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| Order this document by MC3425/D MC3425 Power Supply Supervisory/ Over and Undervoltage Protection Circuit 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 open-collector output for fault indication. * Dedicated Over and Undervoltage Sensing POWER SUPPLY SUPERVISORY/ OVER AND UNDERVOLTAGE PROTECTION CIRCUIT SEMICONDUCTOR TECHNICAL DATA * * * * * * 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 8 1 P1 SUFFIX PLASTIC PACKAGE CASE 626 Symbol VCC VIR IOS(DRV) VIND IIND PD RJA TJ TA Tstg Value 40 -0.3 to +40 Internally Limited 0 to 40 30 1000 80 +150 0 to +70 -55 to +150 Unit Vdc Vdc mA Vdc mA mW C/W C C C O.V. DRV Output O.V. DLY O.V. Sense U.V. Sense 1 2 3 4 (Top View) Vout 8 7 6 5 VCC Gnd U.V. IND Output U.V. DLY MAXIMUM RATINGS Rating Power Supply Voltage Comparator Input Voltage Range (Note 1) Drive Output Short Circuit Current Indicator Output Voltage Indicator Output Sink Current Power Dissipation and Thermal Characteristics Maximum Power Dissipation @ TA = 70C Thermal Resistance, Junction-to-Air Operating Junction Temperature Operating Ambient Temperature Range Storage Temperature Range PIN CONNECTIONS 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 VCC, without device destruction. Simplified Application Overvoltage Crowbar Protection, Undervoltage Indication Vin DC Power Supply + Cout MC3425 Undervoltage Indication Device ORDERING INFORMATION Operating Temperature Range TA = 0 to +70C Package Plastic DIP Rev 2 MC3425P1 (c) Motorola, Inc. 1996 MOTOROLA ANALOG IC DEVICE DATA 1 MC3425 ELECTRICAL CHARACTERISTICS (4.5 V VCC 40 V; TA = Tlow to Thigh [Note 2], unless otherwise noted.) Characteristics REFERENCE SECTION Sense Trip Voltage (Referenced Voltage) VCC = 15 V TA= 25C Tlow to Thigh (Note 2) Line Regulation of VSense 4.5 V VCC 40 V; TJ = 25C Power Supply Voltage Operating Range Power Supply Current VCC = 40 V; TA = 25C; No Output Loads O.V. Sense (Pin 3) = 0 V; U.V. Sense (Pin 4) = VCC O.V. Sense (Pin 3) = VCC; U.V. Sense (Pin 4) = 0 V INPUT SECTION Input Bias Current, O.V. and U.V. Sense Hysteresis Activation Voltage, U.V. Sense VCC = 15 V; TA = 25C; IH = 10% IH = 90% Hysteresis Current, U.V. Sense VCC = 15 V; TA = 25C; U.V. Sense (Pin 4) = 2.5 V Delay Pin Voltage (IDLY = 0 mA) Low State High State Delay Pin Source Current VCC = 15 V; VDLY = 0 V Delay Pin Sink Current VCC = 15 V; VDLY = 2.5V OUTPUT SECTION Drive Output Peak Current (TA = 25C) Drive Output Voltage IDRV = 100 mA; TA = 25 C Drive Output Leakage Current VDRV = 0 V Drive Output Current Slew Rate (TA = 25C) Drive Output VCC Transient Rejection VCC = 0 V to 15 V at dV/dt = 200 V s; O.V. Sense (Pin 3) = 0 V; TA = 25C Indicator Output Saturation Voltage IIND = 30 mA; TA = 25C Indicator Output Leakage Current VOH(IND) = 40 V Output Comparator Threshold Voltage (Note 3) Propagation Delay Time (VCC = 15 V; TA = 25C) Input to Drive Output or Indicator Output 100 mV Overdrive, CDLY = 0 F Input to Delay 2.5 V Overdrive (0 V to 5.0 V Step) IDRV(peak) VOH(DRV) IDRV(leak) di/dt