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skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201971d ? skyworks proprietary information ? products and product information are subject to change without notice ? september 11, 2013 1 data sheet aat1110: fast transient 800 ma step-down converter applications ? cellular phones ? digital cameras ? handheld instruments ? microprocessor/dsp core/io power ? pdas and handheld computers ? usb devices features ? v in range: 2.7 v to 5.5 v ? v out fixed or adjustable from 0.6 v to v in ? 27 ? a no-load quiescent current ? output current up to 800 ma ? 1.4 mhz switching frequency ? 120 ? s soft start ? fast load transient ? over-temperature protection ? current limit protection ? 100% duty cycle low-dropout operation ? shutdown current: <1 ? a ? temperature range: ? 40 c to +85 c ? sc70jw (8-pin, 2.2 mm ? 2 mm) package (msl1, 260 c per jedec-j-std-020) description the aat1110 switchreg? is a member of skyworks' total power management ic (tpmic?) product family. it is a 1.4 mhz step-down converter with an input voltage range of 2.7 v to 5.5 v and output as low as 0.6 v. its low supply current, small size, and high switching frequency make the aat1110 the ideal choice for portable applications. the aat1110 is available in either a fixed version with internal feedback or a adjustable version with external feedback resistors. it can deliver up to 800 ma of load current while maintaining a low 27 ? a no-load quiescent current. the 1.4 mhz switching frequency minimizes the size of external components while keeping switching losses low. the aat1110 has excellent load regulation and transient response with a small output inductor and capacitor. the aat1110 is designed to maintain high efficiency throughout the operating range and provides fast turn-on time. the aat1110 is available in a space-saving 2.0 mm ? 2.2 mm sc70jw-8 package and is rated over the ? 40 c to +85 c temperature range. a typical application circuit is shown in figure 1. the pin configuration is shown in figure 2. signal pin assignments and functional pin descriptions are provided in table 1. s kywork s green? product s are compliant with all applicable legi s lation and are halogen-free. for additional information, refer to skyworks de?ition of green , document number s q04-0074. 4.7 h l1 10 f c 1 4.7 f c 2 en 1 out 2 vin 3 lx 4 agnd 5 pgnd 6 pgnd 7 pgnd 8 aat1110 u1 v in v out tc87 figure 1. aat1110 typical application circuit downloaded from: http:///
preliminary data sheet ? aat1110 fast transient 8 00 ma step-down converter skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 2 september 11, 2013 ? skyworks proprietary information ? pr oducts and product information ar e subject to change without no tice ? 201971d out vin lx pgndpgnd pgnd agnd en 12 3 45 6 7 8 tc88 figure 2. aat1110 8-pin sc70jw-8 (top view) table 1. aat1110 pin descriptions pin # name description 1 en enable pin. 2 out feedback input pin. this pin is connected eith er directly to the converter output or to an external resis tive divider for an adjustable output. 3 vin input supply voltage for the converter. 4 lx switching node. connect the inductor to this pin. it is inte rnally connected to the drain of both high- and low-side mosfe ts. 5 a g nd non-power signal ground pin. 6, 7, 8 p g nd main power ground return pin. connect to the output and input capacitor return. electrical and mechanical specifications the absolute maximum ratings of the aat1110 are provided in table 2, and the electrical specifications are provided in table 3. typical performance characteristics of the aat1110 are illustrated in figures 3 through 24. table 2. aat1110 absolute maximum ratings (note 1) parameter symbol minimum typical maximum units input voltage to g nd v in 6.0 v lx to g nd v lx ? 0.3 vin + 0.3 v out to g nd v out ? 0.3 vin + 0.3 v en to g nd v en ? 0.3 +6.0 v operating junction temperature t j ? 40 +140 c maximum soldering temperature (at leads, 10 seconds) t lead 300 c maximum power dissipation (sc70jw-8) p d 719 mw thermal resistance (sc70jw-8) (note 2) ? ja 160 c/w note 1: exposure to maximum rating conditions for extended periods may reduce device reliability. there is no damage to device with onl y one parameter set at the limit and all other parameters set at or below their nominal value. exceeding any of the limits listed may result in permanent damage to the device . note 2: mounted on an fr4 board. caution : although this device is designed to be as robust as possible, electrostatic discharge (esd) can damage this device. this devi ce must be protected at all times from esd. static charges may ea sily produce potentials of several kilovolts on the human body or equipment, which can discharge without detection. industr y-standard esd precautions should be used at all times. downloaded from: http:///
