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? semiconductor components industries, llc, 2010 april, 2010 ? rev. 6 1 publication order number: cat3644/d cat3644 4-channel ultra high efficiency quad-mode led driver description the cat3644 is a high efficiency quad ? mode ? fractional charge pump that can drive up to four leds programmable by a one wire digital interface. the inclusion of a 1.33x fractional charge pump mode increases device efficiency by up to 10% over traditional 1.5x charge pumps with no added external capacitors. low noise input ripple is achieved by operating at a constant switching frequency which allows the use of small external ceramic capacitors. the multi ? fractional charge pump supports a wide range of input voltages from 2.5 v to 5.5 v. the en/dim logic input functions as a chip enable and a digital dimming interface for current setting of all leds. six different current ratios are available via the interface. the device is available in the tiny 16 ? pad tqfn 3 mm x 3 mm package with a max height of 0.8 mm. on semiconductor?s quad ? mode ? 1.33x charge pump switching architecture is patented. features ? high efficiency 1.33x charge pump ? quad ? mode charge pump: 1x, 1.33x, 1.5x, 2x ? drives up to 4 leds at 25 ma each ? 1 ? wire ezdim led current programming ? power efficiency up to 92% ? low noise input ripple in all modes ? ?zero? current shutdown mode ? soft start and current limiting ? short circuit protection ? thermal shutdown protection ? 3 mm x 3 mm, 16 ? pad tqfn package ? these devices are pb ? free, halogen free/bfr free and are rohs compliant applications ? lcd display backlight ? cellular phones ? digital still cameras ? handheld devices http://onsemi.com tqfn ? 16 hv3 suffix case 510ad pin connections jaag axxx yww marking diagrams device package shipping ordering information cat3644hv3 ? t2 (note 1) tqfn ? 16 (pb ? free) 2,000/ tape & reel 1. matte ? tin plated finish (rohs ? compliant). 2. nipdau plated finish (rohs ? compliant). led1 gnd nc nc c2 ? c2+ c1 ? c1+ led2 led3 led4 rset en/dim vout nc vin 1 (top view) jaah axxx yww cat3644hv3 ? gt2 (note 2) tqfn ? 16 (pb ? free) jaad = cat3644hv3 ? t2 jaah = cat3644hv3 ? gt2 a = assembly location xxx = last three digits of assembly lot number y = production year (last digit) ww = production week (two digits)
cat3644 http://onsemi.com 2 figure 1. typical application circuit gnd 2.4 v to 5.5 v 20 ma 4.02 k led1 led2 led3 led4 rset en/dim cat3644 1 f 1 f cin c1 ? c1+ c2 ? c2+ 1 f 1 f 1 ? wire programming c out v out v out v in v in ezdim table 1. absolute maximum ratings parameter rating unit v in , ledx, c1 , c2 , en/dim voltage 6 v v out voltage 7 v storage temperature range ? 65 to +160 c junction temperature range ? 40 to +150 c stresses exceeding maximum ratings may damage the device. maximum ratings are stress ratings only. functional operation above t he recommended operating conditions is not implied. extended exposure to stresses above the recommended operating conditions may af fect device reliability. table 2. recommended operating conditions parameter rating unit v in 2.5 to 5.5 v ambient temperature range ? 40 to +85 c i led per led pin up to 30 ma led forward voltage range 1.3 to 4.3 v note: typical application circuit with external components is shown above.
