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july 2, 2003 toko, inc. page 1 TK65600B lcd modules cellular telephone battery powered systems consumer electronics TK65600B top view inductive white led driver with synchronous rectifer block diagram advanced information features applications description minimum external components efficiency as high as 80% led current regulated internal synchronous rectifer pwm signal intensity control can drive mulitple strings of 3 wled in series 700 khz pwm operation low supply current enable pin short circuit protection over voltage protection 8 pin flip chip package the enable pin can take a pwm signal provided by the user to reduce the display brightness. a pwm signal is prefered to pulse the leds with a regulated value of current and to maintain better consistency of chromaticity. toko?s tk65600 white led driver ic has been optimized for battery controlled systems where power consumption and size are primary concerns. high efficiency has been opti- mized for this application. the miniature flip chip package device, together with the miniature toko coil d31fb or low profile d412f coil, further helps system designers reduce the space required to drive the white leds. the ic uses current-mode pwm (pulse width modulation) method of regulating the current through the string of leds. this time-proven method of regulation works at a fixed switching frequency which is preferred in rf systems, because the switching noise rf spectrum is more predict- able. with a switching frequency of 700 khz the operation of the ic should not disturb 455 khz if subsystem. enable a2 a3 n/c b3 fb c3 pgnd v out c1 v dd b1 agnd a1 c2 ind tape/reel code ordering information tape/reel code TK65600B package code package code ind fb pgnd v dd v out gate drive agnd scp/ovp pwm v ref osc enable enable a1 a2 c2 c1 c3 b3 b1
page 2 july 2, 2003 toko, inc. TK65600B TK65600B electrical characteristics v dd = 3.7 v, t a = t j = 25 c, unless otherwise specified. absolute maximum ratings advanced information all pins except ind, v out and gnd ........................... 6 v ind, and v out pins ............................................... 16.5 v storage temperature range ..................... -55 to +150 c operating temperature range ..................... -30 to +85 c junction temperature t jmax (note 3) ..................... 150 c package power dissipation t a = 25c (note 3) .... 560mw ja thermal resistance (note 3) ......................... 220c/w l o b m y sr e t e m a r a ps n o i t i d n o c t s e tn i mp y tx a ms t i n u v d d e g n a r y l p p u s t u p n i 7 . 2 7 . 3 5 . 5 v i d d v n i t n e r r u c t n e c s e i u q n i p d d v n e v 2 . 10 5 10 0 5a i b t s t n e r r u c y b d n a t sv n e v 3 . 02a v ) n o ( n e e g a t l o v n o l l u f e l b a n en o t u p t u o2 . 1 v d d 3 . 0 + v v ) f f o ( n e e g a t l o v f f o e l b a n ef f o t u p t u o3 . 0 -3 . 0v i n e t n e r r u c n i p e l b a n e5 - a i m i l t i m i l t n e r r u c t e f t s o o b g n i t t e s 0 0 4a m t a ) 4 e t o n ( c 5 8 + o t 0 3 - = r ) n o ( s d e c n a t s i s e r n o t e f t s o o b 5 . 1 ? p v on o i t c e t o r p e g a t l o v r e v o d a o l o n5 . 3 15 . 4 15 . 5 1v t a ) 4 e t o n ( c 5 8 + o t 0 3 - = r h c n y s n o r e i f i t c e r s u o n o r h c n y s e c n a t s i s e r 0 . 3 ? v b f e c n e r e f e r k c a b d e e f e g a t l o v 6 4 . 05 . 03 5 . 0v t a ) 4 e t o n ( c 5 8 + o t 0 3 - = i d e l ) t e s ( g n i w o l f t n e r r u c e g a r e v a d e l h g u o r h t v n e , v 2 . 1 2 . 3 3 = r o t s i s e r e s n e s ( , ? ) % 1 4 15 16 1a m i d e l ) r a v ( t n e r r u c e g a r e v a f o n o i t a i r a v d e l h g u o r h t v n e v < v 7 . 2 v 2 . 1 n i v 5 . 5 <5 . 1 -i d e l ) t e s (5 . 1 +% i d e l ) e n i l (i d e l n o i t a l u g e r e n i l v n e v < v 7 . 2 v 2 . 1 n i v 5 . 5 < i d e l ) 1 e t o n ( a m 5 1 = 1 6 1 . 0v / a m v dd pin operation enable pin operation ind pin operation v out pin operation fb pin operation
