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1 cat32 cmos white led driver features low quiescent ground current (0.5ma typical) power efficiency over 80% compatible pinout with lt1932 adjustable output current (up to 40ma) high frequency 1.2mhz operation input voltage operation down to 2.0v low resistance (0.5 ? ? ? ? ? ) high voltage power switch drives up to 4 white leds in series shutdown current less than 1 a load fault protection against open-circuits low value external components low profile (1mm) 6-lead sot23 and tdfn (0.8mm) package description the cat32 is a dc/dc step up converter that delivers a regulated output current. operation at a constant switching frequency of 1.2mhz allows the device to be used with very small value external inductor and ceramic capacitors. the cat32 is targeted to drive multiple white light- emitting diodes (leds) connected in series and provides the necessary regulated current to control the brightness and the color purity. an external resistor r set controls the output current level. led currents of up to 40ma can be supported over a wide range of input supply voltages from 2v to 7v, making the device ideal for battery-powered applications. ?2003 by catalyst semiconductor, inc. characteristics subject to change without notice doc no. 5001, rev. x preliminary information applications color lcd and keypad backlighting cellular phones handheld terminals a high voltage output stage allows up to 4 white leds to be driven in series. series drive provides inherent current matching. led dimming can be done by using a dc voltage, a logic signal, or a pulse width modulation (pwm) signal. the shutdown input pin allows the device to be placed in power-down mode with ?ear zero?quiescent current. in addition to overcurrent limiting protection, the device also includes detection circuitry to ensure protection against open-circuit load fault conditions. the device is available in a low profile (1mm max height) 6-lead thin sot23 package and in a tdfn (0.8mm max height) package. typical application c1: taiyo yuden jmk212bj475 c2: taiyo yuden emk212bj105 d1: zetez zhcs400 l1: sumida clq4d106r8 (panasonic eljea6r8) digital cameras pdas/games portable mp3 players 15ma 4 2 3 1 6 5 sw vin shdn rset d1 vin 2.7v to 4.2v pwm dimming control cat32 led gnd sot23 pin numbers figure 1. li-ion driver for four high-brightness white leds
cat32 2 doc. no. 5001, rev. x cat32 1 2 3 6 5 4 sw gnd led vin shd n rset 6-lead sot-23 1mm maximum height [free air] ordering information pin configuration pin descriptions pin number pin number sot23 tdfn name function 1 8 sw switch pin. this is the drain of the internal power switch. for minimum emi, minimize the trace area connected to this pin. 2 5 gnd ground pin. connect pin 2 to ground. 3 6 led led (cathode) connection pin. 4 4 rset reset pin. a resistor connected from pin 4 to ground sets the led current. this pin is also used to dim the leds. 53 shdn shutdown pin. 6 2 vin input supply pin. this pin should be bypassed with a capacitor to ground. a 4.7 f capacitor mounted close to the pin is recommended. 1 power power ground ground (top view) tdfn package: 3mm x 3mm 0.8mm maximum height (rd4) (top view) tdfn package: 3mm x 4.9mm 0.8mm maximum height (rd2) 1 2 3 4 8 7 6 5 sw nc led gnd power ground vin shdn rset 1 2 3 4 8 7 6 5 sw nc led gnd power ground vin shdn rset r e b m u n t r a pe g a k c a p e b u t y t i t n a u q l e e r y t i t n a u q e g a k c a p e d o c g n i k r a m e r u t a r e p m e t e g n a r 3 1 e t - t k e 2 3 t a c m m 1 ( 3 2 t o s , d a e l - 6 l e e r & e p a t ) t h g i e h 0 0 0 3d bc 5 8 o t c 0 4 - 3 1 e t - 2 d r 2 3 t a c , m m 9 . 4 x 3 ( n f d t d a p - 8 ) t n i r p t o o f p o s m l e e r & e p a t 0 0 5 3l e c cc 5 8 o t c 0 4 - 3 1 e t - 4 d r 2 3 t a c ) m m 3 x 3 ( n f d t d a p - 8 l e e r & e p a t 0 0 5 3m e c cc 5 8 o t c 0 4 - 2 d r 2 3 t a c , m m 9 . 4 x 3 ( n f d t d a p - 8 ) t n i r p t o o f p o s m 0 2 1 l e c cc 5 8 o t c 0 4 - 4 d r 2 3 t a c) m m 3 x 3 ( n f d t d a p - 80 2 1 m e c cc 5 8 o t c 0 4 -