cat3644 http://onsemi.com 3 table 3. electrical operating characteristics (over recommended operating conditions unless specified otherwise) v in = 3.6 v, en = high, t amb = 25 c. symbol name conditions min typ max units i q quiescent current 1x mode, no load 1.33x mode, no load 1.5x mode, no load 2x mode, no load 1.0 1.7 2.2 2.4 ma i qshdn shutdown current v en = 0 v 1 a i led ? acc led current accuracy (i ledavg ? i nominal ) / i nominal rset = 5 k 2 % i led ? dev led channel matching (i led ? i ledavg ) / i ledavg 1.5 % v rset rset regulated voltage 0.58 0.6 0.62 v r out output resistance (open loop) 1x mode 1.33x mode, v in = 3 v 1.5x mode, v in = 2.7 v 2x mode, v in = 2.4 v 0.8 5 5 10 f osc charge pump frequency 1.33x and 2x mode 1.5x mode 0.8 1 1 1.3 1.3 1.6 mhz i sc_max output short circuit current limit v out < 0.5 v 50 ma i in_max input current limit v out > 1 v 250 ma led th 1x to 1.33x or 1.33x to 1.5x or 1.5x to 2x transition thresholds at any led pin 130 mv v hys 1x mode transition hysteresis 400 mv t df transition filter delay 500 s r en/dim v hi v lo en/dim pin ? internal pull ? down resistor ? logic high level ? logic low level 1.3 100 0.4 k v v t sd thermal shutdown 150 c t hys thermal hysteresis 20 c v uvlo undervoltage lockout (uvlo) threshold 1.6 1.8 2.0 v
cat3644 http://onsemi.com 4 table 4. recommended en/dim timing (for 2.4 v v in 5.5 v, over full ambient temperature range ? 40 c to +85 c.) symbol name conditions min typ max units t setup en/dim setup from shutdown 10 s t lo en/dim program low time 0.2 100 s t hi en/dim program high time 0.2 s t pwrdwn en/dim low time to shutdown 1.5 ms t led led current settling time 40 s figure 2. en/dim digital dimming timing diagram en/dim led current shutdown shutdown 100% 50% 25% 12.5% 6.25% 3.12% 100% t led t setup t hi t lo t pwrdwn led current setting the nominal led current is set by the external resistor connected between the rset pin and ground. table 5 lists standard resistor values for several led current settings. table 5. resistor rset and led current led current (ma) rset (k ) 2 40.0 5 15.8 10 7.87 15 5.23 20 4.02 25 3.16 30 2.67
cat3644 http://onsemi.com 5 typical performance characteristics (v in = 3.6 v, i out = 80 ma (4 leds at 20 ma), c in = c out = c 1 = c 2 = 1 f, t amb = 25 c unless otherwise specified.) figure 3. efficiency vs. input voltage figure 4. efficiency vs. li ? ion voltage input voltage (v) input voltage (v) 2.0 2.5 3.0 3.5 4.0 4.5 40 50 60 70 80 90 100 3.0 3.2 3.4 3.6 3.8 4.0 4.2 40 50 60 70 80 90 100 figure 5. quiescent current vs. input voltage figure 6. quiescent current vs. temperature input voltage (v) temperature ( c) 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 0 1 2 3 4 120 80 40 0 ? 40 0 1 2 3 4 figure 7. led current change vs. input voltage figure 8. led current change vs. temperature input voltage (v) temperature ( c) 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 ? 10 ? 8 ? 4 ? 2 2 4 8 10 120 80 40 0 ? 40 ? 10 ? 8 ? 6 ? 2 2 4 8 10 efficiency (%) efficiency (%) quiescent current (ma) quiescent current (ma) led current variation (%) led current variation (%) 1x 1.33x 1.5x v f = 3.3 v 2x 1x 1.33x v f = 3.3 v leds off v f = 3.3 v 2x 1.5x 1.33x 1x v f = 3.3 v ? 6 0 6 ? 4 0 6 v f = 3.3 v
cat3644 http://onsemi.com 6 typical performance characteristics (v in = 3.6 v, i out = 80 ma (4 leds at 20 ma), c in = c out = c 1 = c 2 = 1 f, t amb = 25 c unless otherwise specified.) figure 9. switching frequency vs. temperature figure 10. output resistance vs. input voltage temperature ( c) input voltage (v) 120 80 40 0 ? 40 0.7 0.8 0.9 1.0 1.1 1.2 1.3 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 0 2 4 6 8 10 12 figure 11. power up in 1x mode figure 12. power up in 1.33x mode figure 13. power up in 1.5x mode figure 14. power up in 2x mode switching frequency (mhz) output resistance ( ) 1.5x mode 1.33x, 2x mode 1x 1.33x 1.5x 2x
