LDP24M ? march 1996 - ed : 4 transil tm load dump protection transient voltage suppressor diode especially designed for load dump effect protection high surge current capability : 30 a / 40 ms exponential wave compliant with main standards such as: -iso / dtr 7637 -saej 1113a ... surface mount technology compatible features transient voltage suppressor diode especially developed for sensitive circuit protection in automotive systems such as dash board, car radios etc. its high surge current capability and instantaneous response to transients provide an efficient protection against the load dump effect. description power so-10 tm plastic, non isolated smd with copper tab symbol parameter value unit v pp repetitive peak pulse load dump overvoltage - 5 pulses (1 minute between each pulse) - (see note 1 and 2) 100 v i fsm non repetitive surge peak forward current t p =10ms 120 a t stg t j storage junction temperature range maximum operating junction temperature - 40 to + 150 150 c c t l maximum lead temperature for soldering during 10 s 260 c absolute maximum ratings (-40 c symbol parameter v rm stand-off voltage. v br breakdown voltage. v cl clamping voltage. i pp peak pulse current. a t temperature coefficient of v br . c capacitance v f peak forward voltage drop electrical characteristics i i f v f v v cl v br v rm i pp i rm v symbol test conditions min. typ. max. unit i rm t c = -40 c t c =25 c t c =85 c v rm =24v 5 10 100 m a v br t c =25 ci r = 1ma 25.5 32 v v f tc = 25 ci fm = 10a 0.9 v v cl t c = -40 c t c =25 c t c =85 c i pp =30a (note 2) 36 38 40 v a t 910 -4 / c cf=1mhzv r = 0v 8000 pf note 2 : see load dump test generator circuit (page 4/10) pp(kw) 10.0 5.0 2.0 1.0 0.5 0.2 0.1 12 51020 50100 tp(ms) fig.1 : peak pulse power versus exponential pulse duration (tj initial = 85 c). vcl(v) 50 45 40 35 30 25 20 1 2 5 10 20 50 100 200 ipp(a) tp=40ms tp=1ms fig.2 : clamping voltage versus peak pulse cur- rent (tj initial = 85 c). exponential waveform tp=40msandtp=1ms. ? LDP24M 2/10
ipp(a) 500 200 100 50 20 10 12 51020 50100 tp(s) fig.3 : peak pulse current versus exponential pulse duration (tj initial = 85 c). zth(j-c)/rth(j-c) 1e-3 1e-2 1e-1 1e +0 1 e +1 tp(s) 1.0 0.5 0.2 0.1 fig.5 : relative variation of thermal impedance junction to case versus pulse duration. 0 25 50 75 100 125 150 175 0.0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10 tj initial ( c) pp[tj]/pp[tj initial=85 c] fig.4 : relative variation of peak pulse power ver- sus junction temperature. vfm(v) 1 2 5 10 20 50 100 200 ifm(a) 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 tj = 25 c tj = 150 c fig.6 : peak forward voltage drop versus peak for- ward current (typical values). 0.01 0.02 0.05 0.10 10 20 50 100 200 300 tp(s) ifsm(a);i t(a s) tj initial=25 c ifsm i t fig. 7 : non repetitive surge peak current versus pulse duration (sinusoidal pulse) and correspond- ing value of i2t. ? LDP24M 3/10
- cathode : pins 1 to 5 - anode : connected to base tab. - n.c. : pins 6 to 10. pin out configuration : top view p tab in 6 pin 1 order code ldp 24 m stand-off voltage load dump protection powerso-10 load dump test generator circuit (schaffner nsg 506c) u r i 47 mf 100 w 4 w 2 w 470 m f 12 mh + load dump waveform 0 t i pp i pp /2 i tp = 40ms current through d.u.t marking : logo, date code, LDP24M ? LDP24M 4/10
+12 v LDP24M input output car automotive module voltage regulator m p basic application the drawing above shows the typical use of the LDP24M. this provides protection of the +12 v supply rail directly on the car electronique module. this overvoltage suppressor was developped to immunize the sensitive parts from both long duration (load dump) and short duration (esd) surges. ? LDP24M 5/10
fig 1 : typical reflow soldering heat profile time (s) temperature ( c) 0 40 80 120 160 200 240 280 320 360 0 50 100 150 200 250 o 215 c o soldering preheating cooling 245 c o epoxy fr4 board metal-backed board soldering recommendation the soldering process causes considerable thermal stress to a semiconductor component. this has to be minimized to assure a reliable and extended lifetime of the device. the powerso-10 package can be exposed to a maximum temperature of 260 c for 10 seconds. however a proper soldering of the package could be done at 215 c for 3 seconds. any solder temperature profile should be within these limits. as reflow techniques are most common in surface mounting, typical heating profiles are given in figure 1,either for mounting on fr4 or on metal-backed boards. for each particular board, the appropriate heat profile has to be adjusted experimentally. the present proposal is just a starting point. in any case, the following precautions have to be considered : - always preheat the device - peak temperature should be at least 30 c higher than the melting point of the solder alloy chosen - thermal capacity of the base substrate voids pose a difficult reliability problem for large surface mount devices. such voids under the package result in poor thermal contact and the high thermal resistance leads to component failures. the powerso-10 is designed from scratch to be solely a surface mount package, hence symmetry in the x- and y-axis gives the package excellent weight balance. moreover, the powerso-10 offers the unique possibility to control easily the flatness and quality of the soldering process. both the top and the bottom soldered edges of the package are accessible for visual inspection (soldering meniscus). coplanarity between the substrate and the package can be easily verified. the quality of the solder joints is very important for two reasons : (i) poor quality solder joints result directly in poor reliability and (ii) solder thickness affects the thermal resistance significantly. thus a tight control of this parameter results in thermally efficient and reliable solder joints. ? LDP24M 6/10
