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device operating temperature range package semiconductor technical data power supply supervisory/ over and undervoltage protection circuit ordering information MC3425p1 t a = 0 to +70 c plastic dip pin connections order this document by MC3425/d p1 suffix plastic package case 626 1 8 1 2 3 45 6 7 8 o.v. drv output o.v. dly o.v. sense u.v. sense v cc gnd u.v. ind output u.v. dly (top view) 1 motorola analog ic device data

the MC3425 is a power supply supervisory circuit containing all the necessary functions required to monitor over and undervoltage fault conditions. these integrated circuits contain dedicated over and undervoltage sensing channels with independently programmable time delays. the overvoltage channel has a high current drive output for use in conjunction with an external scr crowbar for shutdown. the undervoltage channel input comparator has hysteresis which is externally programmable, and an opencollector output for fault indication. ? dedicated over and undervoltage sensing ? programmable hysteresis of undervoltage comparator ? internal 2.5 v reference ? 300 ma overvoltage drive output ? 30 ma undervoltage indicator output ? programmable time delays ? 4.5 v to 40 v operation maximum ratings rating symbol value unit power supply voltage v cc 40 vdc comparator input voltage range (note 1) v ir 0.3 to +40 vdc drive output short circuit current i os(drv) internally limited ma indicator output voltage v ind 0 to 40 vdc indicator output sink current i ind 30 ma power dissipation and thermal characteristics maximum power dissipation @ t a = 70 c thermal resistance, junctiontoair p d r q ja 1000 80 mw c/w operating junction temperature t j +150 c operating ambient temperature range t a 0 to +70 c storage temperature range t stg 55 to +150 c note: 1. the input signal voltage should not be allowed to go negative by more than 300 mv note: 1. or positive by more than 40 v, independent of v cc , without device destruction. simplified application overvoltage crowbar protection, undervoltage indication dc power supply v in v out undervoltage indication MC3425 c out + ? motorola, inc. 1996 rev 2
MC3425 2 motorola analog ic device data electrical characteristics (4.5 v v cc 40 v; t a = t low to t high [note 2], unless otherwise noted.) characteristics symbol min typ max unit reference section sense trip voltage (referenced voltage) v cc = 15 v t a = 25 c t low to t high (note 2) v sense 2.4 2.33 2.5 2.5 2.6 2.63 vdc line regulation of v sense 4.5 v v cc 40 v; t j = 25 c reg line 7.0 15 mv power supply voltage operating range v cc 4.5 40 vdc power supply current v cc = 40 v; t a = 25 c; no output loads o.v. sense (pin 3) = 0 v; u.v. sense (pin 4) = v cc i cc(off) 8.5 10 ma o.v. sense (pin 3) = v cc ; u.v. sense (pin 4) = 0 v i cc(on) 16.5 19 ma input section input bias current, o.v. and u.v. sense i ib 1.0 2.0 m a hysteresis activation voltage, u.v. sense v cc = 15 v; t a = 25 c; i h = 10% i h = 90% v h(act) 0.6 0.8 v hysteresis current, u.v. sense v cc = 15 v; t a = 25 c; u.v. sense (pin 4) = 2.5 v i h 9.0 12.5 16 m a delay pin voltage (i dly = 0 ma) low state high state v ol(dly) v oh(dly) v cc 0.5 0.2 v cc 0.15 0.5 v delay pin source current v cc = 15 v; v dly = 0 v i dly(source) 140 200 260 m a delay pin sink current v cc = 15 v; v dly = 2.5v i dly(sink) 1.8 3.0 ma output section drive output peak current (t a = 25 c) i drv(peak) 200 300 ma drive output voltage i drv = 100 ma; t a = 25 c v oh(drv) v cc 2.5 v cc 2.0 v drive output leakage current v drv = 0 v i drv(leak) 15 200 na drive output current slew rate (t a = 25 c) di/dt 2.0 a/ m s drive output v cc transient rejection v cc = 0 v to 15 v at dv/dt = 200 v m s; o.v. sense (pin 3) = 0 v; t a = 25 c i drv(trans) 1.0 ma (peak) indicator output saturation voltage i ind = 30 ma; t a = 25 c v ind(sat) 560 800 mv indicator output leakage current v oh(ind) = 40 v i ind(leak) 25 200 na output comparator threshold voltage (note 3) v th(oc) 2.33 2.5 2.63 v propagation delay time (v cc = 15 v; t a = 25 c) input to drive output or indicator output 100 mv overdrive, c dly = 0 m f t plh(in/out) 1.7 m s input to delay 2.5 v overdrive (0 v to 5.0 v step) t plh(in//dly) 700 ns notes: 2. t low to t high = 0 to +70 c 3. the v th(oc) limits are approximately the v sense limits over the applicable temperature range.