cat32 3 doc no. 5001, rev. x absolute maximum ratings v in , led, shdn voltage ....................................... 8v sw voltage ........................................................... 20v rset voltage ......................................................... 1v junction temperature ....................................... 125 c electrical specifications over recommended operating conditions unless otherwise specified. t a = 25 c, v in = 2v and v shdn = 1.2v. lead soldering temperature (10 secs) ............ 300 c storage temperature .......................... -65 c to 150 c esd rating - human body model .................... 2000v these are stress ratings only and functional operation is not implied. exposure to absolute maximum ratings for prolonged time periods may affect device reliability. all voltages are with respect to ground. recommended operating conditions r e t e m a r a pe g n a rt i n u v n i 7 o t 2v e g n a r e r u t a r e p m e t t n e i b m a5 8 + o t 0 4 - c 1 l r o t c u d n il a c i p y t % 0 2 8 . 6h 1 c r o t i c a p a c t u p n il a c i p y t % 0 2 7 . 4f 2 c r o t i c a p a c t u p t u ol a c i p y t % 0 2 0 . 1f i d e l s e i r e s n i s d e l 4 o t 1 h t i w0 2 o t 0a m l o b m y sr e t e m a r a ps n o i t i d n o cn i mp y tx a ms t i n u i q t n e r r u c t n e c s e i u qv t e s r v 2 . 0 =5 . 07 . 0a m i d n g n w o d t u h s n i t n e r r u c d n u o r gv n d h s v 0 =5 0 . 01a v d e l e g a t l o v n i p d e lv n i v < t u o i , d e l a m 5 1 =0 2 10 8 1v m i d e l e g n a r t s u j d a t n e r r u c d e l50 4a m i d e l t n e r r u c d e l d e m m a r g o r p r t e s 2 6 5 = ? 3 38 35 4 a m r t e s 0 5 7 = ? 5 20 36 3 r t e s k 5 . 1 = ? 5 . 2 15 15 . 7 1 r t e s k 3 5 . 4 = ? 5 i d e l t n e i c i f f e o c e r u t a r e p m e t t n e r r u c n i p d e li d e l a m 5 1 =1 0 . 0 -c / a m v t e s r r t e s e g a t l o v n i pr t e s k 5 . 1 = ? 0 0 1v m l e v e l h g i h c i g o l n i p n w o d t u h s5 8 . 0v l e v e l w o l c i g o l n i p n w o d t u h s 5 2 . 0v f w s y c n e u q e r f r e t r e v n o c t s o o b8 . 02 . 16 . 1z h m i l w s t i m i l t n e r r u c h c t i w s0 0 40 5 50 8 7a m r w s e c n a t s i s e r h c t i w s v n i i , v 2 = w s a m 0 0 1 =7 . 02 . 1 ? v n i i , v 3 = w s a m 0 0 1 =5 . 09 . 0 ? t n e r r u c e g a k a e l h c t i w sv , f f o h c t i w s w s v 5 =1 0 . 05a y c n e i c i f f e n w o h s s t n e n o p m o c 1 e r u g i f n o 3 8%
cat32 4 doc. no. 5001, rev. x typical characteristics v in =3.6v, t amb =25 ? c, c in =4.7 f, c out =1 f, l=6.8 h, unless otherwise specified. quiescent current vs. input voltage 200 300 400 500 600 234567 input voltage [v] quiescent current vs. temperature 200 300 400 500 600 -50 -25 0 25 50 75 100 125 . vin = 7v vin = 2v switching frequency vs. input voltage 0.00 0.40 0.80 1.20 1.60 2.00 234567 input volt age [v] switch frequency [mhz ] switching frequency vs. temperature 0.0 0.4 0.8 1.2 1.6 2.0 -50 -25 0 25 50 75 100 125 switch frequency [mhz ] led current vs. input voltage 0 5 10 15 20 25 30 35 234567 input voltage [v] led current [ma] rset = 1.5k rset = 2.26k rset = 750 rset = 1.13k led current vs. temperature 0 5 10 15 20 -50 -25 0 25 50 75 100 125 led current [ma]
