an0007 rev 3 08/2004 steward www.steward.com north america - u.s.a. ? phone: +1 423 308 1690 fax +1 423 308 1622 e-mail: americas@steward.com north america - mexico phone: +52 662 260-4832 fax: +52 662 216 1202 e-mail: mexico@steward.com europe - scotland, uk phone: +44 (0)1506 414200 fax +44 (0)1506 410694 e-mail: europe@steward.com asia / pacific - singapore phone: +65 6272 2646 fax : +65 6272 6165 e-mail: asia@steward.com china phone: +86- 757-2563 8860 fax : +86- 757-2563 8862 e-mail: china@steward.com emi suppression for firewire & usb 2.0 applications 1. 1. 1. 1. 1. problem: problem: problem: problem: problem: traditional common mode choke geometry generates excessive normal mode impedance which causes failure in the transmission signal integrity due to excessive net differential impedance in line. this is exacerbated with firewire and usb2.0 both of which are clocking at greater than 480 mb/s, compared to usb1.1 which was operating @ 12mb/s max. steward solution steward solution steward solution steward solution steward solution: steward?s unique product geometry minimizes net circuit impedance at 500 mhz. the low normal mode impedance will allow for video signals to pass through steward?s common mode chokes without any perturbation to the picture quality. steward?s high performance common mode chokes have the lowest normal mode impedance in the industry today. 2. 2. 2. 2. 2. problem: problem: problem: problem: problem: traditional common mode chokes exhibit excessive amounts of crosstalk between data lines. steward solution: steward solution: steward solution: steward solution: steward solution: steward?s unique ferrite material used in all steward multi-line common mode chokes has high volume resistivity (ohms per cm) which eliminates electrical crosstalk. also, steward?s unique part geometry minimizes inter-winding capacitance which is the primary source of crosstalk in most traditional wire wound common mode chokes. this is reflected in the higher normal mode performance seen in other products. 3. 3. 3. 3. 3. problem: problem: problem: problem: problem: the usb protocol is normally a fully differential serial data set in that d+ and d- are usually 180o out of phase with each other. however, in low-speed 1.5mb/s and full-speed 12mb/s signaling as specified in usb 1.1 there is a time period at the end of every packet of data called eop. during this time period both d+ and d- are held at approx. 0.8v for a specified period of time and this eop signals an end of packet. this state where both d+ and d- are held at the same potential is commonly known as the signal going ?single ended?. the ?single ended? state can also be used as a reset to a downstream port and can wake a usb device from the suspend state. the time period where d+ and d- are both at the same potential is effectively a common mode signal and could be rejected by a high impedance common mode choke. overview a primary problem for the firewire ieee1394 and usb2.0 as with the usb1.1 port designer is common mode noise conducted through the power and signal lines from various sources. emi susceptibility on data/power lines is also a major concern. the use of a common mode choke in this application will provide a complete low cost, effective, modular, filter solution. steward?s cm2722 (for single and dual ports), cm3822 (for tri ports), and cm5022 (for quad ports) series of components have the lowest normal mode impedance in the industry and suppress a wide range of digital common mode noise. normal mode impedance is net circuit impedance i.e. the impedance seen by the differential signal. discussion firewire and usb2.0 is a serial data / power port providing a broad range of data and current loads. the initial usb industry specification called for a serial port which operates in a hybrid full duplex mode and a power port that operates up to 1 amp o f current. this design has created several layers of emi problems that must be corrected. also, usb component performance requirements have been stretched beyond initial specifications which has caused field failures of 1 amp and even 3 amp rated ferrite chip beads. firewire and usb2.0 have increased the expected design loading to a minimum of 4.0 amps to insure failure free operation. the source of most usb emi problems is the two outside conductors in the connector for the power port. the primary problem is conducted common mode noise on the power line and the best emi solution is a common mode choke. common mode chokes have not traditionally been considered complete power and data line solutions because:
