10/08/02 www.irf.com 1 advanced analog high reliability dc/dc converters AHF2815T series description 16 to 40 vdc input range (28 vdc nominal) 5v, 15 volt output infinite short circuit and overload protection 8 watts output power fast loop response for superior transient characteristics operating temperature range from -55c to +125c available popular industry standard pin-out resistance seam welded case for superior long term hermeticity efficiency up to 75% shutdown from external signal 400,000 hour mtbf at 85% features ahf 28v input, triple output the AHF2815T 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, these devices have nominal 28vdc inputs with +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 550khz. input to output isolation is achieved through the use of transformers in the forward and feedback circuits. the proprietary 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 character- istics. this feedback method is also inherently tem- perature and radiation insensitive. this gives the ahf series an important advantage over converters that incorporate opto-couplers in their design. manufactured in a facility 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 tem- perature 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 accom- modated. contact advanced analog for special re- quirements. constant switching frequency (550khz nominal) pd - 94542
2 www.irf.com AHF2815T series specifications for notes to specifications, refer to page 3 t case = -55c to +125c, v in = +28v 5% unless otherwise specified 7 typical characteristics temperature range 7 operating -55 c to +125 c case storage -65 c to +135 c isolation 100 megaohms at 500 volts dc weight 35 grams conversion frequency 550 khz test symbol conditions -55c tc +125c vin = 28 vdc 5%, c l = 0 unless otherwise specified 7 AHF2815T limits unit min max static characteristics output voltage 1 v out i out = 0 (main) tc = 25 c over temp 4.95 4.90 5.05 5.10 v v current 1,2,3 ripple voltage 1,4 power 1,2,3 i out v rip p out i out = 0 (dual) 1 v in = 16, 28, and 40 vdc (main) v in = 16, 28, and 40 vdc (dual) v in = 16, 28, and 40 vdc bw = dc to 2 mhz (main) v in = 16, 28, and 40 vdc bw = dc to 2 mhz (dual) v in = 16, 28, and 40 vdc (main) (+dual) (-dual) (total) tc = 25 c over temp 14.50 14.35 120 0.0 5 1.5 1.5 8 15.50 15.65 1200 66.7 60 80 v v ma ma mv p-p mv p-p w w w w regulation line 1,3 load 1,3 vr line vr load v in = 16, 28, and 40 vdc i out = 120, 600,1200 ma (main) i out = 0, 33.4, 66.7 ma (dual) v in = 16, 28, and 40 vdc i out = 120, 600, 1200ma (main) i out = 0, 33.4, 66.7 ma (dual) t c = 25 c over temp 25 35 75 50 75 mv mv mv mv mv input current i in i out = 0, inhibit (pin 1) tied to input return (pin 7) 15 ma i out = 0, inhibit (pin 1) = open 50 ma ripple current 4 i rip i out = 1200ma (main) i out = 66.7 ma (dual) bw = dc to 2mhz 50 ma p-p efficiency e ff p out = full load t c = 25 c 68 % t c = 25 c isolation iso input to output or any pin to case (except pin 6) at 500 v dc tc = +25c t c = 25 c 100 m ? load fault power dissipation 3 p d overload, t c = 25 c 5 short circuit, t c = 25 c t c = 25 c 8 6 w w switching frequency f s 500 600 khz inhibit open circuit voltage v oi 9 13 v
www.irf.com 3 AHF2815T series notes to specifications 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 khz 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 125 c case temperature, derate output power linearly to 0 at 135 c case. 7. t case = -55 c to 85 c for non screened grade. application information 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 a of current. the open circuit voltage of the inhibit input is 11.5 1 vdc. inhibit function thermal management assuming that there is no forced air flow, the package tem- perature rise above ambient ( ? t) may be calculated using the following expression: ? t = 80 a ?0.7 p 0.85 ( c) where a = the effective surface area in square inhes(in- cluding 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 as- sumed, then the case temperature rise can be calculated as follows: w eff p p out 66 . 2 1 78 . 1 8 1 1 = ? ? ? ? ? ? ? = ? ? ? ? ? ? ? = ? t = 80 (4.9) -0.7 (2.66) 0.85 = 60.4 c hence, if t ambient = +25 c, the dc/dc converter case temperature will be approximately 85 c if no heat sink or air flow is provided. AHF2815T block diagram 2 +vout pulse w idth modulator primary housekeepin g supply emi filter 8 1 7 +input enable input return error amp & ref fb cs drive 4 -vout 6 case 5 3 +vout return filter & re g ulator
4 www.irf.com AHF2815T series AHF2815T pin designation AHF2815T case outlines 1.450 (36.83) 0.260 (6.600) 0.030 dia., 8 pins (0.760) 0.800 (20.32) 4 7 5 8 6 1 2 3 1.120 (28.45) 0.090 r typ (2.290) 0.330 (8.380) max 1.105 (28.07) 0.905 (22.99) 0.705 (17.91) 0.505 (12.83) 0.205 (5.21) standard flanged ahf 28 15 t f / ch model input volta g e 28 = 28v nominal output volta g e 15 = 5v,15v outputs t = triple screenin g ? , es, hb, ch packa g e options f = flange omit for standard part numbering pin no. designation 1 enable input 2 +dual output 3 output return 4 -dual output 5 +5v output 6 case ground 7 input return 8 positive input
www.irf.com 5 AHF2815T series available standard military drawing (smd) cross reference world headquarters: 233 kansas st., el segundo, california 90245, tel: (310) 322 3331 advanced analog: 2270 martin av., santa clara, california 95050, tel: (408) 727-0500 visit us at www.irf.com for sales contact information . data and specifications subject to change without notice. 10/02 available screening levels and process variations for AHF2815T series * per commercial standards requirement mil-std-883 method no suffix es suffix hb suffix ch suffix temperature range -20 to +85 c -55 c to +125 c -55 c to +125 c -55 c to +125 c element evaluation mil-prf-38534 internal visual 2017 ? yes yes yes temperature cycle 1010 cond b cond c cond c constant acceleration 2001 500g cond a cond a burn-in 1015 48hrs @ 85 c 48hrs @ 125 c 160hrs @ 125 c 160hrs @ 125 c final electrical (group a) mil-prf- 38534 specification 25 c 25 c -55, +25, +125 c -55, +25, +125 c seal, fine & gross 1014 cond a cond a, c cond a, c cond a, c external visual 2009 ? yes yes yes standardized military drawing pin vendor cage code vendor similar pin 5962-9462301 52467 AHF2815T
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