preliminary data sheet ? aat1110 fast transient 8 00 ma step-down converter skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201971d ? skyworks proprietary information ? products and product information are subject to change without notice ? september 11, 2013 3 table 3. aat1110 electrical specifications (note 1) (v in = 3.6 v, t a = ? 40 c to 85 c, unless otherwise noted. typical values are at t a = 25 c) parameter symbol test condition min typical max units step-down converter input voltage v in 2.7 5.5 v uvlo threshold v uvlo vin rising 2.7 v hysteresis 100 mv v in falling 1.8 v output voltage tolerance ? v out i out = 0 to 800 ma, v in = 2.7 v to 5.5 v ? 3.5 +3.5 % output voltage v out 0.6 v in v quiescent current i q no load, 0.6 v adjustable version 27 70 ? a shutdown current i shdn en = a g nd = p g nd 1.0 ? a p-channel current limit i lim 800 1200 ma high-side switch on resistance r ds ( on ) h 0.45 ? low-side switch on resistance r ds ( on ) l 0.40 ? line regulation ? v linere g v in = 2.7 v to 5.5 v 0.1 %/v out pin leakage current i out _ leak 0.6 v output 0.2 ? a output impedance r out >0.6 v output 250 k ? soft-start time t ss from enable to output regulation 120 ? s oscillator frequency f osc t a = 25 c 1.0 1.4 2.0 mhz over-temperature shutdown threshold t sd 140 c over-temperature shutdown hysteresis t hys 15 c en enable threshold low v en ( l ) 0.6 v enable threshold high v en ( h ) 1.4 v input low current i en v in = v out = 5.5 v ? 1.0 1.0 ? a note 1: performance is guaranteed only under th e conditions listed in this table. downloaded from: http:///
preliminary data sheet ? aat1110 fast transient 8 00 ma step-down converter skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 4 september 11, 2013 ? skyworks proprietary information ? pr oducts and product information ar e subject to change without no tice ? 201971d 6typical performance characteristics output c urrent (ma) ef?ciency (%) 50 6 0 70 80 9 0 100 0.1 1 10 100 1000 v in = 2.7 v v in = 3. 6 v v in = 4.2 v figure 3. efficiency vs load (v out = 1.8 v, l = 4.7 ? h) output c urrent (ma) ef?ciency (%) 50 6 0 70 80 9 0 100 0.1 1 10 100 1000 v in = 5.0 v v in = 3. 6 v v in = 3.0 v v in = 4.2 v figure 5. efficiency vs load (v out = 2.5 v, l = 6.8 ? h) output c urrent (ma) ef?ciency (%) 50 6 0 70 80 9 0 100 0.1 1 10 100 1000 v in = 5.0 v v in = 3. 6 v v in = 4.2 v figure 7. efficiency vs load (v out = 3.3 v, l = 6.8 ? h) output c urrent (ma) output error (%) -1.0 -0.5 0.0 0.5 1.0 0.1 1 10 100 1000 v in = 2.7 v v in = 3. 6 v v in = 4.2 v figure 4. dc regulation (v out = 1.8 v) output c urrent (ma) output error (%) -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 0.1 1 10 100 1000 v in = 5.0 v v in = 3. 6 v v in = 3.0 v v in = 4.2 v figure 6. dc regulation (v out = 2.5 v) output c urrent (ma) output error (%) -1.0 -0.5 0.0 0.5 1.0 0.1 1 10 100 1000 v in = 5.0 v v in = 4.2 v figure 8. dc regulation (v out = 3.3 v) downloaded from: http:///
preliminary data sheet ? aat1110 fast transient 8 00 ma step-down converter skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201971d ? skyworks proprietary information ? products and product information are subject to change without notice ? september 11, 2013 5 typical performance characteristics time (100 s /div) enable and output voltage (top) (v) inductor c urrent (bottom) (a) -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 -0.2 0.0 0.2 0.4 0. 6 0.8 1.0 1.2 1.4 1. 6 1.8 v en v out i l ^ ^ ^ figure 9. soft start (v in = 3.6 v, v out = 1.8 v, i out = 800 ma) temperature ( c ) output error (%) -2.0 -1.0 0.0 1.0 2.0 -40 -20 0 20 40 6 0 80 100 figure 11. output voltage error vs temperature (v in = 3.6 v, v out = 1.8 v, i out = 400 ma) input voltage (v) frequency variation (%) -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 2.7 3.1 3.5 3. 