ait s e m ic o n d u c t o r in c . www.ait-ic.com a7 4 0 4 dc -dc converter/buck (step-down) 42v input standoff voltage, 0.4a step-down converter rev1.0 - dec 201 5 released - - 1 - des cr ip tion fea tur e s the a7404 is a wide input range, high-efficiency, and high frequency dc- to -dc step-down switching regulator, capable of delivering up to 0.4a of output current. with a fixed switching frequency of 750khz, this current mode pwm controlled converter allows the use of small external components, such as ceramic input and output caps, as well as small inductors. a7404 also employs a proprietary control scheme that switches the device into a power save mode during light load, thereby extending the range of high efficiency operation. an ovp function protects the ic itself and its downstream system against input voltage surges. with this ovp function, the ic can stand off input voltage as high as 42v, making it an ideal solution for industrial applications such as smart meters as well as automotive applications. in automotive systems, power comes from the battery, with its voltage typically between 9v and 24v. including cold crank and double battery jump-starts, the minimum input voltage may be as low as 4v and the maximum up to 36v, with even higher transient voltages. with these high input voltages, linear regulators cannot be used for high supply currents without overheating the regulator. instead, high efficiency switching regulators such as a7404 must be used to minimize thermal dissipation. the a7404 is available in sot- 26 package. orderi ng i nfor m a tion p ac k ag e ty pe p art n um be r sot- 26 e6 a7404e6r A7404E6VR note v: halogen free package r: tape & reel ait provides all rohs products suffix v means halogen free package ? wide input operating range from 4v to 38v ? standoff input voltage: 42v ? high efficiency at 20 v in 12 v out up to 95% ? high efficiency pfm mode at light load ? capable of delivering 0.4 a of output current. ? no external compensation needed ? current mode control ? logic control shutdown ? thermal shutdown and uvlo ? available in sot- 26 package a p p l icati on ? smart meters ? industrial applications ? automotive applications typ ical a p p l icati on
ait s e m ic o n d u c t o r in c . www.ait-ic.com a7 4 0 4 dc -dc converter/buck (step-down) 42v input standoff voltage, 0.4a step-down converter rev1.0 - dec 201 5 released - - 2 - p in de s cr ip tion top view p i n # s y mb ol f u nc ti on 1 bst bootstrap pin. connect a 10nf capacitor from this pin to sw 2 gnd ground 3 fb feedback input. connect an external resistor divider from the output to fb and gnd to set v out 4 en enable pin for the ic. drive this pin high to enable the part, low to disable. 5 in supply voltage. bypass with a 10f ceramic capacitor to gnd 6 sw inductor connection. connect an inductor between sw and the regulator output.
ait s e m ic o n d u c t o r in c . www.ait-ic.com a7 4 0 4 dc -dc converter/buck (step-down) 42v input standoff voltage, 0.4a step-down converter rev1.0 - dec 201 5 released - - 3 - a b s ol ute max imu m rati ngs input voltage range - 0.3v ~42v t j , max operating junction temperature 150 c sw, en voltage - 0.3v ~v in +0.3v bst voltage - 0.3v ~sw+6v fb voltage - 0.3v ~ 6v sw to ground current internally limited t o , operating temperature - 40c ~ 85c jc , package thermal resistance sot- 26 110c /w t s , storage temperature - 55c ~ 150c stress beyond above listed absolute maximum ratings may lead permanent damage to the device. these are stress ratings only and operations of the device at these or any other condit ions beyond those indicated in the operational sections of t he specifications are not implied. exposure to absolute maximum rating conditions for ex tended periods may affect device reliability. e l e ctr ical characteris tics v in =12v, unless otherwise specified. typical values are at t a =25 c . p ara me t er c on d i t i on s m i n . t y p. m ax . u ni t input standoff voltage 42 v input voltage range 4 38 v input uvlo rising, hysteresis=140mv 3.8 0 v input ovp rising, hysteresis=1.3v 38 v input supply current v fb =0.85v 0.6 ma input shutdown current 6 a fb feedback voltage 0.780 0.8 00 0.820 v fb input current 0.01 a switching frequency 750 khz maximum duty cycle 90 % foldback frequency v fb =0v 95 khz high side switch on resistance i sw =200ma 550 m high side switch current limit 0.7 a sw leakage current v in =12v, v sw =0, en=gnd 10 a en input current v in =12v, v en =5v 1 5 a en input low voltage rising, hysteresis=100mv 0.8 1.1 1.4 v thermal shutdown hysteresis=40c 150 c
