PD-97388 AHP28XXS SERIES 28V Input, Single Output HIGH RELIABILITY HYBRID DC/DC CONVERTERS Description The AHP Series of DC/DC converters feature high power density without derating over the full military temperature range. This series is offered as lower cost alternatives to the legendary AFL series with improved performance for new design applications. The AHPs are form, fit and functional replacement to the AFL series. The new AHP series offers a full compliment of single and dual output voltages operating from nominal +28 or +270 volt inputs with output power ranging from 66 to 120 watts. For applications requiring higher output power, multiple converters can be operated in parallel. The internal current sharing circuits assure equal current distribution among the paralleled converters. Same as the AFL, the AHP series incorporates International Rectifier'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. Under-voltage lockout, primary and secondary referenced inhibit, soft-start and load fault protection are provided on all models. Also included is input overvoltage protection, a new protection feature unique to the AHP. 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 International Rectifier’s rugged ceramic lead-to-package seal assuring long term hermeticity in 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 MILPRF-38534 for class H. The HB grade is fully processed and screened to the class H requirement, but does not have material element evaluated to the class H requirement. Both grades are tested to meet the www.irf.com AHP Features n n n n n n n n n n n n n n n n n 16 To 40 Volt Input Range 3.3, 5, 8, 9,12,15 and 28 Volts Outputs Available High Power Density - up to 84 W / in3 Up To 120 Watt Output Power Parallel Operation with Stress and Current Sharing Input Over-Voltage Protection High Efficiency - to 85% Continuous Short Circuit and Overload Protection External Synchronization Port Remote Sensing Terminals Primary and Secondary Referenced Inhibit Functions Line Rejection > 40 dB - DC to 50KHz Fault Tolerant Design Full Military Temperature Range Ceramic Feedthru Copper Core Pins Low Profile (0.380") Seam Welded Package Dual Output Versions Available complete group “A” test specification over the full military temperature range without output power de-rating. Two grades with more limited screening are also available for use in less demanding applications. Variations in electrical, mechanical and screening can be accommodated. Please contact IR Santa Clara for special requirements. 1 04/16/09 AHP28XXS Series Specifications ABSOLUTE MAXIMUM RATINGS Input Voltage Soldering Temperature -0.5V to 50V 300°C for 10 seconds Case Temperature - Operating Case Temperature - Storage -55°C to +125°C -65°C to +135°C Static Characteristics -55°C < TCASE < +125°C, 16V< VIN < 40V unless otherwise specified. Group A Subgroups Parameter Test Conditions Min Nom Max Unit 16 28 40 V 1 1 1 1 1 1 1 3.27 4.95 7.92 8.91 11.88 14.85 27.72 3.30 5.00 8.00 9.00 12.00 15.00 28.00 3.33 5.05 8.08 9.09 12.12 15.15 28.28 V 2, 3 2, 3 2, 3 2, 3 2, 3 2, 3 2, 3 3.23 4.90 7.84 8.82 11.76 14.70 27.44 INPUT VOLTAGE Note 6 OUTPUT VOLTAGE AHP2803R3S AHP2805S AHP2808S AHP2809S AHP2812S AHP2815S AHP2828S AHP2803R3S AHP2805S AHP2808S AHP2809S AHP2812S AHP2815S AHP2828S VIN = 28V, 100% Load OUTPUT CURRENT AHP2803R3S AHP2805S AHP2808S AHP2809S AHP2812S AHP2815S AHP2828S VIN = 16, 28, 40V - Note 6 OUTPUT POWER Note 6 AHP2803R3S AHP2805S AHP2808S AHP2809S AHP2812S AHP2815S AHP2828S 3.37 5.10 8.16 9.18 12.24 15.30 28.56 20 16 10 10 9.0 8.0 4.0 A 66 80 80 90 108 120 112 W µF MAXIMUM CAPACITIVE LOAD Note 1 10,000 OUTPUT VOLTAGE TEMPERATURE COEFFICIENT VIN = 28V, 100% Load – Notes 1, 6 -0.015 +0.015 %/°C -70 -20 +70 +20 mV mV -1.0 +1.0 % OUTPUT VOLTAGE REGULATION AHP2828S Line All Others Line Load OUTPUT RIPPLE VOLTAGE AHP2803R3S AHP2805S AHP2808S AHP2809S AHP2812S AHP2815S AHP2828S 1, 2, 3 1, 2, 3 No Load, 50% Load, 100% Load VIN = 16, 28, 40V 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 1, 2, 3 VIN = 16, 28, 40V, 100% Load, BW = 10MHz 30 30 40 40 45 50 100 mVpp For Notes to Specifications, refer to page 4 2 www.irf.com AHP28XXS Series Static Characteristics (Continued) Group A Subgroups Parameter INPUT CURRENT No Load Inhibit 1 Inhibit 2 INPUT RIPPLE CURRENT AHP2803R3S AHP2805S AHP2808S AHP2809S AHP2812S AHP2815S AHP2828S 1 2, 3 1, 2, 3 1, 2, 