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发表于 2023-6-28 11:11:32
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This application note is intended to provide recommendations concerning incorporation of circuit
3 L* c7 v) @. M) Wprotection devices and PCB layout guidelines to enhance an application's immunity in electrically noisy* [/ Z( I/ Y1 x$ B
environments and survivability of EMI, EMC, EFT, and ESD events as described in the International7 m! J# b; s9 m/ f
Electrotechnical Commission (IEC) standards: IEC 61000-4-2, IEC 61000-4-4, and IEC 61000-4-5.. w/ c+ s* z+ k
We will begin with:- y. p$ {- _% b7 i
1. A brief review of EMI, EFT, and ESD specifications.
% e% d- l0 O/ f+ N: ^5 s2. Key ESD protection device specifications definitions.9 b( `2 |* l+ E& `: S; ~/ _
3. A quick summary of EMI, EFT, and ESD protection strategies.
6 f& o0 Q- {; V- T/ j) D4 I4. Capacitor filter selection and characteristics.
2 w9 _. ~! a% H4 I! S7 C2 ^5. PCB Hardware design best practices and layout considerations checklists:
2 w" f6 n2 M; ^1 v& q– Standard PCB design/layout practices& x( n3 }+ x$ p( {
– Special Ethernet layout considerations
* A. Z3 o0 v1 \& d– Special DDR Layout considerations6 f& s ^! M$ P! Y% M/ ~% z
6. Software protection techniques." h' P( m5 A4 I) X2 A. }% l
7. Microcontroller reference circuit schematics with protection examples:" C. B3 z( `0 |: k- D0 v
– RS-232
0 y; }9 ]. C( n" N" r– USB
2 ~" Z$ O5 b$ o2 J' T3 E" f! U– CAN FD and LIN+ l1 I$ W. M! `2 d2 x9 [- y k
– Ethernet
5 J4 q5 ?; E5 @– Audio and mechanical switches
- a9 [. q5 s8 Y. R– LCD- I1 G4 D, s+ p9 u) t' S3 [
– Power supplies: ]: j) x9 q9 {! X. |
– Reset and ICSP programming interface
$ w. ?9 x% L& X( K– SD memory card$ c3 c# f6 H. n4 Z* w# d7 l
– I2C! H/ P/ v9 q' B
Reference Designs Note:4 V# q" l- i/ y6 _: w+ p
Cost pressure is a constant consideration in any design. All of the circuit components in support of the
/ ^1 q6 J$ Y: v9 ZCPU were selected based on the lowest cost and availability, which met the threat protection
: n! X" P9 R# y" |requirements. A user should carefully consider any substitutions. It is also highly recommended that the
& m+ \( u2 n( b) ?( k! J: ]% guser consider designing in the protection elements in their layout, and then depopulate with zero ohm
; i( ^" K4 \2 [2 Zresistors as they think necessary, based on ESD, EMI, and EFT prototype board testing. This will save
: M, C V1 K* _1 d7 r1 ^& hsignificant board redesign time to market in the final product. |
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