1 www.semtech.com smf3.3 3.3 volt tvs array for esd and latch-up protection protection products protection products description features circuit diagram schematic & pin configuration revision 01/15/08 applications mechanical characteristics ? cellular handsets and accessories ? cordless phones ? personal digital assistants (pdas) ? notebooks and handhelds ? portable instrumentation ? digital cameras ? peripherals ? mp3 players ? esd protection for data lines to iec 61000-4-2 (esd) 15kv (air), 8kv (contact) iec 61000-4-4 (eft) 40a (5/50ns) ? small package for use in portable electronics ? protects four i/o lines ? working voltage: 3.3v ? low leakage current ? low operating and clamping voltages ? solid-state epd tvs technology ? eiaj sc70-5l package ? molding compound flammability rating: ul 94v-0 ? marking : marking code ? packaging : tape and reel 1 2 34 5 2 1345 sc70-5l (top view) the smf series of tvs arrays are designed to protect sensitive electronics from damage or latch-up due to esd, lightning, and other voltage-induced transient events. each device will protect up to four lines operat- ing at 3.3 volts . the smf3.3 is a solid-state devices designed specifi- cally for transient suppression. it is constructed using semtech?s proprietary epd process technology. the epd process provides low standoff voltages with significant reductions in leakage currents and capaci- tance over traditional pn junction processes. they offer desirable characteristics for board level protection including fast response time, low clamping voltage and no device degradation. the smf3.3 may be used to meet the immunity re- quirements of iec 61000-4-2, level 4 (15kv air, 8kv contact discharge). the small sc70-5l package makes them ideal for use in portable electronics such as cell phones, pdas, and notebook computers.
2 ? 2008 semtech corp. www.semtech.com smf3.3 protection products absolute maximum rating electrical characteristics 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 4s 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 5a ) 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 2 5 1 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 6 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 3 . 3 f m 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 3 . 3v 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 =5 . 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 v 3 . 3 =5 0 . 05 . 0a 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 =5 . 5v 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 5 =0 . 8v e g a t l o v d r a w r o f e d o i d g n i r e e t sv f i p p s 0 2 / 8 = p t , a 1 = o / i y n a o t d n u o r g 4 . 2v e c n a t i c a p a c n o i t c n u jc j d n a n i p o / i h c a e d n u o r g v r z h m 1 = f , v 0 = 5 20 3f p o / i o t o / i v r z h m 1 = f , v 0 = 2 1f p
3 ? 2008 semtech corp. www.semtech.com smf3.3 protection products 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 forward voltage vs. forward current 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 01234567 forward current - i f (a) forward voltage- v f (v) waveform parameters: tr = 8s td = 20s capacitance vs. reverse voltage 0 10 20 30 0123 reverse voltage - v r (v) capacitance - c j (pf) l to g l to l f = 1mhz 0.00 2.00 4.00 6.00 8.00 10.00 01234567 peak pulse current - i pp (a) clamping voltage - v c (v) waveform parameters: tr = 8s td = 20s 0.01 0.1 1 0.1 1 10 100 1000 pulse duration - tp (s) peak pulse power - p pp (kw)
4 ? 2008 semtech corp. www.semtech.com smf3.3 protection products typical characteristics analog crosstalk (i/o to i/o) insertion loss s21, i/o to i/o ch1 s21 log 3 db/ ref 0 db start. 030 mhz 3 stop 000.000000 mhz start. 030 mhz 3 stop 000.000000 mhz ch1 s21 log 3 db/ ref 0 db insertion loss s21, i/o to ground ch1 s21 log 20 db/ ref 0 db start. 030 mhz 3 stop 000.000000 mhz
5 ? 2008 semtech corp. www.semtech.com smf3.3 protection products smf circuit diagram protection of four unidirectional lines device connection for protection of four data lines the smf3.3 is designed to protect up to four unidirec- tional data lines. the device is connected as follows: 1. unidirectional protection of four i/o lines is achieved by connecting pins 1, 3, 4, and 5 to the data lines. pin 2 is connected to ground. the ground connection should be made directly to the ground plane for best results. the path length is kept as short as possible to reduce the effects of parasitic inductance in the board traces. due to the ?snap-back? characteristics of the low voltage tvs, it is not recommended that any of the i/o lines be directly connected to a dc source greater than snap-back votlage (v sb ) as the device can latch on as described below. epd tvs characteristics the smf3.3 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 smf3.3 can effectively oper- ate at 3.3v 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. since the epd tvs devices use a 4-layer structure, they exhibit a slightly different iv characteristic curve when compared to conventional devices. during normal operation, the device represents a high-impedance to the circuit up to the device working voltage (v rwm ). during an esd event, the device will begin to conduct and will enter a low impedance state when the punch through voltage (v pt ) is exceeded. unlike a conventional device, the low voltage tvs will exhibit a slight negative resistance characteristic as it conducts current. this characteris- tic aids in lowering the clamping voltage of the device, but must be considered in applications where dc voltages are present. 2 1345 applications information when the tvs is conducting current, it will exhibit a slight ?snap-back? or negative resistance characteris- tics due to its structures. this point is defined on the curve by the snap-back voltage (v sb ) and snap-back current (i sb ). to return to a non-conducting state, the current through the device must fall below the i sb (approximately <50ma) and the voltage must fall below the v sb (normally 2.8 volts for a 3.3v device). if a 3.3v tvs is connected to 3.3v dc source, it will never fall below the snap-back voltage of 2.8v and will therefore stay in a conducting state.
