MR2525L

MR2520L MOTOROLA | Alldatasheet

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7 6367255 MOTOROLA SC (DIODES/OPTO) 59C 61866 OD T//~235

59 DEM 6367255 O0b14bb 3 I

®& MOTOROLA MR2520L lan SEMICONDUCTORS MR2525L P.O. BOX 20912 # PHOENIX, ARIZONA 85036 OVERVOLTAGE TRANSIENT SUPPRESSORS . .. designed for applications requiring @ diode with reverse ava- OVERVOLTAGE lanche characteristics for use as reverse power transient suppres- TRANSIENT SUPPRESSORS sors, Developed to suppress transients in the automotive system, these devices operate in the forward mode as standard rectifiers or 2.5K-10K WATTS reverse mode as power zener diodes and will protect expensive mobile transceivers, radios and tape decks from over-voltage conditions. © High Power Capability © Economical © Increased Capacity by Parallel Operation : MAXIMUM RATINGS DC Peak Repetitive Reverse Voltage VRRM Volts Working Peak Reverse Voltage VawM DC Blocking Voltage VR Repetitive Peak Reverse Surge Current Amp -_ MR2520L 68 MR2526L. 110 (Time Constant = 10 ms, Duty Cycle < 1.0%, Tc = 25°C) ©) A Operating and Storage Junction TyTstg |-65to +176]. °C | Temperature Range in ELECTRICAL CHARACTERISTICS K Characteristic [ symbol [min [Max [Unit Reverse Current Ade (VR = 20 Vde, To = 26°C) (VR = 20 Vdo, To = 100°C) a Breakdown Voltage Vier) 24 Volts 8 (ig = 100 mAdo, To = 25°C) k Breakdown Voltage (1) MR2526L only | Var) Volts (ip = 40 Amp, To = 85°C) (1) Pulse Test: Pulse Width < 10 ms, Duty Cycle < 2.0%, MILLIMETERS: THERMAL CHARACTERISTICS fom tt Pa a Length [ef see faze Loz oe | Thermal Resistance, Junction 18" Rese 76 °cWW Hectares eas se | to Lead @ Both Leads to Heat Sink, | 3/8" 10 Equal Length 1/2" 13 CASE 194-01 (1) Pulse Test: Pulse Width < 10 ms, Duty Cycle < 2.0%, (MR2526L) 7-~_ | MECHANICAL CHARACTERISTICS: [ama anaaneERS|_—_tncues | CASE: Transfer Molded Plastic [A | 8431" 8.68 [0.332] 0.342_] FINISH: All external surfaces are corrosion-resistant, leads are readily solderable POLARITY: Indicated by diode symbol or cathode band one LoL WEIGHT: 2.5 Grams (approx.) ( ’ © mororotaine,, 1984 DS6134R1

6367255 MOTORO

ROLA SC (DIODES7OPTOD 59C 61867 OMENS MR2520L © MR2525L 59 DEB b3b7255 oben? 5 REVERSE SURGE DESIGN LIMITS NOTE 1 — TRANSIENTS IN THE AUTOMOTIVE ELECTRICAL SYSTEM a FIGURE 1 — i iT PEAK CURRENT The introduction of electronics into the automobi oduction ¢ bile has = brought with it the interesting sidelight of characterizing en a a | the automotive electrical system for transients. g watcha COMIC Te= 26°C, Duy Ope 1% nl ‘ince most electro-mechanical systems exhibit a wear- : CEL CRM CTT 1 out phenomenon as electrical stresses are increased, there has been no need to separately define transi E oo steps LIM Ll from the normal load conditions. Any transiont condition

8 EES was simply accounted for by increasing contact ratings,

2 KH a SO etc. The introduction of semiconductors cha ic~ & of CC PSN i ibit a di viewers g COCCI PIECE ture since they exhibit a different sensitivity to transients.

