PD - 94456A AFL50XXD SERIES 50V Input, Dual Output ADVANCED ANALOG HIGH RELIABILITY HYBRID DC/DC CONVERTERS Description The AFL Series of DC/DC converters feature high power density with no derating over the full military temperature range. This series is offered as part of a complete family of converters providing single and dual output voltages and operating from nominal +28, +50, +120 or +270 volt inputs with output power ranging from 80 to 120 watts. For applications requiring higher output power, individual converters can be operated in parallel. The internal current sharing circuits assure equal current distribution among the paralleled converters. This series incorporates Advanced Analog’s proprietary magnetic pulse feedback technology providing optimum dynamic line and load regulation response. This feedback system samples the output voltage at the pulse width modulator fixed clock frequency, nominally 550 KHz. Multiple converters can be synchronized to a system clock in the 500 KHz to 700 KHz range or to the synchronization output of one converter. Undervoltage lockout, primary and secondary referenced inhibit, softstart and load fault protection are provided on all models. These converters are hermetically packaged in two enclosure variations, utilizing copper core pins to minimize resistive DC losses. Three lead styles are available, each fabricated with Advanced Analog’s rugged ceramic lead-to-package seal assuring long term hermeticity in the most harsh environments. Manufactured in a facility fully qualified to MIL-PRF38534, these converters are available in four screening grades to satisfy a wide range of requirements. The CH grade is fully compliant to the requirements of MIL-H38534 for class H. The HB grade is fully processed and screened to the class H requirement, may not necessarily meet all of the other MIL-PRF-38534 requirements, e.g., element evaluation and Periodic Inspection (P.I.) not required. Both grades are tested to meet the complete group “A” test specification over the full military www.irf.com AFL Features n n n n n n n n n n n n n n n n n 30 To 80 Volt Input Range ±5, ±12, and ±15 Volts Outputs Available High Power Density - up to 70 W / in3 Up To 100 Watt Output Power Parallel Operation with Stress and Current Sharing Low Profile (0.380") Seam Welded Package Ceramic Feedthru Copper Core Pins High Efficiency - to 85% Full Military Temperature Range Continuous Short Circuit and Overload Protection Output Voltage Trim Primary and Secondary Referenced Inhibit Functions Line Rejection > 40 dB - DC to 50KHz External Synchronization Port Fault Tolerant Design Single Output Versions Available Standard Military Drawings Available temperature range without output power deration. Two grades with more limited screening are also available for use in less demanding applications. Variations in electrical, mechanical and screening can be accommodated. Contact Advanced Analog for special requirements. 1 07/09/02 AFL50XXD Series Specifications ABSOLUTE MAXIMUM RATINGS Input Voltage -0.5V to 100V Soldering Temperature 300°C for 10 seconds Case Temperature Operating Storage -55°C to +125°C -65°C to +135°C Static Characteristics -55°C < TCASE < +125°C, 30V< VIN < 80V unless otherwise specified. Group A Subgroups Parameter Test Conditions INPUT VOLTAGE Note 6 OUTPUT VOLTAGE VIN = 50 Volts, 100% Load Min Nom Max Unit 30 50 80 V AFL5005D 1 1 Positive Output Negative Output 4.95 -5.05 5.00 -5.00 5.05 -4.95 V V AFL5012D 1 1 Positive Output Negative Output 11.88 -12.12 12.00 -12.00 12.12 -11.88 V V AFL5015D 1 1 Positive Output Negative Output 14.85 -15.15 15.00 -15.00 15.15 -14.85 V V AFL5005D 2, 3 2, 3 Positive Output Negative Output 4.90 -5.10 5.10 -4.90 V V AFL5012D 2, 3 2, 3 Positive Output Negative Output 11.76 -12.24 12.24 -11.76 V V AFL5015D 2, 3 2, 3 Positive Output Negative Output 14.70 -15.30 15.30 -14.70 V V OUTPUT CURRENT VIN = 30, 50, 80 Volts - Notes 6, 11 AFL5005D Either Output 12.8 A AFL5012D Either Output 6.4 A AFL5015D Either Output 5.3 A OUTPUT POWER