled by its internal impedance. The external divider resistors have no effect on system gain, so a wide range of values can be used. A 10 k resistor is recommended as a good trade-off for quiescent current and noise immunity. The MCP16301 device features integrated slope compensation to prevent the bimodal operation of the pulse-width modulation (PWM) duty cycle. Internally, approximately half of the inductor current down slope is summed with the internal current sense signal. For the proper amount of slope compensation, it is recommended to keep the inductor down-slope current constant by varying the inductance with VOUT. For 5.0V output, a 22 µH inductor is recommended. The input capacitor must filter the high input ripple current, as a result of pulsing or chopping the input voltage. The MCP16301 input voltage pin is used to supply voltage for the power train and as a source for internal bias. A low Equivalent Series Resistance (ESR), preferably a ceramic capacitor, is recommended. The necessary capacitance is dependent upon the maximum load current and source impedance. Minimum capacitance at light load is 2.2 µF. The output capacitor helps in providing a stable output voltage during sudden load transients, and reduces the output voltage ripple. The minimum value of the output capacitance is limited to 20 µF, due to the integrated compensation of the MCP16301. The freewheeling diode creates a path for inductor current flow after the internal switch is turned off. The efficiency of the converter is a function of the forward drop voltage value and speed of the freewheeling Schottky diode. For detailed information, see the MCP16301 Data Sheet (DS25004). DS50002063B-page 16  2012-2013 Microchip Technology Inc. Installation and Operation 2.2.4 Reduction of the High Frequency Switching Noise Because the MCP16301’s internal MOSFET is switching at 500 kHz, high-frequency noise may appear. This can affect the circuitry in close proximity. Parasitic elements generate ringing. There are two main noise sources. The first source occurs at the fundamental switching frequency and is called “Output Ripple”. The second source, associated with high-frequency ringing, occurs during the ON-OFF transition of the integrated N-Channel MOSFET switch. This results in a high-frequency noise that can be in the range of 100s of MHz and up to 500 mV peak-to-peak voltage ripple. Both noise components require separate filtering. Figure 2-3 shows an example of the two noise components. FIGURE 2-3: VOUT Ripple and Noise for an MCP16301 Buck Converter Without Any Noise Reduction Components. The low-frequency output ripple of the MCP16301 is generally less than 20 mV peak-to-peak, and it depends on the output capacitor value and capacitor dielectric type. Low ESR and Equivalent Series Inductance (ESL) ceramic capacitors significantly decrease the output voltage low-frequency ripple. Additional output capacitance does not remove the high-frequency noise. Ceramic capacitors have high-impedance in the frequency band in which this noise occurs. The ringing frequency is very high, and the output capacitor alone or an extra low-value capacitor in parallel with it are ineffective in attenuating this noise. First, the noise can be attenuated by good PCB design practices. A four-layer board is recommended in this case. The solution is to place the SW node of the MCP16301 pin into the inner layer (Mid-Layer 2) as an individual plane between two ground planes (Mid-Layer 1 and Layer 4 - Bottom plane). High-quality shielded inductors reduce the spreading of electromagnetic fields, a desirable characteristic of any power supply. An example of a high-quality shielded inductor is the CoilCraft Inc. XAL6060.  2012-2013 Microchip Technology Inc. DS50002063B-page 17 MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board User’s Guide The third and most effective method to reduce switching noise is to slow down the turn-on of the integrated N-Channel MOSFET switch, addressing the noise at its source. This method lowers the efficiency of the converter insignificantly (see Figure 2-6), but the noise in the system is significantly reduced. A RBOOST resistance value between 47 and 100 Ohms was typical for this analysis. Placing an RC snubber in parallel with the external Schottky diode is another method that can be used to reduce high-frequency noise. Some basic equations are used to calculate the RC snubber values. For example, the Schottky rectifier diode MBRA140T (1A/40V) has a parasitic Lp = 2 nH and Cp = 38 pF (see the MBRA140T data sheet for details). When measuring the MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board circuit without an RC snubber (for 12V Input and 100 mA load), the ringing frequency is approximately 250 MHz. Considering