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general description the aat3166 is a low noise, constant frequency charge pump dc/dc converter that uses a tri- mode load switch (1x), fractional (1.5x), and dou- bling (2x) conversion to maximize efficiency for white led applications. the aat3166 is capable of driving four leds for a total of 108ma from a 2.7v to 5.5v input. the current sinks may be operated individually or in parallel for driving higher-current leds. a low external parts count (two 1f flying capacitors and two small 1f capacitors at in and outcp) make this part ideally suited for small, battery-powered applications. analogictech's as 2 cwire? (advanced simple serial control?) serial digital input is used to enable, dis- able, and set current for each led with a 16-level logarithmic scale plus four low-current settings down to 115a. for optimized efficiency, low-current set- tings require only 50a of housekeeping current. each output of the aat3166 is equipped with built- in protection for output short-circuit and auto-dis- able for load short-circuit condition. built-in soft- start circuitry prevents excessive inrush current during start-up. a low-current shutdown feature dis- connects the load from the input and reduces qui- escent current to less than 1a. the aat3166 is available in a pb-free, space sav- ing, 3 3mm tdfn33-12 package and is rated over the -40c to +85c temperature range. features ?v in range: 2.7v to 5.5v ? fully programmable current with single wire ? 16-step logarithmic scale ? 14/18/27ma max current ? four low-current settings down to 115a ? low i q (50a) for single-channel, low- current mode ? tri-mode 1x, 1.5x, 2x charge pump for maximum efficiency and v f coverage ? drives up to four leds ? individual main-sub (3-1) group control ? no inductors, low noise operation ? 1mhz constant switching frequency ? small application circuit ? built-in thermal protection ? built-in auto-disable for open circuit ? automatic soft start ?i q <1ua in shutdown ? tdfn33-12 package applications ? color (rgb) lighting ? programmable current sink ? transmissive lcd display ? white led backlighting ? white photo flash for digital still cameras aat3166 high efficiency 1x/1.5x/2x charge pump for white led applications typical application 3166.2006.05.1.2 1 chargepump ? 2.7v to 5.5v en/set in en/set c2+ c2- c1+ c1- outcp d1 d2 d3 gnd aat3166 c in 1 f d1 c1 1 f c2 1 f d2 d3 d4 c out 1 f d4
pin descriptions pin configuration tdfn33-12 (top view) pin # symbol function 1 d4 current sink input #4. 2 en/set as 2 cwire serial interface control pin. 3 c1+ flying capacitor 1 positive terminal. connect a 1f capacitor between c1+ and c1-. 4 c1- flying capacitor 1 negative terminal. 5 outcp charge pump output to drive load circuit. requires 1f capacitor connected between this pin and ground. 6 c2+ flying capacitor 2 positive terminal. connect a 1f capacitor between c2+ and c2-. 7 c2- flying capacitor 2 negative terminal. 8 in input power supply. requires 1f capacitor connected between this pin and ground. 9 gnd ground. 10 d1 current sink input #1. 11 d2 current sink input #2. 12 d3 current sink input #3. ep exposed paddle; connect to ground as closely as possible to package. aat3166 high efficiency 1x/1.5x/2x charge pump for white led applications 2 3166.2006.05.1.2 d4 en/set c1+ 1 c1- outcp c2+ d3 d2 d1 gnd in c2- 2 3 4 5 6 12 11 10 9 8 7
absolute maximum ratings 1 thermal information 3 symbol description value units p d maximum power dissipation 4 2.0 w ja maximum thermal resistance 50 c/w symbol description value units v in input voltage to gnd -0.3 to 6 v v en/set en/set voltage to gnd -0.3 to v in + 0.3 v i out 2 maximum dc output current 150 ma t j operating junction temperature range -40 to 150 c t lead maximum soldering temperature (at leads, 10 sec) 300 c aat3166 high efficiency 1x/1.5x/2x charge pump for white led applications 3166.2006.05.1.2 3 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 tim e. 2. based on long-term current density limitation. 3. mounted on an fr4 board. 4. derate 20mw/c above 25c.