Total of Both Outputs. Notes 6,11 80 AFL5005D AFL5012D 96 AFL5015D 100 MAXIMUM CAPACITIVE LOAD Each Output Note 1 OUTPUT VOLTAGE TEMPERATURE COEFFICIENT VIN = 50 Volts, 100% Load - Notes 1, 6 OUTPUT VOLTAGE REGULATION Line Load 1, 2, 3 1, 2, 3 Note 10 No Load, 50% Load, 100% Load VIN = 30, 50, 80 Volts. W W W µfd 10,000 -0.015 +0.015 %/°C -0.5 -1.0 +0.5 +1.0 % % VIN = 30, 50, 80 Volts. Note 12 Cross AFL5005D 1, 2, 3 Positive Output Negative Output -1.0 -8.0 +1.0 +8.0 % % AFL5012D 1, 2, 3 Positive Output Negative Output -1.0 -5.0 +1.0 +5.0 % % AFL5015D 1, 2, 3 Positive Output Negative Output -1.0 -5.0 +1.0 +5.0 % % For Notes to Specifications, refer to page 4 2 www.irf.com AFL50XXD Series Static Characteristics (Continued) Parameter Group A Subgroups OUTPUT RIPPLE VOLTAGE Min Nom VIN = 30, 50, 80 Volts, 100% Load, BW = 10MHz Max Unit AFL5005D 1, 2, 3 60 mVpp AFL5012D 1, 2, 3 80 mVpp AFL5015D 1, 2, 3 80 mVpp No Load 1 2, 3 1, 2, 3 1, 2, 3 50 60 5 5 mA mA mA mA INPUT CURRENT Inhibit 1 Inhibit 2 VIN = 50 Volts IOUT = 0 Pin 4 Shorted to Pin 2 Pin 12 Shorted to Pin 8 VIN = 50 Volts, 100% Load INPUT RIPPLE CURRENT AFL5005D 1, 2, 3 60 AFL5012D 1, 2, 3 60 mApp mApp AFL5015D 1, 2, 3 60 mApp 125 115 140 % % % 32 W CURRENT LIMIT POINT Expressed as a Percentage of Full Rated Load 1 2 3 Overload or Short Circuit VOUT = 90% VNOM , Current split equally on positive and negative outputs. Note 5 115 105 125 VIN = 50 Volts LOAD FAULTPOWER DISSIPATION 1, 2, 3 VIN = 50 Volts, 100% Load EFFICIENCY AFL5005D AFL5012D AFL5015D ENABLE INPUTS (Inhibit Function) Converter Off Sink Current Converter On Sink Current SWITCHING FREQUENCY SYNCHRONIZATION INPUT Frequency Range Pulse Amplitude, Hi Pulse Amplitude, Lo Pulse Rise Time Pulse Duty Cycle ISOLATION Test Conditions 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 78 80 81 Logical Low on Pin 4 or Pin 12 Note 1 Logical High on Pin 4 and Pin 12 - Note 9 Note 1 -0.5 2.0 1, 2, 3 500 1, 2, 3 1, 2, 3 1, 2, 3 500 2.0 -0.5 Note 1 Note 1 1 Input to Output or Any Pin to Case (except Pin 3). Test @ 500VDC DEVICE WEIGHT Slight Variations with Case Style MTBF MIL-HDBK-217F, AIF @ TC = 40°C 81 84 85 550 20 100 0.8 100 50 100 V µA V µA 600 KHz 700 10 0.8 100 80 KHz V V nSec % MΩ 85 300 % % % gms KHrs For Notes to Specifications, refer to page 4 www.irf.com 3 AFL50XXD Series Dynamic Characteristics -55°C < TCASE < +125°C, VIN=50V unless otherwise specified. Parameter Group A Subgroups AFL5012D Either Output AFL5015D Either Output Min Nom Max Unit Note 2, 8 LOAD TRANSIENT RESPONSE AFL5005D Either Output Test Conditions Amplitude Recovery 4, 5, 6 4, 5, 6 Load Step 50% ⇔ 100% -450 450 200 mV µSec Amplitude Recovery 4, 5, 6 4, 5, 6 Load Step 10% ⇔ 50% 10% ⇒ 50% 50% ⇒ 10% -450 450 200 400 mV µSec µSec Amplitude Recovery Amplitude Recovery 4, 5, 6 4, 5, 6 Load Step 50% ⇔ 100% -750 750 200 mV µSec 4, 5, 6 4, 5, 6 Load Step 10% ⇔ 50% 10% ⇒ 50% 50% ⇒ 10% -750 750 200 400 mV µSec µSec Load Step 50% ⇔ 100% -750 750 200 mV µSec Load Step 10% ⇔ 50% 10% ⇒ 50% 50% ⇒ 10% -750 750 200 400 mV µSec µSec Amplitude Recovery Amplitude Recovery 4, 5, 6 4, 5, 6 4, 5, 6 4, 5, 6 Note 1, 2, 3 LINE TRANSIENT RESPONSE VIN Step = 30 ⇔ 80 Volts Amplitude Recovery 500 500 mV µSec 250 120 mV mSec Note 4 TURN-ON CHARACTERISTICS Overshoot Delay -500 4, 5, 6 4, 5, 6 Enable 1, 2 on. (Pins 4, 12 high or open) LOAD FAULT RECOVERY Same as Turn On Characteristics. LINE REJECTION MIL-STD-461D, CS101, 30Hz to 50KHz Note 1 50 75 40 50 dB Notes to Specifications: 1. 2. Parameters not 100% tested but are guaranteed to the limits specified in the table. Recovery time is measured from the initiation of the transient to where Vout has returned to within ±1% of Vout at 50% load. 3. Line transient transition time ≥ 100 µSec. 4. Turn-on delay is measured with an input voltage rise time of between 100 and 500 volts per millisecond. 5. Current limit point is that condition of excess load causing output voltage to drop to 90% of nominal. 