cat32 5 doc no. 5001, rev. x typical characteristics v in =3.6v,t amb =25 ? c, c in =4.7 f, c out =1 f, l=6.8 h, unless otherwise specified. switch resistance vs. input voltage 0.0 0.2 0.4 0.6 0.8 1.0 23456 input volt age [v] switch resistance [ohm] . switch resistance vs. temperature 0.0 0.2 0.4 0.6 0.8 1.0 -50 -25 0 25 50 75 100 125 switch resistance [ohm] . vin = 3v led pin voltage vs. led current 0 50 100 150 200 250 300 0 816 24 32 40 led current [ma] vsw, i l , & vout signal waveforms vin = 3.7v with 15ma load through 4 leds h inductor inductor current waveform (v in = 2.7v, 15ma load) 5khz pwm shutdown response (v in = 2.7v, 15ma load)
cat32 6 doc. no. 5001, rev. x operation the cat32 device is a high efficiency, constant frequency, current regulating boost converter. the device includes a switch and an internally compensated loop for the regulation of the led current. operation can be best understood by examining the block diagram. the rset pin is regulated at 100mv and the current through the external resistor will set the regulated current in the leds (from 5ma to 40ma) with a multiplication factor of 225. while maintaining led current regulation, the cat32 automatically adjusts the led pin voltage to be as low as possible. a low led pin voltage ensures high efficiency. current through the internal power switch is continuously monitored cycle-by-cycle. if the current limit is exceeded, the switch is immediately turned off, protecting the device, for the remainder of the cycle. pwm dimming operation can be achieved by switching the shdn pin or by pulling the rset pin higher than 0.1v. block diagram figure 2. cat32 block diagram sot23 pin numbers vin 1.2 mhz oscillator d1 l1 c1 4 2 r set led current sense amp sw 1 cat32 3 i led c2 gnd + - i led = 225 x i s current control pwm & logic i s + - 100mv r set shdn 6 5 v in over voltage protection (22v) 225x
cat32 7 doc no. 5001, rev. x application information inductor selection and efficiency inductor vendors are shown below. contact the manufacturer for detailed technical data and new product information. table 1: inductor manufacturers capacitor selection low esr (equivalent series resistance) capacitors should be used at the output to minimize the output ripple voltage. the low esr and small package options available with multilayer ceramic capacitors make them excellent choices. the x5r and x7r capacitor types are preferred because they retain their capacitance over wider voltage and temperature ranges than the y5v or z5u types. a 1.0 f or 2.2 f output capacitor is recommended for most applications. the voltage rating of the output capacitor c2 depends on the number of leds driven in series. a 10v ceramic capacitor is recommended when driving two leds. a 16v ceramic capacitor is recommended when driving 3 or 4 leds. low profile ceramic capacitors with a 1mm maximum height/thickness are available for designs height requirements. ceramic capacitors also make a good choice for the input capacitor, which should be mounted as close as possible to the cat32. a 2.2 f or 4.7 f input capacitor is recommended. table 2 shows a list of several ceramic capacitor manufacturers. consult the manufacturers for detailed information as new products and package options are introduced regularly. table 2: ceramic capacitor manufacturers supplier phone web taiyo yuden 408.573.4150 www.t-yuden.com murata 814.237.1431 www.murata.com kemet 408.986.0424 www.kemet.com inductor l ( h) maximum maximum vendor web dcr (m ? ) height (mm) eljea4r7 4.7 180 2.2 panasonic eljea6r8 6.8 250 2.2 714.373.7334 www.panasonic.com lqh3c4r7m24, 4.7 260 2.2 lqh32cn4r7m11 murata lqh3c100k24, 10 300 2.2 770.436.1300 www.murata.com lqh32cn100k11 lb2016b4r7 4.7 250 2.0 taiyo yuden lb2016b100 3.8 350 2.0 408.573.4150 www.t-yuden.com cmd4d06-4r7 4.7 216 0.8 cmd4d06-6r8 6.8 296 0.8 sumida clq4d10-4r7 4.7 162 1.2 847.956.0666 www.sumida.com clq4d10-6r8 6.8 195 1.2