electrical characteristics 1 c in = c out = c 1 = c 2 = 1.0f; t a = -40c to +85c, unless otherwise noted. typical values are at t a = 25c, v in = 3.6v. symbol description conditions min typ max units input power supply v in operation range 2.7 5.5 v 1x mode, 3.0 v in 5.5, active, 0.3 no load current, high current mode 1.5x mode, 3.0 v in 5.5, active, 1ma i cc operating current no load current, high current mode 2x mode, 3.0 v in 5.5, active, 1 no load current, high current mode 1x mode, 3.0 v in 5.5, active, 50 a no load current, low current mode i shdn shutdown current v en/set = 0v 1 a i dx high current accuracy i set = 18ma, t a = 25c -10 10 % low current accuracy i set = 400a, t a = 25c 15 % i (d-match) current matching 2 v f :d1:d4 = 3.6v 0.5 1 % v th 1x to 1.5x or 1.5x to 2x transition 150 mv threshold at any i sink pin charge pump section t ss soft-start time 100 s f clk clock frequency 1000 khz en/set v en(l) enable threshold low v in = 2.7v 0.4 v v en(h) enable threshold high v in = 5.5v 1.4 v t en/set lo en/set 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 off en/set off timeout 500 s t lat en/set latch timeout 500 s i en/set en/set input leakage -1 1 a aat3166 high efficiency 1x/1.5x/2x charge pump for white led applications 4 3166.2006.05.1.2 1. the aat3166 is guaranteed to meet performance specifications over the -40c to +85c operating temperature range and is assu red by design, characterization, and correlation with statistical process controls. 2. current matching is defined as the deviation of any sink current from the average of all active channels.
typical characteristics unless otherwise noted, v in = 3.5v, c in = c out = c 1 = c 2 = 1f, t a = 25c. aat3166 high efficiency 1x/1.5x/2x charge pump for white led applications 3166.2006.05.1.2 5 current matching vs. temperature temperature ( c) current (ma) 17.0 17.2 17.4 17.6 17.8 18.0 18.2 18.4 18.6 18.8 19.0 -40 -20 0 20 40 60 80 channel 1 channel 4 channel 3 channel 2 turn-off from 1.5x mode (v in = 3.5v; 18ma load) 100 s/div en (2v/div) i in (100ma/div) v f (1v/div) turn-on to 2x mode (v in = 2.8v; 18ma load) 100 s/div en (2v/div) v out (2v/div) i in (200ma/div) v sink (500mv/div) turn-on to 1.5x mode (v in = 3.5v; 18ma load) 100 s/div en (2v/div) v out (2v/div) i in (200ma/div) v sink (500mv/div) turn-on to 1x mode (v in = 4.2v; 18ma load) 100 s/div en (2v/div) v out (2v/div) i in (200ma/div) v sink (500mv/div) efficiency vs. supply voltage supply voltage (v) efficiency (%) 0 10 20 30 40 50 60 70 80 90 100 2.5 2.8 3.0 3.3 3.5 3.8 4.0 4.3 4.5 4.8 5.0 5.3 5.5 5.1ma v f = 3.0v 350 a v f = 2.7v 18ma v f = 3.4v
typical characteristics unless otherwise noted, v in = 3.5v, c in = c out = c 1 = c 2 = 1f, t a = 25c. aat3166 high efficiency 1x/1.5x/2x charge pump for white led applications 6 3166.2006.05.1.2 input ripple vs. input voltage input voltage (v) input ripple (mv) 0 2 4 6 8 10 12 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 27ma 18ma 14ma load characteristics (v in = 3.2v; 2x mode; 27ma load) 500ns/div v out (40mv/div) v sink (40mv/div) v in (40mv/div) load characteristics (v in = 4.1v; 1.5x mode; 27ma load) 500ns/div v out (40mv/div) v sink (40mv/div) v in (40mv/div) load characteristics (v in = 2.8v; 2x mode; 18ma load) 500ns/div v out (40mv/div) v sink (40mv/div) v in (40mv/div) load characteristics (v in = 3.8v; 1.5x mode; 18ma load) 500ns/div v out (40mv/div) v sink (40mv/div) v in (40mv/div)
typical characteristics unless otherwise noted, v in = 3.5v, c in = c out = c 1 = c 2 = 1f, t a = 25c. aat3166 high efficiency 1x/1.5x/2x charge pump for white led applications 3166.2006.05.1.2 7 enable threshold low vs. input voltage input voltage (v) enable threshold low (v) 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5 -40 c 25 c 85 c enable threshold high vs. input voltage input voltage (v) enable threshold high (v) 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5 -40 c 25 c 85 c en/set off timeout vs. input voltage input voltage (v) en/set off timeout ( s) 0 50 100 150 200 250 300 350 400 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5 -40 c 25 c 85 c en/set latch timeout vs. input voltage input voltage (v) en/set latch timeout ( s) 0 50 100 150 200 250 300 350 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5 -40 c 25 c 85 c