IDRV(trans) 200 VCC-2.5 - - - 300 VCC-2.0 15 2.0 1.0 - - 200 - - mA V nA A/s mA (Peak) mV nA V IIB VH(act) - - IH 9.0 0.6 0.8 12.5 - - 16 A V VOL(DLY) VOH(DLY) IDLY(source) IDLY(sink) - VCC-0.5 140 1.8 0.2 VCC-0.15 200 3.0 0.5 - 260 - A mA - 1.0 2.0 A V VSense 2.4 2.33 Regline VCC - 4.5 2.5 2.5 7.0 - 2.6 2.63 15 40 mV Vdc Vdc Symbol Min Typ Max Unit ICC(off) ICC(on) - - 8.5 16.5 10 19 mA mA VIND(sat) IIND(leak) Vth(OC) - - 2.33 560 25 2.5 800 200 2.63 tPLH(IN/OUT) tPLH(IN//DLY) - - 1.7 700 - - s ns NOTES: 2. Tlow to Thigh = 0 to +70C 3. The Vth(OC) limits are approximately the VSense limits over the applicable temperature range. 2 MOTOROLA ANALOG IC DEVICE DATA MC3425 Figure 1. Hysteresis Current versus Hysteresis Activation Voltage 14 IH, HYSTERESIS CURRENT (A) 12 10 8.0 6.0 4.0 2.0 0 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 VH(act), HYSTERESIS ACTIVATION VOLTAGE (V) 1.6 VCC = 40 V VCC = 15 V TA = 25C V H(act) , HYSTERESIS ACTIVATION VOLTAGE (V) Figure 2. Hysteresis Activation Voltage versus Temperature 1.2 1.0 0.8 0.6 0.4 0.2 0 -55 VCC = 5.0 V VCC = 15 V VCC = 40 V VH(act) = Voltage Level at which Hysteresis Current (IH) is 90% of full value. VCC = 5.0 V -25 0 25 50 75 TA, AMBIENT TEMPERATURE (C) 100 125 15.0 IH, HYSTERESIS CURRENT (A) U.V. Sense = 2.5 V 14.0 13.0 12.0 11.0 10.0 -55 V Sense , SENSE TRIP VOLTAGE CHANGE (mW) Figure 3. Hysteresis Current versus Temperature Figure 4. Sense Trip Voltage Change versus Temperature 0 -10 -20 -30 -40 -50 -55 -25 0 25 50 75 100 125 VCC = 15 V *VSense at TA = 25C VSense* = 2.400 V * = 2.500 V * = 2.600 V -25 0 25 50 75 TA, AMBIENT TEMPERATURE (C) 100 125 TA, AMBIENT TEMPERATURE (C) IDLY(source), DELAY PIN SOURCE CURRENT ( A) Figure 5. Output Delay Time versus Delay Capacitance 100 t DLY , OUTPUT DELAY TIME (mS) 10 1.0 0.1 tDLY = 0.01 VCC = 15 V TA = 25C Figure 6. Delay Pin Source Current versus Temperature 260 240 220 VCC = 15 V 200 180 160 -55 VCC = 5.0 V VCC = 40 V 2.5 CDLY 200 A 0.001 0.0001 0.001 0.01 0.1 1.0 10 -25 CDLY, DELAY PIN CAPACITANCE (F) 0 25 50 75 TA, AMBIENT TEMPERATURE (C) 100 125 MOTOROLA ANALOG IC DEVICE DATA 3 MC3425 V OH(DRV), DRIVE OUTPUT SATURATION VOLTAGE (V) V IND(sat) , INDICATOR OUTPUT SATURATION VOLTAGE (V) Figure 7. Drive Output Saturation Voltage versus Output Peak Current 5.0 4.0 3.0 2.0 1.0 0 VCC = 15 V 1.0% Duty Cycle @ 300 Hz TA = 25C Figure 8. Indicator Output Saturation Voltage versus Output Sink Current 0.4 0.3 0.2 VCC = 15 V TA = 25C 0.1 0 100 200 300 400 0 0 10 20 30 40 IIND, INDICATOR OUTPUT SINK CURRENT (mA) IDRV(peak), DRIVE OUTPUT PEAK CURRENT (mA) V OH(DRV), DRIVE OUTPUT SATURATION VOTLAGE (V) Figure 9. Drive Output Saturation Voltage versus Temperature 2.500 2.460 2.420 2.380 2.340 2.300 -55 VCC = 15 V IDRV(peak) = 200 mA 1.0% Duty Cycle @ 300 Hz I CC, POWER SUPPLY CURRENT (mA) 28 24 20 16 12 8.0 4.0 0 -25 0 25 50 75 100 125 0 5.0 Figure 10. Power Supply Current versus Voltage Curve O.V. Sense U.V. Sense A VCC Gnd B Gnd VCC A B TA = 25C 10 15 20 25 30 35 40 TA, AMBIENT TEMPERATURE (C) VCC, POWER SUPPLY VOLTAGE (V) 4 MOTOROLA ANALOG IC DEVICE DATA MC3425 APPLICATIONS INFORMATION Figure 11. Overvoltage Protection and Undervoltage Fault Indication with Programmable Delay +VO Vin Figure 12. Overvoltage Protection of 5.0 V Supply with Line Loss Detector VO = 5.0 V VO(trip) = 6.25 V 8 VCC 4 U.V. Sense MC3425 3 O.V. Sense O.V. 1 DRV U.V. 6 IND 1.0k Line Loss Output +5.0V Power Supply 15k R1A R1B 8 VCC 4 IH 3 U.V. Sense MC3425 O.V. Sense O.V. 1 DRV U.V. 6 IND + Power Supply 4.5V to 40V - AC Line U.V. Fault Indicator 10k 100 U.V. O.V. DLY Gnd DLY 2 7 5 0.01F 0.33F R2A R2B CDLY U.V. O.V. DLY Gnd DLY 2 7 5 CDLY Gnd R1A R2A U.V. Sense Pin 4 U.V. DLY Pin 5 U.V. IND Pin 6 2.5V 2.5V OFF ON U.V. Hysteresis = IH tDLY = 12500 CDLY R1B R2B , VO(trip) - 2.5 V R1B + R2B 1+ Figure 13. Overvoltage Audio Alarm Circuit Figure 14. Programmable Frequency Switch 12V 8 VCC 3 10k O.V. Sense MC3425 4 U.V. Sense O.V. U.V. DLY Gnd DLY 5 7 2 CDLY O.V. 1 DRV +VO 8 12k 3 + 12V Power Supply 2.7k 4 82k 6.8k 0.1F Gnd U.V. Sense U.V. O.V. DLY DLY Gnd 5 2 7 O.V. Sense VCC O.V. DRV 1 Alarm On when: VO = 13.6 V Input Signal I.V. p-p 5.0F 10k Output Pulse when: 1 f(input) < 25000 CDLY 1.0k MC3425 100 0.1F O.V. Sense Pin 3 O.V. DLY Pin 2 O.V. DRV Pin 1 2.5V 2.5V ON OFF MOTOROLA ANALOG IC DEVICE DATA 5 MC3425 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 A current sink (IH) which is used for programming the input hysteresis voltage (VH). The source resistance feeding this input (RH) determines the amount of hysteresis voltage by VH = IHRH = 12.5 x 10-6 RH. 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, IDLY(source), of typically 200 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 (tDLY) 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 (tDLY) is based on the constant current source, IDLY(source), charging the external delay capacitor (CDLY) to 2.5 V. Vref CDLY 2.5 CDLY = 12500 CDLY tDLY = = IDLY(source) 200 A Figure 5 provides CDLY 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, IDLY(sink), capability of the Delay pins is 1.8 mA and is much greater than the typical 200 A source current, thus enabling a relatively fast delay capacitor discharge time. The Overvoltage Drive Output is a current-limited emitter-follower capable of sourcing 300 mA at a turn-on slew rate at 2.0 A/s, ideal for driving "Crowbar" SCR's. The Undervoltage Indicator Output is an open-collector, NPN transistor, capable of sinking 30 mA to provide sufficient drive for LED's, small relays or shut-down 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. Figure 15. Representative Block Diagram VCC 8 + O.V. Sense 3 + Input Comparator - O.V. + 200A +Output Comparator - O.V. + + 200A U.V. Sense 4 IH 12.5A 5 2 U.V. O.V. DLY DLY + Input Comparator - U.V. 1 - Output Comparator + U.V. + 2.5V Reference Regulator 6 O.V. DRV U.V. IND Input Section Note: All voltages and currents are nominal. 7 Gnd Output Section 6 MOTOROLA ANALOG IC DEVICE DATA MC3425 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, Cout. 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 I2t. 