ARH2812S

PD-95887A ARH28XXS SERIES HYBRID - HIGH RELIABILITY RADIATION HARDENED DC/DC CONVERTERS Description The ARH Series of DC/DC converters has been designed specifically for use in the hostile environments The high level of radiation tolerance inherent in the ARH design is the result of extensive research, thorough analysis and testing and of careful component specification. Designed to supplement the triple output configuration provided by the ART series, the ARH circuit topology is the follow-on to the successful ART design and incorporates many of the design features characterizing that product line. Capable of uniform high performance over long term exposures in radiation intense environments, this series expands the standard for distributed power systems demanding high performance and reliability in the harsh environments. The ARH converters are hermetically sealed in a rugged, low profile package utilizing copper core input and output pins to minimize resistive DC losses. Longterm hermeticity is assured through use of parallel seam welded lid attachment along with rugged ceramic pinto-package seal. Axial orientation of the leads facilitates preferred bulkhead mounting placing the converter on the principal heat-dissipating surface. Manufactured in a facility fully qualified to MIL-PRF38534, these converters are fabricated utilizing DSCC qualified processes. For available screening options, refer to device screening table in the data sheet. Variations in electrical, mechanical and screening specifications can be accommodated. Contact IR Santa Clara for special requirements. 28V Input, Single Output ARH Features n n n n n n n n n n n n n n n n n Total Dose > 100 krad (Si), 2:1 Margin SEE Hardened to LET up to 83 MeV.cm2/mg Derated per MIL-STD-975 & MIL-STD-1547 Output Power to 30 Watts Regulates to No-Load 18 to 50 Volt Input Range Input Undervoltage Lockout Fully Characterized from -55°C to +125°C Continuous Short Circuit Protection 12.8 W/in3 Output Power Density True Hermetic Package External Inhibit Port Externally Synchronizable Fault Tolerant Design Available with Outputs from 2.5V to 15V Overload Protection Standard Microcircuit Drawings Available www.irf.com 1 08/11/06 ARH28XXS Series Specifications Absolute Maximum Ratings Input Voltage range Soldering temperature Storage case temperature -0.5V to +80VDC 300°C for 10 seconds -65°C to +135°C Recommended Operating Conditions Input Voltage range Output Power Operating case temperature +18V to +60VDC +18V to +50V for full derating to MIL-STD-1547 0 to 30W -55°C to +125°C -55°C to +85°C for full derating to MIL-STD-975 Electrical Performance Parameter Output voltage accuracy ARH2802R5S ARH2803R3S ARH2805S ARH2805R2S ARH2812S ARH2815S Output power -55°C < TCASE < +125°C, VIN = 28V±5% , CL = 0 unless otherwise specified. Symbol VOUT Test Conditions POUT = 30 W, TC = +25°C Limit MIN 2.487 3.283 4.975 5.174 11.940 14.925 Limit MAX 2.513 3.317 5.025 5.226 12.060 15.075 30 Units Vdc POUT 18 Vdc < VIN < 50Vdc 0 W Output current ARH2802R5S ARH2803R3S ARH2805S ARH2805R2S ARH2812S ARH2815S Line regulation Note 3 Load regulation Note 4 Total regulation IOUT 18 Vdc < VIN < 50Vdc 0 0 0 0 0 0 12000 9090 6000 5770 2500 2000 +1.0 +2.0 +4.0 100 mA inhibited (Pin 3 shorted to pin 2) — 8.0 18 Vdc < VIN < 50Vdc, IOUT = IMAX 30 30 40 40 50 50 mAdc VRLINE VRLOAD VR 18 Vdc < VIN < 50Vdc, 0 < IOUT < IMAX 18 Vdc < VIN < 50Vdc, 0 < IOUT < IMAX All conditions of Line, Load, Temperature, Radiation and End of Life IOUT = 0 (Pin 3 open) -1.0 -2.0 -4.0 — % % % No-load input current Output ripple and noise voltage Note 5 ARH2802R5S ARH2803R3S ARH2805S ARH2805R2S ARH2812S ARH2815S IIN VRIP mVp.p For Notes to Specifications, refer to page 4 2 www.irf.com ARH28XXS Series Electrical Performance Parameter Input ripple current Note 5 Switching frequency Efficiency ARH2802R5S ARH2803R3S ARH2805S ARH2805R2S ARH2812S ARH2815S Enable Input open circuit