9 4.3 4.7 5.1 5.5 v out = 1.8 v v out = 2.5 v v out = 3.3 v figure 13. frequency vs input voltage (i out = 800 ma) input voltage (v) accuracy (%) -0.40 -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6 .0 i out = 1 ma i out = 400 ma i out = 800 ma i out = 10 ma figure 10. line regulation (v out = 1.8 v) temperature ( c ) variation (%) -15.0 -12.0 - 9 .0 - 6 .0 -3.0 0.0 3.0 6 .0 9 .0 12.0 15.0 -40 -20 0 20 40 6 0 80 100 figure 12. switching frequency vs temperature (v in = 3.6 v, v out = 1.8 v) input voltage (v) s upply c urrent (m m a) 10 15 20 25 30 35 40 45 50 2.7 3.1 3.5 3. 9 4.3 4.7 5.1 5.5 85 c 25 c C40 c figure 14. no load quiescent current vs input voltage downloaded from: http:///
preliminary data sheet ? aat1110 fast transient 8 00 ma step-down converter skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 6 september 11, 2013 ? skyworks proprietary information ? pr oducts and product information ar e subject to change without no tice ? 201971d typical performance characteristics output voltage (top) (v) load and inductor c urrent (500 ma/div) (bottom) time (50 s /div) 1.5 2.0 2.5 -0.5 0.0 0.5 v out ( a c ) ^ l load ^ i l ^ figure 15. load transient response (1 ma to 600 ma, v in = 3.6 v, v out = 1.8 v, c1 = 10 ? f) 1. 6 1.8 2.0 2.2 -0.5 0.0 0.5 output voltage (top) (v) load and inductor c urrent (500 ma/div) (bottom) time (50 s /div) v out ( a c ) ^ l load ^ i l ^ figure 17. load transient response (1 ma to 600 ma, v in = 3.6 v, v out = 1.8 v, c1 = 10 ? f, c ff = 100 pf) 1.8 2.0 2.2 -0.5 0.0 0.5 output voltage (top) (v) load and inductor c urrent (500 ma/div) (bottom) time (50 s /div) v out ( a c ) ^ i load ^ ^ i l figure 19. load transient response (1 ma to 600 ma, v in = 3.6 v, v out = 1.8 v, c1 = 22 ? f, c ff = 100 pf) time (50 s /div) 1.7 1.8 1. 9 2.0 0.4 0.5 0. 6 0.7 0.8 output voltage (top) (v) load and inductor c urrent (100 ma/div) (bottom) v out ( a c ) ^ i load ^ ^ i l figure 16. load transient response (600 ma to 800 ma, v in = 3.6 v, v out = 1.8 v, c1 = 10 ? f) 1.7 1.8 1. 9 2.0 0.4 0.5 0. 6 0.7 0.8 output voltage (top) (v) load and inductor c urrent (100 ma/div) (bottom) time (50 s /div) v out ( a c ) ^ i load ^ ^ i l figure 18. load transient response (600 ma to 800 ma, v in = 3.6 v, v out = 1.8 v, c1 = 22 ? f) 1.7 1.8 1. 9 2.0 0.4 0.5 0. 6 0.7 0.8 output voltage (top) (v) load and inductor c urrent (100 ma/div) (bottom) time (50 s /div) v out ( a c ) ^ i load ^ ^ i l figure 20. load transient response (600 ma to 800 ma, v in = 3.6 v, v out = 1.8 v, c1 = 10 ? f, c ff = 100 pf) downloaded from: http:///
preliminary data sheet ? aat1110 fast transient 8 00 ma step-down converter skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201971d ? skyworks proprietary information ? products and product information are subject to change without notice ? september 11, 2013 7 typical performance characteristics 1. 66 1. 6 8 1.70 1.72 1.74 1.7 6 1.78 1.80 1.82 1.84 1.8 6 2. 6 3.1 3. 6 4.1 4. 6 5.1 5. 6 6 .1 6 . 6 7.1 7. 6 output voltage (top) (v) input voltage (bottom) (v) time (50 s /div) figure 21. line response (v out = 1.8 v @ 800 ma) -120 -100 -80 - 6 0 -40 -20 0 20 40 -0.10 -0.05 0.00 0.05 0.10 0.15 0.20 0.25 0.30 time (10 s /div) output voltage (a c c oupled) (top) (mv) inductor c urrent (bottom) (a) figure 23. output ripple (v in = 3.6 v, v out = 1.8 v, i out = 1 ma) - 6 0 -50 -40 -30 -20 -10 0 10 20 0.5 0. 6 0.7 0.8 0. 9 1.0 1.1 1.2 1.3 output voltage (a c c oupled) (top) (mv) inductor c urrent (bottom) (a) time (500 n s /div) figure 22. output ripple (v in = 3.6 v, v out = 1.8 v, i out = 800 ma) input voltage (v) r d s ( on ) (m ) 300 350 400 450 500 550 6 00 6 50 700 750 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6 .0 25 c 120 c 100 c 85 c figure 24. p-channel r ds ( on ) vs input voltage (v out = 1.8 v; c ff = 100 pf) downloaded from: http:///
