m.s.kennedy corp. features: manufactured using space qualified rh 117 die total dose hardened to 100 krads(si) (method 1019.7 condition a) output current limit internal thermal overload protection output current to 1.5 amps adjustable output using two external resistors available in 3 lead form options: straight, up and down (to257) available to dscc smd 5962r09213 satellite system power supplies switching power supply post regulators constant voltage/current regulators high efficiency linear regulators typical applications pin-out information 5972rh rad hard 1.5a, adjustable linear regulator description: the msk5972rh is a radiation hardened 3-terminal positive adjustable regulator capable of supplying up to 1.5a of current. the output is adjustable using external resistors for a range of vref to 37v. excellent line and load regulation characteristics ensure accurate performance. the msk5972rh has full protection with current and thermal limiting. the msk5972 is packaged in two space saving packages, the 3 pin power surface mount ceramic smd-1 or the to-257 package with 3 lead form options: straight, up and down. equivalent schematic 1 1 2 3 adj vout vin smd-1 to-257 adj input output 1 2 3 to-257 smd-1 3 pad ceramic mil-prf-38534 and 38535 certified facility 8548-131 rev. g 9/14
storage temperature range lead temperature range (10 seconds) case operating temperature msk5972rh msk5972(k/h)rh +40v dc internally limited 1.5a +150c -65c to +150c 300c -40c to +85c -55c to +125c absolute maximum ratings t st t ld t c input voltage (vin-vout) power dissipation output current junction temperature vin p d i out t j electrical specifications 8 1 2 3 4 5 6 7 8 9 10 11 output is decoupled to ground using 10 f low esr capacitors. guaranteed by design but not tested. typical parameters are representative of actual device performance but are for reference only. all output parameters are tested using a low duty cycle pulse to maintain tj = tc. industrial grade and devices shall be tested to subgroup 1 unless otherwise specified. military grade devices ("h" and "k" suffix) shall be 100% tested to subgroups 1,2 and 3. subgroup 1 ta=tc=+25c subgroup 2 ta=tc=+125c subgroup 3 ta=tc=-55c the output current limit function provides protection from transient overloads but it may exceed the maximum continuous rating. continuous operation in current limit may damage the device. 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 100krad tid, are identical unless otherwise specified. reference dscc smd 5962r09213 for electrical specification for devices purchased as such. internal solder reflow temperature is 180c, do not exceed. notes: 2 11 8548-131 rev. g 9/14
application notes the msk5972rh develops a nominal 1.25v reference voltage between the output and adjustment terminal. the reference volt- age is dropped across program resistor r1 and, since the volt- age is constant, a constant current then flows through the out- put set resistor r2. since the current from the adjustment termi- nal represents an error in the programmed output voltage, the msk5972rh was designed to minimize i adj and make it very constant with line and load changes. to do this, all quiescent operating current is returned to the output establishing a mini- mum load current requirement. if there is insufficient load on the output, the output will rise. figure 1 shows the output voltage calculations. 3 output voltage figure 1 the msk5972rh is capable of providing extremely good load regulation but a few precautions are needed to obtain maximum performance. the current set resistor connected between the adjustment terminal and the output terminal should be tied di- rectly to the output pin as close to the case of the regulator as possible rather than near the load. this eliminates package pin and trace drops from appearing effectively in series with the reference and degrading regulation. for example, a 5v regulator with 0.05 resistance between the regulator and the current set resistor will droop 225mv at 1a due to package pin and trace resistance. the amount of droop can be calculated as follows: (vout at 5ma) - (1.250-(0.05 *il))*(1+r2/r1). the ground of r2 can be returned near the ground of the load to provide remote ground sensing and improve load regulation. figure 2a shows the effect of resistance between the regulator and 240 set resistor. figure 2a (degraded regulation) external capacitors input bypassing with a 1uf tantalum in parallel with a 0.1uf ceramic on the input is suitable in most applications. to maxi- mize transient response and minimize input supply transients more input capacitance can be added. the adjustment terminal can be bypassed to ground on the msk5972rh to improve ripple rejection. this bypass capacitor prevents ripple from be- ing amplified at higher output voltages. the impedance of the adjust pin capacitor at the ripple frequency should be less than the value of r1. for most application a 10 f bypass capacitor will provide sufficient ripple rejection at any output level. in- creases over 10 f do not appreciably improve the ripple rejec- tion at frequencies above 120hz. output bypassing with 1 f low esr tantalum in parallel with a 0.1 f ceramic attached as close to the regulator's output as possible is best. this will ef- fectively lower the regulator output impedance, increase tran- sient response and eliminate any oscillations. any increase of the load capacitance larger than 1 f will merely improve the loop stability and output impedance. see figure 3 for typical application schematic. figure 2b (best case regulation) load regulation 8548-131 rev. g 9/14