3 1, 1, 1, 1, 1, 1, 1, CURRENT LIMIT POINT As a percentage of full rated load LOAD FAULT POWER DISSIPATION Overload or Short Circuit 2, 3 2, 3 2, 3 2, 3 2, 3 2, 3 2, 3 1 2 3 1, 2, 3 EFFICIENCY AHP2803R3S AHP2805S AHP2808S AHP2809S AHP2812S AHP2815S AHP2828S 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 1, 1, 1, 1, 1, 1, 1, 2, 3 2, 3 2, 3 2, 3 2, 3 2, 3 2, 3 1, 2, 3 1, 2, 3 Test Conditions Min VIN = 28V IOUT = 0 Pin 4 Shorted to Pin 2 Pin 12 Shorted to Pin 8 VIN = 28V, 100% Load, BW = 10MHz VOUT = 90% VNOM, VIN = 28V, Note 5 60 60 60 60 60 60 60 115 105 125 VIN = 28V VIN = 28V, 100% Load Logical Low on Pin 4 or Pin 12 Note 1 Logical High on Pin 4 and Pin 12 - Note 9 Note 1 72 78 79 80 80 81 81 2.0 1, 2, 3 1, 2, 3 1, 2, 3 500 2.0 -0.5 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 = 70°C 550 20 100 mA mApp % 33 W % 0.8 100 50 100 V µA V µA 600 KHz 700 10 0.8 100 80 KHz V V ns % MΩ 85 300 Unit 125 115 140 74 81 82 83 84 85 84 -0.5 500 Note 1 Note 1 Max 80 100 5.0 50 1, 2, 3 1 Nom g KHrs For Notes to Specifications, refer to page 4 www.irf.com 3 AHP28XXS Series Dynamic Characteristics -55°C < TCASE < +125°C, VIN=28V unless otherwise specified. Group A Subgroups LOAD TRANSIENT RESPONSE Test Conditions Min Nom Max Unit Note 2, 8 AHP2803R3S / AHP2805S AHP2808S AHP2809S AHP2812S AHP2815S AHP2828S Amplitude Recovery 4, 5, 6 4, 5, 6 Load Step 50% ⇔ 100% -450 450 200 mV µs Amplitude Recovery 4, 5, 6 4, 5, 6 Load Step 10% ⇔ 50% -450 450 400 mV µs Amplitude Recovery 4, 5, 6 4, 5, 6 Load Step 50% ⇔ 100% -500 500 200 mV µs Amplitude Recovery 4, 5, 6 4, 5, 6 Load Step 10% ⇔ 50% -500 500 400 mV µs Amplitude Recovery 4, 5, 6 4, 5, 6 Load Step 50% ⇔ 100% -600 600 200 mV µs Amplitude Recovery 4, 5, 6 4, 5, 6 Load Step 10% ⇔ 50% -600 600 400 mV µs Amplitude Recovery 4, 5, 6 4, 5, 6 Load Step 50% ⇔ 100% -750 750 200 mV µs Amplitude Recovery 4, 5, 6 4, 5, 6 Load Step 10% ⇔ 50% -750 750 400 mV µs Amplitude Recovery 4, 5, 6 4, 5, 6 Load Step 50% ⇔ 100% -750 750 200 mV µs Amplitude Recovery 4, 5, 6 4, 5, 6 Load Step 10% ⇔ 50% -750 750 400 mV µs Amplitude Recovery 4, 5, 6 4, 5, 6 Load Step 50% ⇔ 100% -1200 1200 200 mV µs Amplitude Recovery 4, 5, 6 4, 5, 6 Load Step 10% ⇔ 50% -1200 1200 400 mV µs -500 500 500 mV µs 12 10 % ms Note 1, 2, 3 LINE TRANSIENT RESPONSE VIN Step = 16 ⇔ 40V Amplitude Recovery TURN-ON CHARACTERISTICS Overshoot Delay 4, 5, 6 4, 5, 6 VIN = 16, 28, 40V. Note 4 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 0 4.0 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 V OUT has returned to within ±1% of VOUT at 50% load. Line transient transition time ≥ 100 µs. Turn-on delay is measured with an input voltage rise time of between 100 and 500 volts per millisecond. Current limit point is that condition of excess load causing output voltage to drop to 90% of nominal. Parameter verified as part of another test. All electrical tests are performed with the remote sense leads connected to the output leads at the load. Load transient transition time ≥ 10 µs. Enable inputs internally pulled high. Nominal open circuit voltage ≈ 4.0VDC. 3. 4. 5. 6. 7. 8. 9. 4 www.irf.com AHP28XXS Series AHP28XXS Circuit Description Figure I. AHP Single Output Block Diagram DC Input 1 Enable 1 Input Filter 4 Output Filter Primary Bias Supply 7 +Output 10 +Sense Current Sense Sync Output 5 Sync Input 6 Control FB Case 3 Error Amp & Ref Share Amplifier 11 Share 12 Enable 2 Sense Amplifier Input Return 2 9 -Sense 8 Output Return Circuit Operation and Application Information Inhibiting Converter Output The AHP 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 pin 4 is 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. A power MOSFET is used to chop the DC input voltage into a high frequency square wave, applying this chopped voltage to the power transformer at the nominal converter switching frequency. Maintaining a DC voltage within the specified operating range at the input assures continuous generation of the primary bias voltage. 