preliminary data sheet ? aat1110 fast transient 8 00 ma step-down converter skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 8 september 11, 2013 ? skyworks proprietary information ? pr oducts and product information ar e subject to change without no tice ? 201971d en lx error . amp. logic dh dl pgnd vin out agnd voltage reference input s ee note note: for adju s table ver s ion, the internal feedback divider i s omitted and the out pin i s tied directly to the internal error ampli?er. tc89 figure 25. aat1110 functional block diagram functional description the aat1110 is a high performance 800 ma, 1.4 mhz monolithic step-down converter. it has been designed with the goal of minimizing external component size and optimizing efficiency over the complete load range. apart from the small bypass input capacitor, only a small l-c filter is required at the output. typically, a 4.7 ? h inductor and a 10 ? f ceramic capacitor are recommended.. a functional block diagram is shown in figure 25. the fixed output version requires only three external power components (c in , c out , and l). the adjustable version can be programmed with external feedback to any voltage, ranging from 0.6 v to the input voltage. an additional feed-forward capacitor (c4) can also be added to the external feedback to provide improved transient response (see figure 26). at dropout, the converter duty cycle increases to 100% and the output voltage tracks the input voltage minus the r dson drop of the p-channel high-side mosfet. the input voltage range is 2.7 v to 5.5 v. the converter efficiency has been optimized for all load conditions, ranging from no load to 800 ma. the internal error amplifier and compensation provides excellent transient response, load, and line regulation. soft start eliminates any output voltage overshoot when the enable is applied. control loop the aat1110 is a peak current mode step-down converter. the current through the p-channel mosfet (high side) is sensed for current loop control, as well as short circuit and overload protection. a fixed slope compensation signal is added to the sensed current to maintain stability for duty cycles greater than 50%. the peak current mode loop appears as a voltage- programmed current source in parallel with the output capacitor. the output of the voltage error amplifier programs the current mode loop for the necessary peak switch current to force a constant output voltage for all load and line conditions. internal loop compensation terminates the transconductance voltage error amplifier output. for fixed voltage versions, the error amplifier reference voltage is internally set to program the converter output voltage. for the adjustable output, the error amplifier reference is fixed at 0.6 v. downloaded from: http:///
preliminary data sheet ? aat1110 fast transient 8 00 ma step-down converter skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201971d ? skyworks proprietary information ? products and product information are subject to change without notice ? september 11, 2013 9 l1: cdrh3d16-4r7 l1 c1 c2 u1: aat1110 sc70jw-8 c2: 4.7 ? f, 10 v, 0805 x5r v out 1.8 v g nd 1 2 3 enable lx en 1 out 2 vin 3 lx 4 a g nd 5 p g nd 6 p g nd 7 p g nd 8 aat1110 u1 g nd2 118 k ? r1 59 k ? r2 c1: 10 ? f, 6.3 v, 0805 x5r 100 pf c4 n/a c3 v in 4.7 ? h 10 ? f tc 9 0 figure 26. enhanced transient response schematic soft start/enable soft start limits the current surge seen at the input and eliminates output voltage overshoot. when pulled low, the enable input forces the aat1110 into a low power, non- switching state. the total input current during shutdown is less than 1 ? a. current limit and over-temperature protection for overload conditions, the peak input current is limited. to minimize power dissipation under current limit and short-circuit conditions, switching is terminated after entering current limit for a series of pulses. switching is terminated for seven consecutive clock cycles after a current limit has been sensed for a series of four consecutive clock cycles. thermal protection completely disables switching when internal dissipation becomes excessive. the junction over-temperature threshold is 140 c with 15 c of hysteresis. once an over- temperature or over-current fault conditions is removed, the output voltage automatically recovers. under-voltage lockout internal bias of all circuits is controlled via the v in input. under- voltage lockout (uvlo) guarantees sufficient v in bias and proper operation of all internal circuitry prior to activation. applications information inductor selection the step-down converter uses peak current mode control with slope compensation to maintain stability for duty cycles greater than 50%. the output inductor value must be selected so the inductor current down slope meets the internal slope compensation requirements. the