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aat1274 1.5a single flash led driver ic data sheet 1 skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201981a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 21, 2012 general description the aat1274 is a high-efficiency, 1.5a high-current boost converter for led photo flash applications. it maintains output current regulation by switching the internal high-side and low-side switch transistors, pulse- width modulated at a fixed frequency of 2mhz. the high switching frequency allows the use of a small external inductor and output capacitor, making the aat1274 ide- ally suited in all single cell, li-ion-powered applications. skyworks' proprietary as 2 cwire? (advanced simple serial control?) serial digital interface is used to enable, disable, configure, and program the operation of the aat1274. using the as 2 cwire interface, the movie-mode current level for each led, and the flash-to-movie-mode current ratio can be programmed to one of 16 levels. the aat1274 includes a separate flash enable input to initi- ate the flash operation and a flash inhibit pin which reduces the flash current to movie-mode levels during high battery demand. the maximum flash and movie-mode current is set by one external resistor where the ratio of flash to movie- mode current is set at approximately 7.3:1. the aat1274 can drive one high current led. the aat1274 contains a thermal management system to protect the device in the event of an output short-circuit condition. built-in circuitry prevents excessive inrush current during start-up. the shutdown feature reduces quiescent current to less than 1.0 a. the aat1274 is available in a pb-free, thermally-enhanced tdfn33-14 package and operates ov er the -40c to 85c temperature range. features ? input voltage range: 2.7v to 5.5v ? single channel flash output ? up to 1.5a regulated output current ? up to 88% efficiency ? 2 mhz switching frequency ? separate flash enable ? single resistor sets flash and movie mode current ? as 2 cwire single wire programming: ? movie mode current ? flash/movie mode current ratio ? true load disconnect ? soft-start and input current limit ? over-voltage (open led, open circuit), short circuit, and over-temperature protection ? -40c to +85c temperature range ? tdfn33-14 package applications ? led photo flash / torch ? camera enabled mobile devices ? cellphones/smartphones ? digital still cameras (dscs) ? multimedia mobile phones typical application aat1274 r set c in 2.2f c out 2.2f in out en/set flen agnd pgnd flgnd rset flash led enable/set input flash enable fl v bat = 2.7v to 5.5v sw l1 1h flinh flash inhibit
aat1274 1.5a single flash led driver ic data sheet 2 skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201981a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 21, 2012 pin descriptions pin # symbol description 1,5 agnd analog ground pin. connect agnd to pgnd, and flgnd at a single point as close to the aat1274 as possible. 2 en/set enable and serial control input. en/set is the as2cwire addressing and programming input to: a) adjust the movie-mode current level; b) select the flash-to-movie-mode ratio; 3 fl led flash current sink pin. connect the cathode of flash led to fl. 4 flen flash enable pin. a low-to-high transition on the flen pin initiates a ash pulse and a high-to-low transition on the flen pin terminates a ash pulse 6in flash output boost converter power input. connect in to the input power source. connect a 2.2 f or larger ceramic capacitor from in to pgnd and locate as close as possible to the aat1274 package for optimum per- formance. 7 pgnd power ground. connect pgnd to the same single point as agnd located as close to the aat1274 as possible 8 out power output of the boost converter. connect a 2.2 f or larger ceramic capacitor from out to pgnd as close as possible to the aat1274. connect out to the anode of the flash led. 9, 12 nc not connected 10 sw boost converter switching node. connect a 1 h inductor between sw and in. 11 flinh flash inhibit pin. flinh is an active high control input with an internal 200k resistor to agnd. a low-to- high transition on the flinh pin reduces fl sink current to the maximum (default) movie-mode current level. 13 flgnd flash ground pin. connect flgnd to pgnd, and agnd at a single point as close to the aat1274 as possible. 14 rset flash current set pin. connect a resistor from rset to agnd to program the desired ash current for the cur- rent sink fl. ep electrical back contact. connect to a good thermal ground pad pin configuration tdfn33-14 (top view) agnd en/set fl 1 flen agnd in rset flgnd n/c flinh sw n/c 2 3 4 5 6 pgnd 7 12 11 14 13 10 9 out 8
