4704 dey road liverpool, n.y. 13088 (315) 701-6751 m.s.kennedy corp. iso 9001 certified by dscc isr2800d radiation hardened high-power, high efficiency dc-dc power converter description: the isr2800d is the first in a series of radiation-hardened, high-reliability power supplies to be offered by msk. the isr2800d is specifically optimized to drive transmit/receive (t/r) modules in phased array antennas (paa), but as a result of its high-performance capabilities and numerous built-in features, it is ideal for many other applications. the isr2800d utilizes two dc-dc converters to optimize power conversion efficiency and facilitate voltage sequenc- ing necessary to protect t/r modules during power-up and power-down. a small flyback converter, referenced to input return and switching at 200khz, is used to provide electrical input-output isolation, generate nominal +10vdc bias voltages for the input and output control circuits of the power supply, and generate a nominal -5vdc negative output voltage for the t/r modules. the negative output voltage for the t/r modules is cross-regulated via a tap on the flyback transformer and referenced to output return. a low drop-out (ldo) linear regulator is then used to further post-regulate this output voltage to ensure tight regulation and low ripple, typically less than 5mvp-p. a single transistor forward converter, referenced to output return and switching at 100khz, provides the positive adjustable output voltage. they are enclosed in a hermetic silicon aluminum (sial) package and weigh less than tbd grams. the package utilizes rugged ceramic feed-through glid-cop pins and is sealed using parallel seam welding. features: 82.5w output power 18-40vdc steady-state input voltage range adjustable positive output voltage - 3.3v to 5.0v fixed -5v negative output typical 90% efficiency from half load to full load total dose - 100krad(si)(max) single-event effects - let>82mev-cm2/mg segr hardened mosfets integrated circuits are sel immune internal emi filter meets mil-std-461 input inrush current limiting remote sense for main output voltage soft-start circuitry prevents output voltage overshoot input undervoltage lockout output overload and short circuit protection output overvoltage protection synchronization capability external inhibit 1 rev. - 3/01 preliminary typical applications geostationary (geo) earth orbit satellites low earth orbit (leo) satellites deep space satellites/probes communication systems pin-out information crow bar -5v out vout rtn +vout vout rtn +vout vout rtn +vout vout rtn +vout rem sense vout adj vout ovp adj pri inhibit eterm input input rtn input input rtn input input rtn input input rtn sec on/off sync out sync in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
2 -0.5v to +50v internally limited -0.5v to +50v -0.5v to +50v -0.5v to +5.0v +vout 0.5v +300c for 10 seconds -55c to 85c -55c to 150c input voltage range ouput power pri inhibit sec on/off sync in rem sense lead temperature operating temperature storage temperature absolute maximum ratings rev. - 3/01 preliminary equivalent schematic
3 input characteristics input voltage input voltage -5vout output converter frequency output voltage output current output power output ripple output current limit output over-voltage limit +vout output converter frequency output voltage adjustable range output voltage regulation output current output power output ripple output current limit output over-voltage limit output step-load response output step-line response output step-line recovery time output efficiency +vout power supply efficiency turn-on response -5v out output overshoot -5v out output turn-on time +v out overshoot +v out turn-on time max. 40 50 240 -4.75 500 2.5 10 1.75 -5.50 115 5.00 5.0 - 80 1.0 24.0 130 1.6 1.6 50 - - - 200 - 500 typ. 28 - 200 -5.00 200 1 5 1.50 -6.00 100 - 0.0 - - 0.4 21.3 120 0.8 0.8 - 90 89 0 - 0 - min. 18 -0.5 160 -5.25 - - - 1.25 -6.50 85 3.30 -5.0 16 - - 16.0 110 -1.6 -1.6 - 86 85 - - - - v v khz v ma w mvp-p a v khz v %vo a w %vo-p-p a %vo %vo-p %vo-p us % % mv ms mv ms steady-state transient, 50ms zero load to/from half load, v in =22-40v dc zero load to/from half load, v in =22-40v dc recovery to within 1% of v out 18v to/from 40v 18v to/from 40v, recovery to within 1% of v out +v out =5v, i out =8-16a; -i out =-200ma +v out =5v, i out =16a; -i out =-500ma input voltage stepped from 0 to 28v dc parameter units isr2800d test conditions group a subgroup 1,2,3 1,2,3 4,5,6 1,2,3 1,2,3 1,2,3 4,5,6 1,2,3 1,2,3 4,5,6 1,2,3 1,2,3 1,2,3 1,2,3 4,5,6 1,2,3 1,2,3 4,5,6 4,5,6 4,5,6 1,2,3 1,2,3 - 4,5,6 - 4,5,6 electrical specifications rev. a 10/99 preliminary output step-load recovery time 4,5,6 continued on next page - -50 us 1 4 5 2 3 2 3 2 2 2 3 3 3 3 3 3 3
