1 lambda advanced analog inc. l l ahf2815t series triple output, hybrid - high reliability dc/dc converter description features the ahf2800t series of dc/dc converters provide 8 watts of power and an extended temperature range for use in military and industrial applications. designed to the nominal input requirements of mil- std-704, thse devices have nominal 28vdc inputs with +5v and 12v or +5v and 15v triple outputs to satisfy a wide range of requirements. the basic circuit utilizes a pulse width modulated, feed forward topology at a nominal switching frequency of 550khx. input to output isolation is achieved through the use of transformers in the forward and feedback circuits. the poprietary magnetic feedback circuit provides for an extremely wide bandwidth control loop with a high phase margin. the closed loop frequency response of this converter family extends to approximately 50khz, resulting in superior line and load transient characteristics. this feedback method is also inherently temperature and radiation insensitive. this gives the ahf series an important advantage over converters that incorporate opto- couplers in their design. manufactured in a facility fully qualified to mil-prf- 38534, these converters are available in four screening grades to satisfy a wide range of requirements. the ch grade is fully compliant to the requirements of mil-prf-38534 for class h. the hb grade is processed and screened to the class h requirement, but may not necessarily meet all of the other mil-prf-38534 requirements, e.g., element evaluation and periodic inspection (p.i.) not required. both grades are tested to meet the complete group "a" test specification over the full military temperature range without output power deration. two grades with more limited screening are also available for use in less demanding applications. variations in electrical, mechanical and screening can be accommodated. contact lambda advanced analog for special requirements. n n 16 to 40 v dc input range (28v dc nominal) n n 5v , 15 volt output n n indefinite short circuit and overload protection n n 8 watts output power n n fast loop response for superior transient characteristics n n operating temperature range from -55c to +125c available n n popular industry standard pin-out n n resistance seam welded case for superior long term hermeticity n n efficiencies up to 75% n n shutdown from external signal n n 400,000 hour mtbf at 85% n n constant switching frequency (550 khz nominal)
2 specifications t case = -55c to +125c, v in = +28 v 5% unless otherwise specified 7 typical characteristics temperature range 7 operating -55c to 125c case storage -65c to +135c isolation 100 megaohms at 500 volt s dc weight 3 5 grams conversion frequency 55 0 khz notes: 1 . tested at each output. 2 . parameter guaranteed by line and load regulation tests. 3 . at least 20 percent of the total output power should be taken from the (+5 volt) main output. 4 . bandwidth guaranteed by design. tested for 20 k hz to 2 mhz. 5 . an overload is that condition with a load in excess of the rated load but less than that necessary to trigger the short circuit protection and is the condition of maximum power dissipation. 6 . above 125c case temperature, derate output power linearly to 0 at 135c case. 7. t case = -55c to 85c for non screened grade. conditions ahf2815t -55c - tc - +125c , v in = 28 v dc limits units test symbol 5%, c l =0, unless otherwise specified 7 min m a x static characteristics output voltage 1 v out i out = 0 (main) t c = 25c 4.95 5.05 v over temp 4.90 5.10 v i out = 0 (dual) 1 t c = 25c 14.50 15.50 v over temp 14.35 15. 65 v current 1,2,3 i out v in = 16, 28, and 40 v dc (main) 12 0 1200 m a v in = 16, 28, and 40 v dc (dual) 1 0 . 