cat3644 http://onsemi.com 7 typical performance characteristics (v in = 3.6 v, i out = 80 ma (4 leds at 20 ma), c in = c out = c 1 = c 2 = 1 f, t amb = 25 c unless otherwise specified.) figure 15. power up delay (1x mode) figure 16. power down delay (1x mode) figure 17. operating waveforms in 1x mode figure 18. switching waveforms in 1.33x mode figure 19. switching waveforms in 1.5x mode figure 20. switching waveforms in 2x mode
cat3644 http://onsemi.com 8 typical performance characteristics (v in = 3.6 v, i out = 80 ma (4 leds at 20 ma), c in = c out = c 1 = c 2 = 1 f, t amb = 25 c unless otherwise specified.) figure 21. foldback current limit figure 22. led current vs. led pin voltage output current (ma) led pin voltage (mv) 400 300 200 100 0 0 0.5 1.0 1.5 2.0 3.0 3.5 4.0 300 250 200 150 100 50 0 0 10 20 30 40 figure 23. dimming waveform figure 24. led current vs. rset rset resistance (k ) 100 10 1 0 10 20 30 40 50 output voltage (v) led current (ma) led current (ma) 1x mode 2.5
cat3644 http://onsemi.com 9 table 6. pin description pin # name function 1 led2 led2 cathode terminal. 2 led3 led3 cathode terminal. 3 led4 led4 cathode terminal. 4 rset connect resistor rset to set the led current. 5 en/dim device enable (active high) and dimming control. 6 vout charge pump output connected to the led anodes. 7 nc not connected inside the package. 8 vin charge pump input, connect to battery or supply. 9 c1+ bucket capacitor 1 positive terminal 10 c1 ? bucket capacitor 1 negative terminal 11 c2+ bucket capacitor 2 positive terminal 12 c2 ? bucket capacitor 2 negative terminal 13 nc not connected inside the package. 14 nc not connected inside the package. 15 gnd ground reference 16 led1 led1 cathode terminal. tab gnd connect to gnd on the pcb. pin function vin is the supply pin for the charge pump. a small 1 f ceramic bypass capacitor is required between the vin pin and ground near the device. the operating input voltage range is from 2.5 v to 5.5 v. whenever the input supply falls below the under ? voltage threshold (1.8 v), all the led channels are disabled and the device enters shutdown mode. en/dim is the enable and one wire dimming input for all led channels. levels of logic high and logic low are set at 1.3 v and 0.4 v respectively. when en/dim is initially taken high, the device becomes enabled and all led currents are set to the full scale according to the resistor r set . to place the device into ?zero current? shutdown mode, the en/dim pin must be held low for at least 1.5 ms. vout is the charge pump output that is connected to the led anodes. a small 1 f ceramic bypass capacitor is required between the v out pin and ground near the device. gnd is the ground reference for the charge pump. the pin must be connected to the ground plane on the pcb. c1+, c1 ? are connected to each side of the ceramic bucket capacitor c 1 . c2+, c2 ? are connected to each side of the ceramic bucket capacitor c 2 . led1 to led4 provide the internal regulated current source for each of the led cathodes. these pins enter high ? impedance zero current state whenever the device is placed in shutdown mode. tab is the exposed pad underneath the package. for best thermal performance, the tab should be soldered to the pcb and connected to the ground plane. rset is connected to the resistor (r set ) to set the full scale current for the leds. the voltage at this pin regulated to 0.6 v. the ground side of the external resistor should be star connected back to the gnd of the pcb. in shutdown mode, rset becomes high impedance.
