AFL28XXD SERIES HYBRID-HIGH RELIABILITY DC/DC CONVERTER Series DC
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PD-94458C
AFL28XXD SERIES HYBRID-HIGH RELIABILITY DC/DC CONVERTER
Series DC/DC converters feature high power density with derating over full military temperature range. This series offered part complete family converters providing single dual output voltages operating from nominal +28V +270V inputs with output power ranging from 120W. applications requiring higher output power, individual converters operated parallel. internal current sharing circuits assure equal current distribution among paralleled converters. This series incorporates International Rectifier's proprietary magnetic pulse feedback technology providing optimum dynamic line load regulation response. This feedback system samples output voltage pulse width modulator fixed clock frequency, nominally 550KHz. Multiple converters synchronized system clock 500KHz 700KHz range synchronization output converter. Undervoltage lockout, primary secondary referenced inhibit, soft-start load fault protection provided models. These converters hermetically packaged enclosure variations, utilizing copper core pins minimize resistive losses. Three lead styles available, each fabricated with International Rectifier's rugged ceramic lead-to-package seal assuring long term hermeticity most harsh environments. Manufactured facility fully qualified MIL-PRF38534, these converters fabricated utilizing DSCC qualified processes. available screening options, refer device screening table data sheet. Variations electrical, mechanical screening accommodated. Contact Santa Clara special requirements.
Input, Dual Output
Features
Input Range ±5V, 12V, ±15V Outputs Available High Power Density 70W/in3 100W Output Power Parallel Operation with Power Sharing Profile (0.380") Seam Welded Package Ceramic Feedthru Copper Core Pins High Efficiency Full Military Temperature Range Continuous Short Circuit Overload Protection Output Voltage Trim Primary Secondary Referenced Inhibit Functions Line Rejection 40dB 50KHz External Synchronization Port Fault Tolerant Design Single Output Versions Available Standard Microcircuit Drawings Available
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12/18/06
AFL28XXD Series
Specifications
Absolute Maximum Ratings
Input voltage Soldering temperature Operating case temperature Storage case temperature -0.5V +50VDC 300°C seconds -55°C +125°C -65°C +135°C
Static Characteristics -55°C TCASE +125°C, 16V< unless otherwise specified.
Parameter INPUT VOLTAGE OUTPUT VOLTAGE AFL2805D AFL2812D AFL2815D AFL2805D AFL2812D AFL2815D OUTPUT CURRENT AFL2805D AFL2812D AFL2815D OUTPUT POWER AFL2805D AFL2812D AFL2815D MAXIMUM CAPACITIVE LOAD OUTPUT VOLTAGE TEMPERATURE COEFFICIENT OUTPUT VOLTAGE REGULATION Line Load Cross AFL2805D AFL2812D AFL2815D Group Subgroups Note Volts, 100% Load Positive Output Negative Output Positive Output Negative Output Positive Output Negative Output Positive Output Negative Output Positive Output Negative Output Positive Output Negative Output Volts Notes Either Output Either Output Either Output Total Both Outputs. Notes 6,11 10,000 -0.015 -0.5 -1.0 +0.015 +0.5 +1.0 Test Conditions 4.95 -5.05 11.88 -12.12 14.85 -15.15 4.90 -5.10 11.76 -12.24 14.70 -15.30 5.00 -5.00 12.00 -12.00 15.00 -15.00 5.05 -4.95 12.12 -11.88 15.15 -14.85 5.10 -4.90 12.24 -11.76 15.30 -14.70 12.8 Unit
%/°C
Each Output Note Volts, 100% Load Notes Note Load, Load, 100% Load Volts. Volts. Note Positive Output Negative Output Positive Output Negative Output Positive Output Negative Output
-1.0 -8.0 -1.0 -5.0 -1.0 -5.0
+1.0 +8.0 +1.0 +5.0 +1.0 +5.0
Notes Specifications, refer page
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AFL28XXD Series
Static Characteristics (Continued)
Parameter OUTPUT RIPPLE VOLTAGE AFL2805D AFL2812D AFL2815D INPUT CURRENT Load Inhibit Inhibit AFL2805D AFL2812D, INPUT RIPPLE CURRENT AFL2805D AFL2812D AFL2815D CURRENT LIMIT POINT Expressed percentage Full Rated Load Volts, 100% Load Group Subgroups Test Conditions Volts, 100% Load, 10MHz Unit
mVpp
Volts IOUT Shorted Shorted
mApp
VOUT VNOM Equal current positive negative outputs. Note