steward www.steward.com north america - u.s.a. phone: +1 423 308 1690 fax +1 423 308 1622 e-mail: americas@steward.com north america - mexico phone: +52 662 260-4832 fax: +52 662 216 1202 e-mail: mexico@steward.com europe - scotland, uk phone: +44 (0)1506 414200 fax +44 (0)1506 410694 e-mail: europe@steward.com asia / pacific - singapore phone: +65 6272 2646 fax : +65 6272 6165 e-mail: asia@steward.com china phone: +86- 757-2563 8860 fax : +86- 757-2563 8862 e-mail: china@steward.com an0007 rev 3 08/2004 the use of common mode chokes in the power circuit is the preferred solution. in some applications, a dual two channel common mode choke can provide filtration for both power and signal lines. steward?s line of common mode chokes provides a simple, reliable and cost effective usb port filter solution. steward solution: steward solution: steward solution: steward solution: steward solution: the industry has grown to understand that low normal mode impedance (as defined problem 1. ) and common mode impedance below approximately 150 ohms of pure common mode impedance provides an effective filter solution for the data lines. the non-differential signals i.e. end of packet signals will continue to function and will not be rejected by the common mode choke. this has allowed for the use of 80-120 ohm common mode chokes without any functional issues. using an impedance greater then 150 ohms of common mode impedance will affect the data stream in that an end of packet may not be recognized, leading to data corruption issues. in virtually all applications the noise coupled to the data lines is common mode energy. for example, most printers / fax / scanner / pda have primarily common mode noise on the data lines. therefore a cm choke solution is recommended. pa rt number fig # # of lines a mm (inches) b mm (inches) c mm (inches) d mm (inches) e mm (inches) e1 mm (inches) t1 mm (inches) dcr max ohms typical impedance @ 100 mhz cm2722r450r-00 14 6.99 + 0.10 (0.275 + 0.004) 5.72 + 0.10 (0.225 + 0.004 2.34 + 0.08 (0.092 + 0.003) 2.41 + 0.008 (0.095 + 0.003) 0.89 + 0.13 (0.035 + 0.005) 1.91 + 0.13 (0.075 + 0.005) 1.91 + 0.25 (0.075 + 0.010) .020 45 cm2722r800r-00 14 6.99 + 0.10 (0.275 + 0.004) 5.72 + 0.10 (0.225 + 0.004) 4.32+ 0.08 (0.170 + 0.003) 2.41 + 0.008 (0.095 + 0.003) 0.89 + 0.13 (0.035 + 0.005) 1.91 + 0.13 (0.075 + 0.005) 1.91 + 0.25 (0.075 + 0.010) .020 80 cm2722r151r-00 14 6.99 + 0.10 (0.275 + 0.004) 5.72 + 0.10 (0.225 + 0.004 7.62 + 0.13 (0.300 + 0.005) 2.41 + 0.008 (0.095 + 0.003) 0.89 + 0.13 (0.035 + 0.005) 1.91 + 0.13 (0.075 + 0.005) 1.91 + 0.25 (0.075 + 0.010) .020 150 CM2722R201R-00 14 6.99 + 0.10 (0.275 + 0.004) 5.72 + 0.10 (0.225 + 0.004 9.53 + 0.15 (0.375 + 0.006) 2.41 + 0.008 (0.095 + 0.003) 0.89 + 0.13 (0.035 + 0.005) 1.91 + 0.13 (0.075 + 0.005) 1.91 + 0.25 (0.075 + 0.010) .020 200 cm3822r800r-00 36 9.78 + 0.15 (0.385 + 0.006) 5.72 + 0.10 (0.225 + 0.004) 4.32 + 0.08 (0.170 + 0.003) 2.41 + 0.08 (0.095 + 0.003) 0.89 + 0.13 (0.035 + 0.005) 1.91 + 0.13 (0.075 + 0.005) 1.91 + 0.25 (0.075 + 0.010) .020 80 cm3822r151r-00 36 9.78 + 0.15 (0.385 + 0.006) 5.72 + 0.10 (0.225 + 0.004) 7.62 + 0.13 (0.300 + 0.005) 2.41 + 0.08 (0.095 + 0.003) 0.89 + 0.13 (0.035 + 0.005) 1.91 + 0.13 (0.075 + 0.005) 1.91 + 0.25 (0.075 + 0.010) .020 150 cm3822r201r-00 36 9.78 + 0.15 (0.385 + 0.006) 5.72 + 0.10 (0.225 + 0.004) 9.53 + 0.15 (0.375 + 0.006) 2.41 + 0.08 (0.095 + 0.003 0.89 + 0.13 (0.035 + 0.005) 1.91 + 0.13 (0.075 + 0.005) 1.91 + 0.25 (0.075 + 0.010 .020 200 cm5022r800r-00 28 12.57 + 0.20 (0.495 + 0.008) 5.72 + 0.10 (0.225 + 0.004) 4.32 + 0.08 (0.170 + 0.003) 2.41 + 0.08 (0.095 + 0.003) 0.89 + 0.13 (0.035 + 0.005) 1.91 + 0.13 (0.075 + 0.005) 1.91 + 0.25 (0.075 + 0.010 .020 80 cm5022r151r-00 28 12.57 + 0.20 (0.495 + 0.008) 5.72 + 0.10 (0.225 + 0.004) 7.62 + 0.13 (0.300 + 0.005) 2.41 + 0.08 (0.095 + 0.003) 0.89 + 0.13 (0.035 + 0.005) 1.91 + 0.13 (0.075 + 0.005)) 1.91 + 0.25 (0.075 + 0.010) .020 150 cm5022r201r-00 28 12.57 + 0.20 (0.495 + 0.008) 5.72 + 0.10 (0.225 + 0.004) 9.53 + 0.15 (0.375 + 0.006) 2.41 + 0.08 (0.095 + 0.003 0.89 + 0.13 (0.035 + 0.005) 1.91 + 0.13 (0.075 + 0.005) 1.91 + 0.25 (0.075 + 0.010 .020 200 steward part numbering system example cm 2722 r 800 r - 00 product part rated impedance packaging additional part series code size code current code value code code description