aat3166 high efficiency 1x/1.5x/2x charge pump for white led applications 8 3166.2006.05.1.2 functional block diagram functional description the aat3166 is a tri-mode load switch (1x) and high efficiency (1.5x or 2x) charge pump device intended for white led backlight applications. to maximize power conversion efficiency, an internal sensing circuit monitors the voltage required on each constant current sink input and sets the load switch and charge pump modes based on the input battery voltage and the current sink input voltage. as the battery discharges over time, the aat3166 charge pump is enabled when any of the four cur- rent sink inputs near dropout. the charge pump initially starts in 1.5x mode. if the charge pump output drops enough for any current source output to become close to dropout, the charge pump will automatically transition to 2x mode. the aat3166 requires only four external components: two 1f ceramic capacitors for the charge pump flying capacitors (c1 and c2), one 1f ceramic input capacitor (c in ), and one 0.33f to 1f ceramic charge pump output capacitor (c out ). the four constant current sink inputs (d1 to d4) can drive four individual leds with a maximum cur- rent of 27ma nominal each. unused sink inputs should be connected to outcp, otherwise the part will operate only in 2x charge pump mode. the as 2 cwire serial interface enables the aat3166 and sets the current sink magnitudes. as 2 cwire addressing allows independent control of two groups of current sink input: d1~d3 and d4. constant current output level settings the constant current sink levels for d1 to d4 are set via the serial interface according to a logarith- mic scale where each code is approximately 1.8db lower than the previous code. in this manner, led d/a d/a d/a d/a 6 x 16 bit rom 1x, 1.5x, 2x charge pump 6 x 16 bit rom as 2 cwire interface voltage reference 1mhz oscillator soft-start control in en/set gnd d4 d3 d2 d1 outcp c1+ c1- c2+ c2-
brightness appears linear with each increasing code count. because the inputs d1 to d4 are true independent constant current sinks, the voltage observed on any single given input will be deter- mined by the actual forward voltage (v f ) for the led being driven. since the input current sinks of the aat3166 are programmable, no pwm (pulse width modulation) or additional control circuitry is needed to control led brightness. this feature greatly reduces the burden on a microcontroller or system ic to manage led or display brightness, allowing the user to "set it and forget it." with its high-speed serial interface (1mhz data rate), the input sink current of the aat3166 can be changed successively to brighten or dim leds in smooth transitions (e.g., to fade-out) or in abrupt steps, giving the user complete programmability and real-time control of led brightness. the 16 individual current level settings are each approximately 1.8db apart (see table 1). code 1 is full scale; code 15 is full scale attenuated by approximately 25db; and code 16 is reserved as a "no current" setting. table 1: current level settings. as 2 cwire serial interface the current sink input magnitude of the aat3166 is controlled by analogictech's advanced simple serial control (as 2 cwire) serial digital input. as 2 cwire adds addressing capability for multiple data registers over the simple serial control? (s 2 cwire?), which is capable of controlling only a single register. the aat3166 has four registers: bank1, bank2, max current, and low current. three addresses are used to control the two regis- ters. address 0 addresses both registers simultane- ously to allow the loading of both registers with the same data using a single write protocol. address 1 addresses register 1 for d1 to d3 current level set- tings. address 2 addresses register 2 for d4 cur- rent level settings. as 2 cwire relies on the number of rising edges of the en/set pin to address and load the registers. as 2 cwire latches data or address after the en/set pin has been held high for time t lat . address or data is differentiated by the number of en/set ris- ing edges. since the data registers are 4 bits each, the differentiating number of pulses is 2 4 or 16, so that address 0 is signified by 17 rising edges, address 1 by 18 rising edges, and address 2 by 19 rising edges. data is set to any number of rising edges between 1 and including 16. a typical write protocol is a burst of en/set rising edges signify- ing a particular address, followed by a pause with en/set held high for the t lat timeout period, a burst of rising edges signifying data, and a t lat timeout for the data registers. once an address is set, then multiple writes consisting of data only (without address) to the corresponding data regis- ter are allowed. address 0 is the default address on the first rising edge after the aat3166 has been disabled. if data is presented on the first rising edge with no prior address, both