aat1274 1.5a single flash led driver ic data sheet 3 skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201981a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 21, 2012 1. stresses above those listed in absolute maximum ratings may cause permanent damage to the device. functional operation at co nditions other than the operating conditions specified is not implied. 2. mounted on an fr4 board. 3. derate 20mw/c above 25c. absolute maximum ratings 1 t a = 25c unless otherwise noted. symbol description value units in, out, sw maximum rating -0.3 to 6.0 v en/set, flen, flinh, rset, fl maximum rating -0.3 to v in + 0.3 t j operating junction temperature range -40 to 150 ? c t s storage temperature range -65 to 150 t lead maximum soldering temperature (at leads, 10 sec) 300 thermal information 2 symbol description value units ? ja thermal resistance 3 50 o c/w p d maximum power dissipation 2 w
aat1274 1.5a single flash led driver ic data sheet 4 skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201981a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 21, 2012 electrical characteristics v in = 3.6v; c in = c out = 2.2 f; r set = 107k ; l = 1 h. t a = -40 o c to 85c unless otherwise noted. typical values are at t a = 25c. symbol description conditions min typ max units power supply ? switching flash driver v in input voltage range 2.7 5.5 v v out(max) maximum output voltage 5.5 v i in(q) supply current en/set = flen = in, set fl load = 1.5a 0.67 1 ma en/set = in, flen = agnd 0.23 i shdn(max) input shutdown current en/set, flen, = agnd 1.0 a i fl output current, flash mode r set = 107k 1.2 1.5 a i fl(acc) flash current accuracy r set = 107k = 1.2a 10 % i mm(load) total output current, movie mode r set = 107k , movie mode current set to 100% 206 ma f osc switching frequency t a = 25c 1.5 2.0 2.5 mhz t sd over-temperature shutdown threshold 140 c t sd(hys) over-temperature shutdown hysteresis 15 c en/set, flen v en/set(h) , v flen(h) en/set, flen input high threshold 1.4 v v en/set(l) , v flen(l) en/set, flen input low threshold 0.4 v i en/set, i flen en/set, flen input leakage current v en/set , v flen = in = 5v -1 1 a v t(flinh) flinh input threshold voltage ? in v r in(flinh) flinh input resistance to agnd 200 k t en/set(lo) en/set serial interface low time 0.3 75 s t en/set(hi-min) minimum en/set high time 50 ns t en/set(hi-max) maximum en/set high time 75 s t en/set(off) en/set off timeout time 500 s t enset(lat) en/set latch timeout time 500 s t flen(on) flen on delay time en/set = agnd 40 s t flen(off) flen off delay time en/set = agnd 10 s t flinh_on flinh on delay tim e 93 s
aat1274 1.5a single flash led driver ic data sheet 5 skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201981a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 21, 2012 typical characteristics flash mode efficiency vs. input voltage input voltage (v) efficiency (%) 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 40 50 60 70 80 90 100 320ma, v f = 2.91v 540ma, v f = 3.00v 700ma, v f = 3.04v 900ma, v f = 3.04v 1500ma, v f = 3.15v 1200ma, v f = 3.27v movie mode efficiency vs. input voltage input voltage (v) efficiency (%) 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 50 55 60 65 70 75 80 85 90 204ma 104ma 52ma boost switching frequency vs. input voltage (movie mode; l = 1h) input voltage (v) switching frequency (mhz) 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 0 0.5 1 1.5 2 2.5 3 85c 25c -40c shutdown current vs. input voltage (v en/set = v flen = 0v) input voltage (v) shutdown current (a) 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 0 0.005 0.01 0.015 0.02 0.025 0.03 25c -40c supply current vs. input voltage (v en = v flen = 3.6v) input voltage (v) supply current (a) 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 0 100 200 300 400 500 600 700 800 900 1000 85c 25c -40c movie mode led current vs. temperature (i fl = 206ma/ch; v in = 3.6v; l = 1h) temperature (c) output current (ma) -40 -15 10 35 60 85 185 190 195 200 205 210 215 220 225
aat1274 1.5a single flash led driver ic data sheet 6 skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201981a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 21, 2012 typical characteristics movie mode led current accuracy vs. input voltage (i fl = 206ma; l = 1h) input voltage (v) output current (ma) 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 -10 -8 -6 -4 -2 0 2 4 6 8 10 movie mode output ripple (i fl = 206ma; v in = 3.6v; l = 1h) time (500ns/div) v out (ac coupled) (50mv/div) i inductor (100ma/div) v inductor (2v/div) 100ma 0v flash mode output ripple (i fl = 1.5a; v in = 4v; l = 1h) time (200ns/div) v out (ac coupled) (50mv/div) i inductor (50ma/div) v inductor (2v/div) 1.65a 0v flash led current vs. temperature (i fl = 1.5a; v in = 4.2v; l = 1h) temperature (c) output current (ma) -40 -15 10 35 60 85 1420 1440 1460 1480 1500 1520 1540 1560 1580 flash on time delay vs. input voltage (i fl = 1.5a; c out = 2.2f; l = 1h) input voltage (v) t flen_ond (s) 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 0 10 20 30 40 50 60 70 80 -40c 25c 85c movie mode line transient (i fl = 206ma; v in = 4.2v to 3.6v) time (50s/div) i fl (ac coupled) (50ma/div) v in (500mv/div) 4.2v 3.6v