an0007 rev 3 08/2004 steward www.steward.com north america - u.s.a. phone: +1 423 308 1690 fax +1 423 308 1622 e-mail: americas@steward.com north america - mexico phone: +52 662 260-4832 fax: +52 662 216 1202 e-mail: mexico@steward.com europe - scotland, uk phone: +44 (0)1506 414200 fax +44 (0)1506 410694 e-mail: europe@steward.com asia / pacific - singapore phone: +65 6272 2646 fax : +65 6272 6165 e-mail: asia@steward.com china phone: +86- 757-2563 8860 fax : +86- 757-2563 8862 e-mail: china@steward.com v bus d+ d- d+ d- gnd v bus gnd d+ d- v bus gnd typical application example 3 - tri port cm3822r800r-00 figure 3 v bus gnd d+ d- v bus gnd d+ d- figure 1 typical application example 2 - dual port or x2 for a quad port typical application example 1 - single port cm2722 cm3822 cm5022 land pattern for reflow soldering land pattern for reflow soldering land pattern for reflow soldering * wire length [ t1 = 1.91 (.075) ] * wire width [ t2 = 0.38 (.015) ] * wire thickness [ t3 = 0.38 (.015) ] cm2722r800r-00 c m 2 7 2 2 r 8 0 0 r - 0 0 cm5022r800r-00 7.75 [.305] d 0.25 [.010] t2 4.83 [.190] 0.89 [.035] 3.05 [.120] 1.65 [.065] 0.076 [.030] 0.38 [.015] e 0.13 [.005] t1 0.89 [.035] 0.89 [.035] 7.75 [.305] 7.75 [.305] d 0.25 [.010] d 0.25 [.010] 1.65 [.065] 0.38 [.015] 0.13 [.005] 1.65 [.065] 0.38 [.015] 0.13 [.005] t2 t1 t2 t1 e e 7.62 [.300] 10.41 [.410] 3.05 [.120] 3.05 [.120] 0.076 [.030] 0.076 [.030] e1 e1 figure 2 one turn / 2x series equivalent circuits cm2722r800r-00
frequency (mhz) cm2722r800r-00, cm3822r800r-00, cm5022r800r-00 z, r, x l vs. frequency impedance, resistance, inductive reactance impedance ( ? ) 100 0 20 1 10 100 1000 r x l z cm2722r800r-00, cm3822r800r-00, cm5022r800r-00 z, vs. frequency open, common, and normal mode impedance ( ? ) 100 0 frequency (mhz) 100 open common normal 40 60 80 20 40 60 80 10000 cm2722r151r-00, cm3822r151r-00, cm5022r151r-00 z, r, x l vs. frequency impedance, resistance, inductive reactance impedance ( ? ) 180 0 frequency (mhz) 1 10 r x l z 20 cm2722r151r-00, cm3822r151r-00, cm5022r151r-00 z, vs. frequency open, common, and normal mode impedance ( ? ) 0 frequency (mhz) 1 10 100 1000 10000 open common norma l 40 60 80 100 120 140 160 180 20 40 60 80 100 120 140 160 CM2722R201R-00, cm3822r201r-00, cm5022r201r-00 z, r, x l vs. frequency impedance, resistance, inductive reactance impedance ( ? ) 0 50 frequency (mhz) 1 10 100 1000 r x l z CM2722R201R-00, cm3822r201r-00, cm5022r201r-00 z, vs. frequency open, common, and normal mode impedance ( ? ) 0 frequency (mhz) 1 10 100 1000 10000 open common normal 100 150 200 250 50 100 150 200 250 10000 frequency (mhz) cm2722r450r-00 z, r, x l vs. frequency impedance, resistance, inductive reactance impedance ( ? ) 0 1 10 100 1000 r x l z 10 35 15 20 25 30 40 45 50 5 10000 frequency (mhz) cm2722r450r-00 z vs. frequency open, common, and normal mode impedance ( ? ) 0 1 10 100 1000 10 15 20 50 5 25 30 35 40 45 open common normal 10000 1000 100 10000 10 1 1000 10000 steward www.steward.com north america - u.s.a. phone: +1 423 308 1690 fax +1 423 308 1622 e-mail: americas@steward.com north america - mexico phone: +52 662 260-4832 fax: +52 662 216 1202 e-mail: mexico@steward.com europe - scotland, uk phone: +44 (0)1506 414200 fax +44 (0)1506 410694 e-mail: europe@steward.com asia / pacific - singapore phone: +65 6272 2646 fax : +65 6272 6165 e-mail: asia@steward.com china phone: +86- 757-2563 8860 fax : +86- 757-2563 8862 e-mail: china@steward.com an0007 rev 3 08/2004
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