internal slope compensation for the adjustable and low-voltage fixed versions of the aat1110 is 0.24 a/ ? s. this equates to a slope compensation that is 75% of the inductor current down slope for a 1.5 v output and 4.7 ? h inductor. s a 24.0 h 7.4 v5.1 75.0 l v 75.0 m out ? ? ? ? ? ? ? this is the internal slope compensation for the adjustable (0.6 v) version or low-voltage fixed versions. when externally programming the 0.6 v version to 2.5 v, the calculated inductance is 7.5 ? h. h 5.7 v5.2 a s 3 v a s 3 s a 24.0 v 75.0 m v 75.0 l out out out ? ? ? ? ? ? ? ? ? ? ? ? ? in this case, a standard 6.8 ? h value is selected. for high-voltage fixed versions ( ? 2.5 v), m = 0.48 a/ ? s. manufacturers specifications list both the inductor dc current rating, which is a thermal limitation, and the peak current rating, which is determined by the saturation characteristics. the inductor should not show any appreciable saturation under normal load conditions. some inductors may meet the peak and average current ratings yet result in excessive losses due to a high dcr. always consider the losses associated with the dcr and its effect on the total converter efficiency when selecting an inductor. input capacitor select a 4.7 ? f to 22 ? f x7r or x5r ceramic capacitor for the input. to estimate the required input capacitor size, determine the acceptable input ripple level (v pp ) and solve for c. the calculated value varies with input voltage and is a maximum when v in is double the output voltage. s out pp in out in out in f esr i v v v 1 v v c ? ? ?? ? ? ?? ? ? ? ?? ? ? ?? ? ? ? ? 4 1 v v 1 v v in out in out ? ? ?? ? ? ?? ? ? ? for out in v 2 v ? ? downloaded from: http:///
preliminary data sheet ? aat1110 fast transient 8 00 ma step-down converter skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 10 september 11, 2013 ? skyworks proprietary information ? pr oducts and product information ar e subject to change without n otice ? 201971d s out pp )min(in f 4 esr i v 1 c ? ? ? ?? ? ? ?? ? ? ? where, f s is the switching frequency. always examine the ceramic capacitor dc voltage coefficient characteristics when selecting the proper value. for example, the capacitance of a 10 ? f, 6.3 v, x5r ceramic capacitor with 5.0 v dc applied is actually about 6 ? f. the maximum input capacitor rms current is: ? ?? ? ? ?? ? ? ? ? ? in out in out out rms v v 1 v v i i the input capacitor rms ripple current varies with the input and output voltage and always is less than or equal to half of the total dc load current. ?? 2 1 5.0 d 1 d v v 1 v v 2 in out in out ? ? ? ? ? ? ?? ? ? ?? ? ? ? for v in = 2 ? v out 2 i i out max rms ? the term ? ?? ? ? ?? ? ? ? in out in out v v 1 v v appears in both the input voltage ripple and input capacitor rms current equations and is a maximum when v out is twice v in . this is why the input voltage ripple and the input capacitor rms current ripple are a maximum at 50% duty cycle. the input capacitor provides a low impedance loop for the edges of pulsed current drawn by the aat1110. low esr/esl x7r and x5r ceramic capacitors are ideal for this function. to minimize stray inductance, the capacitor should be placed as closely as possible to the ic. this keeps the high frequency content of the input current localized, minimizing emi and input voltage ripple. the proper placement of the input capacitor (c2) can be seen in the evaluation board layout in figure 28. a laboratory test setup typically consists of two long wires running from the bench power supply to the evaluation board input voltage pins. the inductance of these wires, along with the low-esr ceramic input capacitor, can create a high-q network that may affect converter performance. this problem often becomes apparent in the form of excessive ringing in the output voltage during load transients. errors in the loop phase and gain measurements can also result. because the inductance of a short pcb trace feeding the input voltage is significantly lower than the power leads from the bench power supply, most applications do not exhibit this problem. in applications where the input power source lead inductance cannot be reduced to a level that does not affect the converter performance, a high esr tantalum or aluminum electrolytic should be placed in parallel with the low esr, esl bypass ceramic. this dampens the high-q