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AN14395
EMC Guidelines for MCXA14x/15x MCU Designs
Rev. 1 — 22 July 2024
Document information
Information
Keywords
Abstract
Content
AN14395, MCXA14x/15x, EMC, MCXA153, MCU, EMI model, Bypass circuit, Decoupling circuit,
Inter-board interface, Communication interface, Debug interface, PCB stack-up, USB High Speed
signal, Shield connection, Signal return path, Digital filter
This document introduces how to conduct a reasonable EMC design based on the MCXA14x/15x
MCU, which helps the users maintain the robustness of the product's EMC performance.
Application note
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Table of Contents
Related Manuals for NXP Semiconductors MCXA14 Series
Summary of Contents for NXP Semiconductors MCXA14 Series
- Page 1 AN14395 EMC Guidelines for MCXA14x/15x MCU Designs Rev. 1 — 22 July 2024 Application note Document information Information Content Keywords AN14395, MCXA14x/15x, EMC, MCXA153, MCU, EMI model, Bypass circuit, Decoupling circuit, Inter-board interface, Communication interface, Debug interface, PCB stack-up, USB High Speed signal, Shield connection, Signal return path, Digital filter Abstract This document introduces how to conduct a reasonable EMC design based on the MCXA14x/15x...
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Page 2: Introduction
AN14395 NXP Semiconductors EMC Guidelines for MCXA14x/15x MCU Designs 1 Introduction This document introduces some common methods to improve the Electromagnetic compatibility (EMC) performance based on the MCXA14x/15x MCU. It uses MCXA153 as an example to introduce the basic methods of EMC design. In addition, this document can be used as a guide or reference for customers in practical applications. -
Page 3: Basic Principles Of Emc Design
AN14395 NXP Semiconductors EMC Guidelines for MCXA14x/15x MCU Designs 1.3 Basic principles of EMC design Any problem occurrence in the electronic compatibility of the product causes a rework in the product design. To avoid this situation, the subsequent topics of this document are designed to help the designers understand better on how to enhance the immunity (sensitivity) and meet the radiation requirements. -
Page 4: Pcb Design
AN14395 NXP Semiconductors EMC Guidelines for MCXA14x/15x MCU Designs 2 PCB design In the board design, some key circuits design play a decisive role in EMC/EMI/ESD performance, such as: • Crystal oscillator circuit • Reset circuit • Unused pin configuration •... -
Page 5: Inter-Board Interface
AN14395 NXP Semiconductors EMC Guidelines for MCXA14x/15x MCU Designs Generally, data sheets provide recommendations for unused pin connections. For details, refer to the following configurations: • To determine whether the unused pins are allowed to float, refer the data sheet. -
Page 6: Communication Interface
AN14395 NXP Semiconductors EMC Guidelines for MCXA14x/15x MCU Designs 2. Move the operational amplifier circuit to the power board and connect VDDA and AGND from the control board to the power board. This results in a relatively smaller loop between the ADC signal, VDDA and AGND, thereby improving the EMC performance. -
Page 7: Debug Interface
AN14395 NXP Semiconductors EMC Guidelines for MCXA14x/15x MCU Designs P5V_USB_FS GND1 GND3 330 Ω MPZ1608S331A VBUS1 VBUS3 SBU2 USB0_DM 3 33 Ω 4.7 µF USB0_DP 3 SBU1 33 Ω R121 5.1 kΩ VBUS2 VBUS4 2.2 µF R122 5.1 kΩ GND2... -
Page 8: Power Topology
AN14395 NXP Semiconductors EMC Guidelines for MCXA14x/15x MCU Designs • Parasitic capacitance and inductance to charge and discharge frequently, thus causing ground failure. • Power supply failure, which affects some sensitive signals. Especially, the signals with same power domain as these are parallel interfaces. -
Page 9: Pcb Layout
AN14395 NXP Semiconductors EMC Guidelines for MCXA14x/15x MCU Designs 3 PCB layout 3.1 PCB stack-up and multi-layer board layout designs This section provides different ways to reduce the EMI and EMC of the boards using PCB stack-up design. In addition, it provides recommended measures to reduce the impedance of power and ground planes in multilayer board layout design. -
