4707 dey road liverpool, n.y. 13088 m.s.kennedy corp. (315) 701-6751 features: manufactured using space qualified rh3080 die mil-prf-38535 class v processing & screening total dose hardened to 300 krads(si) (method 1019.7 condition a) low dropout to 250mv output adjustable to zero volts internal short circuit current limit output voltage is adjustable with 1 external resistor output current capability to 0.7a internal thermal overload protection outputs may be paralleled for higher current available in straight or gull wing lead form contact msk for mil-prf-38535 certification and qualification status high efficiency linear regulators constant voltage/current regulators space system power supplies switching power supply post regulators very low voltage power supplies typical applications pin-out information 5978rh rad hard positive, 0.7a, ldo, single resistor adj voltage regulator description: the msk 5978rh offers low dropout down to 250mv and an output voltage range down to zero volts while offering radiation tolerance for space applications. this, combined with the low jc, allows increased output current while providing exceptional device efficiency. output voltage is selected by the user through the use of 1 external resistor. additionally, the regulator offers internal short circuit current and thermal limiting, which allows circuit protection and eliminates the need for external components and excessive derating. because of the increased efficiency, a small hermetic 10 pin ceramic flatpack can be used providing maximum performance while occupying minimal board space. the msk 5978rh is available in two lead options: straight or gull wing. equivalent schematic mil-prf-38534 certified 1 rev. c 10/10 1 2 3 4 5 ctl vin vin vin nc 10 9 8 7 6 set vout sense vout vout vout
1 2 3 4 5 6 7 8 storage temperature range lead temperature range (10 seconds) case operating temperature msk 5978rh msk 5978vrh 40v 40v internally limited 0.7a +150c -65c to +150c 300c -40c to +85c -55c to +125c absolute maximum ratings t st t ld t c input voltage control voltage power dissipation output current junction temperature vin v ctl p d i out t j output is decoupled to ground using a 220 f tantalum low esr capacitor in parallel with 3 pieces of 1.0 f and one 0.1 f ceramic capacitor unless otherwise specified. (see figure 1) guaranteed by design but not tested. typical parameters are representative of actual device performance but are for reference only. industrial grade devices shall be tested to subgroup 1 unless otherwise specified. class v devices shall be 100% tested to subgroups 1,2 and 3. subgroup 1 t a =t c =+25c subgroup 2 t a =t c =+125c subgroup 3 t a =t c =-55c minimum load current verified while testing line regulation. continuous operation at or above absolute maximum ratings may adversely effect the device performance and/or life cycle. pre and post irradiation limits at 25c, up to 300 krad tid, are identical unless otherwise specified. electrical specifications 2 notes: 7 7 rev. c 10/10
application notes paralleling devices when currents greater than 0.7a are needed, the msk 5978rh's may be paralleled to multiply the current capacity. as shown in figure 4, the vin and set pins must be tied together. the vout pins are connected to the load with consideration to the conductor resistance. the conductor resistance of each msk 5978rh vout connection to the load, must be equal to create equal load sharing. as little as 10m ballast resistance typically ensures better than 80% equal sharing of load current at full load. additional consideration must be given to the effect the additional vout conductor resistance has on load regulation; see paragraph titled "load regulation". output capacitance for stability purposes, the msk 5978rh requires a minimum output capacitor of 2.2 f with an esr of 0.5 or less. tantalum or ceramic capacitors are recommended. a larger capacitance value will improve transient response for increased load current changes. consideration must also be given to temperature characteristics of the capacitors used. figure 1 output voltage 3 figure 3 figure 4 a single resistor (r set ) from the set pin to ground creates the reference voltage for the internal error amplifier. the msk 5978rh set pin supplies a constant current of 10ua that develops the refer- ence voltage. the output voltage is simply r set x 10ua. since the output is internally driven by a unity-gain amplifier, an alternative to using r set is to connect a high quality reference source to the set pin. with a minimum load requirement of 1ma on the output, the output voltage can be adjusted to near 0v. to bring the output volt- age to 0v, the load must be connected to a slightly negative voltage supply to sink the 1ma minimum load current from a 0v output. additional stability a capacitor placed in parallel with the set pin resistor to ground, will improve the output transient response and filter noise in the sys- tem. to reduce output noise, typically less than 100pf is all that will be required. capacitors up to 1 f can be used, however consideration must be given to the effect the time constant created will have on the startup time. load regulation the msk 5978rh specified load regulation is kelvin sensed, there- fore the parasitic resistance of the system must be considered to design an acceptable load regulation. the overall load regulation in- cludes the specified msk 5978rh load regulation plus the parasitic resistance multiplied by the load current as shown in figure 3. r so is the series resistance of all conductors between the msk 5978rh output and the load. it will directly increase output load regulation error by a voltage drop of i o x r so . r ss is the series resistance between the set pin and the load. r ss will have little effect on load regulation if the set pin trace is connected as close to the load as possible keeping the load return current on a separate trace as shown. r sr is the series resistance of all of the conductors between the load and the input power source return. r sr will not effect load regulation if the set pin is connected with a kelvin sense type connection as shown in figure 3, but it will increase the effective dropout voltage by a factor of i o x r sr . keeping r so and r sr as low as possible will ensure minimal voltage drops and wasted power. rev. c 10/10 figure 2 low dropout using separate vin and ctl power supplies allows for lower drop- out and improved efficiency. figure 2 shows the msk 5978rh output transistor collector is connected to the vin pin. the regulator control circuitry is powered by the ctl input. the dropout of the regulator is determined by the saturation voltage of the output transistor, typical 250mv at 0.7a i load . the ctl supply must supply the base drive current for the output transistor. the ctl current minus the 10 a set current is supplied to the load. see the typical performance characteristics curves for expected dropout voltage, ctl pin voltage and current requirements under various conditions. with separate sup- plies for vin and ctl, power dissipation is reduced and efficiency improves. output current/current limit available output current and current limit values have been derived from the msk 5978vrhg which assumes a lead length of approxi- mately 0.1 inch. increased lead length will decrease current limit due to lead resistance. this is especially important to note with use of the msk 5978vrh, which allows the potential for lead lengths to exceed 0.1 inch. as an approximation, every 50mil increase in lead length will decrease the current limit by 40ma.
