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1 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 general description the AAT1282 is a high-efficiency, high-current step-up converter capable of 2a maximum output current. it is an ideal power solution for led photo flash applications in all single cell li-ion powered products. the AAT1282 maintains output current regulation by switching the internal high-side and low-side switch transistors. the transistor switches are pulse-width modulated at a fixed frequency of 2mhz. the high switching frequency allows the use of a small inductor and output capacitor, making the AAT1282 ideally suited for small battery-powered applications. a high-capacity super capacitor on the secondary side of the step-up converter provides the high-peak flash led current, thereby reducing the peak current demand from the li-ion battery. to achieve this, the step-up converter features a fixed, input current limiter. an industry-standard i 2 c serial digital input is used to enable, disable and set the movie-mode current for each flash led with up to 16 movie-mode settings. the AAT1282 also includes a separate flash enable input to initiate both the flash operation and the default timer which can be used either to terminate a flash event at the end of a user-programmed delay or as a safety feature. the maximum flash and movie-mode current is set by one external resistor where the ratio between flash to movie-mode current is set at approximately 7.3:1. one or two leds can be connected to the AAT1282, where in the case of two leds the output current is matched between each diode. the ratio of maximum flash current to movie- mode current can also be adjusted via the i 2 c control. the AAT1282 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 AAT1282 is available in a pb-free, thermally- enhanced 14-pin 3 x 3mm tdfn package. features ?? v in range: 2.7v to 5.5v ?? dual channel output ? up to 2a regulated output current ?? 1a per channel ?? integrated fixed input current limit ? 800ma* ? suited for super capacitor applications ?? up to 80% efficiency with small magnetics ?? 2mhz switching frequency ?? independent flash enable ?? user-programmable safety timer ?? single resistor sets flash and movie-mode current ?? two wire, i 2 c compliant serial interface: ? fast, 400khz serial transfer rate ? 16 level movie-mode current ? flash/movie-mode ? current output channel control ? safety timer ? true load disconnect ? supply current in shutdown: <1.0 a ? tdfn33-14 package applications ? camcorder video light (torch light) ? camera phones/smartphones ? digital still cameras (dsc) ? led photo flash light (strobe light) ? mobile handsets * contact sales for alternative current limits.
2 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 typical application circuit AAT1282 r set 80.6k c in 2.2f c t 47nf l1 1h in sw out flouta ct rset agnd pgnd floutb flgnd c out 2.2f flash leds r scb1 30k r scb2 30k super capacitor en scl sda enable sda scl i 2 c interface flen flash enable v bat pin descriptions pin # symbol function description 1ct i flash timer control input. connect a capacitor between ct and agnd to set default on time for the ash output. a 47nf ceramic capacitor defaults the ash timer to 600ms. alternative timeout periods can be programmed via i 2 c. to disable the ash timer, connect ct to agnd. 2en i enable control input, an active high asserted input. en must be strobed low-to-high to enable the AAT1282 to accept i 2 c programming instructions. 3 flen i flash enable pin. a low-to-high transition on the flen pin initiates a ash pulse and starts the ash timer. 4 agnd p analog ground pin. connect agnd to pgnd and flgnd at a single point as close to the AAT1282 as possible. 5in pi power input. connect in to the input power supply voltage. connect a 2.2 f or larger ceramic capacitor from in to pgnd as close as possible to the AAT1282. 6 sw o step-up converter switching node. connect a 1 h inductor between sw and in. 7 pgnd p power ground pin. connect pgnd to agnd and flgnd at a single point as close to the AAT1282 as possible. 8 out o power output of the step-up converter. connect a 2.2 f or larger ceramic capacitor from out to pgnd as close as possible to the AAT1282. connect out to the super capacitor and the anode(s) of the flash led(s). 9 scl i i 2 c interface: serial control line. 10 sda i i 2 c interface: serial data/address. 11 floutb o flash output b. connect cathode of flash ledb to floutb. for a single ash led, connect floutb and flouta together. for two ash leds, each output will conduct 50% of the total ash output current. can be turned off or on via i 2 c. 12 flgnd p flash ground pin. connect flgnd to pgnd and agnd at a single point as close to the AAT1282 as possible. 13 flouta o flash output a. connect cathode of flash led a to flouta. for a single ash led, connect flouta and floutb together. for two ash leds, each output will conduct 50% of the total ash output current. can be turned off or on via i 2 c. 14 rset i flash current setting input. a 80.6k resistor from rset to agnd sets the maximum ash cur- rent available at flouta and floutb to 2000ma. each flouta and floutb channel will con- duct 50% of the maximum programmed current (1000ma). the AAT1282?s ash-to-movie-mode default ratio is a xed at 7.3 but can be adjusted via i 2 c. ep exposed paddle (bottom); connect ep to pgnd as close as possible to the AAT1282.
