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aat3153 high efficiency 1x/1.5x/2x charge pump for white led applications preliminary information 3153.2005.12.0.93 1 chargepump ? general description the aat3153 is a low noise, constant frequency charge pump dc/dc converter that uses a tri-mode load switch (1x), fractional (1.5x), and doubling (2x) conversion to maximize efficiency for white led applications. the aat3153 is capable of driving six led channels 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 v in and v out ) makes this part ideally suited for small, battery-powered applications. analogictech's s 2 cwire? (simple serial control?) serial digital input is used to enable, disable, and set current for each led with eight settings (20ma down to 50a) including main and sub-display group control. the aat3153 consumes extremely low current internally (50a typical) at light load for optimized efficiency. each output of the aat3153 is equipped with built- in protection for v out short-circuit and auto-disable for load short-circuit conditions. built-in soft-start circuitry prevents excessive inrush current during start-up. a low current shutdown feature discon- nects the load from v in and reduces quiescent cur- rent to less than 1a. the aat3153 is available in a pb-free, space-saving, thermally-enhanced 16-pin 4x4mm qfn package. features ?v in range: 2.7v to 5.5v ? fully programmable current with single wire ? eight-step current: 20ma to 50a ? individual main-sub group control ? low i q (50a) at light load ? tri-mode 1x, 1.5x, and 2x charge pump for maximum efficiency and v f coverage ? drives up to six led channels ? no inductors, low noise operation ? 1mhz constant switching frequency ? small application circuit ? built-in thermal protection ? built-in auto-disable for short-circuit ? automatic soft start ?i q <1a in shutdown ? thermally-enhanced 4x4mm 16-pin qfn package applications ? color (rgb) lighting ? programmable current sinks ? white led backlighting ? white photo flash for digital still cameras typical application c1 1 f c2 1 f d1 d2 d3 d4 d5 d6 c ou t 1 f c in 1 f 2.7v to 5.5v en/set vin en/set c1+ c1- c2+ c2- vout d1 d2 d3 d4 d5 d6 gnd aat3153
pin descriptions pin configuration qfn44-16 (top view) 1 2 3 4 12 11 10 9 5 6 7 8 16 15 14 13 d6 en/set n/c vout c2+ c1+ c1- c2- gnd in gnd d1 aat3153 d2 d3 d4 d5 pin # symbol function 1 d6 current sink input #6. 2 en/set s 2 cwire serial interface control pin. 3 n/c no connection. 4 vout charge pump output to drive load circuit. requires 1f capacitor connected between this pin and ground. 5 c2+ flying capacitor 2 positive terminal. connect a 1f capacitor between c2+ and c2-. 6 c1+ flying capacitor 1 positive terminal. connect a 1f capacitor between c1+ and c1-. 7 c1- flying capacitor 1 negative terminal. 8 c2- flying capacitor 2 negative terminal. 9, 11 gnd ground. 10 in input power supply. requires 1f capacitor connected between this pin and ground. 12 d1 current sink input #1. 13 d2 current sink input #2. 14 d3 current sink input #3. 15 d4 current sink input #4. 16 d5 current sink input #5. ep exposed paddle (bottom); connect to gnd directly beneath package. aat3153 high efficiency 1x/1.5x/2x charge pump for white led applications 2 3153.2005.12.0.93
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 -0.3 to 6 v v en/set en/set to gnd voltage -0.3 to v in + 0.3 v i out 2 maximum dc output current 180 ma t j operating junction temperature range -40 to 150 c t lead maximum soldering temperature (at leads, 10 sec) 300 c aat3153 high efficiency 1x/1.5x/2x charge pump for white led applications 3153.2005.12.0.93 3 1. stresses above those listed in absolute maximum ratings may cause permanent damage to the device. functional operation at co ndi- tions other than the operating conditions specified is not implied. only one absolute maximum rating should be applied at any o ne time. 2. based on long-term current density limitation. 3. mounted on an fr4 board. 4. derate 6.25mw/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 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 1 no load current 1.5x mode, 3.0 v in 5.5, active, 1 3 ma i cc operating current no load current 2x mode, 3.0 v in 5.5, active, 2.0 3.7 no load current 50a setting, 1x mode 50 a i shdn shutdown current en/set = 0 1 a i dx i sink average current accuracy i set = 30ma, t a = 25c 18 20 22 ma i (d-match) current matching between any v f :d1:d4 = 3.6v 0.5 % two current sink inputs 2, 3 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 aat3153 high efficiency 1x/1.5x/2x charge pump for white led applications 4 3153.2005.12.0.93 1. the aat3153 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. 3. specification applies only to the tri-mode charge pump.