cat3644 http://onsemi.com 10 block diagram figure 25. cat3644 functional block diagram mode control 1, 1.3 mhz oscillator current setting dac serial interface registers reference voltage 1x mode (ldo) 4/3x, 3/2x, 2x charge pump en/dim rset 100 k gnd led1 led2 led3 led4 led channel current regulators v out v in c 2+ c 2 ? c 1 ? c 1+ basic operation at power ? up, the cat3644 starts operating in 1x mode where the output will be approximately equal to the input supply voltage (less any internal voltage losses). if the output voltage is sufficient to regulate all led currents, the device remains in 1x operating mode. if the input voltage is insufficient or falls to a level where the regulated currents cannot be maintained, the device automatically switches into 1.33x mode (after a fixed delay time of about 400 s). in 1.33x mode, the output voltage is approximately equal to 1.33 times the input supply voltage (less any internal voltage losses). this sequence repeats in the 1.33x and 1.5x mode until the driver enters the 2x mode. in 1.5x mode, the output voltage is approximately equal to 1.5 times the input supply voltage. while in 2x mode, the output is approximately equal to 2 times the input supply voltage. if the device detects a sufficient input voltage is present to drive all led currents in 1x mode, it will change automatically back to 1x mode. this only applies for changing back to the 1x mode. the difference between the input voltage when exiting 1x mode and returning to 1x mode is called the 1x mode transition hysteresis (v hys ) and is about 500 mv.
cat3644 http://onsemi.com 11 led current selection at power ? up, the initial led current is set to full scale (100% brightness) by the external resistor r set as follows: led current 132 0.6 v r set the en/dim pin has two primary functions. one function enables and disables the device. the other function is led current dimming with six different levels by pulsing the input signal, as shown on figure 26. on each consecutive pulse rising edge, the led current is divided by half to 50%, then 25%, 12.5%, 6.25% and 3.125% dimming levels. pulses faster than the minimum t lo may be ignored and filtered by the device. pulses longer than the maximum t lo may shutdown the device. the led driver enters a ?zero current? shutdown mode if en/dim is held low for 1.5 ms or more. figure 26. en/dim digital dimming timing diagram en/dim led current shutdown shutdown 100% 50% 25% 12.5% 6.25% 3.12% 100% t led t setup t lo t hi t pwrdwn table 7. led current dimming levels en/dim # of pulses * r set gain led current en = high 132 132 x 0.6 v / r set 1 st 66 66 x 0.6 v / r set 2 nd 33 33 x 0.6 v / r set 3 rd 16.5 16.5 x 0.6 v / r set 4 th 8.25 8.25 x 0.6 v / r set 5 th 4.125 4.125 x 0.6 v / r set 6 th 132 132 x 0.6 v / r set x th device cycling through gain selection gain x 0.6 v / r set * the gain is changed on the rising edges of the en/dim input.
cat3644 http://onsemi.com 12 unused led channels for applications not requiring all the channels, it is recommended the unused led pins be tied directly to v out (see figure 27). figure 27. application with 3 leds gnd led2 led3 led1 led4 rset en/dim cat3644 1 f 1 f c1 ? c1+ c2 ? c2+ 1 f 1 f enable dimming c out v out v in v in c in r set protection mode if an led is disconnected, the driver senses that and automatically ignores that channel. when all leds are disconnected, the driver goes to 1x mode where the output is equal to the input voltage. as soon as the output exceeds about 6 v, the driver resets itself and reevaluate the mode. if the die temperature exceeds +150 c, the driver will enter a thermal protection shutdown mode. when the device temperature drops by about 20 c, the device will resume normal operation. led selection leds with forward voltages (v f ) ranging from 1.3 v to 4.3 v may be used. selecting leds with lower v f is recommended in order to improve the efficiency by keeping the driver in 1x mode longer as the battery voltage decreases. for example, if a white led with a v f of 3.3 v is selected over one with v f of 3.5 v, the driver will stay in 1x mode for lower supply voltage of 0.2 v. this helps improve the efficiency and extends battery life. external components the driver requires four external 1 f ceramic capacitors for decoupling input, output, and for the charge pump. both capacitors type x5r and x7r are recommended for the led driver application. in all charge pump