3 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 pin configurations tdfn33-14 (top view) ct en flen 1 a gnd in sw pgnd rset flout a flgnd floutb sda scl out 2 3 4 5 6 7 14 13 12 11 10 9 8 ep absolute maximum ratings 1 t a = 25 o c unless otherwise noted. symbol description value units v in , v sw , v out in, sw, out to gnd or pgnd -0.3 to 6.0 v v rset , v en , v flen , v scl , v sda , v ct , v flouta , v floutb rset, en, flen, scl, sda, ct, flouta, floutb to gnd, pgnd, or flgnd v in + 0.3 i out flout1 and flout2 2 2200 ma thermal information 3 symbol description value units ja thermal resistance 50 o c/w p d maximum power dissipation 2 w t j maximum junction operating temperature -40 to +150 o c t lead maximum soldering temperature (at leads, 10 sec) 300 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. only one absolute maximum rating should be applied at any one time. 2. based on long-term current density limitation. 3. mounted on an fr4 circuit board.
4 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 electrical characteristics 1 v in = 3.6v; c in = 2.2 f; c out = 2.2 f; l = 1 h; r set = 80.6k ; t a = -40c to +85, unless otherwise noted. typical values are t a = 25c. symbol description conditions min typ max units power supply v in input voltage range 2.7 5.5 v i in(q) supply current en = in; flen = agnd; set load = 2a; r set = 80.6k ? 0.57 1 ma i shdn(max) shutdown current en = flen = agnd 1.0 a i fl(total) total output current, flash mode r set = 80.6k ? ; flouta + floutb 1800 2000 2200 ma i fl(match) flouta and floutb current matching 10 % i mm(total) total output current, movie-mode r set = 80.6k ? ; movie-mode current set = 100%; flouta + floutb 274 ma f osc switching frequency t a = 25c 1.5 2.0 2.5 mhz t default default on time c t = 47nf 600 ms t sd thermal shutdown threshold 140 ? c t sd(hys) thermal shutdown hysteresis 15 ? c i 2 c control ? sda, scl v il input threshold low 0.4 v v ih input threshold high 1.4 v i i input current -1.0 1.0 a v ol output logic low (sda) i pullup = 3ma 0.4 v f scl scl clock frequency 0 400 khz t low scl clock low period 1.3 s t high scl clock high period 0.6 s t hd_sta hold time start condition 0.6 s t su_sta setup time for repeat start 0.6 s t su_dat sda data setup time 100 ns t hd_dat sda data hold time 0.9 s t su_sto setup time for stop condition 0.6 s t buf bus free time between stop and start condition 1.3 s en, flen logic control v en(l) , v flen(l) en, flen input low threshold 0.4 v v en(h) , v flen(h) en, flen input high threshold 1.4 v t flen_ond flen on delay time en = agnd 40 s t flen_offd flen off delay time en = agnd 10 s 1. the AAT1282 is guaranteed to meet performance specifications over the -40c to +85c operating temperature range and is assu red by design, characterization, and correla- tion with statistical process controls.