network and stabilizes the system. output capacitor the output capacitor limits the output ripple and provides holdup during large load transitions. a 4.7 ? f to 10 ? f x5r or x7r ceramic capacitor typically provides sufficient bulk capacitance to stabilize the output during large load transitions and has the esr and esl characteristics necessary for low output ripple. the output voltage droop due to a load transient ( ? i load ) is dominated by the capacitance of the ceramic output capacitor. during a step increase in load current, the ceramic output capacitor alone supplies the load current until the loop responds. within two or three switching cycles, the loop responds and the inductor current increases to match the load current demand. the relationship of the output voltage droop during the three switching cycles to the output capacitance can be estimated by: s droop load out f v i 3 c ? ? ? ? once the average inductor current increases to the dc load level, the output voltage recovers. the above equation establishes a limit on the minimum value for the output capacitor with respect to load transients. the internal voltage loop compensation also limits the minimum output capacitor value to 4.7 ? f. this is due to its effect on the loop crossover frequency (bandwidth), phase margin, and gain margin. increased output capacitance reduces the crossover frequency with greater phase margin. the maximum output capacitor rms ripple current is given by: ? ? )max(in s out )max(in out max rms v f l v v v 3 2 1 i ? ? ? ? ? ? dissipation due to the rms current in the ceramic output capacitor esr is typically minimal, resulting in less than a few degrees rise in hot-spot temperature. downloaded from: http:///
preliminary data sheet ? aat1110 fast transient 8 00 ma step-down converter skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201971d ? skyworks proprietary information ? products and product information are subject to change without notice ? september 11, 2013 11 adjustable output resistor selection for applications requiring an adjustable output voltage, the 0.6 v version can be externally programmed. resistors r1 and r2 of figure 28 program the output to regulate at a voltage higher than 0.6 v. to limit the bias current required for the external feedback resistor string while maintaining good noise immunity, the minimum suggested value for r2 is 59 k ? . although a larger value can further reduce quiescent current, it also increases the impedance of the feedback node, making it more sensitive to external noise and interference. table 4 summarizes the resistor values for various output voltages with r2 set to either 59 k ? for good noise immunity or 221 k ? for reduced no-load input current. ? ? k5.88 k59 1 v6.0 v5.1 2r 1 v v r1 ref out ? ? ?? ? ?? ? ? ? ? ? ?? ? ? ?? ? ? ? the adjustable version of the aat1110, combined with an external feed-forward capacitor (c4 in figure 26), delivers enhanced transient response for extreme pulsed load applications. addition of the feed-forward capacitor typically requires a larger output capacitor c1 for stability. table 4. adjustable resistor values for use with 0.6 v step- down converter v out (v) r1 (k ? ) (r2 = 5 9 k ? ) r1 (k ? ) (r2 = 221 k ? ) 0.8 19.6 75 0.9 29.4 113 1.0 39.2 150 1.1 49.9 187 1.2 59.0 221 1.3 68.1 261 1.4 78.7 301 1.5 88.7 332 1.8 118 442 1.85 124 464 2.0 137 523 2.5 187 715 3.3 267 1000 thermal calculations there are three types of losses associated with the aat1110 step-down converter: switching losses, conduction losses, and quiescent current losses. conduction losses are associated with the r ds ( on ) characteristics of the power output switching devices. switching losses are dominated by the gate charge of the power output switching devices. at full load, assuming continuous conduction mode (ccm), a simplified form of the losses is given by: ? ? ? ? ?? in q out s sw in out in l)on(ds out h)on(ds 2 out total v i i f t v v v r v r i p ? ? ? ? ? ? ? ? ? ? ? i q is the step-down converter quiescent current. the term t sw is used to estimate the full load step-down converter switching losses. for the condition where the step-down converter is in dropout at 100% duty cycle, the total device dissipation reduces to: in q h)on(ds 2 out total v i r i p ? ? ? ? since r ds ( on ) , quiescent current, and switching losses all