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. The switched voltage impressed on the secondary output transformer winding is rectified and filtered to generate the converter DC output voltage. An error amplifier on the secondary side compares the 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 controller section of the converter varying the pulse width of the square wave signal driving the MOSFET, narrowing the width if the output voltage is too high and widening it if it is too low, thereby regulating the output voltage. Remote Sensing Connection of the + and - sense leads at a remotely located load permits compensation for excessive resistance between the converter output and the load when their physical separation could cause undesirable voltage drop. This connection allows regulation to the placard voltage at the point of application. When the remote sensing feature is not used the sense leads should be connected to their respective output terminals at the converter. Figure III. illustrates a typical remotely sensed application. www.irf.com Figure II. Enable Input Equivalent Circuit +5.6V Pin 4 or Pin 12 1N4148 100K Disable 290K 2N3904 200K Pin 2 or Pin 8 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 save for minor differences in standby current. (See specification table). 5 AHP28XXS Series 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 AHP series converters provide both a synchronization input and a synchronization output. The sync input port permits synchronization of an AHP connverter 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 than 100 ns, maximum low level of +0.8 volts and a minimum high 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 open (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 AHP 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. This output has adequate drive reserve to synchronize at least five additional converters. A typical connection is illustrated in Figure III. Figure III. Preferred Connection for Parallel Operation Power 1 Enable 2 Vin Input Share Rtn Case Enable 1 Optional Synchronization Connection 12 AHP + Sense - Sense Sync Out Return Sync In + Vout 6 7 1 12 Share Bus Enable 2 Vin Rtn Share Case Enable 1 AHP + Sense - Sense Sync Out Return Sync In + Vout 6 to Load 7 1 Vin Enable 2 Rtn Share Case Enable 1 AHP + Sense - Sense Sync Out Return Sync In + Vout 6 12 7 (Other Converters) Parallel Operation-Current and Stress Sharing Figure III. illustrates the preferred connection scheme for operation of a set of AHP converters with outputs operating in parallel. Use of this connection permits equal sharing among the members of a set whose load current exceeds the capacity of an individual AHP. An important feature of 6 AHP 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 compensation for the temperature induced stress on that device. www.irf.com AHP28XXS 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 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 output and return pins connected at a star point which is located as close as possible to the load. As a consequence of the topology utilized in the current sharing circuit, the share pin may be used for other functions. In 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 total output current to +2.20v at full load. Thermal Considerations Because of the incorporation of many innovative technological concepts, the AHP 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. Because 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 provide 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 ∆T = Case temperature rise above ambient ⎧ 1 ⎫ − 1⎬ P = Device dissipation in Watts = POUT ⎨ ⎩ Eff ⎭ As an example, it is desired to maintain the case temperature of an AHP2815S 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 From the Specification Table, the worst case full load efficiency for this device is 83%; therefore the power dissipation at full load is given by ⎧ 1 ⎫ P = 120 • ⎨ − 1⎬ = 120 • ( 0.205) = 24.6W ⎩ .83 ⎭ and the required heat sink area is . ⎧ ⎫ −143 60 ⎬ − 3.0 = 71 in 2 A HEAT SINK = ⎨ ⎩ 80 • 24.6 0.85 ⎭ Thus, a total heat sink surface area (including fins, if any) of 71 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 9" (36 in 2 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 ambient air. 1Sil-Pad is a registered Trade Mark of Bergquist, Minneapolis, MN www.irf.com 7 AHP28XXS Series Input Filter The AHP28XXS 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 3.5µH Pin 1 11.2 µfd ⎡ ⎤ V NOM R ADJ = 1000 ⋅ ⎢ ⎥ ⎣VOUT − V NOM − 0.25 ⎦ For VNOM < VOUT < (VNOM + 0.25V), a resistor is connected between the +Sense and +Output pins with the –Sense connected to the output return as shown in Figure VI. The resistor value (RADJ ) is calculated as follows: R ADJ = Pin 