aat1274 1.5a single flash led driver ic data sheet 7 skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201981a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 21, 2012 typical characteristics flash turn on characteristic (i fl = 1.5a; v in = 3.6v; l = 1h) time (50s/div) v flen (5v/div) i fl (1a/div) v fl (2v/div) v out (2v/div) 0v 0v 0v 0v movie mode to flash turn on characteristic (i fl = 206ma to 1.5a; v in = 3.6v; l = 1h) time (50s/div) v flen (2v/div) i floutx (1a/div) v fl (500mv/div) v out (2v/div) 0a 0v 2v 0v movie mode turn on characteristic (i fl = 206ma; v in = 3.6v; l = 1h) time (100s/div) v en/set (5v/div) i fl (200ma/div) v fl (500mv/div) v out (2v/div) 0v 0a 0v 0v movie mode transition characteristic (i fl = 206ma to 376ma; c out = 0.22f; v in = 3.6v; l = 1h) time (100s/div) v en/set (2v/div) i fl (200ma/div) v fl (500mv/div) v out (2v/div) 0v 0a 0v 0v en, flen high threshold voltage vs. input voltage input voltage (v) v en/set(h) , v flen(h) (v) 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 85c 25c -40c en, flen low threshold voltage vs. input voltage input voltage (v) v en/set(l) , v flen(l) (v) 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 85c 25c -40c
aat1274 1.5a single flash led driver ic data sheet 8 skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201981a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 21, 2012 typical characteristics en/set off timeout vs. input voltage input voltage (v) t en/set(off) (s) 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 50 100 150 200 250 300 85c 25c -40c en/set latch timeout vs. input voltage input voltage (v) t en/set(lat) (s) 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 50 100 150 200 250 300 85c 25c -40c
aat1274 1.5a single flash led driver ic data sheet 9 skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201981a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 21, 2012 functional description the aat1274 is a boost converter with a current regu- lated output designed to drive high current white led used in camera flash applications. the aat1274 has a constant current sink channel to accurately regulate the current flow through a high current, high intensity white flash led. the aat1274 has two basic operating modes; a flash mode controlled by the flen pin and the movie/ torch light mode controlled through the as 2 cwire inter- face. flash mode a flash pulse may be initiated by pulling the flen input pin from a logic low-to-high state, which initiates a flash pulse. the maximum flash current in the aat1274 is set by an external resistor, r set , which sets the flash current and the maximum movie-mode current. in mobile gsm systems where the phone remains in constant contact with the base station by regular com- munication, a flinh pin is provided to prevent both the camera flash and pa transmission pulses from occurring simultaneously. this avoids potential dips to the li-ion battery voltage below the system?s undervoltage lockout threshold (uvlo). during a flash event, strobing the flinh pin low-to-high reduces the led current to the default movie-mode current level for the duration of flinh. strobing flinh high-to-low instructs the aat1274 to revert the flash led current to its maximum level, assuming that the flen pin is still active (high). movie (torch) mode the movie / torch mode current level, and the flash to maximum movie mode current ratio are programmed by the aat1274 as 2 cwire interface. the movie-mode cur- rent level can be adjusted to one of 16 steps using a logarithmic scale where each code level is 1db below the previous code. the flash to maximum movie mode cur- rent ratio can be set from 1:2 to 1:30 with respect to the maximum programmed flash current as set by the r set resistor. the manual flen signal has priority over movie- mode operation. functional block diagram system control enable and as 2 c interface out (to flash led) fl flgnd rset pgnd agnd flen en/set in sw flinh
aat1274 1.5a single flash led driver ic data sheet 10 skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201981a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 21, 2012 movie mode operation is controlled entirely by the as 2 cwire interface via the en/set pin. the flen signal will override movie-mode aat1274 operation when tog- gled to a logic high level. the part will not reenter movie mode when flen is brought low. to reenter movie mode after a flash event the part must be cycled off and back on to reset the movie mode and reprogrammed via the as 2 cwire interface to the desired movie mode operation. over-voltage protection (open flash led, open circuit) the aat1274 boost converter output is voltage limited by internal overvoltage protection circuitry to prevent dam- age to the device in the event an open led or open circuit condition occurs. during an open circuit condition, the output voltage will rise to 5.5v (typical). the ovp circuit disables the boost converter to prevent the output voltage from rising above 5.5v. once the open circuit condition is removed, normal boost operation will resume. short circuit protection the aat1274 is equipped with an auto-disable feature for the flash led channel. after the ic is enabled and system start up commences, a test current of 2-3ma (typical) is forced through the sink channel. the