vary with input voltage, the total losses should be investigated over the complete input voltage range. g iven the total losses, the maximum junction temperature can be derived from the ? ja for the sc70jw-8 package which is 160 c/w. a ja total j(max) t p t ? ? ? ? layout the following guidelines should be used to help ensure a proper layout. ? the input capacitor (c2) should connect as closely as possible to vin (pin 3) and p g nd (pins 6-8). ? c1 and l1 should be connected as closely as possible. the connection of l1 to the lx pin should be as short as possible. ? the feedback trace or out pin (pin 2) should be separate from any power trace and connect as closely as possible to the load point. sensing along a high-current load trace degrades dc load regulation. if external feedback resistors are used, they should be placed as closely as possible to the out pin (pin 2) to minimize the length of the high impedance feedback trace. ? the resistance of the trace from the load return to the p g nd (pins 6-8) should be kept to a minimum. this helps minimize any error in dc regulation due to differences in the potential of the internal signal ground and the power ground. evaluation board description the aat1110 evaluation board schematic diagram is provided in figure 27. the pcb layer details are shown in figure 28. table 5 lists the evaluation board component values. tables 6 and 7 give the typical surface mount inductors and surface mount capacitors. downloaded from: http:///
preliminary data sheet ? aat1110 fast transient 8 00 ma step-down converter skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 12 september 11, 2013 ? skyworks proprietary information ? pr oducts and product information ar e subject to change without n otice ? 201971d out 2 en 1 vin 3 lx 4 agnd 5 pgnd 7 pgnd 8 pgnd 6 u1 aat1110 1 2 3 jp1 gnd gnd c 4(option) option c 3 4.7 h l1 10 f c 1 c 2 118 k r1 5 9 k r2 v in 4.7 f v out l1: c drh3d1 6 -4r7 u1: aat1110 sc 70jw-8 c 2: 4.7 f, 10 v, 0805 x5r c 1: 10 f, 6 .3 v, 0805 x5r tc91 figure 27. aat1110 adjustable evaluation board schematic top s ide bottom s ide tc92 figure 28. aat1110 evaluation board layer details downloaded from: http:///
preliminary data sheet ? aat1110 fast transient 8 00 ma step-down converter skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201971d ? skyworks proprietary information ? products and product information are subject to change without notice ? september 11, 2013 13 table 5. evaluation board component values adjustable version (0.6 v device) v out (v) r1 (k ? ) (r2 = 5 9 k ? ) r1 (k ? ) (r2 = 221 k ? ) (note 1) l1 ( ? h) 0.8 19.6 75.0 2.2 0.9 29.4 113 2.2 1.0 39.2 150 2.2 1.1 49.9 187 2.2 1.2 59.0 221 2.2 1.3 68.1 261 2.2 1.4 78.7 301 4.7 1.5 88.7 332 4.7 1.8 118 442 4.7 1.85 124 464 4.7 2.0 137 523 6.8 2.5 187 715 6.8 3.3 267 1000 6.8 fixed version v out (v) r1, r2 not used l1 ( ? h) 0.6-3.3v 4.7 note 1: for reduced quiescent current, r2 = 221 k ? . table 6. typical surface mount inductors manufacturer part number/type inductance ( ? h) max. dc current (a) dcr (m ? ) size (mm) l ? w ? h toko 1276as-h-2r2n 2.2 1.60 98 3.2 ? 2.5 ? 1.0 toko 1239as-h-4r7m 4.7 1.30 200 2.5 ? 2.0 ? 1.2 toko 1277as-h-6r8n 6.8 1.20 230 3.2 ? 2.5 ? 1.2 murata lqm2hpn2r2mmr 2.2 1.38 68 2.5 ? 2.0 ? 1.1 murata lqh32pn4r7nnc 4.7 1.20 155 3.1 ? 3.1 ? 1.5 coilcraft lps3015-222mlb 2.2 2.0 110 3.1 ? 3.1 ? 1.5 table 7. surface mount capacitors manufacturer part number value ( ? f) voltage (v) temperature coefficient case murata g rm219r61a475ke19 4.7 10 x5r 0805 murata g rm21br60j106ke19 10 6.3 x5r 0805 murata g rm21br60j226me39 22 6.3 x5r 0603 downloaded from: http:///
preliminary data sheet ? aat1110 fast transient 8 00 ma step-down converter skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 14 september 11, 2013 ? skyworks proprietary information ? pr oducts and product information ar e subject to change without n otice ? 201971d package information package dimensions and tape & reel dimensions are shown in figures 29 and 30, respectively. 0.225 0.075 0.45 0.10 0.05 0.05 2.10 0.30 2.00 0.20 7 3 4 4 1.75 0.10 0.85 0.15 0.15 0.05 1.10 max. 0.100 2.20 0.20 0.048 ref. 0.50 b sc 0.50 b sc 0.50 b sc tc13 top view s ide view front view all dimensions are in millimeters. figure 29. aat1110 8-pin sc70jw package dimensions 1.55 0.05 8.00 0.30 4.00 0.10 2.00 0.05 1.75 0.05 3.50 0.05 pin 1 location 4.00 0.10 1.30 0.10 0.20 0.03 2.40 0.10 2.50 0.10 tc38 all dimensions are in millimeters. figure 30. aat1110 carrier tape dimensions downloaded from: http:///