5 CECI NNT Semiconductors tend to have a black and white failure

: SN SN characteristic when exposed to transients in that no dam- als Ht Tine LETT SST age is caused belowa certain level and total failure results onstant Definition CCCI ST above a certain level. Unfortunately these two levels are ‘0 77 ooo 0100-200 sb5-ib00 separate and the problem is further complicated by the 7, TIME CONSTANT (ms) fact that the energy tolerance of semiconductors is nor- mally subject to a production distribution. This leaves solid state systems open to problems which are discovered only after many units are in the field. FIGURE 2 — PEAK POWER SUMMARY OF TRANSIENTS 10000, ients ii i SeSeesie eee ereeaiit Transients in the automotive electrical system have roo HEHE detroit widely varying energy levels occurring over widely varing B soo aH Ett times, but most become insignificant compared to the E PSOE worst transient known as “Load Dump". Load dump = ns: i: i sod CSCC CCI CET ns ppe wl ent e battery becomes disconnected while =~ ati =" @ alternator is supplying charging current, or the dis- ‘ 5 met ORS ll connection of some other load with no battery present. 3 mtd oad dump transients generall i. F Re : 9 y are of 200 to 600 milli- E Hot AT seconds duration, having an exponential decay from a § sooo Da Sill worst case peak voltage of 80-120 volts. A clamped load Fy Etehe abe atari EES EE dump, it should be noted, will be of considerably shorter § 700|—f content dation Et HESH duration. Z cote hr HEHEHE Although the possibility of the battery becoming dis- nex aa So connected while the engine is running may seem remote, 7. TIME CONSTANT (na itis not reasonable this occurtenco should result in the total failure of the electrical system of a car. The following table lists some of the transients the auto- motive electronic designer must consider and should FIGURE 3 — ENERGY cause him to provide some level of protection. 3005 8 on TT TT pune ine, oo Velen

4 A Battery Line 1, +200 Volts f i

SCOOT eA 2 Sane bump resent 3 ved Te = 26°C, Duty Cycle <1% a) || Ignition Line and 1, -300 Volts for milliseconds = at i 5 Sams ees hey allie ee! Accessory Line 2, +200 Volts for microseconds ¥ a 2 3. tLoad Dump

6 A 2a |

i eT exponential decay. z CULO ‘ The voltages and times shown are reasonable values 3 la DA rom many on-car measurements. Since the nonload- Blunts tH Set Note 2 er Tine | dump transients are of low energy, but high voltage, it is meezan | MILI TTT Constant Definition il recommended they be clamped rather than blocked. It is 10-20 0 10 20 $0 100-740 00” 1000 imperative that source impedances also be known to allow 0" TWE CORSA fey proper selection of clamp devices. @) MOTOROLA Semiconductor Products Inc.

6367255 MOTOROLA SC CDIODES/OPTO) 59C 61868 OTe Men

59 DEP§b3b7es5 O0b1 |

MR2520L @ MR2525L 255 OOLLALA 7 STOPPING THE TRANSIENTS AT THE SOURCE e™ Figure 4 shows the most straight forward method of To complete the job, protection is needed against load preventing large negative transients from disrupting the dump. The easiest method is to simply clamp the output accessory and ignition busses. At the instant the switch is of the alternator with an avalanche device, as shown in opened, the current flowing in the inductance will transfer Figure 7. The completed suppressor would then appear as to the diode producing about 1 volt negative on that par- in Figure 8. It could easily be more cost effective to ticular buss. This condition will remain until the current incorporate the load dump suppressor into the alternator in the inductance decays at a rate determined by the L/R itself. The end effect would be identical to Figure 7, time constant for the circuit. It can be shown that the peak currents and transient durations available in the car FIGURE 7 can easily be absorbed by a 1N4003 diode. Vout (Battery FIGURE 4 Wire) Accessory Vout 5 MR2625R Switch | Suppressor H2V 6 om (0) Battery )