Page 10: Layout
AN14395 NXP Semiconductors EMC Guidelines for MCXA14x/15x MCU Designs Following are the recommendations to maintain or reduce the impedance of the power and ground planes: • Refer to Rule 20-H. The 20-H rule is a guideline for the design of power and ground layers in multilayer boards. -
Page 11: Crystal Oscillator Circuit
AN14395 NXP Semiconductors EMC Guidelines for MCXA14x/15x MCU Designs Figure 10. Decoupling capacitors and bypass circuit placement and return paths 3.4 Crystal oscillator circuit The two types of crystal oscillator circuits used are: • Passive crystal oscillator: Connected between the XTALIN and XTALOUT pins of the microcontroller •... -
Page 12: Shielded Connection
AN14395 NXP Semiconductors EMC Guidelines for MCXA14x/15x MCU Designs Note: The propagation delay and impedance control must be considered to ensure good communication between the devices. 3.6 Shielded connection Some connectors are in metal and can have either conductive shells, exposed shells, or accessible to components, such as USB and network interface sockets. -
Page 13: Signal Return Path
AN14395 NXP Semiconductors EMC Guidelines for MCXA14x/15x MCU Designs Figure 12. RS485 IO isolation circuit 3.8 Signal return path It is known that a circuit is a closed loop between a source device and a terminal device. Regarding the signal return path and power supply loop, the signal return path has always received higher attention. In reality, both signal and power have their own return paths. -
Page 14: Software Design
AN14395 NXP Semiconductors EMC Guidelines for MCXA14x/15x MCU Designs 4 Software design Good software design is a good way to improve EMC performance. It also improves the system stability without adding any additional costs. 4.1 Filter configuration for certain peripherals To avoid noise interference, some peripherals support digital filters, such as the LPI2C, QDC in the MCXA14x/15x MCU. -
Page 15: Emc Testing
AN14395 NXP Semiconductors EMC Guidelines for MCXA14x/15x MCU Designs 5 EMC testing Taking MCXA153 as an example, the EMC performance is evaluated based on the IEC61000-4-2 standards. 5.1 Test System Setup Figure 15 shows the EMC test items. The EMC package includes various test items conducted in board level at NXP internal laboratory. - Page 16 AN14395 NXP Semiconductors EMC Guidelines for MCXA14x/15x MCU Designs – The lowest level was +4 kV injected at Pin USB0_DM(26) • For IO Pins under the negative ESD pulse injection: – P0_0(49) and Pin P0_3(52) were damaged at -7 kV injection –...
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Page 17: References
AN14395 NXP Semiconductors EMC Guidelines for MCXA14x/15x MCU Designs 6 References For additional information, you can refer to the following documents: • AN2321, Designing for Board Level EMC • AN3747, Pad Layout Application Note • MCXA1XX Reference Manual from www.nxp.com AN14395 All information provided in this document is subject to legal disclaimers. -
Page 18: Revision History
AN14395 NXP Semiconductors EMC Guidelines for MCXA14x/15x MCU Designs 7 Revision history Table 4 summarizes the revisions to this document. Table 4. Revision history Document ID Release date Description AN14395 v.1 22 July 2024 Initial public release AN14395 All information provided in this document is subject to legal disclaimers. -
Page 19: Legal Information
NXP Semiconductors. In the event that customer uses the product for design-in and use in In no event shall NXP Semiconductors be liable for any indirect, incidental, automotive applications to automotive specifications and standards, punitive, special or consequential damages (including - without limitation - customer (a) shall use the product without NXP Semiconductors’... -
Page 20: Table Of Contents
AN14395 NXP Semiconductors EMC Guidelines for MCXA14x/15x MCU Designs Contents Introduction ............2 EMC significance ..........2 Basic EMC concepts ......... 2 Basic principles of EMC design ......3 PCB design ............4 Crystal oscillator circuit ........4 Reset circuit ............4 Unused pin configuration ........4...
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