a i t s em i c ond u ctor i n c . www.ait - ic.com a 74 06 a dc - dc converter buck (step - down) 40v, 600ma a synchronous rev 1.0 - mar 20 18 released - - 1 - de s cri p t i o n f eat u r es the A7406A is a high frequency (1.8mhz) step - down switching regulator with integrated internal high - side high voltage power mosfet. it provides single 0.6a(or less) highly efficient output with current mode control for fast loop response. the wide input range(4.2v to 40v) accommodates a variety of step - down applications. low shutdown mode quiescent current allows use in b attery - powered applications. high efficiency at light load condition is achieved by scaling down the switching frequency to reduce the switching and gate driving losses. the A7406A is available in sot - 26 package. o rde ri ng i nf o rm a t i o n p ac k ag e t y pe p ar t n um ber sot - 26 spq: 3,0 00pcs/reel e6 A7406Ae6r A7406A e6vr note v: halogen free package r: tape & reel ait provides all rohs products ? 4.2 v to 40 v operating input range ? 230ua operating quiescent current. ? low shutdown supply current ? 500m internal power mosfet ? 1.8 mhz fixed switching frequency ? >90% efficiency ? internally compensated ? stable with ceramic output capacitors ? internal soft - start ? thermal shutdown function ? precision current limit without current sensing resistor ? available in sot - 26 package appl i c at i o n ? high voltage power conversion ? industrial power systems ? power meter ? battery powered systems t ypi c al ap pl i c at i o n
a i t s em i c ond u ctor i n c . www.ait - ic.com a 74 06 a dc - dc converter buck (step - down) 40v, 600ma a synchronous rev 1.0 - mar 20 18 released - - 2 - p i n de s cri p t i o n top view p i n # s y mb ol f u nc t i on 1 bst bootstrap. this is the positive power supply for the internal floating high side mosfet driver. connect a bypass capacitor between this pin and sw pin. 2 gnd ground. it should be connected as close as possible to the output capacitor. 3 fb feedback. this is the input to the error amplifier. an external resistive divider connected between the output and gnd is compared to the internal +0.8v reference to set the regulation voltage. 4 en enable input. pull this pin below the specified threshold to disable. pull it above the specified threshold to enable. float this pin to disable. 5 v in input supply. a decoupling capacitor to ground is required close to this pin to reduce switching spikes. 6 sw switch node. this is the output from the high - side switch. a low v f
a i t s em i c ond u ctor i n c . www.ait - ic.com a 74 06 a dc - dc converter buck (step - down) 40v, 600ma a synchronous rev 1.0 - mar 20 18 released - - 3 - abso l u t e m ax i m u m r at i n g s v in , supply voltage - 0.3v ~ 43v v sw , switch voltage - 0.3v ~ v in (max) +0.3v bst to sw - 0.3 v ~ 6.0v all other pins - 0.3v ~ 5.0v continuous power dissipation(t a =+25) 0.57w junction temperature 150 lead temperature 260 storage temperature - 65c ~ 150 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 conditions beyond those indicated in the operational sections of the specifications are not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. re co m m e nde d o p e ra t i ng co ndi t i o ns p ar a met er s y mb ol v a lu e u n it supply voltage v in 4.2 ~ 40 v output voltage v out up to 40 v operating junction temp t j - 40 ~ +125 t h er m al r esi st an c e p ac k ag e ja jc sot - 26 220 /w 110 /w
a i t s em i c ond u ctor i n c . www.ait - ic.com a 74 06 a dc - dc converter buck (step - down) 40v, 600ma a synchronous rev 1.0 - mar 20 18 released - - 4 - e l e ct ri ca l cha ra ct e ri s t i cs v in = 12 v, v en =2v, t a =25oc, unless otherwise stated. p ar a met er s y mb ol c ond i t i ons mi n. t y p. m ax . u n it feedback voltage v fb - 0.794 - v upper switch on resistance r sw vbst -v sw =5v - 500 - m upper switch leakage i swleak v en =0v, v sw =0v - 0.1 1 a current limit i lim - 1 - a transconductance gcs comp to sense - 3 - a/v minimum operating voltage v in min 4.2 - - v uvlo up threshold v in(uvlo) 3.3 - 4.2 v uvlo hysteresis v in(uvlo) hys - 0.8 - v soft - start time t ss fb from 0 to 1.8v - 0.5 - ms oscillator frequency f osc - 1.8 - mhz minimum switch on time t on min - 100 - ns shutdown current i sd v en <0.3v - 3 15 a quiescent current i q v fb =0.9v no load - 200 - a thermal shutdown t sd - 150 - c enable up threshold v enh 1.6 - 2.0 v enable threshold hysteresis v enhys - 0.6 - v
a i t s em i c ond u ctor i n c . www.ait - ic.com a 74 06 a dc - dc converter buck (step - down) 40v, 600ma a synchronous rev 1.0 - mar 20 18 released - - 5 - t y p i ca l a p p l i ca t i o n ci r cui t s