2 1000 ⎛ ⎞ 0.25 ⎜⎜ − 1⎟⎟ ⎝ VOUT − V NOM ⎠ Input Over-Voltage Protection VNOM = device nominal output voltage One additional protection feature is incorporated into the AHP input circuit. It is an input over-voltage protection. The output will shutdown and restart at approximately 110% of the maximum rated input voltage. This protection feature is unique to the AHP. VOUT = desired output voltage Undervoltage Lockout Finding a resistor value for a particular output voltage, is simply a matter of substituting the desired output voltage and the nominal device voltage into the equation and solving for the corresponding resistor value. A minimum voltage is required at the input of the converter to initiate operation. This voltage is set to 14.0 ± 0.5 volts. To preclude the possibility of noise or other variations at the input falsely initiating and halting converter operation, a hysteresis of approximately 1.0 volts is incorporated in this circuit. Thus if the input voltage droops to 13.0 ± 0.5 volts, the converter will shut down and remain inoperative until the input voltage returns to ≈14.0 volts. Output Voltage Adjust In addition to permitting close voltage regulation of remotely located loads, it is possible to utilize the converter sense pins to incrementally increase the output voltage over a limited range. The adjustments made possible by this method are intended as a means to “trim” the output to a voltage setting for some particular application, but are not intended to create an adjustable output converter. These output voltage setting variations are obtained by connecting an appropriate resistor value in the locations as shown in Figure V or Figure VI depending on the desired output voltage. The range of adjustment and corresponding range of resistance values can be determined by use of the equations presented below. For (V NOM + 0.25V) < VOUT < (V NOM + 0.5V), a resistor is connected between the +Sense and Sense pins with the Sense connected to the output return as shown in Figure V. The resistor value (R ADJ) is calculated as follows: 8 RADJ = value of the external resistor required to achieve the desired Vout Figure V. Connection for VOUT > VNOM+ 0.25V Enable 2 Share AHP28XXS +Sense RADJ - Sense Return To Load +Vout Figure VI. Connection for VNOM< VOUT < (VNOM+ 0.25V) Enable 2 Share AHP28XXS +Sense RADJ - Sense Return +Vout To Load www.irf.com AHP28XXS Series Attempts to adjust the output voltage to a value greater than 120% of nominal should be avoided because of the potential of exceeding internal component stress ratings and subsequent operation to failure. Under no circumstance should the external setting resistor be made less than 500Ω. By remaining within this specified range of values, completely safe operation fully within normal component derating is assured. Examination of the equation relating output voltage and resistor value reveals a special benefit of the circuit topology utilized for remote sensing of output voltage in the AHP28XXS series of converters. It is apparent that as the resistance increases, the output voltage approaches the nominal set value of the device. In fact the calculated limiting value of output voltage as the adjusting resistor becomes very large is ≅ 250mV above nominal device voltage. The consequence is that if the +sense connection is unintentionally broken, an AHP28XXS has a fail-safe output voltage of Vout + 250mV, where the 250mV is independent of the nominal output voltage. It can be further demonstrated that in the event of both the + and - sense connections being broken, the output will be limited to Vout + 500mV. This 500mV is also essentially constant independent of the nominal output voltage. While operation in this condition is not damaging to the device, not all performance parameters will be met. General Application Information The AHP28XXS series of converters are capable of providing large transient currents to user loads on demand. Because the nominal input voltage range in this series is relatively low, the resulting input current demands will be correspondingly large. It is important therefore, that the line impedance be kept very low to prevent steady state and transient input currents from degrading the supply voltage between the voltage source and the converter input. In applications requiring high static currents and large transients, it is recommended that the