july 2, 2003 toko, inc. page 3 TK65600B typical application and test circuit advanced information TK65600B top view TK65600B electrical characteristics v dd = 3.7 v, t a = t j = 25 c, unless otherwise specified. note 1: when using test circuit below. note 2: converter efficiency is partly dependent upon the dc resistance of inductor l 1 . higher dc resistances will result in lower converter efficiency. note 3: the absolute maximum power dissipation depends upon the ambient temperature and can be calculated using the formula p dmax =(t jmax -t a ) / ja note 4: verified by design. boost converter operation l o b m y sr e t e m a r a ps n o i t i d n o c t s e tn i mp y tx a ms t i n u f t s o o b y c n e u q e r f t s o o b 5 7 50 0 75 2 8z h k t a ) 4 e t o n ( c 5 8 + o t 0 3 - = c d ) x a m ( y t u d m u m i x a m t s o o b e l c y c 5 85 9% t a ) 4 e t o n ( c 5 8 + o t 0 3 - = ? v t u o e l p p i r e g a t l o v t u p t u o) 1 e t o n ( 0 5v m p x a m t u o t u p t u o r e w o p m u m i x a mv n i v 3 = 0 0 3w m t a ) 4 e t o n ( c 5 8 + o t 0 3 - = f f ey c n e i c i f f e r e t r e v n o c t s o o b i d e l ) 2 , 1 e t o n ( a m 5 1 = 7 2 = l b f 1 3 d h 8 7% i d e l ) 2 , 1 e t o n ( a m 5 1 = 2 2 = l b f 3 1 3 3 d h 2 7% t t r a t s e m i t g n i l t t e s p u - t r a t s) 1 e t o n ( 0 0 3 s 1 f 22 h enable a2 a3 n/c b3 fb c3 pgnd v out c1 v dd b1 c2 ind agnd a1 v battery 33 ? 1 f l=d 3313fb-22 h coil
page 4 july 2, 2003 toko, inc. TK65600B feedback voltage vs. supply voltage su pp l y volta g e ( v ) feedback voltage (mv) 502.5 2.7 3.9 3.3 4.5 5.1 502.0 501.5 501.0 500.5 500.0 499.5 499.0 498.5 498.0 497.5 feedback voltage vs. temperature temperature (c) feedback voltage (mv) -50 -25 0 125 100 75 50 25 502.5 502.0 501.5 501.0 500.5 500.0 499.5 499.0 498.5 498.0 497.5 frequency vs. supply voltage supply volta g e (v) frequency (khz) 580 600 620 640 660 2.7 3.9 3.3 4.5 5.1 680 700 frequency vs. temperature tem p erature ( c ) frequency (khz) -50 640 -25 0 125 100 75 50 25 700 620 520 540 560 580 600 500 660 680 efficiency (22 h d3313fb coil) vs. supply voltage su pp l y volta g e ( v ) efficiency (%) 50.0 2.7 3.9 3.3 4.5 5.1 55.0 60.0 65.0 70.0 75.0 80.0 85.0 90.0 efficiency @15 ma efficiency @40 ma efficiency (22 h d3313fb coil) vs. temperature tem p erature ( c ) efficiency (%) -50 -25 0 125 100 75 50 25 62.0 64.0 66.0 68.0 70.0 72.0 74.0 76.0 60.0 78.0 80.0 efficiency @ 15 ma efficiency @ 40 ma
july 2, 2003 toko, inc. page 5 TK65600B quiescent current vs. supply voltage su pp l y volta g e ( v ) quiescent current (ma) 0 2.7 3.9 3.3 4.5 5.1 100 50 150 200 250 300 350 400 450 quiescent current vs. temperature tem p erature ( c ) quiescent current (ua) -50 -25 0 125 100 75 50 25 170.0 165.0 160.0 155.0 150.0 145.0 140.0 135.0 130.0 standby current vs. supply voltage su pp l y volta g e ( v ) standby current ( a) 2.7 3.9 3.3 4.5 5.1 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 ovp threshold vs. supply voltage su pp l y volta g e ( v ) over voltage protection (v) 2.7 3.9 3.3 4.5 5.1 15.5 15.3 15.1 14.9 14.7 14.5 14.3 14.1 13.9 13.7 13.5 ovp threshold vs. temperature tem p erature ( c ) overvoltage protection threshold (v) -50 -25 0 125 100 75 50 25 15.1 14.9 14.7 14.5 14.3 14.1 13.9 13.7 13.5 15.3 15.5 standby current vs. temperature tem p erature ( c ) standby current (ua) -50 3.5 -25 0 125 100 75 50 25 0.0 0.5 1.0 1.5 2.0 2.5 3.0 4.0