6 ? 2008 semtech corp. www.semtech.com smf3.3 protection products smf3.3 applications information 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 tvs near the input terminals or connec- tors 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. matte tin lead finish matte tin has become the industry standard lead-free replacement for snpb lead finishes. a matte tin finish is composed of 100% tin solder with large grains. since the solder volume on the leads is small com- pared to the solder paste volume that is placed on the land pattern of the pcb, the reflow profile will be determined by the requirements of the solder paste. therefore, these devices are compatible with both lead-free and snpb assembly techniques. in addition, unlike other lead-free compositions, matte tin does not have any added alloys that can cause degradation of the solder joint. typical application diagram
7 ? 2008 semtech corp. www.semtech.com smf3.3 protection products outline drawing - sc-70 5l land pattern - sc-70 5l ccc c 2x n/2 tips 2x e/2 12 n ei seating aaa c bbb c a-b d a bxn a2 a1 d a e1 d b e c plane detail l (l1) 01 0.15 plane gage c h a see detail a side view 3. dimensions "e1" and "d" do not include mold flash, protrusions or gate burrs. -b- controlling dimensions are in millimeters (angles in degrees). datums and to be determined at datum plane notes: 1. 2. -a- -h- reference jedec std mo-203, variation aa. 4. .083 bsc .026 bsc 5 .004 .045 .079 .049 .083 .006 - 5 0.10 1.25 2.10 2.10 bsc 0.65 bsc .053 1.15 2.00 .012 0.15 1.35 0.30 - 1.90 .075 0 .012 - .004 .010 .003 (.017) .014 - .028 .000 - - - .035 0.10 0.30 8 0 - 8 0.90 (0.42) 0.36 .018 .009 0.26 0.08 .043 .039 .004 0.00 0.70 - 0.22 0.46 - 0.10 1.10 1.00 - - 1.30 bsc .051 dim bbb ccc e l1 aaa 01 n e1 l c e1 e d a2 a1 b a millimeters nom inches dimensions min nom max min max e dimensions inches y z dim g p x c millimeters z .033 .106 .039 (.073) .026 .016 1.00 (1.85) 0.65 0.40 0.85 2.70 x dimensions inches y z dim g p x c millimeters this land pattern is for reference purposes only. consult your manufacturing group to ensure your company's manufacturing guidelines are met. notes: 1. c p g y
8 ? 2008 semtech corp. www.semtech.com smf3.3 protection products marking codes ordering information r e b m u n t r a p g n i k r a m e d o c 3 . 3 f m s3 0 f h c n a r b n a w i a t 0 8 3 3 - 8 4 7 2 - 2 - 6 8 8 : l e t fx a0 9 3 3 - 8 4 7 2 - 2 - 6 8 8 : h b m g d n a l r e z t i w s h c e t m e s h c n a r b n a p a j 0 5 9 0 - 8 0 4 6 - 3 - 1 8 : l e t 1 5 9 0 - 8 0 4 6 - 3 - 1 8 : x a f h c n a r b a e r o k tl e7 7 3 4 - 7 2 5 - 2 - 2 8 : f6 7 3 4 - 7 2 5 - 2 - 2 8 : x a ) . k . u ( d e t i m i l h c e t m e s 0 0 6 - 7 2 5 - 4 9 7 1 - 4 4 : l e t 1 0 6 - 7 2 5 - 4 9 7 1 - 4 4 : x a f e c i f f o i a h g n a h s t0 3 8 0 - 1 9 3 6 - 1 2 - 6 8 : l e 1 3 8 0 - 1 9 3 6 - 1 2 - 6 8 : x a f l r a s e c n a r f h c e t m e s 0 0 - 2 2 - 8 2 - 9 6 1 ) 0 ( - 3 3 : l e t 8 9 - 2 1 - 8 2 - 9 6 1 ) 0 ( - 3 3 : x a f f o y r a i d i s b u s d e n w o - y l l o h w a s i g a l a n o i t a n r e t n i h c e t m e s . a . s . u e h t n i s r e t r a u q d a e h s t i s a h h c i h w , n o i t a r o p r o c h c e t m e s h b m g y n a m r e g h c e t m e s 3 2 1 - 0 4 1 - 1 6 1 8 ) 0 ( - 9 4 : l e t 4 2 1 - 0 4 1 - 1 6 1 8 ) 0 ( - 9 4 : x a f contact information for semtech international ag r e b m u n t r a ph s i n i f d a e l r e p y t q l e e r e z i s l e e r c t . 3 . 3 f m sb p n s0 0 0 , 3h c n i 7 t c t . 3 . 3 f m se e r f b p0 0 0 , 3h c n i 7 123 4 5 f03
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