input leads be made of adequate size to minimize resistive losses, and that a good quality capacitor of approximately100µfd be connected directly across the input terminals to assure an adequately low impedance at the input terminals. Table I relates nominal resistance values and selected wire sizes. www.irf.com Table 1. Nominal Resistance of Cu Wire Wire Size, AWG Resistance per ft 24 Ga 25.7 mΩ 22 Ga 16.2 mΩ 20 Ga 10.1 mΩ 18 Ga 6.4 mΩ 16 Ga 4.0 mΩ 14 Ga 2.5 mΩ 12 Ga 1.6 mΩ As an example of the effects of parasitic resistance, consider an AHP2815S operating at full power of 120 W. From the specification sheet, this device has a minimum efficiency of 83% which represents an input power of more than 145 W. If we consider the case where line voltage is at its minimum of 16 volts, the steady state input current necessary for this example will be slightly greater than 9 amperes. If this device were connected to a voltage source with 10 feet of 20 gauge wire, the round trip (input and return) would result in 0.2 Ω of resistance and 1.8 volts of drop from the source to the converter. To assure 16 volts at the input, a source closer to 18 volts would be required. In applications using the paralleling option, this drop will be multiplied by the number of paralleled devices. By choosing 14 or 16 gauge wire in this example, the parasitic resistance and resulting voltage drop will be reduced to 25% or 31% of that with 20 gauge wire. Another potential problem resulting from parasitically induced voltage drop on the input lines is with regard to the operation of the enable 1 port. The minimum and maximum operating levels required to operate this port are specified with respect to the input common return line at the converter. If a logic signal is generated with respect to a ‘common’ that is distant from the converter, the effects of the voltage drop over the return line must be considered when establishing the worst case TTL switching levels. These drops will effectively impart a shift to the logic levels. In Figure VII, it can be seen that referred to system ground, the voltage on the input return pin is given by eRtn = IRtn • RP 9 AHP28XXS Series Incorporation of a 100 µfd capacitor at the input terminals is recommended as compensation for the dynamic effects of the parasitic resistance of the input cable reacting with the complex impedance of the converter input, and to provide an energy reservoir for transient input current requirements. Therefore, the logic signal level generated in the system must be capable of a TTL logic high plus sufficient additional amplitude to overcome eRtn. When the converter is inhibited, IRtn diminishes to near zero and eRtn will then be at system ground. Figure VII. Problems of Parasitic Resistance in input Leads (See text) Rp esource Rp Iin IRtn 100 µfd Vin eRtn Rtn Case System Ground Enable 1 Sync Out Sync In 10 www.irf.com AHP28XXS Series AHP28XXS 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 0.200 Typ Non-cum 6 7 1.260 1.500 1.000 Ref 1.000 Pin ø 0.040 0.220 2.500 0.220 Pin ø 0.040 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 1.150 0.300 ø 0.140 0.25 typ 0.050 0.050 1 12 0.250 0.250 1.000 Ref 6 1.750 1.000 Ref 0.200 Typ Non-cum 7 1.500 1.750 2.00 Pin ø 0.040 0.375 Pin ø 0.040 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 11 AHP28XXS Series Available Screening Levels and Process Variations for AHP28XXS 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-H-38534 9 9 9 1010 Cond B Cond C Cond C 2001, Y1 Axis 500g 3000g 3000g Internal Visual 2017 Temperature Cycle Constant Acceleration Burn-in 1015 48hrs @ 85°C 48hrs @ 125°C 160hrs @ 125°C 160hrs @ 125°C MIL-PRF-38534 Specification 25°C 25°C -55, +25, +125°C -55, +25, +125°C Seal, Fine & Gross 1014 Cond C Cond A, C Cond A, C Cond A, C External Visual 2009 9 9 9 Final Electrical (Group A) * per Commercial Standards AHP28XXS 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 Return Sense 10 Positive Sense 11 Share 12 Enable 2 Part Numbering AHP 28 05 S X / CH Model Input Voltage 28 = 28V 270 = 270V Output Voltage 05 = 5V, 08 = 8V 09 = 9V, 12 = 12V 15 = 15V, 28 = 28V Screening Level ES, HB, CH Blank = min screening Case Style W, X, Y, Z Outputs S = Single D = Dual WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, Tel: (310) 322 3331 IR SANTA CLARA: 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. 04/2009 12 www.irf.com