voltage drive current (sink) voltage range Synchronization Input frequency range pulse high level pulse low level pulse rise time pulse duty cycle Synchronization Output pulse high level Power dissipation, Short circuit ARH2802R5S ARH2803R3S & ARH2805S All Others Output response to step load changes Note 8 ARH2802R5S ARH2803R3S ARH2805S ARH2805R2S ARH2812S ARH2815S Recovery time from step load changes Notes 8, 9 ARH2802R5S ARH2803R3S ARH2805S ARH2805R2S ARH2812S ARH2815S Output response to step line changes Notes 7, 10 ARH2802R5S ARH2803R3S ARH2805S ARH2805R2S ARH2812S ARH2815S PD External clock signal on Sync. input (pin 4) 225 3.5 -0.5 40 20 Signal compatible with Synchronization Input 3.7 Short circuit on output 10 12 9.5 VTLD 50% Load ⇔ 100% load -200 -200 -200 -200 -300 -350 TTLD 50% Load ⇔ 100% load 200 200 200 200 200 200 VTLN IOUT = IMAX, VIN = 18 V to/from 50 V -180 -180 -250 -250 -450 -900 180 180 250 250 450 900 200 200 200 200 300 350 W 4.3 V 310 10 0.25 80 KHz V V V/µs % -55°C < TCASE < +125°C, VIN = 28V±5% , CL = 0 unless otherwise specified. (Continued) Symbol IRIP FS Eff Test Conditions 18 Vdc < VIN < 50Vdc, IOUT = IMAX Synchronization input open. (pin 6) IOUT = IMAX, TC = +25°C Limit MIN Limit MAX 100 Units mAp.p KHz 225 72 75 76 76 80 80 3.0 -0.5 275 % 5.0 100 50 V µA V mVPK µs mVPK For Notes to Specifications, refer to page 4 www.irf.com 3 ARH28XXS Series Electrical Performance Parameter Recovery time from step line changes Notes 7, 9, 10 ARH2802R5S ARH2803R3S ARH2805S ARH2805R2S ARH2812S ARH2815S Turn on overshoot Turn on delay Note 11 Capacitive load Notes 6, 7 ARH2802R5S A RH2803R3S ARH2805S ARH2805R2S ARH2812S ARH2815S Isolation Recovery from a short circuit -55°C < TCASE < +125°C, VIN = 28V±5%, CL = 0 unless otherwise specified. (Continued) Symbol TTLN Test Conditions IOUT = IMAX, VIN = 18 V to/from 50 V Limit MIN Limit MAX Units 600 600 700 700 320 400 VOS TDLY CL IOUT = 10% or 100% of IMAX IOUT = 10% or 100% of IMAX No effect on DC performance 1200 1200 1000 1000 180 120 ISO Vr 500VDC Input to Output or any pin to case Output shorted, then open into max rated load current. Vin = 28 V 100 10 2.0 5.0 20 µs %Vout ms µF MΩ % of Rated Output Voltage % of Max Output Current Overload Trip Current Ovld Maximum current at specified output voltage 105 135 Notes to Specifications Tables 1. 2. 3. 4. 5. 6. Operation outside absolute maximum/minimum limits may cause permanent damage to the device. Extended operation at the limits may permanently degrade performance and affect reliability. Device performance specified in Electrical Performance table is guaranteed when operated within recommended limits. Operation outside recommended limits is not specified. Parameter measured from 28 V to 18 V or to 50 V while load remains fixed at 10%, 50% and 100% of Imax. Parameter measured from 50% to 10% or 100% of maximum load conditions while line remains fixed at 18, 28 or 50 volts. Guaranteed for a bandwidth of DC to 20 Mhz. Tested using a 20 Khz to 2.0 Mhz bandwidth. A capacitive load of any value from 0 to the specified maximum is permitted without compromise to DC performance. A capacitive load in excess of the maximum limit may interfere with the proper operation of the converter’s short circuit protection, causing erratic behavior during turn on. Parameter is tested as part of design characterization or after design or process changes. Thereafter, parameters shall be guaranteed to the limits specified in the table. Load transient rate of change, di/dt ≤ 2.0 A/µs. Recovery time is measured from the initiation of the transient to where V OUT has returned to within ±1% of its steady state value. 7. 8. 9. 10. Line transient rate of change, dv/dt ≤ 50 V/µs. 11. Turn on delay time is for either a step application of input power or a logical low to high transition on the enable pin (pin 3) while power is present at the input. 