cat32 8 doc. no. 5001, rev. x table 4: rset resistor values i led (ma) rset 40 562 ? 30 750 ? 25 909 ? 20 1.13k ? 15 1.50k ? 10 2.26k ? 5 4.53k ? diode selection schottky diodes, with their low forward voltage drop and fast switching speed, are the ideal choice for high efficiency applications. table 3 shows several different schottky diodes that work well with the cat32. make sure that the diode has a voltage rating greater than the table 3: schottky diode suppliers part supplier mbr0520 on semiconductor mbr0530 www.onsemi.com mbr0540 800.282.9855 zhcs400 zetex output voltage. the diode conducts current only when the power switch is turned off (typically less than one- third the time), so a 0.4a or 0.5a diode will be sufficient for most designs. led current programming the led current is programmed with a single resistor connected to the rset pin the rset pin is internally regulated to 100mv, which sets the current flowing out of this pin, iset, equal to 100mv/rset. the cat32 regulates the current into the led pin, i led , to 225 times the value of iset. for the best accuracy, a 1% or better resistor is recommended. table 4 shows several typical 1% r set values. for other led current values, use the following equation to choose r set . r v i set led = ? ? ? ? ? ? 225 01 . most white leds are driven at maximum currents of 15ma to 20ma. some higher power designs will use two parallel strings of leds for greater light output, resulting in 30ma to 40ma (two strings of 15ma to 20ma) flowing into the led pin.
cat32 9 doc no. 5001, rev. x led dimming with pwm signal pwm brightness control provides the widest dimming range (greater than 20:1). by turning the leds on and off using the control signal the leds operate at either zero or full current, but their average current changes with the pwm signal duty cycle. typically, a 5khz to 40khz pwm signal is used. pwm dimming with the cat32 can be accomplished two different ways. the shdn pin can be driven directly or a resistor can be added to drive the r set pin. if the shdn pin is used, increasing the duty cycle will increase the led bright- ness. using this method, the leds can be dimmed and turned off completely using the same control signal. a 0% duty cycle signal will turn off the cat32, reducing the total quiescent current to near zero. if the r set pin is used, increasing the duty cycle will decrease the brightness. using this method, the leds are dimmed using r set and turned off completely using shdn. if the r set pin is used to provide pwm dimming, the approximate value of r pwm should be calculated (where v max is the high value of the pwm signal): rr v v pwm set max = ? ? ? ? ? ? ? 015 1 . in addition to providing the widest dimming range, pwm brightness control also ensures the purest white led color over the entire dimming range. the true color of a white led changes with operating current, and is the purest white at a specific forward current, usually 15ma or 20ma. if the led current is less than or more than this value, the emitted light becomes more blue. applications involving color lcds can find the blue tint objectionable. when a pwm control signal is used to drive the shdn pin of the cat32, the leds are turned off and on at the pwm frequency. the current through them alternates between full current and zero current, so the average current changes with duty cycle. this ensures that when the leds are on, they can be driven at the appropriate current to give the purest white light. led brightness varies linearly with the pwm duty cycle. led dimming with a logic signal for applications that need to adjust the led brightness in discrete steps, a logic signal can be used. r min sets the minimum led current value (when the nmos is off): r v i min led min = ? ? ? ? ? ? 225 01 . () r incr determines how much led current increases when the external nmos switch is turned on. r v i incr led increase = ? ? ? ? ? ? 225 01 . () led dimming with a dc voltage r vv i i adj max led max lead min = ? ? ? ? ? ? ? ? ? ? 225 01 . () () cat32 shdn 5 pwm cat32 rset 4 pwm r pwm r set cat32 rset pwm 4 10k ? r set r pwm 0.1f cat32 rset v dc 4 r set r adj cat32 rset 4 r min r incr logic signal figure 3: led dimming circuits