channel will be disabled if the voltage of the sink pin does not drop to a predetermined threshold. this feature is very convenient for disabling the current sink in the event the flash led fails to a short circuit. this small test current is added to the set output current in both flash and movie mode conditions. over-temperature protection the aat1274 has internal thermal protection circuitry to disable the device if the internal power dissipation exceeds a preset thermal limit. the junction over-temperature threshold is 140c with 15c of temperature hysteresis. during flash or movie-mode operation, if an environmen- tal condition, flash current sink, or the boost converter causes the internal die temperature to rise above 140c, the boost converter will be shut down. the boost con- verter output operation will automatically recover when the over-temperature fault condition is removed. application information flash mode led current flash sink current can be programmed up to a maximum of 1.5a. the maximum flash current is set by the r set resistor. for the desired flash current, the resistor value can be calculated using the following equation: 162k a r set 162k 107k i fl = = = 1.5a a flash event is initiated by asserting the flen pin. a flash event is automatically terminated when flen is deasserted. any time that the flinh pin is asserted, the default movie-mode current level will appear at fl chan- nel. the default movie mode current level will be main- tained on fl as long as the flinh and flen pins are asserted. in addition to setting the flash current via r set , the flash current can be changed after flen is asserted by programming the movie mode current register with 16 different steps. as 2 cwire control of movie mode operation in the aat1274 control of the movie mode operation is managed by the advanced simple serial control (as 2 cwire) interface. as 2 cwire relies on the number of rising edges of the en/set pin to address and load internal data reg- isters. referring to table 1: ?? address 0 controls the movie mode (mm) current level as a percentage of the maximum movie mode current level. ?? address 3 sets the maximum possible current for movie mode operation. the maximum movie mode current is set as a fraction of the flash current with a peak value of 1/2 and default value of 1/7.3. ?? the last column in table 1 shows the default values for each of the address registers.
aat1274 1.5a single flash led driver ic data sheet 11 skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201981a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 21, 2012 address en/set rising edges function default (no programming) 017 movie mode current 100% 1 not used 2 not used 320 flash/movie mode cur- rent ratio 1/7.3 table 1: as 2 cwire serial interface addressing. as 2 cwire serial interface as 2 cwire latches data or address after the en/set pin has been held high for longer than t lat (500 s) . address or data are differentiated by the number of en/set rising edges. since the data registers are 4 bits each, the dif- ferentiating number of pulses is 2 4 or 16, so that address 0 is signified by 17 rising edges, and address 3 by 20 rising edges. data is inclusively applied to any number of rising edges between 1 and 16. a typical write protocol is a burst of en/set rising edges which signify a particular address that is followed by a pause with en/set held high for the prescribed t lat timeout period, then a burst of rising edges signifying data, and a t lat timeout for the data registers. once an address is set, then multiple writes to the corresponding data register are allowed. address 0 is the default address on the first rising edge after the aat1274 has been disabled. when en/set is transitioned from high to low and held low longer than t off (500 s), the device enters a shutdown mode and draws less than 1ua from the input supply. all data and address are cleared (reset to 0) during shutdown. as 2 cwire addressing allows for control of the movie mode output current, and the ratio of movie-mode current to flash current. if there are no programmed write instruc- tions applied to the en/set pin prior to the assertion of the flen pin and the device is enabled, then all registers will be loaded with their default values shown in table 1. in the event that the number of rising edges applied at the en/set pin is less than 17, the internal state machine will interpret instruction to program the output currents to the desired current level for movie-mode operation. movie mode current ? address 0 the aat1274 movie mode current settings are controlled using the as 2 cwire interface. the default ratio between the flash current level and maximum movie mode cur- rent level is 1:7.3. for example, if an r set value of 107k is chosen, then the flash current is set to 1500ma. for movie mode operation, the maximum current available is then: i fl(max) 7.3 1500ma 7.3 i movie mode = = = 206m a address data 1 en/set 2 16 17 address data reg 1 1 2 . . . n 16 01 0n t hi t lo t lat t lat figure 1: as 2 cwire serial interface timing diagram.
