preliminary 1 www.semtech.com protection products slvu2.8-8 epd tvs ? ? ? ? ? diode array for esd and latch-up protection description features circuit diagram (each line) schematic & pin configuration revision 08/21/2002 the slv series of transient voltage suppressors are designed to protect low voltage, state-of-the-art cmos semiconductors from transients caused by electro- static discharge (esd), cable discharge events (cde), lightning and other induced voltage surges. the devices are constructed using semtech?s propri- etary epd process technology. the epd process pro- vides low standoff voltages with significant reductions in leakage currents and capacitance over silicon- avalanche diode processes. the slvu2.8-8 features integrated low capacitance compensation diodes that reduce the maximum capacitance to 8pf per line. this, combined with low leakage current, means signal integrity is preserved in high-speed applications such as 10/100/1000 ethernet. the slvu2.8-8 is in an so-8 package and may be used to protect four high-speed line pairs. the layout of the device minimizes trace inductance and reduces voltage overshoot associated with esd events. the low clamping voltage of the slvu2.8-8 minimizes the stress on the protected ic. the slv series tvs diodes will meet the surge require- ments of iec 61000-4-2 (esd), iec61000-4-5 (light- ning), and etsi ets 300 386. applications mechanical characteristics ? 10/100/1000 ethernet ? wan/lan equipment ? switching systems ? dslams ? desktops, servers, & notebooks ? instrumentation ? base stations ? analog inputs ? 600 watts peak pulse power (tp = 8/20s) ? transient protection for high speed data lines to iec 61000-4-2 (esd) 15kv (air), 8kv (contact) iec 61000-4-4 (eft) 40a (tp = 5/50ns) iec 61000-4-5 (lightning) 24a (tp = 8/20s) ? protects four line pairs (eight lines) ? comprehensive pin out for easy board layout ? low capacitance ? high peak pulse current (30a, 8/20s) ? low leakage current ? low operating and clamping voltages ? solid-state epd tvs process technology ? jedec so-8 package ? molding compound flammability rating: ul 94v-0 ? marking : part number, date code, logo ? packaging : tape and reel per eia 481 so-8 (top view)
2 ? 2002 semtech corp. www.semtech.com protection products slvu2.8-8 absolute maximum rating electrical characteristics (t=25 o c) g n i t a rl o b m y se u l a vs t i n u 0 2 / 8 = p t ( r e w o p e s l u p k a e p ) sp k p 0 0 6s t t a w 0 2 / 8 = p t ( t n e r r u c e s l u p k a e p ) si p p 0 3a ) r i a ( 2 - 4 - 0 0 0 1 6 c e i r e p d s e ) t c a t n o c ( 2 - 4 - 0 0 0 1 6 c e i r e p d s e v d s e 0 3 5 2 v k e r u t a r e p m e t g n i r e d l o s d a e lt l ) s d n o c e s 0 1 ( 0 4 2 o c e r u t a r e p m e t g n i t a r e p ot j 5 2 1 + o t 5 5 - o c e r u t a r e p m e t e g a r o t st g t s 0 5 1 + o t 5 5 - o c 8 - 8 . 2 u v l s r e t e m a r a pl o b m y ss n o i t i d n o cm u m i n i ml a c i p y tm u m i x a ms t i n u e g a t l o v f f o - d n a t s e s r e v e rv m w r 8 . 2v e g a t l o v h g u o r h t - h c n u pv t p i t p a 2 =0 . 3v e g a t l o v k c a b - p a n sv b s i b s a m 0 5 =8 . 2v t n e r r u c e g a k a e l e s r e v e ri r v m w r c 5 2 = t , v 8 . 2 = ) e n i l h c a e ( 0 0 1 .1a e g a t l o v g n i p m a l cv c i p p s 0 2 / 8 = p t , a 1 = ) e n i l h c a e ( 6 . 4v e g a t l o v g n i p m a l cv c i p p s 0 2 / 8 = p t , a 4 2 = ) e n i l h c a e ( 5 1v e g a t l o v g n i p m a l cv c i p p s 0 2 / 8 = p t , a 0 3 = ) e n i l h c a e ( 7 1v t n e r r u c e s l u p k a e p m u m i x a mi p p s 0 2 / 8 = p t0 3a e c n a t i c a p a c n o i t c n u jc j v r z h m 1 = f , v 0 = ) e n i l h c a e ( 8f p
3 ? 2002 semtech corp. www.semtech.com protection products preliminary protection products slvu2.8-8 typical characteristics non-repetitive peak pulse power vs. pulse time 0 10 20 30 40 50 60 70 80 90 100 110 0 25 50 75 100 125 150 ambient temperature - t a ( o c) % of rated power or i pp power derating curve pulse waveform clamping voltage vs. peak pulse current 0 10 20 30 40 50 60 70 80 90 100 110 0 5 10 15 20 25 30 time ( s) percent of i pp e -t td = i pp /2 waveform parameters: tr = 8 s td = 20 s capacitance vs. reverse voltage 0 4 8 12 16 0 5 10 15 20 25 30 35 peak pulse current ipp - (a) clamping voltage vc - (v ) waveform parameters: tr = 8 s td = 20 s 0.01 0.1 1 10 0.1 1 10 100 1000 pulse duration - tp ( s) peak pulse power - p pp (kw) 6 6.2 6.4 6.6 6.8 7 7.2 7.4 0123 bias voltage (v) capacitance (pf) ch1 s21 log 10 db/ ref 0 db start .030 000 mhz stop 3 000 . 000 000 mhz insertion loss s21
