typical applications 4707 dey road liverpool, n.y. 13088 (315) 701-6751 mil-prf-38534 certified 5921rh m.s.kennedy corp. features: satellite system power supplies switching power supply post regulators constant voltage/current regulators microprocessor power supplies rad tolerant ultra low dropout adjustable positive linear regulator equivalent schematic typical applications description: the msk 5921rh is a rad tolerant adjustable linear regulator typically capable of delivering 5.0 amps of output current. the typical dropout is only 0.30 volts with a 3.0a load. an external shutdown function is ideal for power supply sequencing. this device also has latching overload protection that requires no external current sense resistor. the msk 5921rh is radiation tolerant and specifically designed for space/satellite applications. the device is pack- aged in a hermetically sealed space efficient 5 pin sip that is electrically isolated from the internal circuitry allowing for direct heat sinking. pin-out information vin gnd vout shutdown adjust total dose tested to 300k rad ultra low dropout for reduced power consumption external shutdown latching overload protection adjustable output using two external resistors output current limit available in 3 lead form options: straight, up and down available to dscc smd # 5962-05220 1 2 3 4 5 rev. c 1/06 1
input voltage range feedback voltage feedback pin current quiescent current line regulation load regulation dropout voltage minimum output current output voltage range output current limit shutdown threshold ripple rejection phase margin gain margin equivalent noise voltage thermal resistance storage temperature range lead temperature range (10 seconds) power dissipation junction temperature absolute maximum ratings +10v 5a -55c to +125c -40c to +85c supply voltage output current case operating temperature range msk5921k/h/e rh MSK5921RH -65c to +150c 300c see soa curve 150c 1 2 3 4 5 6 7 8 9 10 11 t st t ld p d t c +v in i out t c unless otherwise specified, v in =5.0v, r1=1.62k, v shutdown =0v and i out =10ma. see figure 2. guaranteed by design but not tested. typical parameters are representative of actual device performance but are for reference o nly. industrial grade and "e" suffix devices shall be tested to subgroups 1 and 4 unless otherwise requested. military grade devices ("h" suffix) shall be 100% tested to subgroups 1,2,3 and 4. subgroup 5 and 6 testing available upon request. subgroup 1,4 t c =+25c subgroup 2,5 t c =+125c subgroup 3,6 t a =-55c output current limit is dependent upon the values of v in and v out . see figure 1 and typical performance curves. continuous operation at or above absolute maximum ratings may adversely effect the device performance and/or life cycle. v in shall be as specified or v in min, whichever is greater. not applicable when v out application notes pin functions vin - this pin provides power to all internal circuitry including bias, start-up, thermal limit and overcurrent latch. input voltage range is 2.9v to 6.5v. gnd - internally connected to ground, this pin should be connected externally by the user to the circuit ground. shutdown - there are two functions to the shut- down pin. it may be used to disable the output voltage or to reset a current latch condition. to activate the shut- down/reset functions the user must apply a voltage greater than 1.6v to the shutdown pin. the output voltage will turn on when the shutdown pin is pulled below the threshold voltage. if the shutdown pin is not used, it should be connected to ground. it should be noted that with the shutdown pin tied to ground, a cur- rent latch condition can only be reset by cycling power off, then on. vout - this is the output pin for the device. adjust - the adjust pin is the inverting input of the internal error amplifier. the non-inverting input is con- nected to an internal 1.265v reference. this error ampli- fier controls the drive to the output transistor to force the adjust pin to 1.265v. an external resistor divider is connected to the output, adjust pin and ground to set the output voltage. output capacitor selection output capacitors are required to maintain regulation and stability. a 220f surface mount tantalum capacitor in parallel with a 1.0f ceramic capacitor from the out- put to ground should suffice under most conditions. if the user finds that tighter voltage regulation is needed during output transients, more capacitance may be added. if more capacitance is added to the output, the band- width may suffer. esr of the output capacitors should be maintained at 0.1 ? to 1 ? . current limit and soa the msk 5921rh current limit function is directly af- fected by the input and output voltages. figure 1 illus- trates the relationship between vin and icl for various output voltages. it is very important for the user to con- sult the soa curve when using input voltages which result in current limit conditions beyond 4.5 amps. when using input voltages which result in current limit above 4.5 amps, the user must maintain output current within the soa curve to avoid damage to the device. note that 5 amp maximum is due to current carrying capability of the internal wirebonds. 