1 Regulator a -

= = V _ Figure 5 shows the most straight forward scheme for ‘out protecting against the series L-C type of transient. The forward biased diode action to protect the eat An however, the implementation would require placing 3 sient is similar to the action described for Figure 4. An avalanche devices in place of the present 3 diodes in the avalanche device is required to clip off the positive portion. ground side of the diode bridge in the alternator. aa Just applying these two techniques and calling the . result a master suppressor, overlooks the result of mutual FIGURE 8 coupling. Because of this effect, it becomes apparent that FIGURE 5 Accessory} [Ignition | Vout 7 T REVERSE BATTERY = Installing a battery with the terminals reversed today causes total failure of the charging system. Usually a fuse Load link fails, however, some cars suffer alternator failure. a This condition is caused by a large current in-rush through the diode bridge which is forward biased during reverse = battery condition. The master suppressor proposed in protecting against positive inductive transients at one spot Figure 8 will suffer the same fate. While a suppressor can is useless. Using the technique shown in Figure 6 to easily be devised, which will not drain current during protect the various lines, would not be money well spent, -12V condition, itis apparent that this defeats the purpose since the same level of protection would still be required of the suppressor. In order to make this concept feasible, a at each module anyway, due to mutual coupling. The best circuit breaker must be inserted in series with the main central suppressor for negative transients, then, isshown battery lead. in Figure 6. FIGURE 6 PARALLEL OPERATION Higher surge current capabilities can be obtained by =, i i ils. Contact Motorola (san7] paralleling the basic suppressor ce

3 Semiconductor Products Division through the nearest

= sales office or authorized distributor for more information ‘on number of cells required and package configurations = = = = available. a, MOTOROLA Semiconductor Products Inc. |

39875 EE IE : -

6367255 MOTOROLA SC (DIODES/OPTO) 59C 61869° D0T-)1-23

[55 3E] abs 4 MR2520L © MR2525L Gs GOS FIGURE 9 — STEADY STATE THERMAL RESISTANCE 40 an Single Lead to Heat Sink “||

8 S30] Insignificant Heat Flow Z|

25 Through Other Lead “|

2~ 25) 4} FS ze,| | lo | tLe Zs =a "5 vo 4 | 2 Both Leads to Heat . 33 [A = Sink, Equal Length At | | tT | ff

1 LEAD LENGTH (INCHES)

FIGURE 10 — TYPICAL TRANSIENT THERMAL RESPONSE * A A ER Oe GO RG OG | Swe ge ee g r= Y " INS Se S38"

22 Ea —" SS re

€5,.—— HEAT SINK a A SS cS Se co se Fe 6 -—} eo Eee $2 50) —) |} ee ir . Bg 8.0 = bh ads to heat sink th lengths os shown. Variations Tht] 24, — ree RJ) below 2.0 seconds are independent of lead connec’ |_| oe EE TTT inst 178 inch or geeter sd vary only about.t20% tom} ea ee the values shown, Values fortimes greaterthan2.0 seconds | | BEE nay cine by drawing a crv, with the ond point (at 70 4 as EE seconds) taken from Figure 4, of calculated from the notes, tS SP 95 SEE FFE using te given curves as a guide ithe typical or maximum —t—4 BEES EEE EEE vatuts may b0 used. For Roy values at pulse wins less LJ . = 3 Lert ee than 0.1 secon, the bow curve canbe extapclated down | | 0,3 ti pt FFF FF 10 10 at continuing stone. Cc 01 02 03 a er) 2030 60 70 10 20 30 670 1, TIME (SECONDS) THERMAL CIRCUIT MODEL (For Heat Conduction Through The Leads) Values for thermal resistance components are: Rasa} RoLayRoJay | Rok | Rouk | Rosk Rot = 40°C/WIIN. Typically and 44°C/W/IN Maximum tas | 'e Ta Rey = 2°CW Typically and 4°C/-W Maximum T T Since Ray is so low, measurements of the case tem- perature, Tc will be approximately equal to junction . TA Tea Ty Tek — TLK temperature in practical lead mounted applications, - When used as a 60 Hz rectifier, the slow thermal response holds Ty(px) close to Ty(AvG). Therefore Use of the above model permits junction to lead ther- ‘ee Ror may be found from: mal resistance for any mounting configuration to be The recommended method of mounting to a PC board found, Lowest values occur when one side of the rec- is shown on the sketch, where RgJA is approximately tifier is brought as close as possible to the heat sink as 25°C for a 1-1/2" x 1-1/2" copper surface area, Values , \\ shown below. Terms in the model signify: of 40°C/W are typical for mounting to terminal strips or Ta=Ambient Temperature Reg = Thermal Resistance, PC boards when available surface area is small. Heat Sink to Ambient E TL =Lead Temperature Ro_=Thermal Resistance, Lead to Heat Sink Tc =Case Temperature Rey=Thermal Resistance, Lm | Junction to Case i D Ty =Junction Temperature Pp =Power Dissipation g _ (Subscripts A and K refer to anode and cathode sides /——— Board ground plane = ". respectively.) Recommended mounting for half wave circuit : & MOTOROLA Semiconductor Products Inc. |