6. Parameter verified as part of another test. 7. All electrical tests are performed with the remote sense leads connected to the output leads at the load. 8. Load transient transition time ≥ 10 µSec. 9. Enable inputs internally pulled high. Nominal open circuit voltage ≈ 4.0VDC. 10. Load current split equally between +Vout and -Vout. 11. Output load must be distributed so that a minimum of 20% of the total output power is being provided by one of the outputs. 12. Cross regulation measured with load on tested output at 20% while changing the load on other output from 20% to 80%. 4 www.irf.com AFL50XXD Series AFL50XXD Circuit Description Figure I. AFL Dual Output Block Diagram DC INPUT 1 INPUT FILTER OUTPUT FILTER ENABLE 1 4 PRIMARY BIAS SUPPLY CURRENT SENSE OUTPUT FILTER SYNC OUTPUT 5 SYNC INPUT 6 SHARE CONTROL FB CASE 3 INPUT RETURN 2 Circuit Operation and Application Information The AFL series of converters employ a forward switched mode converter topology. (refer to Figure I.) Operation of the device is initiated when a DC voltage whose magnitude is within the specified input limits is applied between pins 1 and 2. If pins 4 and 12 are enabled (at a logical 1 or open) the primary bias supply will begin generating a regulated housekeeping voltage bringing the circuitry on the primary side of the converter to life. Two power MOSFETs used to chop the DC input voltage into a high frequency square wave, apply this chopped voltage to the power transformer. As this switching is initiated, a voltage is impressed on a second winding of the power transformer which is then rectified and applied to the primary bias supply. When this occurs, the input voltage is excluded from the bias voltage generator and the primary bias voltage becomes internally generated. The switched voltage impressed on the secondary output transformer windings is rectified and filtered to provide the positive and negative converter output voltages. An error amplifier on the secondary side compares the positive output voltage to a precision reference and generates an error signal proportional to the difference. This error signal is magnetically coupled through the feedback transformer into the control section of the converter varying the pulse width of the square wave signal driving the MOSFETs, narrowing the pulse width if the output voltage is too high and widening it if it is too low. These pulse width variations provide the necessary corrections to maintain the magnitude of output voltage within its’ specified limits. Because the primary and secondary sides are coupled by magnetic elements, full isolation from input to output is achieved. ERROR AMP & REF AMPLIFIER 7 + OUTPUT 8 OUTPUT RETURN 9 - OUTPUT 11 SHARE 12 ENABLE 2 10 TRIM ancillary features, basic operation of the AFL50XXD series can be initiated by simply applying an input voltage to pins 1 and 2 and connecting the appropriate loads between pins 7, 8, and 9. Of course, operation of anyconverter with high power density should not be attempted before secure attachment to an appropriate heat dissipator. (See Thermal Considerations, page 7) Inhibiting Converter Output As an alternative to application and removal of the DC voltage to the input, the user can control the converter output by providing TTL compatible, positive logic signals to either of two enable pins (pin 4 or 12). The distinction between these two signal ports is that enable 1 (pin 4) is referenced to the input return (pin 2) while enable 2 (pin 12) is referenced to the output return (pin 8). Thus, the user has access to an inhibit function on either side of the isolation barrier. Each port is internally pulled “high” so that when not used, an open connection on both enable pins permits normal converter operation. When their use is desired, a logical “low” on either port will shut the converter down. Figure II. Enable Input Equivalent Circuit + 5 .6 V 100K P in 4 o r P in 1 2 1N4148 290K D isa b le 2N3904 180K P in 2 o r P in 8 Although incorporating several sophisticated and useful www.irf.com 5 AFL50XXD Series Internally, these ports differ slightly in their