LOAD FAULT POWER DISSIPATION Overload Short Circuit EFFICIENCY AFL2805D AFL2812D AFL2815D ENABLE INPUTS (Inhibit Function) Converter Sink Current Converter Sink Current SWITCHING FREQUENCY SYNCHRONIZATION INPUT Frequency Range Pulse Amplitude, Pulse Amplitude, Pulse Rise Time Pulse Duty Cycle ISOLATION DEVICE WEIGHT MTBF
Volts Volts, 100% Load
-0.5 -0.5
Logical Note Logical High Note Note
Note Note Input Output Case (except Test 500VDC Slight Variations with Case Style MIL-HDBK-217F, 70°C
KHrs
Notes Specifications, refer page
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AFL28XXD Series
Dynamic Characteristics -55°C TCASE +125°C, VIN=28V unless otherwise specified.
Parameter LOAD TRANSIENT RESPONSE AFL2805D Either Output Amplitude Recovery Amplitude Recovery AFL2812D Either Output Amplitude Recovery Amplitude Recovery AFL2815D Either Output Amplitude Recovery Amplitude Recovery LINE TRANSIENT RESPONSE Amplitude Recovery TURN-ON CHARACTERISTICS Overshoot Delay LOAD FAULT RECOVERY LINE REJECTION Group Subgroups Note Load Step 100% Load Step Load Step 100% Load Step Load Step 100% Load Step Note Step Volts Volts. Note Enable (Pins high open) Same Turn Characteristics. MIL-STD-461D, CS101, 30Hz 50KHz Note -500 -450 -450 Test Conditions Unit
-750 -750
-750 -750
Notes Specifications:
Parameters 100% tested guaranteed limits specified table. Recovery time measured from initiation transient where Vout returned within ±1.0% Vout load. Line transient transition time 100µs. Turn-on delay measured with input voltage rise time between 100V 500V millisecond. Current limit point that condition excess load causing output voltage drop nominal. Parameter verified part another test. electrical tests performed with remote sense leads connected output leads load. Load transient transition time 10µs. Enable inputs internally pulled high. Nominal open circuit voltage 4.0VDC. Load current split equally between +Vout -Vout. Output load must distributed that minimum total output power being provided outputs. Cross regulation measured with load tested output maximum load while changing load other output from 80%.
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AFL28XXD Series
Block Diagram
Figure Dual Output
Input Input Filter Primary Bias Supply Current Sense Output Filter Sync Output Sync Input Case Input Return Control Error Share Amplifier Share Enable Output Voltage Trim Output Filter Output Output Return -Output
Enable
Circuit Operation Application Information
series converters employ forward switched mode converter topology. (refer block diagram Figure Operation device initiated when voltage whose magnitude within specified input voltage limits applied between pins enabled logical open) primary bias supply will begin generating regulated housekeeping voltage bringing circuitry primary side converter life. power MOSFET used chop input voltage into high frequency square wave, applying this chopped voltage power transformer nominal converter switching frequency. maintaining voltage within specified operating range input, continuous generation bias voltage assured. switched voltage impressed secondary output transformer windings rectified filtered provide positive negative converter output voltages. error amplifier secondary side compares positive output voltage precision reference generates error signal proportional difference. This error signal magnetically coupled through feedback transformer into control section converter varying pulse width square wave signal driving MOSFETs, narrowing pulse width output voltage high widening low. These pulse width variations provide necessary corrections regulate magnitude output voltage within its' specified limits. Because primary portion circuit coupled secondary side with magnetic elements, full isolation from input output maintained. Although incorporating several sophisticated useful ancilliary features, basic operation AFL28XXD series
series initiated simply applying input voltage pins connecting appropriate loads between pins case with high power density converter, operation should initiated before secure attachment appropriate heat dissipator. (See Thermal Considerations, page Additional application information provided paragraphs following.