4 electrical specifications continued rev. - 3/01 preliminary notes: 1 -55c tc 85c, v in =18-40v dc , i out-main =0-16a, i out-aux =0-500ma, unless otherwise specified 2 this parameter is an operating condition and is verified during device testing. 3 this parameter shall be guaranteed by design and need not be tested. 4 typical parameters are representative of actual device performance but are for reference only. 5 subgroup 1,4 t a =t c =+25c 2,5 t a =t c =+125c 3,6 t a =t c =-55c pri inhibit input input voltage range open circuit voltage input (sink) current sec on/off input voltage range open circuit voltage input (sink) current power dissipation load fault pri input inhibit active sec output inhibit active misc line rejection isolation unit weight capacitive load -5v out +v out short circuit recovery time -5v out +v out sync out amplitude sync in input threshold frequency range input current min pulse width crow bar output high voltage output high current max. 50 18 2 50 12 2.5 10 0.05 2 - - tbd tbd 288 200 500 5.0 - 400 75 500 12 20 typ. - - - - - - - - - 60 - - - - - - - - - - - - v v ma v v ma w w w db m w grams f f ms ms v v khz ma ns v ma main output short circuit i out =0a dc to 50khz input to output, input to case, output to case tested at 100v dc no effect on dc performance. outputs returns to within 1% of nominal voltage i out 10ma v sync =3.5v parameter units isr2800d test conditions group a subgroup 1,2,3 1,2,3 1,2,3 1,2,3 1,2,3 1,2,3 1,2,3 1,2,3 1,2,3 4,5,6 1 - - - 4 4 1,2,3 1,2,3 4,5,6 1,2,3 4,5,6 1,2,3 1,2,3 min. -0.5 9 - -0.5 6 - - - - 40 100 - - - - 3.5 3.5 250 - 20 9 10 2 4 5 2 3 3 3 3 3 3 3
5 rev. - 3/01 preliminary pri inhibit - allows on/off control from circuits referenced to the input return. main and auxiliary outputs are on when this pin is left open and off when this pin is shorted to input return. eterm - allows control of pri inhibit pin in electrically noisy environments. this pin bypasses the internal emi filter to the internal ground reference and must be isolated. connecting this pin to the pri inhibit will disable the unit. input - input power terminals to connect to primary power source. all of these pins must be connected by the user. input rtn - input power terminals to connect to primary power source. all of these pins must be con- nected by the user. sec on/off - allows on/off control from circuits referenced to the output return. +vout and -5vout outputs are on when this pin is left open. +vout is off when this pin is shorted to output return. sync out - allows user to synchronize other devices to the operating frequency of the converter. this ac coupled pin can drive up to 50 w with an output level of 3.4v. sync in - allows user control of the converter operating frequency within a limited range. if unused, connect to output return, or leave open. this pin has an input impedance of 50 w . crow bar - allows user control to ensure proper voltage sequencing during fault conditions. this com- mand may be used to activate a crowbar circuit on the main output to guarantee proper power down sequencing. this output should normally be buffered (e.g. to drive the gate of a fet) in timing critical sequencing applications. for non-critical timing or high impedance input devices, it may be used directly. otherwise, it should be left open. -5vout - provides 2.5w of negative five volt, low noise bias power. sec rtn - output power return terminals to connect to isolated secondary loads. this is the return ground reference for both the outputs. all of these pins must be connected by the user. +vout - main adjustable output voltage. output power terminals connect to isolated secondary loads. this output is adjustable from 3.3v to 5v. all of these pins must be connected by the user. rem sense - remote sense allows user to connect to a remote location near the load for point of regulation. this overcomes a limited amount of voltage drop in the distribution network. otherwise, connect this pin to the +vout output. vout adj - allows adjustment of the +vout voltage over the allowable range using an external resistor from this pin to the output return. vout ovp adj - allows adjustment of the over-voltage protection (ovp) threshold to match the (adjust- able) main output voltage. threshold is adjusted by connecting a resistor from this pin to the output return. application notes isr2800d pin descriptions
6 rev. - 3/01 preliminary application notes cont'd basic architecture: msk power converters utilize two dc-dc converters to opti- mize power efficiency and to provide internal housekeeping power while magnetically isolating the power bus from the load. a small flyback converter, referenced to input return, is used to provide electrical input-output isolation and will generate nominal +10vdc bias voltages for the input and output control circuits of the power supply. a single transistor forward converter, referenced to out- put return, provides the main output voltage. flyback converter: the flyback converter uses peak current-mode pulse width modulator (pwm) control and operates in discontinuous conduc- tion-mode. regulation is achieved by sampling the input bias volt- age directly and feeding it back to the control circuit of the flyback converter, which is referenced to input return. forward converter: the forward converter uses voltage mode pulse width modu- lator (pwm) control with input voltage feed-forward and operates in continuous conduction-mode. regulation is achieved by sam- pling the output voltage directly and feeding it back to the control circuit of the forward converter, which is referenced to output return. since the main output voltage is directly regulated without the use of magnetically-coupled feedback, superior voltage regula- tion can be achieved. a single-stage l-c output filter reduces the typical output ripple to less than 25mvp-p. synchronous rectification: synchronous rectification is used to achieve high-conversion efficiency over a half to full output load range and allows con- verter operation in continuous conduction-mode