5 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 i 2 c interface timing details t su_sto t su_sta t hd_sta t high t low t su_dat t hd_dat sda scl t buf t hd_sta
6 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 typical characteristics boost converter efficiency (p out /p in ) without supercap (l = 1h) input voltage (v) efficiency (% ) 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 60 65 70 75 80 85 90 95 100 274ma 200ma 142ma 100ma flash mode led current matching vs. temperature (i floutx = 1a/channel; v in = 3.6v; supercap [5.5v, 0.55f] ) temperature (c) led current matching (% ) 0 0.5 1 1.5 2 2.5 3 3.5 4 -40 -15 10 35 60 85 flash mode led current vs. temperature (i floutx = 1a/channel; v in = 3.6v; supercap [5.5v, 0.55f] ) temperature (c) flash mode led current (ma ) 0 200 400 600 800 1000 1200 -40 -15 10 35 60 85 flash turn on characteristic (i floutx = 1a/ch; v in = 3.6v; supercap [5.5v, 0.55f] ) time (50ms/div) i led = i floutx (1a/div) v sw (5v/div) v out (2v/div) v floutx (5v/div) 0v 0a 0v 4v movie mode led current accuracy (i floutx = 100ma/channel; l = 1h) input voltage (v) output current accuracy (% ) -8 -6 -4 -2 0 2 4 6 8 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 movie mode led current matching (i floutx = 100ma/channel; l = 1h) input voltage (v) matching (% ) 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
7 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 typical characteristics movie mode ripple (v out = 5.5v; v in = 3.6v; i floutx = 137ma/ch; l = 1h) time (200ns/div) i sw (500ma/div) v in (ac coupled) (50mv/div) v out (ac coupled) (50mv/div) i floutx (ac coupled) (10ma/div) 200ma movie mode transition characteristic (i floutx = 137ma/ch to 50ma/ch; supercap [5.5v, 0.55f ]) time (200s/div) v floutx (ac coupled) (100mv/div) v out (5v/div) sda pin (5v/div) i floutx (100ma/div) 0a 0v 0v movie mode turn on characteristic (i floutx = 137ma/ch; v in = 3.6v; supercap [5.5v, 0.55f] ) time (100s/div) i sw (1a/div) v out (5v/div) sda pin (5v/div) i floutx (100ma/div) 0a 0a 0v 0v shutdown current vs. input voltage (v en = v flen = gnd = agnd = flgnd) input voltage (v) shutdown current (a ) 0 0.005 0.01 0.015 0.02 0.025 0.03 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 -40c 25c flash timeout vs. temperature (v in = 3.6v; c t = 47nf; i floutx = 1a/ch) temperature (c) flash timeout (ms) -40 -15 10 35 60 85 200 300 400 500 600 700 800 900 1000 flash timeout vs. c t capacitor (i floutx = 1a/ch; supercap [5.5v, 0.55f] ) c t capacitor (nf) flash timeout (ms) 0 5 10 15 20 25 30 35 40 45 50 0 100 200 300 400 500 600 700 800
8 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 typical characteristics supply current vs. input voltage (v en = 3.6v; v flen = flgnd) input voltage (v) supply current (a ) 0 100 200 300 400 500 600 700 800 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 -40c 25c 85c enabling and supercap charging characteristic (v in = 3.6v; supercap [5.5v, 0.55f] ) time (1s/div) i sw (1a/div) v in (2v/div) v out (5v/div) i in (1a/div) 0a 0a 0v 3.6v movie mode switching frequency vs. input voltage (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 -40c 85c 25c -40c 25c 85c en, flen high threshold voltage vs. input voltage input voltage (v) v en(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 -40c 25c 85c en, flen low threshold voltage vs. input voltage input voltage (v) v en(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 -40c 25c 85c
9 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 functional description the AAT1282 is a high power, 2a flash led driver. this device utilizes a highly efficient inductive step-up con- verter to achieve to desired output voltage (super capacitor voltage, 5.5v). the current of two output channels are regulated evenly which is discharged from the output super capacitor, mainly for camera flash applications. the maximum flash current is set by an external resistor, r set , which also sets the maximum movie-mode current. the maximum movie-mode current is equal to the maxi- mum programmed flash current reduced by the flash-to- movie-mode ratio with the default value set to 1:7.3. a flash pulse is initiated by strobing the flen input pin low- to-high, which initiates a flash pulse and also starts the internal safety timer. the maximum flash time is deter- mined by an external timing capacitor connected to the ct pin. the flash duration can be set from 50ms up to a maximum of 1s. the flash timer will terminate the flash current regardless of the status of the flen pin. this can be either used as a simple flash timing pulse or can be used as a safety timer in the event of a control logic mal- function to prevent the leds from over-heating. if the safety timer is not needed in the application, it can be disabled by connecting the ct pin directly to agnd. further adjustments to the timeout period can be obtained by programming through the i 2 c interface. when the AAT1282 is enabled, the step-up convertor operates at 2mhz switching and charged up the super