aat1274 1.5a single flash led driver ic data sheet 12 skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201981a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 21, 2012 * denotes the default value. address 0 controls precise movie mode current levels. the movie mode current can be adjusted in a logarithmic fashion to one of 16 steps represented as a fraction of the maximum movie mode current in table 2. on initial en, the movie-mode output immediately supplies 100% of the set movie-mode current. data percentage of maximum mm current 1* 100% 2 89% 3 79% 4 71% 5 63% 6 56% 7 50% 8 45% 9 40% 10 36% 11 32% 12 28% 13 25% 14 22% 15 20% 16 0% table 2: address 0, movie mode (mm) current programming. flash to maximum movie mode current ratio ? address 3 the maximum movie mode current is a fixed ratio of the flash current controlled by address 3. the ratio may be varied from 1:2 to off in 16 linear steps as shown in table 3. the default value for address 3 is data = 4 and represents a flash to maximum movie mode current level of 1 to 7.3. the default maximum movie mode current can be calculated: i fl(max) 7.3 i movie mode = for example, if an r set value of 107k is chosen, then the flash current is set to 1500ma. for movie mode operation, the maximum current available is then: 1500ma 7.3 i movie mode = = 206m a the maximum movie mode current level can be calcu- lated using the following equation: 107k a r set 1 fl to mm ratio i movie mode = = = max movie mode current data flash to movie mode ratio 1? 2 1/3.8 3 1/5.5 4* 1/7.3 5 1/8.9 6 1/10.5 7 1/12.2 8 1/13.8 9 1/14.9 10 1/16.5 11 1/18 12 1/19.6 13 1/21.1 14 1/22.6 15 1/24 16 off table 3: address 3, flash/ movie mode current ratio. shutdown since the flash current sink is the only power returns for the flash led loads, there is no leakage current to load if all the sink switches are disabled. when the en/set pin is held low for an amount of time greater than t off (500 s), the aat1274 flash boost converter section enters shutdown mode and draws less than 1 a from the input power source. all data and address registers for the flash and/or movie mode are cleared (reset to 0) during shutdown. selecting the boost inductor the aat1274 controller utilizes pwm control and the switching frequency is fixed. to maintain 2mhz maximum switching frequency and stable operation, a 1 h inductor is recommended. manufacturer?s specifications list both the inductor dc current rating, which is a thermal limita- tion, and peak inductor current rating, which is deter- mined by the saturation characteristics. measurements at full load and high ambient temperature should be per- formed to ensure that the inductor does not saturate or exhibit excessive temperature rise.
