TB3121. Conducted and Radiated Emissions on 8-Bit Mid-Range Microcontrollers INTRODUCTION ELECTROMAGNETIC COMPATIBILITY CONDUCTED EMISSIONS

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1 Conducted and Radiated Emissions on 8-Bit Mid-Range Microcontrollers TB3121 Author: Enrique Aleman Microchip Technology Inc. INTRODUCTION This technical brief is intended to describe the emissions testing and performance of Microchip s 8-bit PIC microcontroller products. It describes the methods used for both radiated and conducted emissions and the standards referenced for such testing, followed by an overview of PIC mid-range microcontroller performance and behavior. The series of mid-range PIC microcontrollers has integrated a set of features designed for conducted and radiated emissions compliance. These microcontrollers have been developed as true mixedsignal process with emissions robustness enhancement incorporated as part of the design. FIGURE 1: IC RADIATED vs. CONDUCTED EMISSIONS ELECTROMAGNETIC COMPATIBILITY Electromagnetic compatibility (EMC) is the capability of an electronic system to function with other electronic systems and not produce or be affected by interference. That is, a compatible device must not cause electromagnetic interference (EMI) to other systems and is not susceptible to emissions from other systems or from its own. EMI is the conducted or radiated electrical noise generated by a particular system. Knowing that all electronics generate an electromagnetic field (EMF), the ability of these products to minimize their own EMI becomes all that more important. EMI can damage an embedded application with results ranging from simple nuisances in a product s operation to failures causing a cease in product functionality. Embedded system designers understand the importance of selecting devices that will perform and will not cause interference to other components in their designs. As system frequencies and the need for lower supply voltages increase and silicon geometries decrease, the end application becomes more and more vulnerable to the negative effects of EMI. These electrical influences can be generated by either radiated or conductive EMI sources (see Figure 1 and Figure 2). Radiated sources within the microcontroller core include the oscillator, voltage regulator, power lines, PWM modules and other modules within the microcontroller. Conductive EMI primarily shows itself as electrical noise on the power supply lines of an application and can be caused by induced voltage spikes from other devices within a system. FIGURE 2: EMI PATHS 2014 Microchip Technology Inc. DS A-page 1

2 EMISSIONS TESTING Radiated Emissions Microchip s PIC microcontrollers are tested for radiated emissions in accordance to the specifications of the IEC and SAE J1752/3 standards (measurement of radiated emissions from ICs TEM cell method 150 khz to 1 GHz). Radiated noise measurements are performed with the device running code in a loop. Typically, the device is programmed to increment a PORT output in a 100 µs loop. All other pins are configured as output driven low. PIC microcontrollers are tested for radiated emissions in two axes, with the device under test (DUT) mounted on an EMC test board installed in a port cut in the top of the TEM cell (see Figure 3 and Figure 4). FIGURE 3: TRANSVERSAL ELECTROMAGNETIC (TEM) CELL SETUP FIGURE 4: TYPICAL RADIATED EMISSIONS TEST BOARD DS A-page Microchip Technology Inc.

3 TYPICAL RADIATED EMISSION RESULTS Measurements were taken using a spectrum analyzer and an RF TEM cell to detect noise that could potentially be injected into the surrounding electrical system from the PIC microcontroller. With a 5V power supply and 16 MHz internal oscillator, the PIC microcontroller does not generate any noise greater than the noise floor throughout the frequency sweep (see Figure 5 and Figure 6). FIGURE 5: TYPICAL RADIATED NOISE EMISSIONS: X-AXIS PIC16F1503 INTRC, 16 MHz FIGURE 6: TYPICAL RADIATED NOISE EMISSIONS: Y-AXIS PIC16F1503 INTRC, 16 MHz 2014 Microchip Technology Inc. DS A-page 3

4 Conducted Emissions Microchip s PIC microcontrollers are tested for conducted emissions in accordance to the specifications of the IEC (conducted emissions 1Ω/150Ω direct coupling). Conducted noise measurements are performed with the device running code in a loop. Typically, the device is programmed to increment a PORT output in a 100 µs loop. All other pins are configured as output driven low (see Figure 7). Each microcontroller pin is then measured for conducted emissions (see Figure 8). The device is mounted on an IC EMC test board. FIGURE 7: TYPICAL TEST CIRCUIT VDD IC 120 6,8 nf (1) to spectrum analyzer 49 C1 1 VSS Signal pin 51 to spectrum analyzer Note 1: Capacitor value may vary according to maximum capacitive load specified for the pin. FIGURE 8: TYPICAL CONDUCTED EMISSION RESULTS (VDD PIN) PIC16F1503 INTRC, 16 MHz DS A-page Microchip Technology Inc.

5 TESTED PRODUCTS A majority of 8-bit mid-range microcontroller products have been tested in accordance to radiated and conducted emissions standards. All of these products are currently available with the latest EMC silicon methodologies. For the latest list of products please go to Note: The conductive/radiated noise data shown is a typical representation of 8-bit Flash mid-range PIC microcontrollers. Please note that this data will vary based upon process technology, product architecture, packaging and other factors. Contact your local Microchip representative for specific Microchip product data. REFERENCES AND RESOURCES IEC , Integrated Circuits Measurement of Electromagnetic Emissions, 150 khz to 1 GHz, Part 2: Measurement of radiated emissions TEM Cell and Wideband TEM cell method, International Electrotechnical Commission, Geneva, Switzerland 3. IEC , Integrated Circuits Measurement of Electromagnetic Emissions, 150 khz to 1 GHz, Part 4: Measurement of conducted emissions 1 /150 Direct Coupling Method, International Electrotechnical Commission, Geneva, Switzerland Ultimately, prevention of EMI/EMC within a particular application remains the responsibility of the embedded designer. This begins with the implementation of good board design practices including proper PCB layout and grounding, limiting trace lengths, placement of electrical components, as well as selection of the most EMI-resilient silicon products Microchip Technology Inc. DS A-page 5

6 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. Most likely, the person doing so is engaged in theft of intellectual property. Microchip is willing to work with the customer who is concerned about the integrity of their code. Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as unbreakable. Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break Microchip s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act. Information contained in this publication regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer s risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights. QUALITY MANAGEMENT SYSTEM CERTIFIED BY DNV == ISO/TS == Trademarks The Microchip name and logo, the Microchip logo, dspic, FlashFlex, flexpwr, JukeBlox, KEELOQ, KEELOQ logo, Kleer, LANCheck, MediaLB, MOST, MOST logo, MPLAB, OptoLyzer, PIC, PICSTART, PIC 32 logo, RightTouch, SpyNIC, SST, SST Logo, SuperFlash and UNI/O are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. The Embedded Control Solutions Company and mtouch are registered trademarks of Microchip Technology Incorporated in the U.S.A. Analog-for-the-Digital Age, BodyCom, chipkit, chipkit logo, CodeGuard, dspicdem, dspicdem.net, ECAN, In-Circuit Serial Programming, ICSP, Inter-Chip Connectivity, KleerNet, KleerNet logo, MiWi, MPASM, MPF, MPLAB Certified logo, MPLIB, MPLINK, MultiTRAK, NetDetach, Omniscient Code Generation, PICDEM, PICDEM.net, PICkit, PICtail, RightTouch logo, REAL ICE, SQI, Serial Quad I/O, Total Endurance, TSHARC, USBCheck, VariSense, ViewSpan, WiperLock, Wireless DNA, and ZENA 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. Silicon Storage Technology is a registered trademark of Microchip Technology Inc. in other countries. GestIC is a 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. 2014, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. ISBN: 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. DS A-page Microchip Technology Inc.

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