fig 2 : mounting on epoxy fr4 head dissipation by extending the area of the copper layer fig 3 : mounting on epoxy fr4 by using copper-filled through holes for heat transfer fr4 board copper foil fr4 board copper foil heat transfer heatsink substrates and mounting information the use of epoxy fr4 boards is quite common for surface mounting techniques, however, their poor thermal conduction compromises the otherwise outstanding thermal performance of the powerso-10. some methods to overcome this limitation are discussed below. one possibility to improve the thermal conduction is the use of large heat spreader areas at the copper layer of the pc board. this leads to a reduction of thermal resistance to 35 c for 6 cm 2 of the board heatsink (see fig. 2). use of copper-filled through holes on conventional fr4 techniques will increase the metallization and decrease thermal resistance accordingly. using a configurationwith 16 holes under the spreader of the package with a pitch of 1.8 mm and a diameter of 0.7 mm, the thermal resistance (junction - heatsink) can be reduced to 12 c/w (see fig. 3). beside the thermal advantage, this solution allows multi-layer boards to be used. however, a drawback of this traditional material prevents its use in very high power, high current circuits. for instance, it is not advisable to surface mount devices with currents greater than 10 a on fr4 boards. a power mosfet or schottky diode in a surface mount power package can handle up to around 50 a if better substrates are used. ? LDP24M 7/10
powerso-10 package mounted on r th (j-a) p diss 1.fr4 using the recommended pad-layout 50 c/w 1.5 w 2.fr4 with heatsink on board (6cm 2 )35 c/w 2.0 w 3.fr4 with copper-filled through holes and external heatsink applied 12 c/w 5.8 w 4. ims floating in air (40 cm 2 )8 c/w 8.8 w 5. ims with external heatsink applied 3.5 c/w 20 w table 1 a new technology available today is ims - an insulated metallic substrate. this offers greatly enhanced thermal characteristics for surface mount components. ims is a substrate consisting of three different layers, (i) the base material which is available as an aluminium or a copper plate, (ii) a thermal conductive dielectrical layer and (iii) a copper foil, which can be etched as a circuit layer. using this material a thermal resistance of 8 c/w with 40 cm 2 of board floating in air is achievable (see fig. 4). if even higher power is to be dissipated an external heatsink could be applied which leads to an r th (j-a) of 3.5 c/w (see fig. 5), assuming that r th (heatsink-air) is equal to r th (junction-heatsink). this is commonly applied in practice, leading to reasonable heatsink dimensions. often power devices are defined by considering the maximum junction temperature of the device. in practice , however, this is far from being exploited. a summary of various power management capabilities is made in table 1 based on a reasonable delta t of 70 c junction to air. the powerso-10 concept also represents an attractive alternative to c.o.b. techniques. powerso-10 offers devices fully tested at low and high temperature. mounting is simple - only conventional smt is required - enabling the users to get rid of bond wire problems and the problem to control the high temperature soft soldering as well. an optimized thermal management is guaranteed through powerso-10 as the power chips must in any case be mounted on heat spreaders before being mounted onto the substrate. fig 4 : mounting on metal backed board fig 5 : mounting on metal backed board with an external heatsink applied fr4 board copper foil aluminium heatsink copper foil insulation aluminium ? LDP24M 8/10
package mechanical data powerso-10 (plastic) e2 e 1 10 5 6 h eb 0.25 m d h a f a1 e4 e3 e1 seating plane seating plane a b c q detail oao 0.10 a b l a1 a detail oao d1 ref. dimensions millimeters inches min. typ. max. min. typ. max. a 3.35 3.65 0.131 0.143 a1 0.00 0.10 0.00 0.0039 b 0.40 0.60 0.0157 0.0236 c 0.35 0.55 0.0137 0.0217 d 9.40 9.60 0.370 0.378 d1 7.40 7.60 0.291 0.299 e 9.30 9.50 0.366 0.374 e1 7.20 7.40 0.283 0.291 e2 7.20 7.60 0.283 0.299 ref. dimensions millimeters inches min. typ. max. min. typ. max. e3 6.10 6.35 0.240 0.250 e4 5.90 6.10 0.232 0.240 e 1.27 0.05 f 1.25 1.35 0. 0492 0.0531 h 13.80 14.40 0.543 0.567 h 0.50 0.019 l 1.20 1.80 0. 0472 0.0708 q 1.70 0.067 a0 8 0 8 ? LDP24M 9/10
header shape foot print mounting pad layout recommended 6.3 5.9 4.6 9.5 5.13 1.185 1.0 shipping tube 1 2 3 4 5 10 9 8 7 6 10.5 6.30 10.95 14.95 1.27 0.67 0.6 dimensions (mm) typ a b c length tube 18 12 0,8 532 quantity per tube 50 dimensions in millimeters dimensions in millimeters surface mount film taping : contact sales office information furnished is believed to be accurate and reliable. however, sgs-thomson microelectronics assumes no responsability for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of sgs-thomson microelectronics. specifications mentioned in this publication are subject to change without notice. this publication supersedes and replaces all information previously supplied. sgs-thomson microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of sgs-thomson microelectronics. ? 1996 sgs-thomson microelectronics - printed in italy - all rights reserved. sgs-thomson microelectronics group of companies australia - brazil - canada - china - france - germany - hong kong - italy - japan - korea - malaysia - malta - morocco - the netherlands - singapore - spain - sweden - switzerland - taiwan - thailand - united kingdom - u.s.a. b c a ? LDP24M 10/10
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