MC3425 3 motorola analog ic device data i h , hysteresis current ( a) m i h , hysteresis current ( a) m , delay pin source current ( a) dly(source) m i figure 1. hysteresis current versus hysteresis activation voltage figure 2. hysteresis activation voltage versus temperature figure 3. hysteresis current versus temperature figure 4. sense trip voltage change versus temperature figure 5. output delay time versus delay capacitance figure 6. delay pin source current versus temperature 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 v cc =15v 55 25 0 25 50 75 100 125 t a, ambient temperature ( c) , hysteresis activation voltage (v) h(act) v 55 25 0 25 50 75 100 125 t a , ambient temperature ( c) v sense * = 2.400 v * = 2.500 v * = 2.600 v 55 25 0 25 50 75 100 125 d , sense trip voltage change (mw) sense t a , ambient temperature ( c) v cc = 15 v *v sense at t a = 25 c v 0.0001 0.001 0.01 0.1 1.0 10 dly c dly , delay pin capacitance ( m f) v cc = 15 v t a = 25 c t dly = 2.5 c dly , output delay time (ms) t 55 25 0 25 50 75 100 125 t a , ambient temperature ( c) v h(act) , hysteresis activation voltage (v) 14 12 10 8.0 6.0 4.0 2.0 0 1.2 1.0 0.8 0.6 0.4 0.2 0 15.0 14.0 13.0 12.0 11.0 10.0 0 10 20 30 40 50 100 10 1.0 0.1 0.01 0.001 260 240 220 200 180 160 t a = 25 c v cc = 40 v v cc = 5.0 v v cc = 5.0 v v cc = 15 v v cc = 40 v v h(act) = voltage level at which hysteresis current (i h ) is 90% of full value. u.v. sense = 2.5 v 200 m a v cc = 40 v v cc = 15 v v cc = 5.0 v
MC3425 4 motorola analog ic device data figure 7. drive output saturation voltage versus output peak current figure 8. indicator output saturation voltage versus output sink current figure 9. drive output saturation voltage versus temperature figure 10. power supply current versus voltage 0 100 200 300 400 i drv(peak) , drive output peak current (ma) , drive output saturation voltage (v) oh(drv) v cc = 15 v 1.0% duty cycle @ 300 hz t a = 25 c v 010203040 i ind , indicator output sink current (ma) , indicator output saturation voltage (v) ind(sat) v cc = 15 v t a = 25 c v 55 25 0 25 50 75 100 125 t a , ambient temperature ( c) , drive output saturation votlage (v) oh(drv) v curve o.v. sense u.v. sense a b 0 5.0 10 15 20 25 30 35 40 v cc , power supply voltage (v) , power supply current (ma) cc t a = 25 c i v cc = 15 v i drv(peak) = 200 ma 1.0% duty cycle @ 300 hz av cc gnd b gnd v cc 5.0 4.0 3.0 2.0 1.0 0 0.4 0.3 0.2 0.1 0 2.500 2.460 2.420 2.380 2.340 2.300 28 24 20 16 12 8.0 4.0 0
MC3425 5 motorola analog ic device data applications information figure 11. overvoltage protection and undervoltage fault indication with programmable delay figure 12. overvoltage protection of 5.0 v supply with line loss detector figure 13. overvoltage audio alarm circuit figure 14. programmable frequency switch u.v. hysteresis = i h r1b r2b t dly = 12500 c dly , v o(trip) 2.5 v r1a +v o r1a r1b 8 4 3 1 6 r2a 275 c dly c dly gnd u.v. fault indicator v cc u.v. sense o.v. drv MC3425 o.v. sense u.v. ind u.v. dly gnd o.v. dly power supply 4.5v to 40v r2b i h v o = 5.0 v v o(trip) = 6.25 v v cc u.v. sense u.v. ind MC3425 o.v. sense o.v. drv u.v. dly gnd o.v. dly 8 4 31 6 27 5 line loss output v in 15k 1.0k 10k 100 ac line 0.01 m f 0.33 m f 2.5v 2.5v on off u.v. sense pin 4 u.v. dly pin 5 u.v. ind pin 6 +5.0v power supply v cc u.v. sense MC3425 o.v. sense o.v. drv u.v. dly gnd o.v. dly +v o 12k 2.7k 82k 6.8k 27 5 gnd 3 4 1 100 w 12v power supply 0.1 m f alarm on when: v o = 13.6 v 8 + output pulse when: f (input) < 1 25000 c dly input signal 12v 8 i.v. pp 10k 10k o.v. dly gnd u.v. dly v cc u.v. sense MC3425 o.v. sense o.v. drv 1 57 2 3 4 1.0k c dly 0.1 m f 5.0 m f + r1b + r2b r2a 1 + o.v. sense pin 3 o.v. dly pin 2 o.v. drv pin 1 2.5v on off 2.5v
MC3425 6 motorola analog ic device data circuit description the MC3425 is a power supply supervisory circuit containing all the necessary functions required to monitor over and undervoltage fault conditions. the block diagram is shown below in figure 15. the overvoltage (o.v.) and undervoltage (u.v.) input comparators are both referenced to an internal 2.5 v regulator. the u.v. input comparator has a feedback activated 12.5 m a current sink (i h ) which is used for programming the input hysteresis voltage (v h ). the source resistance feeding this input (r h ) determines the amount of hysteresis voltage by v h = i h r h = 12.5 10 6 r h . separate delay pins (o.v. dly, u.v. dly.) are provided for each channel to independently delay the drive and indicator outputs, thus providing greater input noise immunity. the two delay pins are essentially the outputs of the respective input comparators, and provide a constant current source, i dly(source) , of typically 200 m a when the noninverting input voltage is