typical characteristics current matching vs. temperature temperature ( c) current (ma) 19.2 19.4 19.6 19.8 20.0 20.2 -40 -20 0 20 40 60 80 channel 2 channel 1 channel 5 channel 3 channel 4 channel 6 turn-off from 1.5x mode (v in = 3.5v; 20ma load) time (100s/div) en (2v/div) i in (100ma/div) v f (1v/div) turn-on to 2x mode (v in = 2.8v; 20ma load) time (100s/div) en (2v/div) cp (2v/div) i in (200ma/div) v sink (500mv/div) turn-on to 1.5x mode (v in = 3.8v; 20ma load) time (100s/div) en (2v/div) cp (2v/div) i in (200ma/div) v sink (500mv/div) turn-on to 1x mode (v in = 4.2v; 20ma load) time (100s/div) en (2v/div) cp (2v/div) i in (200ma/div) v sink (500mv/div) efficiency vs. supply voltage supply voltage (v) efficiency (%) 50 60 70 80 90 100 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 20ma v f = 3.4v 10ma v f = 3.1v aat3153 high efficiency 1x/1.5x/2x charge pump for white led applications 3153.2005.12.0.93 5
typical characteristics input ripple vs. v in v in (v) amplitude (mv) 0 5 10 15 20 25 2.50 2.67 2.84 3.01 3.18 3.35 3.52 3.69 3.86 4.03 4.20 10ma 20ma 30ma t off vs. v in v in (v) t off ( 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 t lat vs. v in v in (v) t lat ( 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 load characteristics (v in = 3.1v; 2x mode; 20ma load) time (500ns/div) v in (40mv/div) v sink (40mv/div) cp (40mv/div) load characteristics (v in = 4.0v; 1.5x mode; 20ma load) time (500ns/div) v in (40mv/div) v sink (40mv/div) cp (40mv/div) aat3153 high efficiency 1x/1.5x/2x charge pump for white led applications 6 3153.2005.12.0.93 6 3153.2005.12.0.93
typical characteristics v il vs. v in v in (v) v il (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 v ih vs. v in v in (v) v ih (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 aat3153 high efficiency 1x/1.5x/2x charge pump for white led applications 3153.2005.12.0.93 7 3153.2005.12.0.93 7
aat3153 high efficiency 1x/1.5x/2x charge pump for white led applications 8 3153.2005.12.0.93 functional block diagram 1x, 1.5x, and 2x charge pump d/a d/a d/a d/a d/a d/a 6 x 16 bit rom 6 x 16 bit rom s 2 cwire interface soft-start control 1mhz oscillator voltage reference vin en/set d6 d6 d5 d4 d3 d2 d1 vout c1+ c1- c2+ c2- functional description the aat3153 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 aat3153 charge pump is enabled when any of the four cur- rent sink inputs near dropout. the charge pump ini- tially starts in 1.5x mode. if the charge pump out- put drops enough for any current source output to become close to dropout, the charge pump will automatically transition to 2x mode. the aat3153 requires only four external components: two 1f ceramic capacitors for the charge pump flying capacitors (c 1 and c 2 ), one 1f ceramic input capacitor (c in ), and one 0.33f to 1f ceramic charge pump output capacitor (c out ).