page 6 july 2, 2003 toko, inc. TK65600B maximum output power vs. supply voltage su pp l y volta g e ( v ) 0 2.7 3.6 3.3 3.9 4.2 100 200 600 800 1000 1200 output power (mw) 3.0 1100 300 400 500 700 900 1300
july 2, 2003 toko, inc. page 7 TK65600B supply voltage characteristics enable characteristics channel 1 is supply voltage channel 2 is the feedback voltage coming up to regulation. channel 1 supply voltage turns off channel 2 feedback voltage follows. channel 1 is the enable waveform to create a change in intensity channel 2 shows the feedback voltage reacting to the enable signal. channel 1 is the enable waveform channel 2 output voltage reacting to enable signal
page 8 july 2, 2003 toko, inc. TK65600B the tk65600 is an inductive white led driver circuit. the input voltage is 2.7v up to 6v. the load is represented by white led?s - one or more parallel strings of led?s, each string consisting of two or more led?s connected in series. the absolute maximum voltage allowed at the output pin is 16v, dictated by wafer process limits. the forward drop voltage of the led?s dictates how many led?s can be in a string, as the voltage at the output pin is the voltage across the led?s in series in a string, plus the voltage drop across the feedback resistor. the feedback resistor ap- pears in series with the load, connected between the bottom terminal of the led string(s) and ground. the minimum input voltage of 2.7v and the maximum output voltage of about 15v requires this circuit to be a boost circuit - tk65600 is an inductive boost circuit. the circuit regulates the current in the load, as the light intensity of the led?s depends on the current flowing through them. the led current information is provided by a feedback resistor, connected between the load and ground. a classical current -mode control loop, using pulse width modulation (pwm) at a fixed frequency, regulates the boost circuit output, such as to maintain the current in the led?s constant. as with any classical current -mode control loop pwm, the boost converter has the feature of pulse by pulse current limiting. on the tk65600 that current loop limit is set to about 400ma. therefore, the inductor, which is to be used with the tk65600, should have an isat above 400ma. there are a few additional functions the circuit incorporates: disable - allows the circuit to be turned on and off by an external enable signal (off for v enable <0.3v, on for v enable >1.2v) over-voltage protection (ovp) - shuts off the power fet?s if the output voltage rises above a predetermined threshold (14v). this is intended to prevent damage to the circuit for an open load condition, for instance, by not allowing the output voltage to rise above the preset limit. short-circuit protection (scp) - if the output sees an unusually high load or a short-circuit, there is circuitry provided that will cut off the current path to the output, wait a predetermined amount of time, then attempt to restart. if the output short-circuit or heavy loading condition at the output disappeared, the circuit will start and function normally. if the short-circuit condition persists, the circuit will wait again the predetermined amount of time, then it will attempt to restart again. the high load or