4 www.irf.com ARH28XXS Series Group A Tests Test Output voltage accuracy ARH2802R5S ARH2803R3S ARH2805S ARH2805R2S ARH2812S ARH2815S Output power Note 1 Output current Note 1 ARH2802R5S ARH2803R3S ARH2805S ARH2805R2S ARH2812S ARH2815S Output regulation Note 4 ARH2802R5S ARH2803R3S ARH2805S ARH2805R2S ARH2812S ARH2815S IOUT = 0, Pin 3 open No Load Input Current Output ripple Note 2 ARH2802R5S ARH2803R3S ARH2805S ARH2805R2S ARH2812S ARH2815S Switching frequency Input ripple Note 2 Recovery from a short circuit Overload Trip Current IIN Pin 3 shorted to pin 2 (disabled) VRIP VIN = 18 V, 28V, 50 V IOUT = IMAX 1, 2, 3 8.0 VR IOUT = 10%, 50%, 100% of IMAX VIN = 18 V, 28V, 50 V POUT IOUT VIN = 18 V, 28V, 50 V VIN = 18 V, 28V, 50 V 1, 2, 3 1, 2, 3 0 0 0 0 0 0 12000 9090 6000 5770 2500 2000 VIN = 28V, CL = 0 unless otherwise specified. Symbol VOUT Test Conditions IOUT = IMAX , Tc = 25°C Group A Subgroups 1 Limit MIN Limit MAX Units 2.487 3.283 4.975 5.174 11.940 14.925 0 2.513 3.317 5.025 5.226 12.060 15.075 30 V W mA 1, 2, 3 2.425 3.201 4.850 5.044 11.640 14.550 2.575 3.399 5.150 5.356 12.360 15.450 100 V 1, 2, 3 mA 1, 2, 3 30 30 40 40 50 50 225 275 100 5.0 mVP-P FS IRIP Vr Synchronization pin (pin 6) open VIN = 18 V, 28V, 50 V IOUT = IMAX Output shorted, then open into max rated load current. Vin = 28 V Maximum current at specified output voltage 4, 5, 6 1, 2, 3 KHz mAP-P % of Rated Output Voltage % of Max Output Current Ovld 1, 2, 3 105 135 For Notes to Group A Tests, refer to page 6 www.irf.com 5 ARH28XXS Series Group A Tests Test Efficiency ARH2802R5S ARH2803R3S ARH2805S ARH2805R2S ARH2812S ARH2815S ARH2802R5S ARH2803R3S ARH2805S ARH2805R2S ARH2812S ARH2815S Power dissipation, Short circuit ARH2802R5S ARH2803R3S & ARH2805 All Others Output response to step load changes Note 5 ARH2802R5S ARH2803R3S ARH2805S ARH2805R2S ARH2812S ARH2815S Recovery from step load changes Notes 5, 6 ARH2802R5S ARH2803R3S ARH2805S ARH2805R2S ARH2812S ARH2815S Turn on overshoot Turn on delay Note 7 Isolation VTL 50% Load to/from 100% load 4, 5, 6 -200 -200 -200 -200 -300 -350 TTL 50% Load to/from 100% load 4, 5, 6 200 200 200 200 200 200 VOS TDLY ISO IOUT = 10% and 100% IOUT = minimum and full rated 500VDC Input to output or any pin to case (except pin 12) 4, 5, 6 4, 5, 6 1 2.0 100 5.0 20 µs 200 200 200 200 300 350 mVPK PD Short circuit across output VIN = 28V, CL = 0 unless otherwise specified. (continued) Symbol Eff IOUT = IMAX Test Conditions Group A Subgroups Limit MIN Limit MAX Units 1 72 75 76 76 80 80 68 68 72 72 78 78 % 2, 3 1, 2, 3 10 12 9.5 W %Vout ms MΩ Notes to Group A Test Table 1. 2. 3. 4. 5. 6. 7. 8. Parameter verified during dynamic load regulation tests. Guaranteed for DC to 20 MHz bandwidth. Test conducted using a 20KHz to 2.0MHz bandwidth. Deleted Output is measured for all combinations of line and load. Only the minimum and maximum readings for the output are recorded. Load step transition time ≥ 10µS. 0µs. Recovery time is measured from the initiation of the transient to where VOUT has returned to within ±1% of its steady state value. Turn on delay time is tested by application of a logical low to high transition on the enable pin (pin 3) with power present at the input. Subgroups 1 and 4 are performed at +25°C, subgroups 2 and 5 at +125°C and subgroups 3 and 6 at -55°C. 6 www.irf.com ARH28XXS Series Figure I. Block Diagram 1 +Input EMI Filter 11 12 +Vout Under-Voltage Detector 13 14 Output Return Primary Bias & Reference Overload & Short Circuit Error Amp + - 3 Enable Level Translator & Buffer 10 +Sense 9 -Sense 4 S ync In 5 Pulse Width Modulator Sample & Hold S ync Out Input Return 2 Circuit Operation and Application Information The ARH28XXS series of converters have been designed using a single ended forward switched mode converter topology. (Refer to Figure I.) Single ended topologies enjoy certain advantages in radiation hardened designs in that they eliminate the possibility of simultaneous turn on of both switching elements