Inhibiting Converter Output (Enable)
alternative application removal voltage input, user control converter output providing compatible, positive logic signals either enable pins (pin 12). distinction between these signal ports that enable (pin referenced input return (pin while enable (pin referenced output return (pin Thus, user access inhibit function either side isolation barrier. Each port internally pulled "high" that when used, open connection both enable pins permits normal converter operation. When their desired, logical "low" either port will shut converter down.
Figure Enable Input Equivalent Circuit
+5.6V 100K Disable 200K 2N3904 220K
1N4148
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AFL28XXD Series
Internally, these ports differ slightly their function. use, Enable completely shuts down circuits converter, while Enable shuts down secondary side while altering controller duty cycle near zero. Externally, either port transparent user save minor differences idle current. (See specification table). than 100ns, maximum level +0.8V minimumigh level +2.0V. sync output another converter which been designated master oscillator provides convenient frequency source this mode operation. When external synchronization indicted, sync should left open (unconnected) thereby permitting converter operate its' internally frequency. sync output signal continuous pulse train 50KHz, with duty cycle This signal referenced input return been tailored compatible with sync input port. Transition times less than 100ns level output impedance less than This signal active when input voltage within specified operating range converter inhibited. This synch output adequate drive reserve synchronize least five additional converters. typical synchronization connection option illustrated Figure III.
Synchronization Multiple Converters
When operating multiple converters, system requirements often dictate operation converters common frequency. accommodate this requirement, series converters provide both synchronization input output. sync input port permits synchronization connverter compatible external frequency source operating between 500KHz 700KHz. This input signal should referenced input return have duty cycle. Compatibility requires transition times less
Figure III. Preferred Connection Parallel Operation
Power Input
Case Enable Sync Sync
Enable Share
Trim Output Return Output
Optional Synchronization Connection
Share
Case Enable Sync Sync
Enable Share
Trim Output Return Output
Negative Load Positive Load
Case Enable Sync Sync
Enable
Share Trim Output Return Output
(Other Converters)
Parallel Operation-Current Stress Sharing
Figure III. illustrates preferred connection scheme operation converters with outputs operating parallel. this connection permits equal current sharing among members whose load current exceeds capacity individual AFL. important
feature series operating parallel mode that addition sharing current, stress induced temperature will also shared. Thus member paralleled operating higher case temperature, current provides load will reduced compensation temperature induced stress that device.
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AFL28XXD Series
When operating shared mode, important that symmetry connection maintained assurance optimum load sharing performance. Thus, converter outputs should connected load with equal lengths wire same gauge should connected common physical point, preferably load along with converter output return leads. converters paralleled must have their share pins connected together. This arrangement diagrammatically illustrated Figure III. showing output return pins connected star point which located close possible load. consequence topology utilized current sharing circuit, share used other functions. applications requiring only single converter, voltage appearing share used "total current monitor". share open circuit voltage nominally +1.00V load increases linearly with increasing total output current +2.20V full load. Note that current refer here total output current, that positive negative outout currents. conservative estimating total heat sink surface area HEAT SINK required maximum case temperature rise above ambient temperature given following expression:
-143 HEAT SINK 0.85
where
Case temperature rise above ambient Device dissipation Watts POUT
example, assume that desired operate AFL2815D still environment where ambient temperature held constant +25°C while holding case temperature +85°C; then case temperature rise
Thermal Considerations
Because incorporation many innovative technological concepts, series converters capable providing very high output power from package very small volume. These magnitudes power density only obtained combining high circuit efficiency with effective methods heat removal from junctions. This requirement been effectively addressed inside device; when operating maximum loads, significant amount heat will generated this heat must conducted away from case. maintain case temperature below specified maximum 125°C, this heat must transferred conduction appropriate heat dissipater held intimate contact with converter base-plate. Since effectiveness this heat transfer dependent intimacy baseplate/heatsink interface, strongly recommended that high thermal conductivity heat transferring medium inserted between baseplate heatsink. material most frequently utilized factory during testing burn-in processes sold under trade name Sil-Pad® 4001 This particular product insulator electrically conductive versions also available. these materials assures maximum surface contact with heat dissipater thereby compensating minor surface variations. While other available types heat conductive materials thermal compounds provide similar effectiveness, these alternatives often less convenient somewhat messy use.