the parasitic inductance equal to LP, calculate the parasitic impedance, using the following equation: EQUATION 2-2: Z = 2  fL p For this example, Z is approximately 3. Choose a snubber resistor to be similar or greater than this value (4.7 standard value). EQUATION 2-3: R Snubber  Z Where: RSnubber = 4.7 With the value of RSnubber established, the snubber’s capacitor value results from the following equation: EQUATION 2-4: 1 C Snubber = ----------------------------2  fR Snubber Where: CSnubber = 120 pF DS50002063B-page 18  2012-2013 Microchip Technology Inc. Installation and Operation Figures 2-4 – 2-6 show the results for the MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board: • AC output ripple for board with RC snubber only (Figure 2-4) • AC output ripple for RC snubber and RBOOST on board (Figure 2-5) • Efficiency comparison with RC snubber and RBOOST (Figure 2-6) FIGURE 2-4: VOUT Ripple of the Evaluation Board is less than 80 mVp-p using RC Snubber only (12V Input, 100 mA Load). Compare to Figure 2-3. FIGURE 2-5: VOUT Ripple of the Evaluation Board is less than 30 mVp-p using RC Snubber and RBOOST (12V Input, 100 mA Load). Compare to Figures 2-3 and 2-4.  2012-2013 Microchip Technology Inc. DS50002063B-page 19 MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board User’s Guide Efficiency (%) 90 80 70 Vin = 12V, no RC Snubber, no RBoost Vin = 24V no RC Snubber, no RBoost 60 Vin = 12V, RC Snubber, no RBoost Vin = 24V, RC Snubber, no RBoost 50 Vin = 12V, Snubber, RBoost Vin = 24V, Snubber, RBoost 40 0 100 200 300 IOUT (mA) 400 500 600 FIGURE 2-6: Efficiency Comparison for the MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board (12V and 24V Input). DS50002063B-page 20  2012-2013 Microchip Technology Inc. MCP16301 HIGH-PERFORMANCE LOW-NOISE 5V BUCK CONVERTER EVALUATION BOARD USER’S GUIDE Appendix A. Schematic and Layouts A.1 INTRODUCTION This appendix contains the following schematics and layouts for the MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board: • • • • • Board – Schematic Board – Top Silk And Copper Board – Mid-Inner Layer 1 Board – Mid-Inner Layer 2 Board – Bottom Copper and Pads  2012-2013 Microchip Technology Inc. DS50002063B-page 21 BOARD – SCHEMATIC D1 VIN = 12V J1 1N4148WS 1 R5 C2 10uF C3 10uF R1 1M 5 EN SW VFB 2 4 VIN GND BOOST 1 VIN MCP16301 U1 C1 0603 0.1uF VOUT = 5V J2 L1 6 22uH/5A 1 1% R2 52.3K 3 R3 4.7 C7 J3 C6 VOUT C4 10uF C5 10uF 1% 0603 D2 MBRA140T3G 0603 1% R4 10k J4 120p 1 GND 82  2012-2013 Microchip Technology Inc. GND GND GND GND 1 GND GND GND GND GND GND MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board User’s Guide DS50002063B-page 22 A.2 Schematic and Layouts A.3 BOARD – TOP SILK AND COPPER  2012-2013 Microchip Technology Inc. DS50002063B-page 23 MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board User’s Guide A.4 BOARD – MID-INNER LAYER 1 DS50002063B-page 24  2012-2013 Microchip Technology Inc. Schematic and Layouts A.5 BOARD – MID-INNER LAYER 2  2012-2013 Microchip Technology Inc. DS50002063B-page 25 MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board User’s Guide A.6 BOARD – BOTTOM COPPER AND PADS DS50002063B-page 26  2012-2013 Microchip Technology Inc. MCP16301 HIGH-PERFORMANCE LOW-NOISE 5V BUCK CONVERTER EVALUATION BOARD USER’S GUIDE Appendix B. Bill of Materials (BOM) TABLE B-1: Qty. BILL OF MATERIALS (BOM) Reference Description Manufacturer 1 C1 Cap. ceramic 0.1 µF 50V X7R 10% 0603 TDK® 2 C2, C3 Cap. ceramic 10 µF 50V X7S 1210 TDK Corporation Part Number Corporation C1608X7R1H104K C3225X7S1H106M ® 2 C4, C5 Cap. ceramic 10 µF 10V X7R 10% 0805 Murata Electronics GRM21BR71A106KE51L 0 C6 DO NOT POPULATE — — 1 C7 Capacitor, NP0, 0603, 100V, 120 pF KEMET® 1 D1 Diode switch 75V 200 mW SOD323 Diodes® Incorporated 1N4148WS-7-F 1 D2 Diode Schottky 40V 1A SMA ON Semiconductor® MBRA140T3G 4 J1, J2, J3, J4 PC test point tin SMD Harwin Plc. S1751-46R 1 L1 Inductor 22 µH 5A SMD Coilcraft® XAL6060-223MEB 1 PCB Printed Circuit Board - MCP16301 High-Performance Low-Noise 5V Buck Converter Evaluation Board — 104-00433 1 R1 Res. 1.0M Ohm 1/10W 5% 0603 SMD Panasonic® - ECG ERJ-3GEYJ105V 1 R2 Res. 52.3k Ohm 1/10W .1% 0603 SMD Panasonic - ECG ERA-3AEB5232V 1 R4 Res. 10k Ohm 1/10W 1% 0603 SMD Panasonic - ECG ERJ-3EKF1002V 1 R5 Res. 82 Ohm 1/10W 5% 0603 SMD Panasonic - ECG ERJ-3GEYJ820V 1 R3 Res. 4.7 Ohm 1/10W 1% 0603 SMD Panasonic - ECG ERJ-3RQF4R7V 1 U1 High-Voltage Input Integrated Switch Step-Down Regulator Microchip Technology Inc. MCP16301T-E/CH Note 1: Corp. C0603C121J1GACTU The components listed in this Bill of Materials are representative of the PCB assembly. The released BOM used in manufacturing uses all RoHS-compliant components.  2012-2013 Microchip Technology Inc. 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