heat sinking to determine if a heat sink is required for your application and if so, what type, refer to the thermal model and govern- ing equation below. governing equation: tj = pd x (r jc + r cs + r sa) + ta where tj = junction temperature pd = 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 tc = case temperature ta = ambient temperature ts = heat sink temperature example: this example demonstrates an analysis on a 10v regulator where the output current is at 0.5 amp and the input is 15v. conditions for msk5972rh: vin = +15v; iout = 0.5a 1.) assume 45 heat spreading model. 2.) find regulator power dissipation: pd = (vin - vout)(iout) pd = (15v-10v)(0.5a) pd = 2.5w 3.) for conservative design, set tj = +125c max. 4.) for this example, worst case ta= +90c. 5.) r jc = 4.5c/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=((tj - ta)/pd) - (r jc) - (r cs) = (125c-90c)/2.5w - 4.5c/w - 0.15c/ = 9.3c/w in this case the result is 9.3c/w. therefore, a heat sink with a thermal resistance of no more than 9.3c/w must be used in this application to maintain regulator circuit junction temperature under 125c. total dose radiation test performance radiation performance curves for tid testing have been gen- erated for all radiation testing performed by ms kennedy. these curves show performance trends throughout the tid test process and are located in the msk5972rh radiation test report. the complete radiation test report is available in the rad hard products section on the msk website. http://www.mskennedy.com/store.asp?pid=9951&catid=19680 application notes cont'd protection diodes when external capacitors are used with any ic regulator it is sometimes necessary to add protection diodes to prevent the capacitors from discharging through low current points into the regulator. most 10 f capacitors have low enough internal se- ries resistance to deliver 20a spikes when shorted. although the surge is short, there is enough energy to stress msk5972rh. when an output capacitor is connected to a regulator and the input is shorted or crowbarred, the output capacitor will dis- charge into the output of the regulator. the discharge current depends on the value of the capacitor, the output voltage of the regulator, and the rate of decrease of vin. figure 3 shows an msk5972rh with protection diodes included. d2 is only re- quired if the adjust pin has external capacitance tied to it . figure 3 4 input voltage the msk5972rh can operate over a wide input voltage range. vin minimum=vout+dropout to a (vin-vout) maximum of 40v. when operating near the minimum input voltage level suf- ficient overhead must be maintained to eliminate the regulator from dropping out of regulation, reference the dropout curves in the typical performance section. the input level also effects the maximum current that the msk5972rh can supply, this too can be found in the typical performance section. dropout, output current and power dissipation must all be considered when se- lecting the input line level. 8548-131 rev. g 9/14
5 typical performance curves 8548-131 rev. g 9/14
mechanical specifications ordering information 6 lead configurations s= straight; u= bent up; d= bent down radiation hardened screening blank= industrial; h=mil-prf-38534 class h; k=mil-prf-38534 class k general part number msk5972 k rh u the above example is an adjustable class k regulator with leads bent up. ordering information for the 3 pad ceramic smd-1 package is contained on the next page. note: see dscc smd 5962r09213 for dscc part number options. 8548-131 rev. g 9/14 esd triangle indicates pin 1 weight=3.2 grams typical all dimensions are specified in inches
mechanical specifications ordering information 7 3 pad ceramic smd-1 package radiation hardened screening blank= industrial; h=mil-prf-38534 class h; k=mil-prf-38534 class k general part number msk5972 k rh l the above example is an adjustable class k regulator. note: see dscc smd 5962r09213 for dscc part number options. 8548-131 rev. g 9/14 weight=2.2 grams typical all dimensions are specified in inches
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. m.s. kennedy corp. phone (315) 701-6751 fax (315) 701-6752 www.mskennedy.com revision history 8 8548-131 rev. g 9/14
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