capacitor to 5.5v in seconds. as soon as the super capacitor reaches 5.5v, the AAT1282 automatically changes to light load mode operation to maintain output regulation at light load or no load condition. this is dis- continuous mode operation, and is normal behavior for a switching regulator. at this point, the leds are ready to be flashed. during the flash, the boost engine is shut down, and the two leds connected to its corresponding current channel (flouta or floutb) share the output current supplied by the super capacitor equally. (the duration of the flash will be further discussed in the applications information section of this datasheet.) in applications where only one led is connected to either flouta or floutb, the unused current channel must be directly connected to out, thereby disabling that channel. for the single ultra bright led application which requires doubling the flash current, the two current channels can be connected together which allow this ultra bright single led getting the full output current (please check with the led specification from led suppliers). during the movie-mode operation, the safety timer is disabled. enabling each output channel (flouta and floutb can be enabled or disabled individually or together) and programming the flash-to-movie-mode functional block diagram sw pgnd flout a agnd rset in ct floutb flgnd out en flen scl pgnd control sda
10 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 current ratio can be set using the AAT1282?s i 2 c-compliant interface. the movie-mode current level can be adjusted in 16 steps using a logarithmic scale. the maximum flash safety timer can be externally set by ct, and the timer can be programmed from the maximum value in 16 linear steps through i 2 c-compliant interface. the flen signal takes priority over movie-mode operation. lastly, the en pin must be toggled low-to-high to enable the AAT1282 to accept any i 2 c programming instructions. over-temperature protection thermal protection disables the AAT1282 when internal power dissipation becomes excessive, as it disables both mosfets. the junction over-temperature threshold is 140c with 15c of temperature hysteresis. the output voltage automatically recovers when the over-tempera- ture fault condition is removed. over-voltage protection (open led, open super capacitor) the AAT1282?s output voltage is limited by internal over- voltage protection circuitry, which prevents damage to the AAT1282 from an open super capacitor condition. during this condition, the output voltage rises and reaches 5.5v (typical), preventing the output voltage from rising higher. once the open super capacitor condi- tion is removed, charging of the super capacitor will resume. the controller will return to normal operation and maintain an average output voltage. if one led channel accidently becomes open, the remain- ing led channel of AAT1282 will still work, but may not be regulated to the desired current. device start up and shutdown the AAT1282 is put into operation when en is set high. it is put into a shutdown mode when en is set to gnd. in the shutdown mode, AAT1282 draws less than 1 a from the battery. all data and register contents are cleared (reset to the default value) during shutdown. during start up of this led driver, the peak current is limited in order to avoid high peak current drawn from the battery. operating diagram led current flash times out enable flash enable t ct turn on leds in movie mode controlled by i 2 c interface v out = supercap voltage 5.5v
11 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 applications information led selection the AAT1282 is specifically designed to drive ultra bright flash leds with typical forward voltage of 2.5v to 4.0v within 1a forward current. since the flouta and floutb pins have internal current-mirror circuitry which matches both channels with tight accuracy up to 1a per channel; the led-to-led brightness will be matched regardless of the individual led forward voltage (v f ). circuit designers should consult the led supplier for led specifications. flash mode led current the led current is controlled by the r set resistor. for maximum accuracy, a 1% tolerance resistor is recom- mended. flouta and floutb can be programmed up to a maximum total flash current of 2000ma or up to 1000ma per channel. flouta and floutb output current is matched across the programming range. a flash event is initiated by asserting the flen pin. a flash event is automatically terminated when flen is disabled or if the safety timer terminates before the flen pin is disabled. the maximum flash current in each flouta and floutb is set by the r set resistor and can be calculated using the following equation: 81k a r set 81k a 80.6k i flouta = i floutb = = ~1000ma per channel = to prevent excessive power dissipation during higher flash current operation, r set values smaller than 80.6k are not recommended. since the super capacitor is the only source for the led flash current, the duration of the flash is determined by the