during a radiation induced upset. In addition, single ended topologies are not subject to transformer saturation problems often associated with double ended implementations. The design incorporates a two-stage LC input filter to attenuate input ripple current. A low overhead linear bias regulator provides both a bias voltage for the converter primary control logic and a stable, well-regulated reference for the error amplifier. Output control is realized using a wide band discrete pulse width modulator control circuit incorporating a unique non-linear ramp generator circuit. This circuit helps stabilize loop gain over variations in line voltage for superior output transient response. Nominal conversion frequency has been selected as 250 KHz to maximize efficiency and minimize magnetic element size. Output voltages are sensed and fed back to the controller using a patented magnetic feedback circuit. This circuit is designed to be relatively insensitive to variations in temperature, aging, radiation and manufacturing tolerances making it particularly well suited to radiation hardened designs. The control logic has been designed to use only radiation tolerant components, and current paths include series resistances to limit photocurrents. Other key circuit design features include output short circuit and overload protection, input undervoltage lockout and an external synchronization input port, permitting operation at an externally set clock rate. Alternately, a synchronization output is provided to lock frequencies with another converter when using more than one converter in a system. Thermal Considerations The ARH series of converters is capable of providing relatively high output power from a package of modest volume. The power density exhibited by these devices is obtained by combining high circuit efficiency with effective methods of heat removal from the die junctions. Good design practices have effectively addressed this requirement inside the device. However when operating at maximum loads, heat generated at the die junctions depends upon minimally restricted thermal conduction from the base plate for that heat to be carried away. To maintain case temperature at or below the specified maximum of 125°C, this heat can be transferred by attachment of the ARH28XXS to an appropriate heat dissipater held in intimate contact with the converter base-plate. Effectiveness of this heat transfer is dependent on the intimacy of the baseplate to heatsink interface. It is therefore suggested that a heat-transferring medium possessing good thermal conductivity be inserted between the baseplate and heatsink. A material utilized at the factory during testing and burn-in processes is sold under the www.irf.com 7 ARH28XXS Series trade name of Sil-Pad® 4001. This particular product is an insulator but electrically conductive versions are also available. Use of these materials assures optimum surface contact with the heat dissipater by compensating for minor surface variations. While other available types of heat conducting materials and thermal compounds provide similar effectiveness, these alternatives are often less convenient and are sometimes messy to use. A conservative aid to estimating the total heat sink surface area (AHEAT SINK ) required to set the maximum case temperature rise (DT) above ambient temperature is given by the following expression: Inhibiting Converter Output As an alternative to application and removal of the DC voltage at the input, the user can control the converter output by providing an input referenced, TTL compatible, logic signal to the enable pin 3. This port is internally pulled “high” so that when not used, an open connection on the pin permits normal converter operation. When inhibited outputs are desired, a logical “low” on this port will shut the converter down. An open collector device capable of sinking at least 100 µA connected to enable pin 3 will work well in this application. A benefit of utilization of the enable input is that following an initial charge of the input capacitor, subsequent turn-on commands will induce no uncontrolled current inrush. A HEAT SINK where ⎧ ∆T ⎫ ≈⎨ 0.85 ⎬ ⎩ 80 P ⎭ −1. 