data registers are simultaneously loaded. the maximum current level is determined by the value set in register 3, the max current register. three scales are available for high operating cur- rents with maximum current levels of 27ma, 18ma, or 14ma. each scale maintains approximately 1.8db steps between settings. a separate mode is 27ma max 18ma max 14ma max data i out (ma) i out (ma) i out (ma) 127 18 14 222 15 11 3 18 12 8.8 4 14 10 7.1 5 12 7.9 6.0 6 10 6.3 4.8 7 8 5.1 3.8 8 6.2 4.1 3.1 9 5.2 3.5 2.6 10 4.3 2.9 2.1 11 3.3 2.2 1.7 12 2.9 1.9 1.4 13 2.4 1.6 1.2 14 1.9 1.3 1.0 15 1.4 1.0 0.7 16 0 0 0 aat3166 high efficiency 1x/1.5x/2x charge pump for white led applications 3166.2006.05.1.2 9
aat3166 high efficiency 1x/1.5x/2x charge pump for white led applications 10 3166.2006.05.1.2 available for ultra-low led current operation. when the max current register (register 3) is set to the low current setting, the low current regis- ter (register 4) must be programmed. the two most significant bits of the low current register control whether or not a given bank of current sinks is enabled. the least two significant bits of the low current register set the current level for both banks. for low current settings, the charge pump may be enabled if required by the battery voltage and led forward voltage conditions, and 1x mode quiescent current is approximately 100a for multi- ple channels or 50a for channel 4 operation only. both banks of current sinks must be in the same high or low current mode of operation. when en/set is held low for an amount of time greater than t off , the aat3166 enters shutdown mode and draws less than 1a from v in . data and address registers are reset to 0 during shutdown. as 2 cwire serial interface addressing low current register (address 4) auto-disable feature the aat3166 is equipped with an auto-disable fea- ture for each led channel. after the ic is enabled and started up, a test current of 120a (typical) is forced through each sink channel. the channel will be disabled if the voltage of that particular sink pin does not drop to a certain threshold. this feature is very convenient for disabling an unused channel or during an led fail-short event. thermal protection the aat3166 has a built-in thermal protection cir- cuit that will shut down the charge pump if the die temperature rises above the thermal limit, as would be the case during a short circuit of the outcp pin. main low sub low data current on current on current 1no no 2no no 3no no 4no no 5 no yes 115a 6 no yes 175a 7 no yes 280a 8 no yes 400a 9 yes no 115a 10 yes no 175a 11 yes no 280a 12 yes no 400a 13 yes yes 115a 14 yes yes 175a 15 yes yes 280a 16 yes yes 400a data max current 1 18ma 2 27ma 3 14ma 4 low current (see low current register for values) en/set data register address rising edges aat3166 0 17 1&2: d1~d4 current 1 18 1: d1~d3 current 2 19 2: d4 current 3 20 3: max current 4 21 4: low current
applications information led selection although the aat3166 is designed for driving white leds, the device also can be used to drive most types of leds with forward voltage specifications ranging from 2.0v to 4.7v. led applications may include main and sub-lcd display backlighting, camera photo-flash applications, color (rgb) leds, infrared (ir) diodes for remotes, and other loads benefiting from a controlled output current generated from a varying input voltage. since the d1 to d4 input current sinks are matched with neg- ligible voltage dependence, the led brightness will be matched regardless of the specific led forward voltage (v f ) levels. in some instances (e.g., in high-luminous-output applications such as photo flash), it may be neces- sary to drive high-v f type leds. the low-dropout current sinks in the aat3166 make it capable of driving leds with forward voltages as high as 4.7v at full current from an input supply as low as 3.0v. outputs can be paralleled to drive high-current leds without complication. device switching noise performance the aat3166 operates at a fixed frequency of approximately 1mhz to control noise and limit har- monics that can interfere with the rf operation of cellular telephone handsets or other communica- tion devices. back-injected noise appearing on the input pin of the charge pump is 20mv peak-to- peak, typically ten times less than inductor-based dc/dc boost converter white led backlight solu- tions. the aat3166 soft-start feature prevents noise transient effects associated with inrush cur- rents during start-up of the charge pump circuit. capacitor selection careful selection of the four external capacitors (c in , c 