aat3153 high efficiency 1x/1.5x/2x charge pump for white led applications 3153.2005.12.0.93 9 the six constant current sink inputs (d1 to d6) can drive six individual leds with a maximum current of 20ma each. the unused sink inputs must be connected to v out , otherwise the part will operate only in 2x charge pump mode. the s 2 cwire serial interface enables the aat3153 and sets the current sink magnitudes. s 2 cwire addressing allows inde- pendent control of two groups of current sink input: d1-d4 and d5-d6. constant current output level settings the constant current sink levels for d1 to d6 are set via the serial interface. no pwm (pulse width modulation) or additional control circuitry are need- ed 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 (up to 1mhz data rate), the input sink current of the aat3153 can be changed suc- cessively to brighten or dim leds, giving the users real-time control of led brightness. because the inputs d1 to d6 are true independent constant cur- rent sinks, the voltage observed on any single given input will be determined by the actual forward voltage (v f ) for the led being driven. s 2 cwire serial interface the current sink input magnitude on the aat3153 is controlled by analogictech's s 2 cwire serial inter- face. the interface records rising edges of the en/set pin and decodes them into 16 different states, as indicated in table 1. there are four bright- ness levels for the main or sub-display group with the possibility of individually turning on or off each group. to further optimize power efficiency, the aat3153 also offers four low-current levels for dim led operation (data 13 through 16). during this low-current mode, the internal supply current reduces to only 50a typical. the s 2 cwire serial interface has flexible timing. data can be clocked-in at speeds greater than 1mhz, or much slower, such as 15khz. after data is submitted, en/set is held high to latch the data. once en/set has been held in the logic high state for time t lat , the programmed current becomes active and the internal data register is reset to zero. for subsequent current level programming, the number of rising edges corresponding to the desired code must be entered on the en/set pin. when en/set is held low for an amount of time greater than t off , the aat3153 enters into shutdown mode and draws less than 1a from v in . the inter- nal data register is reset to zero during shutdown. table 1: aat3153 current settings. main group sub group (d1-d4) (d5-d6) data i out (ma) i out (ma) 120 20 214 14 310 10 47 7 520 0 614 0 710 0 87 0 90 20 10 0 14 11 0 10 12 0 7 13 0.05 0.05 14 0.5 0.5 15 1 1 16 2 2
aat3153 high efficiency 1x/1.5x/2x charge pump for white led applications 10 3153.2005.12.0.93 auto-disable feature the aat3153 is equipped with an auto-disable fea- ture for each led channel. after the ic is enabled and started up, a test current of 150a (typical) is forced through each sink channel. the channel will be disabled if the voltage of that particular sink pin does not drop to certain threshold. this feature is very convenient for disabling an unused channel or during an led fail short event. thermal protection the aat3153 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 is the case during a short-circuit of the v out pin. applications information led selection although the aat3153 is specifically intended for driving white leds, the device can also 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 dis- play 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 d6 input current sinks are matched with negligible voltage dependence, the led brightness will be matched regardless of the spe- cific led forward voltage (v f ) levels. in some instances (e.g., in high luminous output applica- tions such as photo flash), it may be necessary to drive high-v f type leds. the low-dropout current sinks in the aat3153 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 aat3153 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 aat3153 soft-start feature prevents noise transient effects associated with inrush cur- rents during start-up of the charge pump circuit. power efficiency and device evaluation the charge pump efficiency discussion in the follow- ing sections only accounts for the efficiency of the charge pump section itself. due to the unique circuit architecture and design of the aat3153, it is very dif- ficult to measure efficiency in terms of a percent value comparing input power over output power. since the aat3153 inputs are pure constant current sinks and typically drive individual loads, it is difficult to measure the output voltage for a given input (d1 to d6) to derive an overall output power measure- ment. for any given application, white led forward voltage levels can differ, yet the load drive current will be maintained as a constant. s 2 cwire serial interface timing 1 en/set 2 n n <= 16 data reg 1n 0 t hi t lo t lat t off
