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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
; ~$ K' a* c+ O+ I0 ~( \( Aprotection devices and PCB layout guidelines to enhance an application's immunity in electrically noisy
: E$ C$ B3 N- S+ u8 V3 p6 Uenvironments and survivability of EMI, EMC, EFT, and ESD events as described in the International1 E; T3 q( B7 I) ~. B- w( s! t
Electrotechnical Commission (IEC) standards: IEC 61000-4-2, IEC 61000-4-4, and IEC 61000-4-5.2 H% ~$ c" T/ g, j1 v
We will begin with:
4 o8 a7 U9 R! M- Y1 f1. A brief review of EMI, EFT, and ESD specifications.
( k! S" E: u1 l* g9 r+ Q2. Key ESD protection device specifications definitions.
8 c; h% V7 Q) b9 Q- |) B: D; ^3. A quick summary of EMI, EFT, and ESD protection strategies.
1 ~3 W- g2 U; @, V% ~% ?4. Capacitor filter selection and characteristics.+ P; C5 A, g- m5 \ L, j$ j! S
5. PCB Hardware design best practices and layout considerations checklists:
& B" M! O" v3 v3 e. J– Standard PCB design/layout practices
( H) p+ R! w( ?) M6 L/ r– Special Ethernet layout considerations
5 I- t5 _; |, r- `5 [– Special DDR Layout considerations" [8 ~! S1 @) N4 ?" Q
6. Software protection techniques.
* I! k) R1 k1 }7. Microcontroller reference circuit schematics with protection examples:
; o w! ]4 e8 G– RS-232
) z- W: s! v! X2 f3 R3 x2 @3 {– USB7 A' E {2 O% d# y
– CAN FD and LIN
1 M# m! X8 U/ U) G6 ?( B– Ethernet) [- o2 J, ]9 K7 X5 t
– Audio and mechanical switches
+ @# H8 L5 |% k5 ~0 J l– LCD
# `4 Z% B |" c+ s! T, J– Power supplies# a7 | G" _0 i+ }, q
– Reset and ICSP programming interface9 p$ n: [) s5 B
– SD memory card
& g3 o, @$ o0 m' ]– I2C) c0 a! t9 \3 C5 q0 X9 d
Reference Designs Note:2 y) W, t+ M4 c; V3 ?
Cost pressure is a constant consideration in any design. All of the circuit components in support of the, C: c( h3 }: D
CPU were selected based on the lowest cost and availability, which met the threat protection/ r' g' L1 z _& j; q
requirements. A user should carefully consider any substitutions. It is also highly recommended that the) ?1 D6 L' G, T9 u
user consider designing in the protection elements in their layout, and then depopulate with zero ohm- v" P; ~& t l' R6 H5 ^/ e
resistors as they think necessary, based on ESD, EMI, and EFT prototype board testing. This will save
8 m6 a% i: C1 }4 a$ u. ^: y6 G( ?significant board redesign time to market in the final product. |
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