short-circuit condition is identified, for the purpose of this feature, by a low output voltage (less than 1.2v). in order to provide for start-up condition (when the output voltage is inherently low), the scp circuitry waits for a little while, before asserting the short circuit condition signal. that little while is set now at sixteen (16) clock cycles, while the reset time, that is, the time before the circuit attempts to restart, it is set now at (512) clock cycles. with a clock of 600khz, these times are approximately 27us for asserting the short circuit condi- tion signal and about 853us between attempts to restart the boost circuit. theory of operation
july 2, 2003 toko, inc. page 9 TK65600B a classic boost configuration is not able to provide short circuit protection, as the input voltage source can provide current to the load, through the inductor and diode, even if the circuit is dis- abled. a synchronous rectifier is required, in order to be able to provide short circuit protection. the synchronous rectifier (msr) is replacing the diode found in classic boost circuits. the main advantage is eliminating the need for an external component. the second important advantage is the potential for less voltage drop across this device. a serious drawback is the fact that a fet is a non-directional device, unlike the diode it replaces, so, while the diode operated by itself, careful control of the synchronous rectifier operation is required. the synchronous rectifier must be off , at all times when the inductor switch is on - otherwise, shoot-through current from the boost capacitor, through the synchronous rectifier and through the inductor switch, to the ground, can occur - this cannot be allowed to happen, because of its effect on efficiency. a second issue to consider when driving the synchronous rectifier is the fact that, the fet being a non-directional device, the drive circuitry must ensure that the synchronous rectifier is on only when the boost voltage (output) is smaller than the voltage at the inductor node - otherwise, the boost (output) capacitor will discharge through the synchronous rectifier fet and inductor, to the input voltage source (vdd). when the inductor switch is off and the synchronous rectifier it is held off because the inductor voltage is smaller than the boost voltage, both power fet?s (mind and msr) are off. when this happens, the remaining energy in the inductor may be enough to start ringing, using the inductor and whatever parasitic capacitance can find (both mind and msr are large devices, with large parasitic capacitance). the resulting oscillations can be large enough to trigger the hysteresis comparator in the internal synchronous rectifier driver circuitry. also, this ringing oscillation may cause noise in other parts of the application?s system. to avoid these effects, a snubber circuit is used, to short the inductor node not to ground (that would be a loss of energy), but back to vdd (charging back the source). the snubber circuit must carefully select the moment when mind and msr are off, following the current ramp-up in the inductor, and not preceding it. the state machine inside the snubber does that. there is another moment when both mind and msr are off at the same time - when the inductor switch is cut off, after ramping the current in the inductor, but the synchronous rectifier, msr, is not yet on (due to delays in circuitry, etc.). at this point in time, the inductor node voltage is highest and no snubber effect is acceptable. theory of operation cont.