a i t s em i c ond u ctor i n c . www.ait - ic.com a 74 06 a dc - dc converter buck (step - down) 40v, 600ma a synchronous rev 1.0 - mar 20 18 released - - 6 - bl o c k d i ag r am
a i t s em i c ond u ctor i n c . www.ait - ic.com a 74 06 a dc - dc converter buck (step - down) 40v, 600ma a synchronous rev 1.0 - mar 20 18 released - - 7 - d et ai l ed in f or m a t ion the A7406A is a 1.8mhz, non - synchronous, step - down switching regulator with integrated internal high side mosfet. it provides internally compensated single 0.6a high efficient output. it features wide input voltage range, internal soft - start control, and precision current limit. low operational quiescent current feature is suit for battery powered applications. p w m c ont r o l at heavy load or moderate load condition, the A7406A operates in a fixed frequency, peak current control mode to regulate the output voltage. a pwm cycle is initiated by the internal clock. the power mosfet is turned on and remains on until its current reaches the value set by comp voltage. when the power switch is off, it remains off for at least 100ns before the next cycle starts. if, in one pwm period, the current in the power mosfet does not reach comp set current value, the power mosfet remains on, saving a turn - off operation. at light load condition, the A7406A operates in pulse skipping mode to improve light load effic iency. i nt er n al r e gul at or most of the internal circuitry is powered on by the 2.6v internal regulator. when v in is higher than 4.0v, the output of the regulator is in full regulation. when v in is lower, the output degrades. u nder v o l t age loc k o ut ( u v lo ) v in under voltage lockout (uvlo) is implemented to protect the chip from operating at insufficient supply voltage. t h er ma l s h ut d ow n thermal shutdown is implemented to prevent the chip from thermally running away. when the temperature is higher than its upper threshold, the A7406A will shut down. when the temperature is lower than its lower threshold, the chip is enabled again.
a i t s em i c ond u ctor i n c . www.ait - ic.com a 74 06 a dc - dc converter buck (step - down) 40v, 600ma a synchronous rev 1.0 - mar 20 18 released - - 8 - a p p l ic a t ion in f or m a t ion s et t i n g t he o u t pu t v ol t ag e the output voltage is set using a resistive voltage divider from the output voltage to fb pin. v fb =v out *r2/(r1+r2) the feedback resistor r1 also sets the feedback loop bandwidth with the internal compensation capacitor. choose r1 around 124k for optimal transient response. i nduc t or the inductor is required to supply constant current to the output load. a larger value inductor will result in lower output ripple voltage. generally, a good rule for determining the inductance to use is to allow the peak - to - peak ripple current in the inductor to be approximately 30% of the maximum load current. also, make sure that the peak inductor current is below the maximum switch current limit. i npu t c a pac i t or the input capacitor (c1) can be electrolytic, tantalum or ceramic. when using electrolytic or tantalum capacitors, a small, high quality ceramic capacitor, i.e. 0.1f, should be placed as close to the ic as possible. o ut put c a pac i t or the output capacitor (c2) is used to maintain the dc output voltage. ceramic, tantalum, or low esr electrolytic capacitors are recommended. low es r capacitors are preferred to keep the output voltage ripple low.
a i t s em i c ond u ctor i n c . www.ait - ic.com a 74 06 a dc - dc converter buck (step - down) 40v, 600ma a synchronous rev 1.0 - mar 20 18 released - - 9 - p a c k a ge in f or m a t ion dimension in sot -26 package (unit: mm)
a i t s em i c ond u ctor i n c . www.ait - ic.com a 74 06 a dc - dc converter buck (step - down) 40v, 600ma a synchronous rev 1.0 - mar 20 18 released - - 10 - i m p o rt a nt no t i 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 advises 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, i ntended, authorized, or warranted to be suitable for use in life support applications, devices or systems or other critical 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 server property, or environ mental damage. in order to minimize risks associ ated with the customer's applications, the customer should provide adequate design and operating safeguards. ait semiconductor inc. assumes to no liability to customer product design or applicat ion support. ait warrants the performance of its products of the specifications applicable at the time of sa le.
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