1Sil-Pad registered Trade Mark Bergquist, Minneapolis,
60°C
From Specification Table, worst case full load efficiency AFL2815D 100W: thus, power dissipation full load given
(0.205) 20.5W
required heat sink area
-1.43
HEAT SINK 0.85 20.5
56.3
Thus, total heat sink surface area (including fins, any) this example, would limit case rise 60°C above ambient. flat aluminum plate, 0.25" thick approximate dimension side) would suffice this application still environment. Note that meet criteria this example, both sides plate require unrestricted exposure +25°C ambient air.
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AFL28XXD Series
Input Filter
AFL28XXD series converters incorporate stage input filter whose elements dominate input load impedance characteristic during turn-on sequence. input circuit shown Figure
Table Output Voltage Trim Values Limits
AFL2805D Vout 4.583 Radj 12.5K 33.3K 200K 190K 2.5K AFL2812D Vout 12.5 12.4 12.3 12.2 12.1 12.0 11.7 11.3 10.8 10.6 10.417 Radj 47.5K 127K 285K 760K 975K 288K 72.9K 29.9K AFL2815D Vout 15.5 15.4 15.3 15.2 15.1 15.0 14.6 14.0 13.5 13.0 12.917 Radj 62.5K 167K 375K 1.0M 1.2M 325K 117K 12.5K
Figure Input Filter Circuit
900nH 130nH
11.2
Undervoltage Lockout
minimum voltage required input converter initiate operation. This voltage 0.5V. preclude possibility noise other variations input falsely initiating halting converter operation, hysteresis approximately 1.0V incorporated this circuit. Thus input voltage droops 0.5V, converter will shut down remain inoperative until input voltage returns 14V.
Note that nominal magnitude output voltage resides middle table corresponding resistor value magnitude greater than nominal, adjust resistor connected output return. magnitude less than nominal, adjust resistor connected positive output. (Refer Figure output voltage settings that within limits, between those listed Table suggested that resistor values determined empirically selection variable resistor. value thus determined then replaced with good quality fixed resistor permanent installation. When this adjust feature elected, user should aware that temperature performance converter output voltage will affected temperature performance resistor selected adjustment element therefore, advised employ resistors with tight temperature coefficient resistance.
Output Voltage Adjust
trim (10), magnitude output voltages adjusted over limited range either positive negative direction. Connecting resistor between trim either output return positive output will raise lower magnitude output voltages. span output voltage adjustment restricted limits shown Table
General Application Information
AFL28XXD series converters capable providing large transient currents user loads demand. Because nominal input voltage range this series relatively low, resulting input current demands will correspondingly large. important therefore, that line impedance kept very prevent steady state transient input currents from degrading supply voltage between voltage source converter input. applications requiring high static currents large transients, recommended that input leads made adequate size minimize resistive losses, that good quality capacitor approximately 100µfd connected directly across input terminals assure adequately impedance input terminals. Table relates nominal resistance values selected wire sizes.
