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USB 하드웨어 디자인 가이드

USB 하드웨어 디자인 가이드

  • GND, 샤시에 FB
  • 15 Ohm Termination resistor
  • ESD 인증에 문제가 있을 경우 protection device – NXP IP4220CE6
  • Common mode choke – Murata plw3216s900sq2t1
  • 2개의 USB 신호쌍은  parallel 하게하며, 간극은 최대 150 mil을 넘지 않도록
  • 신호선의 최대 길이는 18인치를 넘지 않도록

참고자료


ESD 모델

HBM, MM, CDM 3가지 모델이 있으며, 각각의 테스트에 해당하는 테스트 회로와 입력 stress 파형의 조건이 다르다.
파형은 rise time (Tr), delay time(Td), 입력 전류 최대치(Ipeak) 가 각각 다르다.
아래 각각의 파형에 기준치가 기록이 되어 있다.

1. HBM (Human Body Model)


The HBM pulse peak current at 400 V must be 0.27 +/- 10% A


Three examples of industry standards that define HBM ESD testing are JEDEC’sJESD22-A114, the  MIL-STD-883 Method 3015 and  ESD Association’s ESD STM5.1: Electrostatic Discharge Sensitivity Testing — Human Body Model


2. MM (Machine Model)


The MM peak current at 400 V must be 5.8 +/- 20% A




Two examples of industry standards that define MM ESD testing are JEDEC’s JESD22-A115 and  ESD Association’s ESD STM5.2: Electrostatic Discharge Sensitivity Testing — Machine Model.



3. CDM (Charged Device Model)


The CDM peak current at 400 V must be 2.1 +/- 20% A


Two examples of industry standards that define CDM ESD testing are JEDEC’s JESD22-C101 and  ESD Association’s ESD STM5.3.1: Electrostatic Discharge Sensitivity Testing — Charged Device Model



4. ESD Sensitivity Classfication Levels
 


Table 1. ESDS Component Sensitivity Classification – Human Body Model


(Per ESD STM5.1-1998*)






























Class


Voltage Range


Class 0


< 250 volts


Class 1A


250 volts to < 500 volts


Class 1B


500 volts to < 1,000 volts


Class 1C


1000 volts to < 2,000 volts


Class 2


2000 volts to < 4,000 volts


Class 3A


4000 volts to < 8000 volts


Class 3B


> = 8000 volts


     


Table 2. ESDS Component Sensitivity Classification – Machine Model
(Per ESD STM5.2-1999*)




















Class


Voltage Range


Class M1


< 100 volts


Class M2


100 volts to < 200 volts


Class M3


200 volts to < 400 volts


Class M4


> or = 400 volts


         


Table 3. ESDS Component Sensitivity Classification – Charged Device Model
(Per ESD STM5.3.1-1999*)





























Class


Voltage Range


Class C1


<125 volts


Class C2


125 volts to < 250 volts


Class C3


250 volts to < 500 volts


Class C4


500 volts to < 1,000 volts


Class C5


1,000 volts to < 1,500 volts


Class C6


1,500 volts to < 2,000 volts


Class C7


=>2,000 volts


출처: http://www.siliconfareast.com/esd.htm