energy stored in the super capacitor. during flash, the energy of the super capacitor is discharged; at the same time, the voltage of the super capacitor is decreased. once the super capacitor voltage is lowered to a level (the minimum sink pin voltage + the led forward voltage), the flash is ended. with a fully charged super capacitor in place, the flash for two 1a leds can last for more than 500ms. movie mode led current the maximum movie-mode current level is set by the maximum, programmed flash current reduced by the programmed flash-to-movie-mode ratio in which the default value is 7.3: i flout[a/b](max) 7.3 i movie-mode[a/b] = = 137ma = 1000ma 7.3 to change the configuration or the settings, the AAT1282 can be programmed via the i 2 c interface. triggering the flen low to high will enable a flash event with the maximum flash current set by the r set resistor or with programmed flash current set via the i 2 c interface. concurrently, the flash timer is also initiated. all data and register contents are cleared (reset to the default value) after each flash event. flash safety timeout the AAT1282 includes a timer circuit that enables the flash current for a programmed period of time. this fea- ture eliminates the need for an external, housekeeping baseband controller to contain a safety delay routine. it also serves as a protection feature to minimize thermal issues with the flash leds in the event an external con- troller?s flash software routine experiences hang-up or freeze. the flash safety timeout, t can be calculated by the following equation: t = 13.5s/ f c t where t is in seconds and c t is the capacitance of the timer capacitor in f. for example, using a 74nf capacitor for c t sets the flash timeout to: flash safety timeout = 13.5s/ f 0.074 f = 1s the relationship between the flash safety timeout and the capacitance of the timer capacitor is illustrated in figure 1. c t capacitor (nf) flash safety timeout (ms) 0102030405060708090 0 200 400 600 800 1000 1200 figure 1: flash safety timeout vs. timer capacitor.
12 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 i 2 c serial interface the AAT1282 is fully compliant with the industry-stan- dard i 2 c interface. the i 2 c two-wire communications bus consists of sda and scl lines. sda provides data, while scl provides clock synchronization with speed up to 400khz. sda data transfers device address followed by a register address and data bits sequence. when using the i 2 c interface, en is pulled high to enable the device or low to disable the device. the i 2 c serial interface requires a master to initiate all the communications with target devices. the AAT1282 is a target device and only supports the write protocol. the AAT1282 is manufac- tured with a target device address of 0x37 (hex). see figure 2 for the i 2 c interface diagram. i 2 c start and stop conditions start and stop conditions are always generated by the master. prior to initiating a start, both the sda and scl pins are in idle mode (idle mode is when there is no activity on the bus and sda and scl are pulled high by the external pull-up resistors). a start condition occurs when the master strobes the sda line low and after a short period strobes the scl line low. a start condition acts as a signal to all ics that transmission activity is about to occur on the i 2 c bus. a stop condition, as shown in figure 2, is when master releases the bus and scl changes from low to high followed by sda low-to- high transition. the master does not issue an acknowledge and releases the scl and sda pins. i 2 c address bit map figure 4 illustrates the address bit transfer. the 7-bit address is transferred with the most significant bit (msb) first and is valid when scl is high. this is followed by the r/w bit in the least significant bit (lsb) location. the r/w bit on the eighth bit determines the direction of the transfer (a '1' for read or a '0' for write). the AAT1282 is a write-only device and the r/w bit must be set low. the acknowledge bit (ack) is set to low by the AAT1282 to acknowledge receipt of the address. i 2 c register address/data bit map figure 5 illustrates the register address or the serial data bit transfer. the 8-bit data is always transferred most significant bit first and is valid when scl is high. the acknowledge bit (ack) is set low by the AAT1282 to acknowledge receipt of the register address or the data. i 2 c acknowledge bit (ack) the acknowledge bit is the ninth bit of each transfer on the sda line. it is used to send back a confirmation to the master that the data has been received properly by the target device. for each ack to take place, the mas- ter must first release the sda line, and then the target device will pull the sda line low, as shown in figures 1, 4, and 5. AAT1282 device address = 37h w ack register address = 00h ack data = 06h ack stop start sda scl start msb device address lsb w ack msb register address lsb ack msb data lsb ack stop ack from slave ack from slave ack from slave figure 2: i 2 c interface diagram.