Figure Connection VOUT Adjustment
Enable Share
AFL28xxD
Trim Vout Return Vout
RADJ
Loads
Connect Radj increase, decrease
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AFL28XXD Series
Table Nominal Resistance Wire Wire Size, Resistance 25.7 16.2 10.1
Another potential problem resulting from parasitically induced voltage drop input lines with regard operation enable port. minimum maximum operating levels required operate this port specified with respect input common return line converter. logic signal generated with respect `common' that distant from converter, effects voltage drop over return line must considered when establishing worst case switching levels. These drops will effectively impart shift logic levels. Figure seen that referred system ground, voltage input return given
example effects parasitic resistance, consider AFL2815D operating full power 100W. From specification sheet, this device minimum efficiency which represents input power more than 120W. consider case where line voltage its' minimum 16V, steady state input current necessary this example will slightly greater than 7.5A. this device were connected voltage source with feet gauge wire, round trip (input return) would result resistance 1.5V drop from source converter. assure input, source closer would required. applications using paralleling option, this drop will multiplied number paralleled devices. choosing gauge wire this example, parasitic resistance resulting voltage drop will reduced that with gauge wire.
eRtn IRtn
Therefore, logic signal level generated system must capable logic high plus sufficient additional amplitude overcome eRtn. When converter inhibited, IRtn diminishes near zero eRtn will then system ground. Incorporation 100µfd capacitor input terminals recommended compensation dynamic effects parasitic resistance input cable reacting with complex impedance converter input, provide energy reservoir transient input current requirements.
Figure Problems Parasitic Resistance input Leads
eRtn Case
esource
IRtn
System Ground
Enable Sync Sync
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AFL28XXD Series
Mechanical Outlines
Case Case
Variation Case
3.000 2.760
0.128
0.050 0.250
0.250 0.050
0.25
BERYLLIA WARNING: These converters hermetically sealed; however they contain substrates should ground subjected other operations including exposure acids, which produce Beryllium dust fumes containing Beryllium
1.260 1.500
1.000
0.200 Non-cum 0.040
1.000
2.500
0.220
0.220 2.800 0.525
0.040
2.975 0.238
0.42
0.380
0.380
Case
1.150 0.300 0.140 0.050
Case
Variation Case
0.050
0.250
0.250
1.500 1.750 2.00
1.000
0.200 Non-cum 0.040
1.000
0.040 0.220 0.36 2.800 0.525
1.750 2.500 2.975 0.238
0.375
0.220
0.380
0.380
Tolerances, unless otherwise specified:
.XXX
±0.010 ±0.005
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AFL28XXD Series
Designation
Designation Input Input Return Case Ground Enable Sync Output Sync Input Output Output Return Output Output Voltage Trim Share Enable
Standard Microcircuit Drawing Equivalence Table
Standard Microcircuit Drawing Number
5962-95795 5962-95796 5962-94724
Standard Part Number
AFL2805D AFL2812D AFL2815D
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AFL28XXD Series
Device Screening
Requirement
Temperature Range Element Evaluation Non-Destructive Bond Pull Internal Visual Temperature Cycle Constant Acceleration PIND Burn-In Final Electrical Group Seal, Fine Gross Radiographic External Visual MIL-PRF-38534 2023 2017 1010 2001, Axis 2020 1015 MIL-PRF-38534 Specification MIL-PRF-38534 1014 2012 2009 Cond Cond
MIL-STD-883 Method
Suffix
-55°C +125°C Class Cond 3000 -55°C, +25°C, +125°C Cond
-20°C +85°C -55°C +125°C Cond
-55°C +125°C
Cond 3000 -55°C, +25°C, +125°C Cond
25°C
hrs@hi temp 25°C
hrs@125°C hrs@125°C
Notes:
Best commercial practice Sample tests high temperatures -55°C +105°C AHE, ATO,
Part Numbering
Model Input Voltage
120V 270V
Screening Level
(Please refer Screening Table)
suffix,
Case Style
Output
Dual
Output Voltage
±12V ±15V
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