cat32 10 doc. no. 5001, rev. x pcb layout guidelines the cat32 is a high-frequency switching regulator and therefore proper pcb board layout and component placement can minimize noise and radiation and increase efficiency. to maximize efficiency, the cat32 design has fast switch rise and fall times. to prevent radiation and high frequency resonance problems minimize the length and area of all traces connected to the sw pin and use a ground plane under the switching regulator. the switch, schottky output diode and output capacitor signal path should be kept as short as possible. the ground connection for the r set resistor should be tied directly to the gnd pin and not be shared with other components. typical application circuits the application diagrams below are shown for the sot23 packages. two leds with dc level dimming control: three leds with dc level dimming control: 15ma 4 2 3 1 6 5 sw vin shdn rset d1 vin 2.5v dc dimming control cat32 led gnd 15ma 4 2 3 1 6 5 sw vin shdn rset d1 vin 2.5v dc dimming control cat32 led gnd 60 65 70 75 80 85 0 5 10 15 20 vin = 4.2v vin = 3.0v efficiency - three leds efficiency [%] led current [ma]
cat32 11 doc no. 5001, rev. x four leds with pwm dimming control: 15ma 4 2 3 1 6 5 sw vin shdn rset d1 vin pwm dimming control cat32 led gnd 60 65 70 75 80 85 0 5 10 15 20 vin = 4.2v vin = 3.0v efficiency - four leds efficiency [%] led current [ma]
cat32 12 doc. no. 5001, rev. x 6 lead sot-23 (aa option) aaa c 2x aaa c d 2x 3 4 3 4 5 bbb c 2x n/2 tips nx b 5 1 2n/2 n/2 +1 n ddd c m a b d d e1 a b e e1 e1/2 e/2 e d ccc c c seating plane a2 a nx a a a1 h b b see view c view a-a l2 r r1 gauge plane l c seating plane view c base metal section b - b c1 with metal b1 (b) c 7 b 5 8 x x=a &/or b odd lead sides top view 5 x x=a &/or b even lead sides top view e/2 (l1) notes: 1. dimensions and tolerancing per asme y14.5m - 1994 2. dimension are in mm. 3. dimension d does not include mold flash, protrusions or gate burrs. mold flash, protrusions or gate burrs shall not exceed 0.15mm per end. dimension e1 does not include interlead flash or protrusion. interlead flash or protrusion shall not exceed 0.15mm per side. d and e1 dimensions are determined at datum h. all dimensions are in millimeters min nom max notes a 1.00 a1 0.01 0.05 0.10 a2 0.84 0.87 0.90 c 0.12 0.15 0.20 7 c1 0.08 0.13 0.16 7 d 2.90bsc 3,4 e 2.80bsc 3,4 e1 1.60bsc 3,4 l 0.30 0.40 0.50 l1 0.60ref l2 0.25bsc r 0.10 r1 0.10 0.25 0 4 8 14 10 12 tolerances of form and position notes aaa 0.15 1,2 bbb 0.25 1,2 ccc 0.10 1,2 variations aa 6 ab ba min nom max min nom max min nom max notes b 0.30 0.45 0.30 0.45 0.22 0.36 7,8 b1 0.31 0.35 0.39 0.31 0.35 0.39 0.22 0.26 0.30 e 0.95bsc 0.95bsc 0.65bsc e1 1.90bsc 1.90bsc 1.95bsc n6 5 8 tolerances of form and position ddd 0.20 0.20 0.13 1,2 4. the package top may be smaller than the package bottom. dimensions d and e1 are determined at the outermost extremes of the plastic body exclusive of mold flash, the bar burrs, gate burrs and interlead flash, but including any mismatch between the top and bottom of the plastic body. d and e1 dime nsions are determined at datum h. 5. datums a & b to be determined at datum h. 6. package varation "ab" is a 5 lead version of the 6 lead variation "aa" where lead #5 has been removed from the 6 lead "aa" v ariation. 7. these dimensions apply to the flat section of the lead between 0.08mm and 0.15mm from the lead tip. 8. dimension "b" does not include dambar protrusion. allowable dambar protrusion shall be 0.08mm total in excess of the "b" dim ension at maximum material condition. the dambar cannot be located on the lower radius of the foot. minimum space between protrusion and an adjacent lead shall not be less than 0.07mm. package outlines
