전자파 연구실 1 9. Connectors
전자파 연구실 2 Primary electrical factors affecting high-speed performance in connectors Mutual inductance – cause crosstalk Series inductance – slows down signal propagation and creates EMI Parasitic capacitance – slows down signal propagation
전자파 연구실 Mutual inductance-how connectors create crosstalk
전자파 연구실 4 Derivation of mutual inductance of connector pins Diameter : D Current H
전자파 연구실 Estimating crosstalk Mutual inductance between two loops The maximum rate of change of the source signal current dI/dt The impedance of receiving network and whether it is source or end terminated.
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How ground alter the return-current path
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Series inductance - How connectors create EMI
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전자파 연구실 12 Example 9.1 Noise radiated from a connector
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전자파 연구실 14 How to reduce connector emissions
전자파 연구실 Parasitic capacitance : 9.3 Parasitic capacitance : using connectors on a multidrop bus
전자파 연구실 16RS-485 Characteristics of RS232, RS422, RS423 and RS485 RS232RS423RS422RS485 Differentialno yes Max number of drivers Max number of receivers Modes of operation half duplex full duplex half duplex Network topologypoint-to-pointmultidrop multipoint Max distance (acc. standard)15 m1200 m Max speed at 12 m Max speed at 1200 m 20 kbs (1 kbs) 100 kbs 1 kbs 10 Mbs 100 kbs 35 Mbs 100 kbs Max slew rate30 V/μsadjustablen/a Receiver input resistance3~7 kΩ ≧ 4 kΩ ≧ 12 kΩ Driver load impedance3~7 kΩ ≧ 450 Ω 100 Ω54 Ω Receiver input sensitivity±3 V±200 mV Receiver input range±15 V±12 V±10 V – 7~12 V Max driver output voltage±25 V±6 V – 7~12 V Min driver output voltage (with load)±5 V±3.6 V±2.0 V±1.5 V Network topology with RS485
전자파 연구실 Measuring coupling in a connector Logic gate 의 출력 임피던스를 흉내냄.
전자파 연구실 Continuity of ground underneath a connector
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전자파 연구실 Fixing EMI problems with external connections Filtered output
전자파 연구실 21 Shielding
전자파 연구실 22 Common mode choke
전자파 연구실 Special connectors for high-speed applications Thin metal plate : low inductance return current carrier Very low crosstalk Z0=50Ω
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전자파 연구실 Differential signaling through a connector