function. In use, a low on Enable 1 completely shuts down all circuits in the converter, while a low on Enable 2 shuts down the secondary side while altering the controller duty cycle to near zero. Externally, the use of either port is transparent to the user save for minor differences in idle current. (See specification table). level of +2.0 volts. The sync output of another converter which has been designated as the master oscillator provides a convenient frequency source for this mode of operation. When external synchronization is not required, the sync in pin should be left unconnected thereby permitting the converter to operate at its’ own internally set frequency. The sync output signal is a continuous pulse train set at 550 ±50 KHz, with a duty cycle of 15 ±5%. This signal is referenced to the input return and has been tailored to be compatible with the AFL sync input port. Transition times are less than 100 ns and the low level output impedance is less than 50 ohms. This signal is active when the DC input voltage is within the specified operating range and the converter is not inhibited. The sync output has adequate drive reserve to synchronize at least five additional converters. A typical connection is illustrated in Figure III. Synchronization of Multiple Converters When operating multiple converters, system requirements often dictate operation of the converters at a common frequency. To accommodate this requirement, the AFL series converters provide both a synchronization input and output. The sync input port permits synchronization of an AFL converter to any compatible external frequency source operating between 500 and 700 KHz. This input signal should be referenced to the input return and have a 10% to 90% duty cycle. Compatibility requires transition times less th an 100 ns, maximum low level of +0.8 volts and a minimum high Figure III. Preferred Connection for Parallel Operation Power Input 1 12 Vin Enable 2 Rtn Share Case Enable 1 AFL Trim - Output Return Sync Out Sync In Optional Synchronization Connection + Output 7 6 Share Bus 1 12 Enable 2 Vin Rtn Share Case Enable 1 AFL Trim to Negative Load - Output Return Sync Out Sync In to Positive Load + Output 7 6 1 12 Vin Enable 2 Rtn Share Case Enable 1 AFL Trim - Output Return Sync Out + Output Sync In 7 6 (Other Converters) Parallel Operation-Current and Stress Sharing Figure III. illustrates the preferred connection scheme for operation of a set of AFL converters with outputs operating in parallel. Use of this connection permits equal current sharing among the members of a set whose load current exceeds the capacity of an individual AFL. An important 6 feature of the AFL series operating in the parallel mode is that in addition to sharing the current, the stress induced by temperature will also be shared. Thus if one member of a paralleled set is operating at a higher case temperature, the current it provides to the load will be reduced as compenstionfor the temperature induced stress on that device. www.irf.com AFL50XXD Series When operating in the shared mode, it is important that symmetry of connection be maintained as an assurance of optimum load sharing performance. Thus, converter outputs should be connected to the load with equal lengths of wire of the same gauge and sense leads from each converter should be connected to a common physical point, preferably at the load along with the converter output and return leads. All converters in a paralleled set must have their share pins connected together. This arrangement is diagrammatically illustrated in Figure III. showing the outputs and return pins connected at a star point which is located close as possible to the load. vide similar effectiveness, these alternatives are often less convenient and can be somewhat messy to use. A conservative aid to estimating the total heat sink surface area (AHEAT SINK) required to set the maximum case temperature rise (∆T) above ambient temperature is given by the following expression: . ∆T −143 − 3.0 A HEAT SINK ≈ 80P 