aat1274 1.5a single flash led driver ic data sheet 13 skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201981a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 21, 2012 selecting the boost capacitors in general, it is a good design practice to place a decou- pling capacitor (input capacitor) between the in and ground. an input capacitor in the range of 2.2 f to 10 f is recommended. a larger input capacitor in this applica- tion may be required for stability, transient response, and/or ripple performance. the high output ripple inher- ent in the boost converter necessitates the use of low impedance output filtering. multi-layer ceramic (mlc) capacitors provide small size and adequate capacitance, low parasitic equivalent series resistance (esr) and equivalent series inductance (esl), and are well suited for use with the aat1274 boost regulator. mlc capacitors of type x7r or x5r are recommended to ensure good capacitance stability over the full operating temperature range. the output capacitor is selected to maintain the output load without significant voltage droop ( ? v out ) dur- ing the power switch on interval. a 2.2 f ceramic output capacitor is recommended (see table tbd). typically, 6.3v or 10v rated capacitors are required for this flash led boost output application. ceramic capacitors selected as small as 0603 are available which meet these require- ments. mlc capacitors exhibit significant capacitance reduction with applied voltage. output ripple measure- ments should confirm that output voltage droop and operating stability are within acceptable limits. voltage de-rating can minimize this factor, but results may vary with package size among specific manufacturers. to maintain stable operation at full load, the output capaci- tor should be selected to maintain ? v out between 100mv and 200mv. the boost converter input current flows dur- ing both on and off switching intervals. the input ripple current is less than the output ripple and, as a result, less input capacitance is required. pcb layout guidelines boost converter performance can be adversely affected by poor layout. possible impact includes high input and output voltage ripple, poor emi performance, and reduced operating efficiency. every attempt should be made to optimize the layout in order to minimize para- sitic pcb effects (stray resistance, capacitance, and inductance) and emi coupling from the high frequency sw node. a suggested pcb layout for the aat1274 1.5a step-up regulator is shown in figures 3 and 4. the fol- lowing pcb layout guidelines should be considered: 1. minimize the distance from capacitor c in and c out ?s negative terminals to the pgnd pins. this is espe- cially true with output capacitor c out , which conducts high ripple current from the output to the pgnd pins. 2. minimize the distance under the inductor between in and switching pin sw; minimize the size of the pcb area connected to the sw pin. 3. maintain a ground plane and connect to the ic pgnd pin(s) as well as the pgnd connections of c in and c out . 4. consider additional pcb exposed area for the flash led to maximize heatsinking capability. this may be necessary when using high current application and long flash duration application. 5. connect the exposed paddle (bottom of the die) to pgnd or gnd. connect agnd, flgnd to gnd as close as possible to the package. manufacturer part number inductance ( h) saturated rated current (a) dcr (m ) size (mm) lxwxh type cooper bussmann sd3812-1r0-r 1 2.69 48 4.0 x 4.0 x 1.2 shielded drum core cooper bussmann sdh3812-1r0-r 1 3 45 3.8 x 3.8 x 1.2 shielded drum core cooper bussmann SD10-1R0-R 1 2.25 44.8 5.2 x 5.2 x 1.0 shielded drum core sumida cdh38d11/s 1 2.69 48 4.0 x 4.0 x 1.2 shielded drum core coilcraft lps4012-102nlc 1 2.5 60 4.1 x 4.1 x 1.2 shielded drum core table 4: typical suggested surface mount inductors. manufacturer part number capacitance ( f) voltage rating (v) temp co. case size murata grm185r60j225ke26 2.2 6.3 x5r 0603 murata grm188r71a225ke15 2.2 10 x7r 0603 murata grm21br70j225ka01 2.2 6.3 x7r 0805 murata grm21br71a225ka01 2.2 10 x7r 0805 murata grm219r61a475ke19 4.7 10 x5r 0805 murata grm21br71a106ke51 10 10 x7r 0805 table 5: typical suggested surface mount capacitors.
aat1274 1.5a single flash led driver ic data sheet 14 skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201981a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 21, 2012 c2 2.2f c1 2.2f r1 133k d1 dc+ vout 0 jp1 vdd 1 gp5 2 gp4 3 gp3 4 gp2 5 gp1 6 gp0 7 vss 8 u2 pic12f675 c3 1f r4 100k (opt) r8 330 led1 red 1 2 3 4 5 0 sw4 flinh 1 2 3 4 5 0 sw1 movie mode control r5 10k led2 grn r9 330 dc- 0 jp2 r2 100k jp4 10k r3 jp5 en/set jp3 mcu 1 2 3 4 5 0 sw2 flash movie mode r6 10k r7 10k l1 cooperbussmann sd3812-1r0-r, 1h, 2.69a, 48m c1, c2 murata grm188r71a225ke15 2.2f, 0603, x7r, 10v d1 lumiled lxcl-pwf4 or equivalent 1uh l1 agnd 5 agnd 1 in 6 out 8 en/set 2 fl 3 pgnd 7 flen 4 n/c 9 sw 10 flinh 11 n/c 12 flgnd 13 rset 14 u1 aat1274 tdfn33-14 c4 220f 1 2 3 4 5 0 sw3 flen r10 100k figure 2: aat1274 evaluation board schematic. figure 3: aat1274 evaluation board figure 4: aat1274 evaluation board top side layout. bottom side layout.