ait s e m ic o n d u c t o r in c . www.ait-ic.com a7 4 0 4 dc -dc converter/buck (step-down) 42v input standoff voltage, 0.4a step-down converter rev1.0 - dec 201 5 released - - 4 - typ ical p e rfor m a n ce ch a racteris tics typical values are at t a = 25 c , unless otherwise specified. 1. efficiency vs. i out 2. output voltage vs. i out 3. frequency vs. temperature 4. maximum i out vs. temperature 5. efficiency vs. i out 6. output voltage vs. i out
ait s e m ic o n d u c t o r in c . www.ait-ic.com a7 4 0 4 dc -dc converter/buck (step-down) 42v input standoff voltage, 0.4a step-down converter rev1.0 - dec 201 5 released - - 5 - 7. efficiency vs. i out 8. output voltage vs. i out 9. switching forms: v in =12v,v out =5v,i out =10ma 10. switching form s : v in =12v,v out =5v,i out =25ma 11. switching forms: v in = 20 v,v out = 12 v,i out =5ma 12. switching forms:v in = 20 v,v out = 12 v,i out =30ma 13. output short response v in = 36 v,v out = 12 v 14. output short recover v in = 36 v,v out = 12 v
ait s e m ic o n d u c t o r in c . www.ait-ic.com a7 4 0 4 dc -dc converter/buck (step-down) 42v input standoff voltage, 0.4a step-down converter rev1.0 - dec 201 5 released - - 6 - b l ock dia gra m
ait s e m ic o n d u c t o r in c . www.ait-ic.com a7 4 0 4 dc -dc converter/buck (step-down) 42v input standoff voltage, 0.4a step-down converter rev1.0 - dec 201 5 released - - 7 - deta il e d inform a tion f u nc ti on a l de s c r i pt i on s l oo p oper ati on the a7404 is a wide input range, high-efficiency, dc- to -dc step-down switching regulator, capable of delivering up to 0.4a of output current, integrated with a 550m high side mosfet. it uses a pwm current-mode control scheme. an error amplifier integrates error between the fb sig nal and the internal reference voltage. the output of the integrator is then compared to the sum of a current-sense sign al and the slope compensation ramp. this operation generates a pwm signal that mo dulates the duty cycle of the power mosfets to achieve regulation for output voltage. l i g ht lo a d op erati on traditionally, a fixed constant frequency pwm dc-dc regulator always switches even when the output load is small. when energy is shuffling back and forth through the power mosfets, power i s lost due to the finite rdsons of the mosfets and parasitic capacitances. at light load, this loss i s prominent and efficiency is therefore very low. a7404 employs a proprietary control scheme that improves effici ency in this situation by enabling the device into a power save mode during light load, thereby extending the r ange of high efficiency operation.
ait s e m ic o n d u c t o r in c . www.ait-ic.com a7 4 0 4 dc -dc converter/buck (step-down) 42v input standoff voltage, 0.4a step-down converter rev1.0 - dec 201 5 released - - 8 - p a cka ge i nfor m a tion dimension in sot-26 package (unit: mm) s y mb o l m in m a x a 1.050 1.250 a1 0.000 0.100 a2 1.050 1.150 b 0.300 0.500 c 0.100 0.200 d 2.820 3.020 e 1.500 1.700 e1 2.650 2.950 e 0.950(bsc) e1 1.800 2.000 l 0.300 0.600 0 8
ait s e m ic o n d u c t o r in c . www.ait-ic.com a7 4 0 4 dc -dc converter/buck (step-down) 42v input standoff voltage, 0.4a step-down converter rev1.0 - dec 201 5 released - - 9 - impo rtant noti ce ait semiconductor inc. (ait) reserves the right to make changes to any its product, specifications, to discontinue any integrated circuit product or service without notice, and advis es its customers to obtain the latest version of relevant information to verify, before placing orders, that the information being relied on is current. ait semiconductor inc.'s integrated circuit products are not designed, intended , authorized, or warranted to be suitable for use in life support applications, devices or systems or other cri tical applications. use of ait products in such applications is understood to be fully at the risk of the customer. as used herei n may involve potential risks of death, personal injury, or servere property, or environmental damage. in order to minimize risks associated with the customer's applications, the customer should provide adequat e design and operating safeguards. ait semiconductor inc. assumes to no liability to customer product design or appl ication support. ait warrants the performance of its products of the specifications applicable at the time of sale.
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