0.85 where As a consequence of the topology utilized in the current sharing circuit, the share pin may be used for other functions. For applications requiring only a single converter, the voltage appearing on the share pin may be used as a “current monitor”. The share pin open circuit voltage is nominally +1.00v at no load and increases linearly with increasing output current to +2.20v at full load. Note that the current we refer to here is the total device output current, that is, the sum of the positive and negative output currents. Thermal Considerations Because of the incorporation of many innovative technological concepts, the AFL series of converters is capable of providing very high output power from a package of very small volume. These magnitudes of power density can only be obtained by combining high circuit efficiency with effective methods of heat removal from the die junctions. This requirement has been effectively addressed inside the device; but when operating at maximum loads, a significant amount of heat will be generated and this heat must be conducted away from the case. To maintain the case temperature at or below the specified maximum of 125°C, this heat must be transferred by conduction to an appropriate heat dissipater held in intimate contact with the converter base-plate. Since the effectiveness of this heat transfer is dependent on the intimacy of the baseplate/heatsink interface, it is strongly recommended that a high thermal conductivity heat transferring medium is inserted between the baseplate and heatsink. The material most frequently utilized at the factory during all testing and burn-in processes is sold under the trade name of Sil-Pad 4001 . This particular product is an insulator but electrically conductive versions are also available. Use of these materials assures maximum surface contact with the heat dissipater thereby compensating for any minor surface variations. While other available types of heat conductive materials and thermal compounds pro- ∆T = Case temperature rise above ambient 1 P = Device dissipation in Watts = POUT − 1 Eff As an example, it is desired to maintain the case temperature of an AFL5015D at ≤ +85°C while operating in an open area whose ambient temperature is held at a constant +25°C; then ∆T = 85 - 25 = 60°C If the worst case full load efficiency for this device is 83% @ 100W; then the power dissipation at full load is given by 1 − 1 = 100 • ( 0.205) = 20.5W P = 100 • .83 and the required heat sink area is 60 A HEAT SINK = 0.85 80 • 20.5 −1.43 − 3.0 = 56.3 in 2 Thus, a total heat sink surface area (including fins, if any) of 56 in2 in this example, would limit case rise to 60°C above ambient. A flat aluminum plate, 0.25" thick and of approximate dimension 4" by 7" (28 in2 per side) would suffice for this application in a still air environment. Note that to meet the criteria in this example, both sides of the plate require unrestricted exposure to the +25°C ambient air. 1Sil-Pad is a registered Trade Mark of Bergquist, Minneapolis, MN www.irf.com 7 AFL50XXD Series Input Filter Table I. Output Voltage Trim Values and Limits The AFL50XXD series converters incorporate a single stage LC input filter whose elements dominate the input load impedance characteristic during the turn-on. The input circuit is as shown in Figure IV. Figure IV. Input Filter Circuit 0.75µH P in 1 2.7µ fd P in 2 AFL5005D Vout 5.5 5.4 5.3 5.2 5.1 5.0 4.9 4.8 4.7 4.6 4.583 Radj 0 12.5K 33.3K 75K 200K ∞ 190K 65K 23K 2.5K 0 AFL5012D Vout 12.5 12.4 12.3 12.2 12.1 12.0 11.7 11.3 10.8 10.6 10.417 Radj 0 47.5K 127K 285K 760K ∞ 975K 288K 72.9K 29.9K 0 AFL5015D Vout 15.5 15.4 15.3 15.2 15.1 15.0 14.6 14.0 13.5 13.0 12.917 Radj 0 62.5K 167K 375K 1.0M ∞ 1.2M 325K 117K 12.5K 0 Undervoltage Lockout A minimum voltage is required at the input of the converter to initiate operation. This voltage is set to 26.5 ± 1.5 volts. To preclude the possibility of noise or other variations at the input falsely initiating and halting converter operation, a hysteresis of