preliminary data sheet ? aat1110 fast transient 8 00 ma step-down converter skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201971d ? skyworks proprietary information ? products and product information are subject to change without notice ? september 11, 2013 15 ordering information model name output voltage (note 1) package marking (note 2) manufacturing part number (note 3) aat1110 fast transient 800 ma step-down converter 3.3 v sc70jw-8 tsxyy aat1110ijs-3.3-t1 adj. ? 0.6 v sc70jw-8 srxyy aat1110ijs-0.6-t1 note 1: contact sales for other voltage options. note 2: xyy = assembly and date code. note 3: sample stock is generally held on part numbers listed in bold . copyright ? 2013 skyworks solutions, inc. all rights reserved. information in this document is provided in connection with skyw orks solutions, inc. (skyworks) products or services. these materials, including the information contained herein, are provided by skyworks as a service to its customers and may be used for info rmational purposes only by the customer. skyworks assumes no res ponsibility for errors or omissions in these materials or the information contained herein. skyworks may change its documentat ion, products, services, specific ations or product descriptions at any time, without notice. sk yworks makes no commitment to update the materials or information and shall have no responsib ility whatsoever for conflicts, incompatibilities, or other diff iculties arising from any future changes. no license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document . skyworks assumes no liability for any materials, products or information provided hereunder, including the sale, distribution, reproduction or use of skyworks products, information or mate rials, except as may be provided in skyworks terms and conditions of sale. the materials, products and information are pr ovided as is without warranty of any ki nd, whether express, implied, statutory, or otherwise, includin g fitness for a particular purpose or use, merchantability, performance, quality or non-infrin g ement of any intellectual property ri g ht; all such warranties are hereby expressly disclaimed. skyworks does not warra nt the accuracy or completeness of the information, text, g raphics or other items contained within these ma terials. skyworks shall not be liable for any dama g es, includin g but not limited to any special, indirect, incidental, statutory, or consequential dama g es, includin g without limitation, lost revenues or lost profits that may result from the use of the materials or information, whet her or not the recipient of mat erials has been advised of the possibility of such dama g e. skyworks products are not intended for use in medical, lifesaving or life-sustaining applications, or other equipment in which the failure of the skyworks products could lead to personal injury, death, physical or environmental damage. skyworks customers using or selling skyworks products for use in such applications do so at their own risk and agree to fully indemnify skyworks for any damages resulting from such improper use or sale. customers are responsible for their products and applications us ing skyworks products, which ma y deviate from published specifi cations as a result of design defects, errors, or operation of products outside of published pa rameters or design specifications. customers sh ould include design and operating safeguards to minimize these and other risks. skyworks assumes no liability for applications assistance, customer product design, or damage to any equipment resulting from the use of skyworks products outsid e of stated published specifications or parameters. skyworks, the skyworks symbol, and breakthro ugh simplicity are trademarks or registered trademarks of skyworks solutions, inc ., in the united states and othe r countries. third-party brands and names are for identification purposes only, and are the proper ty of their respective owners. additional information, includ ing relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference. downloaded from: http:///

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