6367255 MOTOROLA SC (DIODES/OPTO) $9C 61870 DT-//-22

MR2520L @ MR2525L 59 DE@pb3b7255 OObLa? NOTE 2 — METHOD FOR CALCULATING ENERGY DISSIPATED IN A SURGE SUPPRESSOR DURING CAPACITIVE DISCHARGE TESTS One of the major parameters of interest in the rating of EMPIRICAL PARAMETER DETERMINATION a diode surge suppressor is the energy dissipated in the Figure 13 shows the instantaneous current and volt- device during an exponentially decaying transient pulse. age applied to the DUT as obtained with a dual trace Surge suppressor diodes are usually characterized using memory oscilloscope during pulse testing using the ; a capacitive discharge test, as shownin Figures 11 and 12. circuit of Figure 11, Points on the instantaneous power . Calculation of the energy, peak power and the R-C time curve can be found by multiplying the instantaneous constant of the capacitive discharge power pulse is current by the instantaneous voltage at various points in described in the material that follows and correlates with time. both of the circuits. From equation (1): p(t)= Pm e-t/7 (4) FIGURE 11 — AUTOMOTIVE LOAD DUMP TEST CIRCUIT 100n 2N6399 0.169

2200 C159M

5.00 4 + 4 = 15 Vde 30,600 nF (Simulate Car 50-85 Vde Trigger Pulse Battery) T=RC = 0.16" 30.6 x 10-3 = 4.896 ms FIGURE 12 — CAPACITIVE DISCHARGE TEST CIRCUIT . 100 2N6399 cisom 91-100 + + 2200 30,000 pF Pe *] 60-85 Vde Trigger out i FIGURE 13 — REPRESENTATION OF CURRENT AND THEORETICAL ENERGY CALCULATION VOLTAGE APPLIED TO TEST DIODE Assuming that the instantaneous power dissipated in 40 | 2 pcre op ors a exponential decay represented by Zz ioe oe ee ee Lo 3 pit)= Pm e-t/r a) a 3 . where Pm is the peak power at t= O andr is the R-C time s poppe re pone 3 . constant of the test circuit, then the energy dissipated in @ goh---}---}--- $---£---4---J---L-- Jo the DUT can be calculated as: = | Popo gp Pt de 2 wef Pm e-V/T dt (2) z ee ee = ° 24 Nobo ope tort 8 sWe=r Pm (3) = a A eee ee eee ee = ¥ Empirical determination of Pm and7 willallow calculation | of the energy in the pulse using expression (3) above. % m7 ra “0 ry 1, TIME (ms) 4 @®) MOTOROLA Semiconductor Products Inc. ——————