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 turned-on 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 center-gate-fire SCR has more di/dt capability than a corner-gate-fire type, and heavily overdriving ( 3 to 5 times IGT) the SCR gate with a fast < 1.0 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/s, assuming a gate current of five times IGT and < 1.0 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. Figure 16. Typical Crowbar Circuit Configurations (A) SCR Across Input of Regulator Vin Series Regulator MC3425 + Cin Cout + Vout (B) SCR Across Output of Regulator Vin + Cin Series Regulator Cout + * Vout MC3425 *Needed if supply is not current limited. MOTOROLA ANALOG IC DEVICE DATA 7 MC3425 Figure 17. Crowbar SCR Surge Current Waveform l lpk di dt Surge Due to Output Capacitor Current Limited Supply Output 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. Figure 18. Circuit Elements Affecting SCR Surge & di/dt RLead ESR ESL Output Cap To MC3423 LLead 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 I2t 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 MCR310 Series MCR16 Series MCR25 Series 2N6501 Series MCR69 Series MCR264 Series MCR265 Series IRMS 10 A 16 A 25 A 25 A 25 A 40 A 55 A ITSM 100 A 150 A 300 A 300 A 750 A 400 A 550 A R L R & L EMPIRICALLY DETERMINED! UNDERVOLTAGE SENSING An undervoltage sense circuit designed, as shown in Figure equations: V CCU R1 12.5 with hysteresis may be 11, using the following * VCC1 + mA 2.5 R1 R2 + V CC1 * 2.5 where: VCCU is the designed upper trip point (output indicator goes off) VCC1 is the lower trip point (output indicator goes on) 8 MOTOROLA ANALOG IC DEVICE DATA MC3425 OUTLINE DIMENSIONS P1 SUFFIX PLASTIC PACKAGE CASE 626-05 ISSUE K 8 5 -B- 1 4 F NOTE 2 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 A B C D F G H J K L M N MILLIMETERS MIN MAX 9.40 10.16 6.10 6.60 3.94 4.45 0.38 0.51 1.02 1.78 2.54 BSC 0.76 1.27 0.20 0.30 2.92 3.43 7.62 BSC --- 10_ 0.76 1.01 INCHES MIN MAX 0.370 0.400 0.240 0.260 0.155 0.175 0.015 0.020 0.040 0.070 0.100 BSC 0.030 0.050 0.008 0.012 0.115 0.135 0.300 BSC --- 10_ 0.030 0.040 -A- L C -T- SEATING PLANE J N D K M M H G 0.13 (0.005) TA M B M MOTOROLA ANALOG IC DEVICE DATA 9 MC3425 NOTES 10 MOTOROLA ANALOG IC DEVICE DATA MC3425 NOTES MOTOROLA ANALOG IC DEVICE DATA 11 MC3425 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. "Typical" 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 "Typicals" 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; P.O. Box 20912; Phoenix, Arizona 85036. 1-800-441-2447 or 602-303-5454 MFAX: RMFAX0@email.sps.mot.com - TOUCHTONE 602-244-6609 INTERNET: http://Design-NET.com JAPAN: Nippon Motorola Ltd.; Tatsumi-SPD-JLDC, 6F Seibu-Butsuryu-Center, 3-14-2 Tatsumi Koto-Ku, Tokyo 135, Japan. 03-81-3521-8315 ASIA/PACIFIC: Motorola Semiconductors H.K. Ltd.; 8B Tai Ping Industrial Park, 51 Ting Kok Road, Tai Po, N.T., Hong Kong. 852-26629298 12 MOTOROLA ANALOG IC DEVICE DATA M3425/D *MC3425/D* |
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