modes, the input current ripple is kept very low by design and an input bypass capacitor of 1 f is sufficient. in 1x mode, the device operates in linear mode and does not introduce switching noise back onto the supply. recommended layout in charge pump mode, the driver switches internally at a high frequency. it is recommended to minimize trace length to all four capacitors. a ground plane should cover the area under the driver ic as well as the bypass capacitors. short connection to ground on capacitors c in and c out can be implemented with the use of multiple via. a copper area matching the tqfn exposed pad (tab) must be connected to the ground plane underneath. the use of multiple via improves the package heat dissipation. figure 28. recommended layout vin gnd pin1 c2 c1 rset cin cout gnd gnd en/dim
cat3644 http://onsemi.com 13 package dimensions tqfn16, 3x3 case 510ad ? 01 issue a e2 a3 eb a a1 side view top view bottom view e d pin#1 index area pin#1 id front view a1 a l d2 notes: (1) all dimensions are in millimeters. (2) complies with jedec mo-220. symbol min nom max a 0.70 0.75 0.80 a1 0.00 0.02 0.05 a3 0.20 ref b 0.18 0.25 0.30 d 2.90 3.00 3.10 d2 1.40 ??? 1.80 e 3.00 e2 1.40 ??? 1.80 e 2.90 0.50 bsc 3.10 l 0.30 0.40 0.50
cat3644 http://onsemi.com 14 example of ordering information (note 5) prefix device # suffix company id cat 3644 product number 3644 t2 t: tape & reel 2: 2,000 / reel tape & reel (note 7) (optional) hv3 package hv3: tqfn ? g g: nipdau blank: matte ? tin lead finish 3. all packages are rohs ? compliant (lead ? free, halogen ? free). 4. the standard lead finish is nipdau. 5. the device used in the above example is a cat3644hv3 ? gt2 (tqfn, nipdau, tape & reel, 2,000/reel). 6. for additional package and temperature options, please contact your nearest on semiconductor sales office. 7. for information on tape and reel specifications, including part orientation and tape sizes, please refer to our tape and reel packaging specifications brochure, brd8011/d. on semiconductor and are registered trademarks of semiconductor components industries, llc (scillc). scillc reserves the right to mak e changes without further notice to any products herein. scillc makes no warranty, representation or guarantee regarding the suitability of its products for an y particular purpose, nor does scillc assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including wi thout limitation special, consequential or incidental damages. ?typical? parameters which may be provided in scillc data sheets and/or specifications can and do vary in different application s and actual performance may vary over time. all operating parameters, including ?typicals? must be validated for each customer application by customer?s technical experts. scillc does not convey any license under its patent rights nor the rights of others. scillc products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the scillc product could create a sit uation where personal injury or death may occur. should buyer purchase or use scillc products for any such unintended or unauthorized application, buyer shall indemnify and hold scillc and its of ficers, employees, subsidiaries, af filiates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, direct ly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that scillc was negligent regarding the design or manufacture of the part. scillc is an equal opportunity/affirmative action employer. this literature is subject to all applicable copyright laws and is not for resale in any manner. cat3644/d publication ordering information n. american technical support : 800 ? 282 ? 9855 toll free usa/canada europe, middle east and africa technical support: phone: 421 33 790 2910 japan customer focus center phone: 81 ? 3 ? 5773 ? 3850 literature fulfillment : literature distribution center for on semiconductor p.o. box 5163, denver, colorado 80217 usa phone : 303 ? 675 ? 2175 or 800 ? 344 ? 3860 toll free usa/canada fax : 303 ? 675 ? 2176 or 800 ? 344 ? 3867 toll free usa/canada email : orderlit@onsemi.com on semiconductor website : www.onsemi.com order literature : http://www.onsemi.com/orderlit for additional information, please contact your local sales representative ezdim is a trademark of semiconductor components industries, llc. quad ? mode is a registered trademark of semiconductor components industries, llc.

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