down to zero out- put load. this capability results in far superior dynamic perfor- mance when the load is stepped to or from a zero load condition, and is particularly critical in pulsed phased array antenna and modern microprocessor applications which have high peak current demands and fast load transients. input emi filter: the input emi filter is comprised of a multi-stage l-c filter which provides attenuation of the differential-mode emissions from the power supply. a balun, in conjuction with very small line-to- chassis and return-to-chassis capacitors, provides attenuation of the common-mode emissions from the power supply. together these components enable the power supply to meet the conducted emission requirements of mil-std-461. inrush current limiting: inrush current limiting circuitry limits initial peak input charg- ing current at turn-on to less than two times maximum steady- state input current. consequently, even when the input voltage to the power supply is instantaneously stepped, peak charging cur- rent is well controlled. undervoltage lockout: an undervoltage lockout circuit prevents the power supply from operating when the input line voltage is too low to maintain the output voltage. the converter will not start until the line voltage rises to approximately 17v and will shut down when the input voltage drops below approximatley 16v. the approximate 1v of hysteresis reduces the possibility of line noise interfereing with the converter during power-up and power-down. soft-start: soft-start circuitry associated with both the flyback and for- ward converters is guaranteed to prevent output voltage over- shoot during power-up for both the auxiliary and main output volt- ages. user-adjustable main output: the +vout output voltage is user-adjustable over a range of 3.3vdc to 5vdc. setting the positive output voltage is accom- plished by using a single external resistor. the output voltage may be programmed by the user to any desired voltage within this range. the table below shows the value of resistance necessary to set several common output voltages. the equation below may be used to determine the resistor value required for other set points. the output voltage may be adjusted up to 6v and down to 3v, but some performance specifications will not be met. output voltage adjust resistor value (in k w ) f(vout) = -6.7 f(3.0) = 2.98 x 103 f(3.3) = 141.95 f(5.0) = 8.22 f(5.2) = 5.97 overvoltage protection (ovp): overvoltage protection is provided for both the negative and positive output voltages of the power supply. the overvoltage protection circuit for the negative output voltage limits peak volt- age to approximately 120% of nominal. the overvoltage limit for the positive output voltage is programmable with a single external resistor. it is recommended that this overvoltage limit be set at approximately 120% of nominal. the overvoltage protection is programmable over a limited range using only a single external resistor. the ovp voltage may be programmed by the user to any desired voltage within this range. the ovp set point should be coordinated with the positive output voltage and set to approximately 110% to 120% of the nominal output. the table below shows the value of resistance necessary to set the ovp to 120% for several common output voltages. the equation below may be used to determine the resistor value re- quired for other set points. output voltage over-voltage protection (ovp) adjust resistor value (in k w) g(ovp) = -3.44 g(3.6) = 238.12 g(3.96) = 22.51 g(6) = 0.84 g(6.24) = 0.46 voltage sequencing: output voltage sequencing is provided to protect t/r modules from damage when used in paa applications. during power-up, the positive output voltage remains off until the negative output voltage has reached normal regulation limits. during power-down, a crowbar command is available to ensure that the positive output voltage falls to 10% or less of its steady state value before the negative output voltage falls more than 20% from its nominal value. during fault mode the crowbar command allows user control of the crowbar circuit on the positive output to ensure proper voltage sequencing for application specific requirements. 2.5 0.04975vout-0.1484166 10.4667 ovp-3.55667
7 rev. - 3/01 preliminary application notes cont'd radiation performance msk converters give you superior radiation performance with- out the highs and lows of using "typical" dc-dc converters. the design represents a break from the traditional hardening method of simply replacing commercial die elements with radiation screened die in an off-the-shelf dc-dc converter design. special design techniques implemented at both the module level and the transistor circuit element level were used to harden the dc-dc converters. here are some of the engineering steps taken to guarantee the radiation performance. total dose hardness: the converters employ a fully magnetically-isolated configura- tion allowing the positive converter output to be regulated directly without the use of opto-couplers. galvanic isolation between in- put and output is provided by the flyback converter and a small gate-drive transformer which couples the pwm drive signal to the main switching mosfet. this approach provides optimum out- put voltage regulation and avoids the gain degrading effects of total ionizing dose on opto-couplers which can result in converter failure. single-event