4 ? 2002 semtech corp. www.semtech.com protection products slvu2.8-8 slvu2.8-8 circuit diagram differential protection of four line pairs device connection for protection of eight data lines electronic equipment is susceptible to transient distur- bances from a variety of sources including: esd to an open connector or interface, direct or nearby lightning strikes to cables and wires, and charged cables ?hot plugged? into i/o ports. the slvu2.8-8 is designed to protect sensitive components from damage and latch- up which may result from such transient events. the slvu2.8-8 can be configured to protect four high- speed line pairs differentially, or four lines to ground (common mode). the device is connected as follows: 1 . differential protection of four line pairs: line pairs are connected at pins 1 and 2, 3 and 4, 5 and 6, and 7 and 8. circuit board layout recommendations for suppres- sion of esd. good circuit board layout is critical for the suppression of esd induced transients. the following guidelines are recommended: z place the device near the input terminals or con- nectors to restrict transient coupling. z minimize the path length between the tvs and the protected line. z minimize all conductive loops including power and ground loops. z the esd transient return path to ground should be kept as short as possible. z never run critical signals near board edges. z use ground planes whenever possible. applications information 1 2 3 45 6 7 8 from connector
5 ? 2002 semtech corp. www.semtech.com protection products preliminary protection products slvu2.8-8 gigabit ethernet protection circuit typical applications
6 ? 2002 semtech corp. www.semtech.com protection products slvu2.8-8 typical applications one slvu2.8.8 protecting two 10/100 ethernet port
7 ? 2002 semtech corp. www.semtech.com protection products preliminary protection products slvu2.8-8 applications information (continued) i pp i sb i pt i r v rwm v v pt v c v brr i brr sb epd tvs vi characteristic curve epd tvs? characteristics the slvu2.8-8 is constructed using semtech?s propri- etary epd technology. the structure of the epd tvs is vastly different from the traditional pn-junction devices. at voltages below 5v, high leakage current and junction capacitance render conventional avalanche technology impractical for most applications. however, by utilizing the epd technology, the slvu2.8-8 can effectively operate at 2.8v while maintaining excellent electrical characteristics. the epd tvs employs a complex nppn structure in contrast to the pn structure normally found in tradi- tional silicon-avalanche tvs diodes. the epd mecha- nism is achieved by engineering the center region of the device such that the reverse biased junction does not avalanche, but will ?punch-through? to a conduct- ing state. this structure results in a device with supe- rior dc electrical parameters at low voltages while maintaining the capability to absorb high transient currents. the iv characteristic curve of the epd device is shown in figure 1. the device represents a high impedance to the circuit up to the working voltage (v rwm ). during a transient event, the device will begin to conduct as it is biased in the reverse direction. when the punch- through voltage (v pt ) is exceeded, the device enters a low impedance state, diverting the transient current away from the protected circuit. when the device is conducting current, it will exhibit a slight ?snap-back? or negative resistance characteristic due to its structure. this must be considered when connecting the device to a power supply rail. to return to a non-conducting state, the current through the device must fall below the snap-back current (approximately < 50ma).
8 ? 2002 semtech corp. www.semtech.com protection products slvu2.8-8 land pattern - so-8 outline drawing - so-8
9 ? 2002 semtech corp. www.semtech.com protection products preliminary protection products slvu2.8-8 contact information semtech corporation protection products division 200 flynn road, camarillo, ca 93012 phone: (805)498-2111 fax (805)498-3804 ordering information r e b m u n t r a p g n i k r o w e g a t l o v l e e r r e p y t qe z i s l e e r b t . 8 - 8 . 2 u v l sv 8 . 20 0 5h c n i 7 e t . 8 - 8 . 2 u v l sv 8 . 20 0 5 , 2h c n i 3 1 note: (1) no suffix indicates tube pack. sc yyww slvu2.8 -8 1 marking note: (1) yyww = date code top view
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