approximately 2 volts is incorporated in this circuit. Thus if the input voltage droops to 24.5 ± 1.5 volts, the converter will shut down and remain inoperative until the input voltage returns to ≈ 25 volts. Output Voltage Adjust By use of the trim pin (10), the magnitude of output voltages can be adjusted over a limited range in either a positive or negative direction. Connecting a resistor between the trim pin and either the output return or the positive output will raise or lower the magnitude of output voltage. The span of output voltage magnitude is restricted to the limits shown in Table I. Figure V. Connection for VOUT Adjustment Note that the nominal magnitude of output voltage resides in the middle of the table and the corresponding resistor value is set to ∞. To set the magnitude above nominal, the adjust resistor is connected to output return. To set the magnitude below nominal, the adjust resistor is connected to the positive output. (Refer to Figure V.) For output voltage settings that are within the limits, but between those presented in Table I, it is suggested that the resistor values be determined empirically by selection or by use of a variable resistor. The value thus determined can then be replaced with a good quality fixed resistor for permanent installation. When use of the trim feature is elected, the user should be aware that the temperature performance of the converter output voltage will be affected by the temperature performance of the resistor selected as the adjustment element and therefore, the user is advised to employ resistors with an very small temperature coefficient of resistance. 12 E n ab le 2 S h are R ADJ A FL50 xxD T rim + - V o ut To Loads R e turn + V out 7 Connect Radj to + to increase, - to decrease. 8 www.irf.com AFL50XXD Series AFL50XXD Case Outlines Case X Case W Pin Variation of Case Y 3.000 ø 0.128 2.760 0.050 0.050 1 12 0.250 0.250 1.260 1.500 0.200 Typ Non-cum 6 7 1.000 Ref 1.000 Pin ø 0.040 Pin ø 0.040 0.220 2.500 0.220 2.800 2.975 max 0.525 0.238 max 0.42 0.380 Max 0.380 Max Case Y Case Z Pin Variation of Case Y 0.300 1.150 ø 0.140 0.25 typ 0.050 0.050 1 12 0.250 0.250 1.500 1.750 2.00 1.000 Ref 0.200 Typ Non-cum 6 7 1.000 Ref Pin ø 0.040 Pin ø 0.040 1.750 0.375 0.220 0.220 0.36 2.500 2.800 2.975 max 0.525 0.238 max 0.380 Max 0.380 Max Tolerances, unless otherwise specified: .XX .XXX = = ±0.010 ±0.005 BERYLLIA WARNING: These converters are hermetically sealed; however they contain BeO substrates and should not be ground or subjected to any other operations including exposure to acids, which may produce Beryllium dust or fumes containing Beryllium www.irf.com 9 AFL50XXD Series Available Screening Levels and Process Variations for AFL50XXD Series. MIL-STD-883 Method Requirement Temperature Range No Suffix ES Suffix HB Suffix CH Suffix -20°C to +85°C -55°C to +125°C -55°C to +125°C -55°C to +125°C Element Evaluation MIL-PRF-38534 Internal Visual 2017 ¬ Yes Yes Yes Temperature Cycle 1010 Cond B Cond C Cond C Constant Acceleration 2001 500g Cond A Cond A Burn-in 1015 48hrs @ 85°C 48hrs @ 125°C 160hrs @ 125°C 160hrs @ 125°C MIL-PRF-38534 25°C 25°C -55, +25, +125°C -55, +25, +125°C Seal, Fine & Gross 1014 ¬ Cond A, C Cond A, C Cond A, C External Visual 2009 ¬ Yes Yes Yes Final Electrical (Group A) * per Commercial Standards AFL50XXD Pin Designation Pin No. Designation 1 Positive Input 2 Input Return 3 Case 4 Enable 1 5 Sync Output 6 Sync Input 7 Positive Output 8 Output Return 9 Negative Output 10 Output Voltage Trim 11 Share 12 Enable 2 Part Numbering AFL 50 05 D X / CH Model Input Voltage 28= 28 V, 50= 50 V 120=120 V, 270= 270 V Output Voltage 05= 5 V, 12= 12 V, 15= 15 V Screening Case Style – , ES HB, CH W, X, Y, Z Outputs S = Single D = Dual WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, Tel: (310) 322 3331 ADVANCED ANALOG: 2270 Martin Av., Santa Clara, California 95050, Tel: (408) 727-0500 Visit us at www.irf.com for sales contact information. Data and specifications subject to change without notice. 07/02 10 www.irf.com