13 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 sda scl sd a scl start stop figure 3: i 2 c stop and start conditions. start: a high ?1? to low ?0? transition on the sda line while scl is high ?1? stop: a low ?0? to high ?1? transition on the sda line while scl is high ?1? scl 1 2 3 4 567 8 9 sdaa6a5a4a3a2a1a0r/wack device address lsb msb figure 4: i 2 c address bit map; 7-bit slave address (a6-a0), 1-bit read/write (r/w), 1-bit acknowledge (ack). scl 1 2 3 4 567 8 9 sdad7d6d5d4d3d2d1 d0ack register address / data lsb msb figure 5: i 2 c register address and data bit map; 8-bit data (d7-d0), 1-bit acknowledge (ack).
14 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 device register information to program the register through the i 2 c interface, the master needs to send the AAT1282?s device address, 0x37 (hex), first, and then sends an 8-bit register address and 8-bit data. the AAT1282 has two registers, register 0 and register 1. if no instruction is written to the register, the default value is applied. register 0 (reg0), register address: 00h bits [7:4] program the movie-mode current with 16 different percentage levels. bits [3:0] program the flash safety timeout with 16 different fractions from the hardware configuration, ct. 7654321 0 lsb msb flash safety timeout 0000 = 16/16 0001 = 15/16 0010 = 14/16 0011 = 13/16 0100 = 12/16 0101 = 11/16 0110 = 10/16 0111 = 9/16 1000 = 8/16 1001 = 7/16 1010 = 6/16 1011 = 5/16 1100 = 4/16 1101 = 3/16 1110 = 2/16 1111 = 1/16 movie mode current 0000 = 100% 0001 = 89.1% 0010 = 79.4% 0011 = 70.8% 0100 = 63.1% 0101 = 56.2% 0110 = 50.1% 0111 = 44.7% 1000 = 39.8% 1001 = 35.5% 1010 = 31.6% 1011 = 28.2% 1100 = 25.1% 1101 = 22.4% 1110 = 20% 1111 = 0% (default) (default) figure 6: AAT1282 register 0 programming.
15 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 register 1 (reg1); register address: 01h bits [5:4] program the flouta and floutb with four on/off configurations. bits [3:0] program the flash-to-movie mode ratio with 16 different fractions from the hardware configuration, rset. xx54321 0 lsb msb flash-to-movie mode ratio 0000 = 1/2 0001 = 1/3.8 0010 = 1/5.5 0011 = 1/7.3 0100 = 1/8.9 0101 = 1/10.5 0110 = 1/12.2 0111 = 1/13.8 1000 = 1/14.9 1001 = 1/16.5 1010 = 1/18 1011 = 1/19.6 1100 = 1/21.1 1101 = 1/22.6 1110 = 1/24 1111 = off (default) 00 01 10 11 flouta off off* on on floutb off on off* on (default) *with 2-3ma standby current figure 7: AAT1282 register 1 programming. selecting the boost inductor the AAT1282 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. the inductor (l) is selected to avoid saturation at mini- mum input voltage and maximum output load conditions. worst-case peak current occurs at minimum input volt- age (maximum duty cycle) and maximum load. bench measurements are recommended to confirm actual i peak and to ensure that the inductor does not saturate at maximum led current and minimum input supply volt- age. the rms current flowing through the boost inductor is equal to the dc plus ac ripple components. under worst case rms conditions, the current waveform is critically continuous. the resulting rms calculation yields worst case inductor loss. the rms current value should be compared against the inductor manufacturer?s tem- perature rise, or thermal derating guidelines: i peak i rms = 3 for a given inductor type, smaller inductor size leads to an increase in dcr winding resistance and, in most cases, increased thermal impedance. winding resistance degrades boost converter efficiency and increases the inductor?s operating temperature: p loss(inductor) = i 2 rms dcr selecting the boost capacitors in general, it is good design practice to place a decou- pling capacitor (input capacitor) between the in and gnd pins. an input capacitor in the range of 2.2 f to 10 f is