43 − 5.94 ∆T = Case temperature rise above ambient ⎧1 ⎫ P = Device dissipation in Watts = P ⎨ − 1⎬ ⎩ Eff ⎭ OUT Figure II. Enable Input Equivalent Circuit As an example, assume that it is desired to maintain the case temperature of an ARH2815S at +65°C or less while operating in an open area whose ambient temperature does not exceed +35°C; then ∆T = 65 - 35 = 35 ° C. From the Specification Table, the worst case full load efficiency for this device is 80%; therefore the maximum power dissipation at full load is given by ⎫ ⎧1 . P = 30 • ⎨ − 1⎬ = 30 • (0.25) = 75W ⎩ .80 ⎭ and the required heat sink area is Synchronization − 5.94 = 318 in 2 . When using multiple converters, system requirements may dictate operating several converters at a common system frequency. To accommodate this requirement, the ARH28XXS type converter provides a synchronization input port. The sync input port permits synchronization of an ARH converter to any compatible external frequency source operating in the band of 225 to 310 KHz. In the event of failure of an external synchronization source, the converter will revert to its own internally set frequency. When external synchronization is not desired, the sync in port may be left open (unconnected) permitting the converter to operate at its own internally set frequency. 35 ⎧ ⎫ A HEAT SINK = ⎨ 0.85 ⎬ ⎩ 80 • 7.5 ⎭ −1. 43 Thus, a total heat sink surface area (including fins, if any) of approximately 32 in2 in this example, would limit case rise to 35°C above ambient. A flat aluminum plate, 0.25" thick and of approximate dimension 4" by 4" (16 in2 per side) would suffice for this application in a still air environment. Note that to meet the criteria, both sides of the plate require unrestricted exposure to the ambient air. The user should remember that when operating in the vacuum of space, this method does not apply and all heat must be conducted away from the attaching surface. 1Sil-Pad is a registered Trade Mark of Bergquist, Minneapolis, MN 8 www.irf.com ARH28XXS Series When an external frequency source is not available, an internal clock signal is provided through appropriate buffering at the sync out port. This port can drive a minimum of 3 ARH sync in ports thereby allowing all to operate at the same clock frequency. EMI Filtering Although the internal filtering provided at both input and output terminals of the ARH series converters is sufficient for most applications, some critical applications may require additional filtering in order to accommodate particular system requirements. While the internal input filter maintains input ripple current below 50 mA p-p, an external filter can be applied to further attenuate this ripple to a level below the CE03 limits imposed by MIL-STD-461. International Rectifier currently supplies such a filter housed in a complementary package. The catalog number of this part is ARF461. Output Short Circuit Protection Protection against accidental short circuits on the output is provided in the ARH28XXS converter. This protection is implemented by sensing primary switching current and reducing the switching pulse widths when a short occurs. The output current is therefore limited to a maximum value, which protects the converter. Under this condition the internal power dissipation is nearly the same as for maximum loading. Output Noise When attempting noise measurement at the output of switching converters, measurement techniques employed can have a significant influence on results during these tests. Any noise measurements should be undertaken only with test leads dressed as close to the device output pins as is physically possible. Probe ground leads should be kept to a minimum (