aat1274 1.5a single flash led driver ic data sheet 15 skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201981a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 21, 2012 component part number description manufacturer u1 aat1274iwo 1.5a step-up current regulator for flash led; tdfn33-14 package skyworks u2 pic12f675 8-bit cmos, flash-based c; 8-pin soic package microchip sw1 ? sw4 pts645tl50 switch tact, spst, 5mm itt industries r1 chip resistor 133k , 1%, 1/4w; 0402 vishay r2, r4, r10 chip resistor 100k , 1%, 1/4w; 0603 vishay r3, r5, r6, r7 chip resistor 10k , 5%, 1/4w; 0603 vishay r8, r9 chip resistor 330 , 5%, 1/4w; 0603 vishay jp1, jp2 chip resistor 0 , 5% vishay c1, c2 grm188r71a225ke15 2.2 f, 10v, x7r, 0603 murata c3 grm216r61a105ka01 1 f, 10v, x5r, 0805 murata l1 sd3812-1r0-r drum core, 1 h, 2.69a, 48m cooper bussmann d1 fcw401z4 white flash led seoul semiconductor led1 cmd15-21src/tr8 red led; 1206 chicago miniature lamp led2 cmd15-21vgc/tr8 green led; 1206 chicago miniature lamp jp3, jp4, jp5 prpn401paen conn. header, 2mm zip sullins electronics table 6: aat1274 evaluation board bill of materials.
aat1274 1.5a single flash led driver ic data sheet 16 skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201981a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 21, 2012 1. xyy = assembly and date code. 2. sample stock is generally held on part numbers listed in bold . 3. the leadless package family, which includes qfn, tqfn, dfn, tdfn, and stdfn, has exposed copper (unplated) at the end of th e lead terminals due to the manufacturing process. a solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder c onnection. ordering information package marking 1 part number(tape and reel) 2 tdfn33-14 b1xyy aat1274iwo-t1 skyworks green? products are compliant with all applicable legislation and are halogen-free. for additional information, refer to skyworks de?ition of green , document number sq04-0074. package information tdfn33-14 top view bottom view 3.000 0.050 index area 3.000 0.050 detail "a" 1.650 0.050 2.500 0.050 0.203 ref 0.750 0.050 0.000 + 0.100 - 0.000 detail "a" side view 0.425 0.050 0.400 bsc 0.180 0.050 pin 1 indicator (optional)
aat1274 1.5a single flash led driver ic data sheet 17 skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201981a ? skyworks proprietary information ? products and product information are subject to change without notice. ? may 21, 2012 copyright ? 2012 skyworks solutions, inc. all rights reserved. information in this document is provided in connection with skyworks solutions, inc. (?skyworks?) products or services. these m aterials, including the information contained herein, are provided by skyworks as a service to its customers and may be used for informational purposes only by the customer. skyworks assumes no responsibility fo r errors or omissions in these materials or the information contained herein. sky- works may change its documentation, products, services, speci cations or product descriptions at any time, without notice. skyworks makes no commitment to update the materials or informati on and shall have no responsibility whatsoever for con icts, incompatibilities, or other dif culties 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 here- under, including the sale, distribution, reproduction or use of skyworks products, information or materials, except as may be p rovided in skyworks terms and conditions of sale. the materials, products and information are provided ?as is? without warranty of any kind, whether express, implied, statutory, or otherwise, including fitness for a particular purpose or use, merchantability, performance, quality or non-infringement of any intellectual property right; all such warranti es are hereby expressly disclaimed. skyworks does not warrant the accuracy or completeness of the information, text, graphics or other items contained within these materials. sk yworks shall not be liable for any damages, in- cluding but not limited to any special, indirect, incidental, statutory, or consequential damages, including without limitation , lost revenues or lost profits that may result from the use of the materials or information, whether or not the recipient of materials has been advised of the possibility of such damage. 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 en- vironmental 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 using skyworks products, which may deviate from published speci cations as a result of design defects, errors, or operation of products outside of pub- lished parameters or design speci cations. customers should include design and operating safeguards to minimize these and other risks. skyworks assumes no liabi lity for applications assistance, customer product design, or damage to any equipment resulting from the use of skyworks products outside of stated published speci cations or parameters. skyworks, the skyworks symbol, and ?breakthrough simplicity? are trademarks or registered trademarks of skyworks solutions, inc ., in the united states and other countries. third-party brands and names are for identi cation purposes only, and are the property of their respective owners. additional information, including relevant terms and co nditions, posted at www.skyworksinc.com, are incorporated by reference.

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