aat3153 high efficiency 1x/1.5x/2x charge pump for white led applications 3153.2005.12.0.93 11 this makes quantifying output power a difficult task when taken in the context of comparing to other white led driver circuit topologies. a better way to quantify total device efficiency is to observe the total input power to the device for a given led current drive level. the best white led driver for a given applica- tion should be based on trade-offs of size, external component count, reliability, operating range, and total energy usage... not just % efficiency. the aat3153 efficiency may be quantified under very specific conditions and is dependent upon the input voltage versus the output voltage seen across the loads applied to inputs d1 through d6 for a given constant current setting. depending on the combination of v in and voltages sensed at the cur- rent sinks, the device will operate in load switch mode. when any one of the voltages sensed at the current sinks nears dropout, the device will operate in 1.5x or 2x charge pump mode. each of these modes will yield different efficiency values. refer to the following two sections for explanations for each operational mode. load switch mode efficiency the aat3153 load switch mode is operational at all times and functions alone to enhance device power conversion efficiency when v in is greater than the voltage across the load. when in load switch mode, the voltage conversion efficiency is defined as output power divided by input power: the expression to define the ideal efficiency ( ) can be rewritten as: -or- charge pump section efficiency the aat3153 contains a fractional charge pump that will boost the input supply voltage when v in is less than the voltage required on the constant current sink inputs. the efficiency ( ) can be simply defined as a linear voltage regulator with an effective output voltage that is equal to one and one half or two times the input voltage. efficiency ( ) for an ideal 1.5x charge pump can typically be expressed as the out- put power divided by the input power. in addition, with an ideal 1.5x charge pump, the output current may be expressed as 2/3 of the input current. the expression to define the ideal efficiency ( ) can be rewritten as: -or- capacitor selection careful selection of the four external capacitors c in , c 1 , c 2 , and 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 only programmed for light current lev- els, then the capacitor size may be decreased. capacitor characteristics ceramic composition capacitors are highly recom- mended over all other types of capacitors for use with the aat3153. ceramic capacitors offer many advantages over their tantalum and aluminum elec- (%) = 100 v out 1.5v in ?? ?? = p out = v out i out = v out p in v in 1.5i out 1.5v in = p ou t p in (%) = 100 v out v in ?? ?? = p out = v out i out = v out p in v in i out v in = p ou t p in
trolytic counterparts. a ceramic capacitor has very low esr, is lowest cost, has a smaller pcb foot- print, and is non-polarized. low esr ceramic capacitors help to maximize charge pump transient response. since ceramic capacitors are non-polar- ized, they are not prone to incorrect connection damage. equivalent series resistance esr is an important characteristic to consider when selecting a capacitor. esr is a resistance internal to a capacitor that is caused by the leads, internal connections, size or area, material compo- sition, and ambient temperature. capacitor esr is typically measured in milliohms for ceramic capac- itors 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 aat3153 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. aat3153 high efficiency 1x/1.5x/2x charge pump for white led applications 12 3153.2005.12.0.93
aat3153 high efficiency 1x/1.5x/2x charge pump for white led applications 3153.2005.12.0.93 13 ordering information package information qfn44-16 all dimensions in millimeters. 4.000 0.050 pin 1 dot by marking 2.400 0.050 0.600 0.050 4.000 0.050 2.280 ref 0.650 bsc 0.900 0.050 pin 1 identification r0.030max 1 4 5 8 9 13 16 0.450 0.050 0.0125 0.0125 0.203 0.025 0.330 0.050 top view bottom view side view 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. package marking 1 part number (tape and reel) 2 qfn44-16 AAT3153ISN-T1 1. xyy = assembly and date code. 2. sample stock is generally held on part numbers listed in bold .
aat3153 high efficiency 1x/1.5x/2x charge pump for white led applications 14 3153.2005.12.0.93 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 subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warran ty, 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.

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