3 overcurrent latch overcurrent protection is provided by the MSK5921RH series through the use of a timed latch off circuit. the internal latch timeout is triggered by an overcurrent con- dition. to allow for start up surge currents, the timeout is approximately 5.5ms at 25c. if the overcurrent con- dition remains at the end of the timeout cycle, the regu- lator will latch off until the latch is reset. the latch con- dition can be reset by pulling the shutdown pin high or cycling vin off then back on. a thermal limit condition will trigger the latch with no time out delay. input power supply bypassing to maximize transient response and minimize power supply transients it is recommended that a 100f tanta- lum capacitor is connected between vin and ground. a 0.1f ceramic capacitor should also be used for high frequency bypassing. figure 1 rev. c 1/06
application notes cont. 4 heat sink selection to select a heat sink for the msk 5921rh, the follow- ing formula for convective heat flow may be used. 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 a = ambient temperature power dissipation=(v in -v out ) x i out next, the user must select a maximum junction tem- perature. the absolute maximum allowable junction tem- perature is 150c. the equation may now be rearranged to solve for the required heat sink to ambient thermal resistance (r sa ). example: an msk 5921rh is connected for v in =+3.3v and v out =+2.5v. i out is a continuous 3a dc level. the am- bient temperature is +25c. the maximum desired junc- tion temperature is +125c. r jc =4.0c/w and r cs =0.15c/w for most thermal greases power dissipation=(3.3v-2.5v) x (3a) =2.4watts solve for r sa: 125c - 25c 2.4w = 36.5c/w in this example, a heat sink with a thermal resistance of no more than 36.5c/w must be used to maintain a junction temperature of no more than 125c. typical applications circuit output voltage selection as noted in the above typical applications circuit, the formula for output voltage selection is a good starting point for this output voltage selection is to set r2=1k. by rearranging the formula it is simple to calculate the final r1 value. table 1 below lists some of the most probable resistor combinations based on industry standard usage. r1 r2 1+ v out =1.265 v out 1.265 -1 r1=r2 1.5 1.8 2.0 2.5 2.8 3.3 4.0 5.0 r2 ( ? ? ? ? ? ) 1k 1k 1k 1k 1k 1k 1k 1k r1 (nearest 1%) ( ? ? ? ? ? ) 187 422 576 976 1.21k 1.62k 2.15k 2.94k r sa = -4.0c/w - 0.15c/w output voltage (v) thermal limiting the msk 5921rh control circuitry has a thermal shut- down temperature of approximately 150c. this ther- mal shutdown can be used as a protection feature, but for continuous operation, the junction temperature of the pass transistor must be maintained below 150c. proper heat sink selection is essential to maintain these condi- tions. table 1 rev. c 1/06
typical performance curves 5 rev. c 1/06
radiation performance curves 6 rev. c 1/06 note: all radiation performance curve test conditions are in accordance with the electrical specifications table (page 2).
mechanical specifications all dimensions are 0.010 inches unless otherwise labeled. esd triangle indicates pin 1. 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-38534 class h, class k and appendix g (radiation) status. m.s. kennedy corp. 4707 dey road, liverpool, new york 13088 phone (315) 701-6751 fax (315) 701-6752 www.mskennedy.com ordering information 7 weight=7.7 grams typical msk5921 k rh u the above example is an adjustable class k regulator with leads bent up. lead configurations s= straight; u= bent up; d= bent down radiation hardened screening blank= industrial; e=extended reliability h=mil-prf-38534 class h; k= mil-prf-38534 class k general part number rev. b 11/05 note: see dscc smd 5962-05220 for dscc part number options.
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