1 , c 2 , c out ) is important because they will affect turn-on time, output ripple, and transient per- formance. optimum performance will be obtained when low equivalent series resistance (esr) ceramic capacitors are used; in general, low esr may be defined as less than 100m . a value of 1f for all four capacitors is a good starting point when choosing capacitors. if the led current sources are programmed only for light current lev- els, then the capacitor size may be decreased. aat3166 high efficiency 1x/1.5x/2x charge pump for white led applications 3166.2006.05.1.2 11 as 2 cwire serial interface timing address data 1 en/set 2 17 18 address data reg 1 data reg 2 1 2 . . . n <= 16 0 1 0 0 n - 1 t hi t lo t lat t lat
aat3166 high efficiency 1x/1.5x/2x charge pump for white led applications 12 3166.2006.05.1.2 capacitor characteristics ceramic composition capacitors are highly recom- mended over all other types of capacitors for use with the aat3166. ceramic capacitors offer many advantages over their tantalum and aluminum elec- trolytic counterparts. a ceramic capacitor typically has very low esr, is lowest cost, has a smaller pcb footprint, and is non-polarized. low esr ceramic capacitors help maximize charge pump transient response. since ceramic capacitors are non-polarized, they are not prone to incorrect con- nection damage. equivalent series resistance esr is an important characteristic to consider when selecting a capacitor. esr is resistance internal to a capacitor that is caused by the leads, internal con- nections, size or area, material composition, and ambient temperature. capacitor esr is typically measured in milliohms for ceramic capacitors and can range to more than several ohms for tantalum or aluminum electrolytic capacitors. ceramic capacitor materials ceramic capacitors less than 0.1f are typically made from npo or c0g materials. npo and c0g materials generally have tight tolerance and are very stable over temperature. larger capacitor val- ues are usually composed of x7r, x5r, z5u, or y5v dielectric materials. large ceramic capacitors (i.e., greater than 2.2f) are often available in low- cost y5v and z5u dielectrics, but capacitors greater than 1f are not typically required for aat3166 applications. capacitor area is another contributor to esr. capacitors that are physically large will have a lower esr when compared to an equivalent material smaller capacitor. these larger devices can improve circuit transient response when compared to an equal value capacitor in a smaller package size.
ordering information package information tdfn33-12 all dimensions in millimeters. package marking 1 part number (tape and reel) 2 tdfn33-12 pxxyy AAT3166IWP-T1 aat3166 high efficiency 1x/1.5x/2x charge pump for white led applications 3166.2006.05.1.2 13 1. xyy = assembly and date code. 2. sample stock is generally held on part numbers listed in bold . top view bottom view detail "b" detail "a" side view 3.00 2.40 + all analogictech products are offered in pb-free packaging. the term ?pb-free? means semiconductor products that are in compliance with current rohs standards, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. for more information, please visit our website at http://www.analogictech.com/pbfree.
aat3166 high efficiency 1x/1.5x/2x charge pump for white led applications 14 3166.2006.05.1.2 advanced analogic technologies, inc. 830 e. arques avenue, sunnyvale, ca 94085 phone (408) 737-4600 fax (408) 737-4611 ? advanced analogic technologies, inc. analogictech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an analogictech pr oduct. no circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. analogictech reserves the right to make changes to their products or specifi cations or to discontinue any product or service without notice. customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information b eing relied on is current and complete. all products are sold sub- ject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. analogictech warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with anal ogictech?s standard warranty. testing and other quality con- trol techniques are utilized to the extent analogictech deems necessary to support this warranty. specific testing of all param eters of each device is not necessarily performed. analogictech and the analogictech logo are trademarks of advanced analogic technologies incorporated. all other brand and produ ct names appearing in this document are regis- tered trademarks or trademarks of their respective holders.

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