effects hardness: all critical ics in the converter use a latch-up immune, dielectrically-isolated, bicmos process that prevents converter components from entering a potentially catastrophic latched state. the heart of the dc-dc converter is the single-event effects hardened pwm. the chip has seu-immune cmos soft-start con- trol logic which will not upset in a heavy ion environment. the on- chip overcurrent comparator employs a redundant cross-checking comparator design. error amp circuitry incorporates redundant wire or differential input stages which prevent the amplifier out- put from over-ranging, which could cause excessive output pulse widths leading to overcurrent fault sequencing, transformer core saturation or power switch overstress. the toggle flip/flop (f/f) and all pulse control logic functions have been designed in seu- immune cmos to keep pulse phase integrity from being upset. the pwm used in the flyback circuitry incorporates these same improvements with the exception of the soft-start func- tion. dc-dc converters use comparator ics to control various converter functions such as input inrush current limiting, input undervoltage lockout, start-up regulator shutdown, output ov- ervoltage protection, and main/auxiliary output voltage sequenc- ing. a high-energy ion striking the comparator can cause any of these functions to fail or inadvertantly activate causing un- wanted power supply interruptions. the msk converters em- ploy a new hardened, seu immune, quad comparator. the chip uses triple redundant bipolar comparators for analog preci- sion, and is backed by seu-immune voting logic which ensures that no single-particle error can propagate to the output. the potential for catastrophic single-event gate rupture in mosfet's has led to the development of mosfet's with ox- ide structures which resist breakdown up to fully rated mosfet voltage potential under fully off-biased conditions. all mosfet's used in the converters mitigate single-event gate rupture ef- fects up to 82 mev-cm2/mg. a proven design methodology the power supplies were developed using a proven, conserva- tive design methodology which includes selecting radiation-hard- ened and established reliability components and fully de-rated to the requirements of mil-std-975, mil-std-1547 and gsfc ppl- 21 appendix b. proprietary radiation-hardened silicon gate (rsg) process for integrated circuits ensures total dose capability to 300krads and immunity to single-event latch-up (sel). radiation- hardened power mosfets virtually eliminate the possibility of single-event gate rupture and single-event burn-out. direct regu- lation is utilized instead of opto-couplers to minimize temperature, radiation and aging sensitivity. the cadence analog work bench (awb) tool set, including sensitivity/worst case and monte carlo tools, was used extensively to predict and optimize circuit perfor- mance for both beginning and end-of-life. thorough design analy- sis include worst case, component stress and reliability (mtbf). msk's dc-dc converters offer high reliability through "tried and true" methods of passive component procurement and hybrid construction techniques. all stacked capacitors are procured, pre- assembled (stacked) and up screened by the capacitor manufac- turer. capacitor mounting procedures are performed per the supplier's guidelines. magnetics, resistors and capacitors are all procured to the highest standards. full component level traceabil- ity is maintained on all high-rel lots. final hybrid assembly and screening is available up to mil-prf-38534 class k or class h requirements.
8 rev. - 3/01 preliminary typical system operation a typical application shows the isr2805dske connections to an arbitrary load. the remote sense line is used to eliminate voltage drop in the positive distribution lead. the negative output provides bias to hold the gate of fet drive transistors off in radiation environments. a fet crowbar circuit is driven directly to discharge the filter capacitance at the load during shutdown. the two resistors connected to the ovp and vout adj pins set the output over voltage limit and output voltage to the required values. also illustrated is a connection to synchronize two converters to a master clock. an isolated connection is shown to inhibit both converter outputs from the primary referenced input voltage as well as a secondary on/off command referenced to the output to shutdown the positive output.
9 the information contained herein is believed to be accurate at the time of printing. msk reserves the right to make changes to its products or specifications without notice, however, and assumes no liability for the use of its products. please visit out website for the most recent revision of this datasheet. mechanical specifications m.s. kennedy corp. 4704 dey road, liverpool, new york 13088 phone (315) 701-6751 fax (315) 701-6752 www.mskennedy.com isr2800dksrh the above example is a class k adjustable dual output rad-hard converter rad-hard lead configurations s= straight; u= bent up; d= bent down screening blank= industrial; e= extended reliability; h= class h; k= class k dual output output voltage +adj/-5v nominal input voltage general part number ordering information note: all dimensions are 0.010 inches unless otherwise labeled. esd triangle indicates pin 1. rev. - 3/01 preliminary
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