greater than the inverting input level. a capacitor connected from these delay pins to ground, will establish a predictable delay time (t dly ) for the drive and indicator outputs. the delay pins are internally connected to the noninverting inputs of the o.v. and u.v. output comparators, which are referenced to the internal 2.5 v regulator. therefore, delay time (t dly ) is based on the constant current source, i dly(source) , charging the external delay capacitor (c dly ) to 2.5 v. t dly = v ref c dly i dly(source) = 2.5 c dly 200 m a = 12500 c dly figure 5 provides c dly values for a wide range of time delays. the delay pins are pulled low when the respective input comparator's noninverting input is less than the inverting input. the sink current, i dly(sink) , capability of the delay pins is 1.8 ma and is much greater than the typical 200 m a source current, thus enabling a relatively fast delay capacitor discharge time. the overvoltage drive output is a currentlimited emitterfollower capable of sourcing 300 ma at a turnon slew rate at 2.0 a/ m s, ideal for driving acrowbaro scr's. the undervoltage indicator output is an opencollector, npn transistor, capable of sinking 30 ma to provide sufficient drive for led's, small relays or shutdown circuitry. these current capabilities apply to both channels operating simultaneously, providing device power dissipation limits are not exceeded. the MC3425 has an internal 2.5 v bandgap reference regulator with an accuracy of 4.0% for the basic device. note: all voltages and currents are nominal. input section output section v cc o.v. drv u.v. ind o.v. sense u.v. sense u.v. dly o.v. dly gnd 200 m a 3 4 i h 52 7 + 2.5v reference regulator + output comparator u.v. 8 1 6 + + + + + + + output comparator o.v. input comparator o.v. input comparator u.v. 200 m a 12.5 m a figure 15. representative block diagram
MC3425 7 motorola analog ic device data crowbar scr considerations referring to figure 16, it can be seen that the crowbar scr, when activated, is subject to a large current surge from the output capacitance, c out . this capacitance consists of the power supply output capacitors, the load's decoupling capacitors, and in the case of figure 16a, the supply's input filter capacitors. this surge current is illustrated in figure 17, and can cause scr failure or degradation by any one of three mechanisms: di/dt, absolute peak surge, or i 2 t. the interrelationship of these failure methods and the breadth of the applications make specification of the scr by the semiconductor manufacturer difficult and expensive. therefore, the designer must empirically determine the scr and circuit elements which result in reliable and effective ovp operation. however, an understanding of the factors which influence the scr's di/dt and surge capabilities simplifies this task. 1. di/dt as the gate region of the scr is driven on, its area of conduction takes a finite amount of time to grow, starting as a very small region and gradually spreading. since the anode current flows through this turnedon gate region, very high current densities can occur in the gate region if high anode currents appear quickly (di/dt). this can result in immediate destruction of the scr or gradual degradation of its forward blocking voltage capabilities depending on the severity of the occasion. the value of di/dt that an scr can safely handle is influenced by its construction and the characteristics of the gate drive signal. a centergatefire scr has more di/dt capability than a cornergatefire type, and heavily overdriving ( 3 to 5 times i gt ) the scr gate with a fast < 1.0 m s rise time signal will maximize its di/dt capability. a typical maximum number in phase control scrs of less than 50 a(rms) rating might be 200 a/ m s, assuming a gate current of five times i gt and < 1.0 m s rise time. if having done this, a di/dt problem is seen to still exist, the designer can also decrease the di/dt of the current waveform by adding inductance in series with the scr, as shown in figure 18. of course, this reduces the circuit's ability to rapidly reduce the dc bus voltage and a tradeoff must be made between speedy voltage reduction and di/dt. (a) scr across input of regulator (b) scr across output of regulator *needed if supply is not current limited. v in ++ ++ c in c in c out c out v out v out MC3425 series regulator MC3425 series regulator v in * figure 16. typical crowbar circuit configurations