page 10 july 2, 2003 toko, inc. TK65600B pin description . o n n i pl o b m y sn o i t p i r c s e d 1 ad n g a o t h t a p t n e r r u c n r u t e r s e d i v o r p n i p s i h t . n i p d n u o r g g o l a n a e h t n i . n i p d d v e h t h g u o r h t t n e r r u c d e i l p p u s s t i u c r i c r e w o p w o l . e n a l p d n u o r g t a n i p d n g p o t t c e n n o c d r a o b t i u c r i c 2 ae l b a n e g n i h c t i w s t r a t s o t c i e h t n o s n r u t n i p s i h t . n i p t u p n i e l b a n e . c i e h t e l b a n e o t v 2 . 1 t a h t r e h g i h n i p e l b a n e e h t t e s . n o i t c a e v a e l t o n o d . c i e h t e l b a s i d o t v 3 . 0 w o l e b n i p e l b a n e e h t t e s . g n i t a o l f n i p s i h t 3 ac / nn o i t c e n n o c o n 1 bv d d e g a t l o v w o l o t r e w o p s e i l p p u s n i p s i h t . n i p y l p p u s r e w o p . c i e h t n i s t i u c r i c l o r t n o c ) v 6 < ( 3 bb f t u p n i e g a t l o v w o l a . n i p t u p n i n o i t a l u g e r e g a t l o v k c a b d e e f v m 0 0 5 o t d e t a l u g e r s i t a h t 1 cv t u o e h t e v i r d o t e g a t l o v e h t s e i l p p u s n i p s i h t . n i p e g a t l o v t u p t u o s i h c i h w ) v 5 . 6 1 < ( n i p e g a t l o v h g i h a s i t i . s d e l e t i h w c i e h t s p o t s h c i h w , t u c r i c t c e t o r p e g a t l o v r e v o n a y b d e t c e t o r p v 5 . 4 1 t u o b a s e h c a e r n i p s i h t f i g n i h c t i w s 2 cd n i n i p e g a t l o v h g i h a o s l a s i n i p s i h t . n i p n o i t c e n n o c r o t c u d n i t e f s o m l e n n a h c - n t s o o b l a n r e t n i e h t o t d e t c e n n o c s i d n a 3 cd n g p o t h t a p t n e r r u c n r u t e r s e d i v o r p n i p s i h t . n i p d n u o r g r e w o p t u o v d n a d n i e h t h g u o r h t d n u o r g o t g n i w o l f s t n e r r u c h g i h h g u o r h t n i p d n g a o t t c e n n o c d r a o b t i u c r i c e h t n i . s n i p . e n a l p d n u o r g
july 2, 2003 toko, inc. page 11 TK65600B application notes as wtih all switching power converters, care should be given to the circuit board layout. the bolded lines, on the schematic below, show where the high current paths of switched currents are in the circuit. the circuit board traces for these paths should be short and wide to minimize the power losses and electromagnetic interference generated from the switching currents. therefore c in , l and c out should be located close to the ic in the circuit board layout. also, the circuit board layout should keep the sense resistor close to the ic such that there is no voltage differences in the ground references. the (agnd) analog ground and the power ground (pgnd) should short as close to the device as possible. 1 f 22 h v battery 33 ? 1 f l=d 3313fb-22 h coil ind fb pgnd v dd v out gate drive agnd scp/ovp pwm v ref osc enable enable a2 b1 c2 c1 b3 c3 a1 on/off i led
page 12 july 2, 2003 toko, inc. TK65600B marking information marking package outline (flip chip) printed in the usa ? 1999 toko, inc. all rights reserved toko america regional offices toko america, inc. headquarters 1250 feehanville drive, mount prospect, illinois 60056 tel: (847) 297-0070 fax: (847) 699-7864 midwest regional office toko america, inc. 1250 feehanville drive mount prospect, il 60056 tel: (847) 297-0070 fax: (847) 699-7864 ic-xxx-tk65600 0798o0.0k visit our internet site at http://www.toko.com semiconductor technical support toko design center 4755 forge road colorado springs, co 80907 tel: (719) 528-2200 fax: (719) 528-2375 advanced information the information furnished by toko, inc. is believed to be accurate and reliable. however, toko reserves the right to make chang es or improvements in the design, specification or manufacture of its products without further notice. toko does not assume any liability arising from the application or use of any product or circu it described herein, nor for any infringements of patents or other rights of third parties which may result from the use of its products. no license is granted by implication or otherwise under any patent or pa tent rights of toko, inc. toko?s products are not authorized for use as critical components in life support devices or systems without the express written approval of the president of toko, incorporated. 8 bumps 0.300mm 0.010 diameter bumps .5mm pitch between bumps x = 1.500mm y = 1.500mm pin mark 0.5 0.5 x y c l c l bottom view note 1: sn/pb eutectic solder bump 0.60 0.02 0.220 0.015 silicon bump (note 1) c3 b3 a3 a1 a2 c1 b1 c2

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