16 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 recommended. a larger input capacitor in this application may be required for stability, transient response, and/or ripple performance. the high output ripple inherent in the boost converter necessitates the use of low impedance output filtering. multi-layer ceramic (mlc) capacitors pro- vide small size and adequate capacitance, low parasitic equivalent series resistance (esr) and equivalent series inductance (esl), and are well suited for use with the AAT1282 boost regulator. mlc capacitors of type x7r or x5r are recommended to ensure good capacitance sta- bility over the full operating temperature range. the out- put capacitor is selected to maintain the output load without significant voltage droop ( ? v out ) during the power switch on interval. a ceramic output capacitor 2.2 f is recommended (see table 2). typically, 6.3v or 10v rated capacitors are required for this flash led boost output. ceramic capacitors selected as small as 0603 are available which meet these requirements. mlc capacitors exhibit significant capacitance reduction with applied voltage. output ripple measurements should confirm that output voltage droop and operating stability are within acceptable limits. voltage derating can minimize this fac- tor, but results may vary with package size and among specific manufacturers. to maintain stable operation at full load, the output capacitor should be selected to main- tain ? v out between 100mv and 200mv. the boost con- verter input current flows during 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. super capacitor the AAT1282 requires a super capacitor connected to the output and the leds. after the super capacitor is fully charged, sufficient energy is stored and ready to provide large power surges such as flash peak current. when selecting a super capacitor, it is highly recom- mended to select a capacitor with an operating voltage of 5.5v and 500mf dc capacitance for the best results in AAT1282 camera flash applications. low profile, low impedance (low esr below 110m ), and a wide environ- mental operating range (-40c to +85c) should also be considered when selecting a capacitor for portable power management systems. please contact the super capaci- tor manufacturer(s) (such as tdk, cap-xx or murata) for detailed information. 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 parasitic pcb effects (stray resistance, capacitance, and inductance) and emi coupling from the high frequency sw node. a suggested pcb layout for the AAT1282 high power 2a flash led driver is shown in figures 8 through 11. the following 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 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 leds 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 either pgnd or gnd. connect agnd, flgnd to gnd as close as possible to the package.
17 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 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 tdk vls4012t-1ron1r6 1 2.5 60 4.0 x 4.0 x 1.2 shielded drum core table 1: 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 tdk c1608x5r1a225k 2.2 10 x5r 0603 murata grm219r61a475ke19 0.047 10 x5r 0805 tdk c1005x7r1c473k 0.047 16 x7r 0402 murata grm21br71a106ke51 10 10 x7r 0805 table 2: typical suggested surface mount capacitors. manufacturer part number capacitance (f) voltage rating (v) esr (m ) size (mm) lxwxh tdk edlc262020-501-2f50 0.5 5.6 50 20 x 20 x 2.6 cap-xx ha230 0.425 5.5 110 20 x 18 x 3.2 murata ** 0.425 5.5 110 20 x 18 x 3.2 table 3: typical suggested super capacitors. c2 2.2f l1 1h 2.2f c1 80.6k r1 fl 1 vout fl2 0 jp1 0 jp2 47nf c3 in 5 ct 1 sw 6 out 8 en 2 flen 3 pgnd 7 agnd 4 scl 9 sda 10 flb 11 flgnd 12 fla 13 rset 14 AAT1282 tdfn33-14 u1 enable jp3 10k r2 vcc flen sda scl 30.1k r1 2 30.1k r1 3 + 1 bal 3 gnd 2 sc1 0.55f figure 8: AAT1282 db1 microcontroller evaluation board schematic.