MC3425 8 motorola analog ic device data figure 17. crowbar scr surge current waveform l pk surge due to output capacitor current limited supply output di dt l t 2. surge current if the peak current and/or the duration of the surge is excessive, immediate destruction due to device overheating will result. the surge capability of the scr is directly proportional to its die area. if the surge current cannot be reduced (by adding series resistance see figure 18) to a safe level which is consistent with the system's requirements for speedy bus voltage reduction, the designer must use a higher current scr. this may result in the average current capability of the scr exceeding the steady state current requirements imposed by the dc power supply. r & l empirically determined! esr esl r lead l lead output cap to mc3423 r l figure 18. circuit elements affecting scr surge & di/dt undervoltage sensing an undervoltage sense circuit with hysteresis may be designed, as shown in figure 11, using the following equations: r1 v ccu v cc1 12.5 a r2 2.5 r1 v cc1 2.5 where: v ccu is the designed upper trip point (output indicator goes off) v cc1 is the lower trip point (output indicator goes on) a word about fusing before leaving the subject of the crowbar scr, a few words about fuse protection are in order. referring back to figure 16a, it will be seen that a fuse is necessary if the power supply to be protected is not output current limited. this fuse is not meant to prevent scr failure but rather to prevent a fire! in order to protect the scr, the fuse would have to possess an i 2 t rating less than that of the scr and yet have a high enough continuous current rating to survive normal supply output currents. in addition, it must be capable of successfully clearing the high short circuit currents from the supply. such a fuse as this is quite expensive, and may not even be available. the usual design compromise then is to use a garden variety fuse (3ag or 3ab style) which cannot be relied on to blow before the thyristor does, and trust that if the scr does fail, it will fail short circuit. in the majority of the designs, this will be the case, though this is difficult to guarantee. of course, a sufficiently high surge will cause an open. these comments also apply to the fuse in figure 16b. crowbar scr selection guide as an aid in selecting an scr for crowbar use, the following selection guide is presented. device i rms i tsm mcr310 series 10 a 100 a mcr16 series 16 a 150 a mcr25 series 25 a 300 a 2n6501 series 25 a 300 a mcr69 series 25 a 750 a mcr264 series 40 a 400 a mcr265 series 55 a 550 a
MC3425 9 motorola analog ic device data outline dimensions p1 suffix plastic package case 62605 issue k 14 5 8 f note 2 a b t seating plane h j g d k n c l m m a m 0.13 (0.005) b m t notes: 1. dimension l to center of lead when formed parallel. 2. package contour optional (round or square corners). 3. dimensioning and tolerancing per ansi y14.5m, 1982. dim min max min max inches millimeters a 9.40 10.16 0.370 0.400 b 6.10 6.60 0.240 0.260 c 3.94 4.45 0.155 0.175 d 0.38 0.51 0.015 0.020 f 1.02 1.78 0.040 0.070 g 2.54 bsc 0.100 bsc h 0.76 1.27 0.030 0.050 j 0.20 0.30 0.008 0.012 k 2.92 3.43 0.115 0.135 l 7.62 bsc 0.300 bsc m 10 10 n 0.76 1.01 0.030 0.040
MC3425 10 motorola analog ic device data notes
MC3425 11 motorola analog ic device data notes
MC3425 12 motorola analog ic device data motorola reserves the right to make changes without further notice to any products herein. motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does motorola assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. atypicalo parameters which may be provided in motorola data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. all operating parameters, including atypicalso must be validated for each customer application by customer's technical experts. motorola does not convey any license under its patent rights nor the rights of others. motorola products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the motorola product could create a situation where personal injury or death may occur. should buyer purchase or use motorola products for any such unintended or unauthorized application, buyer shall indemnify and hold motorola and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that motorola was negligent regarding the design or manufacture of the part. motorola and are registered trademarks of motorola, inc. motorola, inc. is an equal opportunity/affirmative action employer. how to reach us: usa / europe / locations not listed : motorola literature distribution; japan : nippon motorola ltd.; tatsumispdjldc, 6f seibubutsuryucenter, p.o. box 20912; phoenix, arizona 85036. 18004412447 or 6023035454 3142 tatsumi kotoku, tokyo 135, japan. 038135218315 mfax : rmfax0@email.sps.mot.com touchtone 6 022446609 asia / pacific : motorola semiconductors h.k. ltd.; 8b tai ping industrial park, internet : http://designnet.com 51 ting kok r oad, tai po, n.t., hong kong. 85226629298 m3425/d ?

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