a

6367255 MOTOROLA SC (DIODES/OPTO) _ 59C 61871 0 Je //- 23

MR2520L ¢ MR2525L 2 t thus, Inptt)= In Pm =~ 6 SUMMARY: alewlation oral) and Inpit) using data points off Figure 3 The energy dissipated in a diode in a capacitive dis- lates as st charge test can be calculated from data obtained from a t vit) ite) pit) dual trace memory oscilloscope using the following pro- . (ms) (Volts) (Amps) (Watts) Inp(t) cedure: 05 360 80.0 2880 7,965 1. Record the current and voltage pulses simultane- 1.5 37.5 54.0 2025 7.613 I dual tra: ry oscil 6 usini 26 370 60.0 1860 7.523 ously on a dual trace memory oscilloscope using 3.5 36.5 42.0 1533 7335 appropriate scales to utilize the entire scope to 45 36.0 38.0 1368 7.221 display the decay. 95 34.6 22.0 759 = 6.632 2. Pick off approximately five voltage and current data 196 32.0 80 256 5.645 points across the decay (do not use t = 0 as a data 29.5 = 30.0 2.0 60 4.094 point since the voltage across the DUT is initially . . . very low, the current is at its peak and the energy Expression (5) is the equation form or a straight line : dissipated is negligible), =mx+ yemx¢ . (6) 3. Multiply these instantaneous current and voltage Where mis the slope and b is the intercept values and take the natural logrithm of the product. -1. ; . 4. Perform a least squares regression of Inp(t) vs. t to For expression (5)— is the slope and InPmis the intercept determine the slepe and intercept of the “best fit. “1 ting’ straight line, The R2 (correlation coefficient) thus, T= T~ 7) should be above 90% for good accuracy. m Pm = In-1(b) (8) 6. Calculate 7 and Pm using equations (7) and (8). Accurately fitting a straight line to the Inp(t) vs. t data 6. Calculate the energy using equation (3). points allows determination of Pm andr for use in equa- tion (3). f REGRESSION APPROACH COMMENTS: The method of least squares can be used to determine Using this method, the time constant derived will be the slope and intercept of the line which best fits the data slightly larger than the R-C product of the capacitor and points Inp(t) vs. t calculated above. Least squares resistor used in the circuit. This occurs due to the series regression routines are available on most time sharing resistance of the DUT and the Thyristor in the firing circuit. computer systems as well as on many scientific calcu- The peak energy calculated from this method will be less lators. than whatis indicated by the current and voltage traces at A least squares regression for the above data points t = 0, This difference is of little consequence, however, shows the intercept and slope to be 7.8588 and -0.12429 because of the short duration during which it exists. In respectively, and from (6) and (7). the example used, the current and voltage at t= Oare 100A = In-lip)e ine! . and 30 Volts. These conditions exist for 0.5 ms or less . Pm = Inv{p) = in-"(7.8588) = 2688.4 Watts and thus the energy dissipated is less than 1.5 Joules or : es 7% of the calculated energy. This 7% difference is a T=" Tor2g99 ~ 8.046 ms typical value, Finally, the energy dissipated in the DUT is: Perhaps more accuracy could be obtained by adding W= Pm = 20.828 Joul 7% to the calculated energy, however, without the 7% =r hm= 205 joules “adder” this method can be used as a comparison of The multiple correlation coefficient of the regression for different transient suppressors. : this example was 0,994 indicating a 99.4% accuracy of the fit to the theoretical equation (1), In general, accu- ; racies above 97% can be obtained. vi Motorola reserves the right to make changes without further notice to any products herein to improve reliability, function or design, Motorola does not assume any Ilability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its , H patent rights nor the rights of others, Motorola and) are registered trademarks of Motorola, Inc. Motorola, Inc, is an Equal Employment Opportunity/ 4 Affirmative Action Employer. : & MOTOROLA Semiconductor Products Inc. | BOX 20912 ¢ PHOENIX, ARIZONA 85036 ® A SUBSIDIARY OF MOTOROLA INC.