18 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 dc + vdd 1 gp5 2 gp4 3 gp3 4 gp2 5 gp1 6 gp0 7 vss 8 pic12f675 u2 1f c4 100k r9 330 r3 1 2 3 4 5 0 flen sw4 red led 1 1 2 3 4 5 0 movie mode control sw 1 10k r6 grn led 2 330 r4 dc - 0 jp8 jp4 10 k r8 sda jp6 scl jp5 mcu jp7 1 2 3 4 5 0 safety timer sw 2 10k r5 10k r10 10k r11 10k r7 1 2 3 4 5 0 a / b control sw 3 scl sda flen vcc figure 9: AAT1282 db1 microcontroller evaluation board mcu section schematic. figure 10: AAT1282 db1 microcontroller figure 11: AAT1282 db1 microcontroller evaluation board top side layout. evaluation board bottom side layout.
19 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 2.2f c2 1 h l1 2.2f c1 80.6k r1 fl1 vout fl 2 0 jp1 0 jp2 47nf c3 enable jp3 10k r2 vin 30.1k r4 30.1k r3 + 1 bal 3 gnd 2 0.50f sc1 in 5 ct 1 sw 6 out 8 en 2 flen 3 pgnd 7 agnd 4 scl 9 sda 10 floutb 11 flgnd 12 flouta 13 rset 14 AAT1282 tdfn33-14 u1 1 2 3 4 5 6 7 8 9 10 header 5x2 header vio gnd scl sda flen nc nc nc nc nc flen sda scl c4 opt figure 12: AAT1282 db2 usb/i 2 c evaluation board schematic. figure 13: AAT1282 db2 usb/i 2 c figure 14: AAT1282 db2 usb/i 2 c evaluation board top side layout. evaluation board bottom side layout.
20 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 component part# description manufacturer u1 AAT1282iwo high power 2a flash driver; tdfn33-14 package skyworks u2 pic12f675 8-bit cmos, flash-based c; 8-pin pdip package microchip sw1 ? sw4 pts645tl50 switch tact, spst, 5mm itt industries r1 chip resistor 80.6k , 1%, 1/4w; 0402 vishay r9 chip resistor 100k , 1%, 1/4w; 0603 vishay r2, r5, r6, r7, r8, r10, r11 chip resistor 10k , 5%, 1/4w; 0603 vishay r3, r4 chip resistor 330 , 5%, 1/4w; 0603 vishay r12, r13 chip resistor 30.1k , 1%, 1/4w; 0805 vishay jp1, jp2, jp8 chip resistor 0 , 5% vishay c1, c2 grm188r71a225ke15 2.2 f, 10v, x7r, 0603 murata c1608x5r1a225k 2.2 f, 10v, x5r, 0603 tdk c3 grm155r71a473ka01 47nf, 10v, x7r, 0402 murata c1005x7r1c473k 47nf, 16v, x7r, 0402 tdk c4 grm185r61a105ke36 1 f, 10v, x5r, 0603 murata l1 sd3812-1r0-r drum core, 1 h, 2.69a, 48m cooper bussmann vls4012t-1ron1r6 drum core, 1 h, 2.6a, 60m tdk fl1-fl2 * white flash led * led1 cmd15-21src/tr8 red led; 1206 chicago miniature lamp led2 cmd15-21vgc/tr8 green led; 1206 chicago miniature lamp sc1 edlc262020-501-2f50 5.5v, 0.50f, low esr, 30m tdk jp3, jp4, jp5, jp6, jp7 prpn401paen conn. header, 2mm zip sullins electronics table 4: AAT1282 evaluation board component listing. * lumileds lxcl-pwm1 or lxcl-pwf4, osram lw f65g, seoul semiconductor fcw401zd based on availability from the manufacturer.
21 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 ordering information package marking 1 part number (tape and reel) 2 tdfn33-14 zgxyy AAT1282i w o-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 3 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) all dimensions in millimeters. 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 the 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
22 AAT1282 data sheet 2a driver for high intensity led camera flash skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 202305c ? skyworks proprietary information ? products and product information are subject to change without notice. ? mar ch 20, 2013 copyright ? 2012, 2013 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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