cat32 13 doc no. 5001, rev. x tdfn 3x3 package (rd4) 3.00 + 0.10 (s) 85 1 4 3.00 + 0.10 (s) pin 1 index area c 0.75 + 0.05 0.0 - 0.05 0.30 + 0.07 (8x) 0.25 min. 0.75 + 0.05 a b 58 2.30 + 0.10 c0.35 pin 1 id 1.50 + 0.10 1.95 ref. (2x) 0.65 typ. (6x) 0.30 + 0.10 (8x) 1 2x 2x 0.15 0.15 c c note: 1. all dimension are in mm. angles in degrees. 2. coplanarity shall not exceed 0.08 mm. 3. warpage shall not exceed 0.10 mm. 4. package length / package width are considered as special characteristic(s) 5. refer jedec mo-229 / weec
cat32 14 doc. no. 5001, rev. x tdfn 3x4.9 package (rd2) d 0.08 c f 0.10 c 0.10m c a b 0.15 8 5 a 5 b 8 3.00 + 0.15 2.00 + 0.15 0.10 0.15 0.20 0.25 pin 1 id 0.60 + 0.10 (8x) d 0.15 c 2x 4.90 + 0.10 (5) 1 pin 1 index area 3.00 + 0.10 (s) 4 2x d c 4 0.30 + 0.05 (8x) 8x j 1.95 ref. (2x) 1 0.65 typ. (6x) 0.75 + 0.05 0.0-0.05 8x 0.20 ref. c note: 1. all dimension are in mm. angles in degrees. 2. coplanarity applies to the exposed pad as well as the terminals. coplanarity shall not exceed 0.08mm. 3. warpage shall not exceed 0.10mm. 4. package length / package width are considered as special characteristic(s). 5. refer to jedec mo-229, footprints are compatible to 8 msop.
cat32 15 doc no. 5001, rev. x catalyst semiconductor, inc. corporate headquarters 1250 borregas avenue sunnyvale, ca 94089 phone: 408.542.1000 fax: 408.542.1200 www.catalyst-semiconductor.com publication #: 5001 revison: x issue date: 9/11/03 type: preliminary copyrights, trademarks and patents trademarks and registered trademarks of catalyst semiconductor include each of the following: dpp ae 2 catalyst semiconductor has been issued u.s. and foreign patents and has patent applications pending that protect its products. for a complete list of patents issued to catalyst semiconductor contact the companys corporate office at 408.542.1000. catalyst semiconductor makes no warranty, representation or guarantee, express or implied, regarding the suitability of its products for any particular purpose, nor that the use of its products will not infringe its intellectual property rights or the rights of third parties with respect to any particular use or application and specifically disclaims any and all liability aris ing out of any such use or application, including but not limited to, consequential or incidental damages. catalyst semiconductor products are not designed, intended, or authorized for use as components in systems intended for surgica l implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the catalyst semic onductor product could create a situation where personal injury or death may occur. catalyst semiconductor reserves the right to make changes to or discontinue any product or service described herein without not ice. products with data sheets labeled "advance information" or "preliminary" and other products described herein may not be in production or offered for sale . catalyst semiconductor advises customers to obtain the current version of the relevant product information before placing order s. circuit diagrams illustrate typical semiconductor applications and may not be complete.

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