4 application notes cont'd heat sinking radiation performance curves for tid testing have been gener- ated for all radiation testing performed by ms kennedy. these curves show performance trends throughout the tid test process and can be located in the msk 5978rh radiation test report. the complete radiation test report is available in the rad hard prod- ucts section on the msk website. application notes cont'd total dose radiation test performance rev. c 10/10 improving initial accuracy and reducing temperature drift adding shutdown the msk 5978rh can be easily shutdown by either reducing r set to 0 or connecting a transistor from the set pin to ground. by connecting two transistors, as shown in figure 6, a low current voltage source is all that is required to take the set pin to ground as well as pull the output voltage to ground. q2 pulls the output voltage to ground when no load is present and only needs to sink 10ma. use a low leakage switching diode be- tween vout and set to avoid overstress during shutdown transi- tions. figure 6 the initial output accuracy of the msk 5978rh due to set pin current tolerance and set point resistor accuracy can be reduced to 0.2% using the msk 109rh radiation hardened precision reference. minimal drift of the msk 109rh from temperature extremes and irradiation ensure very tight regulation. the circuit can be configured to use the 2.5v reference to directly set the output at 2.5v or with a slight variation it can provide any out- put within the operating range of the msk 5978rh down to 0v output. select rs to maintain between 1ma and 10ma of cur- rent through the reference; see figure 5 below. rs may be tied to vin or another power source. the optional trim resistor can be used to further trim out initial output and system error. refer- ence the msk 109rh data sheet for application circuits that provide stable output voltages across the full operating range of the msk 5978rh including down to 0v output and the operat- ing characteristics of the msk 109rh. figure 5 additional application information for additional applications information, please reference linear tech- nology corporation's? lt3080 and rh3080 data sheets. to determine if a heat sink is required for your application and if so, what type, refer to the thermal model and governing equation below. governing equation: t j = p d x (r jc + r cs + r sa ) + t a where t j = junction temperature p d = total power dissipation r jc = junction to case thermal resistance r cs = case to heat sink thermal resistance r sa = heat sink to ambient thermal resistance t c = case temperature t a = ambient temperature t s = heat sink temperature example: this example demonstrates the thermal calculations for the regula- tor operating at 0.5a output current. conditions for msk 5978rh: v ctl =vin = +3.0v; i out = +0.50a v out =+1.0v 1.) assume 45 heat spreading model. 2.) find regulator power dissipation: p d = (vin - vout)(i out ) p d = (3-1)(0.50) = 1.0w 3.) for conservative design, set t j = +125c max. 4.) for this example, worst case t a = +90c. 5.) r jc = 6.4c/w from the electrical specification table. 6.) r cs = 0.15c/w for most thermal greases. 7.) rearrange governing equation to solve for r sa : r sa =((t j - t a /p d - (r jc ) - (r cs ) = (125c - 90c)/1.0w - 22.5c/w - 0.15c/w = 12.4c/w in this case the result is 12.4c/w. therefore, a heat sink with a thermal resistance of no more than 12.4c/w must be used in this application to maintain regulator circuit junction temperature under 125c. for enhanced radiation tolerance the die has a glassivation thick- ness of 4ka and is not in accordance with mil-prf-38535. die glassivation
typical performance curves 5 rev. c 10/10
6 typical performance curves cont'd rev. c 10/10
mechanical specifications 7 ordering information esd triangle indicates pin 1 weight=0.37 grams typical the above example is a class v regulator with straight leads. lead configurations blank= straight radiation hardened screening blank= industrial v=mil-prf-38535 class v general part number msk5978 v rh rev. c 10/10
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 our website for the most recent revision of this datasheet. contact msk for mil-prf-38535 class v certification and qualification status. 8 rev. c 10/10 m.s. kennedy corp. 4707 dey road, liverpool, new york 13088 phone (315) 701-6751 fax (315) 701-6752 www.mskennedy.com esd triangle indicates pin 1 weight=0.35 grams typical ordering information lead configurations g=gull wing radiation hardened screening blank= industrial v=mil-prf-38535 class v general part number msk5978 v rh g the above example is a class v regulator with gull wing lead form.
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