0 66 .7 m a ripple voltage 1,4 v rip v in = 16, 28, and 40 v dc 6 0 mv p-p bw = d c to 2 mhz (main) v in = 16, 28, and 40 v dc 8 0 mv p-p bw = d c to 2 mhz (dual) power 1,2,3 p out v in = 16, 28, and 40 v d c (main) 5 w (+dual) 1.5 w (-dual) 1.5 w (total) 8 w regulation line 1,3 vr line v in = 16, 28, and 40 v dc 25 m v i ou t = 12 0 , 6 00, 1 2 00 ma (main) v in = 16, 28, and 40 v d c (dual) t c = 25c 35 m v i ou t = 0, 33 . 4 , 66 .7 ma (dual) ove r temp 75 m v load 1,3 v r load v in = 16, 28, and 40 v dc 50 m v i ou t = 12 0, 6 00, 1 2 00 ma (main) v in = 16, 28, and 40 v dc 7 5 m v i ou t = 0, 33 . 4 , 66 .7 ma (dual) input current i in i ou t = 0, inhibit (pin 1) 15 m a tied to input return (pin 7) i ou t = 0, inhibit (pin 1) = open 5 0 m a ripple current 4 i rip i ou t = 1 2 00 ma (main) 5 0 m a p-p i ou t = 66 . 7 ma (dual) bw = dc t o 2 mhz efficiency e ff p out = full load t c = +25c 68 % t c = 25c isolation iso input to output or any pin to case (except t c = +25c 100 m w pin 6) at 500 v d c , tc = +25c load fault power dissipation 3 p d over load, t c = +25c 5 t c = +25c 8 w short circuit, t c = +25c 6 w switching frequency f s 500 600 k hz inhibit open circuit v oi 9 1 3 v voltage
3 block diagram error amp & ref 3 2 4 controller 7 input filter 1 8 regulator & output filter output filter 5 6 application information inhibit function connecting the inhibit input (pin 1) to input common (pin 7) will cause the converter to shut down. it is recommended that the inhibit pin be driven by an open collector device capable of sinking at least 400 m a of current. the open circuit voltage of the inhibit input is 11.5 + 1 v dc . mechanical outline pin designation ahf2815t pin 1 inhibit input pin 8 positive input pin 2 positive output pin 3 output common pin 7 input common pin 4 negative output pin 5 +5v output pin 6 case ground 1 3 5 8 7 6 4 2 top view 1.450 (36.83) 1.105 (28.07) 0.905 (22.99) 0.705 (17.91) 0.505 (12.83) 0.205 (5.21) 1.120 (28.45) 0.800 (20.32) 0.09 r typ (2.29) 0.03 dia. 8 pins (0.76) 0.330 (8.38) max 0.26 (6.60) 1 2 3 4 5 8 7 6 tolerances: .xx = 0.010, .xxx = 0.005
thermal management assuming that there is no forced air flow, the package termperature rise above ambient (et) may be calculated using the following expression: e t a 80 a -0.7 p 0. 85 ( c) where a = the effective surface area in square inches (including heat sink if used;) p = power dissipation in watts. the total surface area of the ahf package is 4.9 square inches. if a worse case full load efficiency of 75% is assumed, then the case temperature rise can be calculated as follows: p = p out [ 1 - 1 ] = 8 [ 1 - 1 ] = 2.66 w et = 80 (4.9) -0.7 (2.66) 0.85 = 60.4c hence, if t ambient = +25c, the dc/dc converter case temperature will be approximately 85c if no heat sink or air flow is provided. m i l - pr f - 38 53 4 c ertified iso9001 rgstrd 2270 martin avenue santa clara ca 95050-2781 (408) 988-4930 fax (408) 988-2702 9 84 8 e ff .78 part number ahf 28 xx t / x model input voltage output voltage 1515 v dc screening tripl e output no suffix ,es, hb, ch, (class b compliant see table for standard military drawing number) ? lambda advanced analog the information in this data sheet has been carefully checked and is believed to be accurate, however, no responsibility is assumed for possible errors. the specifications are subject to change without notice. available screening levels and process variations for ahf series requirement mil-std-883 method no suffix es suffix hb suffix ch suffix temperatur e range -25c to +85 c -55 c to +125 c -55 c to +125 c -55 c to +125c element evaluation mil-h-38534 internal visual 2017 u 4 4 4 temperature cycle 1010 con d b cond c cond c constan t acceleration 2001 500g cond a cond a burn-in 1015 96hrs @125c 160hrs @125 c 1 60hrs @125c final electrical (group a) mil-h-38534 25 c 25 c -55 , +25 , +125 c -55,+25 , +125 c & specification seal, fine & gross 1014 cond a cond a, c cond a, c cond a, c external visual 2009 u 4 4 4 u per commercial standards
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