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e u p 2588 ds 2 588 ver1.2 dec. 2011 1 4 str ings high current white led driver with boost controller d escription the eup2588 is a high power and high efficiency boost controller with 4-channel current sinker which is ideal for large lcd backlighting applications. eup2588 uses current mode, fixed frequency architecture which can clamp the inductor peak current each cycle. the switching frequency is programmable by an external frequency setting resistor. it drives an external mosfet to boost up the output voltage from a 4.5v to 28v input supply. the eup2588 regulates the current in each led string to the programmed value set by an external current setting resistor. the eup2588 current matching can achieve 1.5% and regulation accuracy can reach 2%. a 3 a shutdown current and 0.85v (iled@180ma) feedback voltage and maximum 65v output allows for up to 18 high-power leds in series will greatly improve efficiency and reduce power dissipation. the device supports pulse width modulation (pwm) brightness dimming. during digital pwm dimming, the wled current is turned on/off at the duty cycle and frequency determined by the pwm signal on the pwmi pin. the eup2588 integrated multiple protect functions, such as led open, led short, output over voltage, over thermal, input over current, and under voltage lockout (uvlo), these protection will prevent the lcd backlight from damage. eup2588 is available in 16pin sop and tssop (ep) packages. features 3 a shutdown current 4 strings in parallel and up to 18 leds per string external pwm dimming control output voltage up to 65v up to 180ma drive capability for each string wide input voltage range 4.5v to 28v better than 1.5% led current regulation accuracy between strings boost switching frequency can be programmed by external resistor multiple fault protections -current limit protection -output short circuit detection -over-temperature protection -output over-voltage protection led current turn off in shutdown mode integrated uvlo/ over thermal protection minimal 0.5 s led on-time regulation thermal enhanced tssop-16 and 16pin sop-16 packages rohs compliant and 100% lead (pb)-free halogen-free applications lcd monitor led backlighting lcd-tv led backlighting typical application circuit figure 1. typical application circuits v?mw`r?y?b? www.gofotech.com
eup2588 ds2588 ver1.2 dec. 2011 2 pin configurations package type pi n configurations package type pin configurations sop-16 tssop-16 (ep) pin description pin name so p-16 tssop-16 (ep) description ch4 1 5 channel 4 led current source. leave it floating if not used. iset 2 6 full-scale led current adjustment pin. the resistance from iset to gnd controls the full-scale current in each led string. iset voltage is around 1.0v, during full lighting, ichx=1200/riset ohm. set riset=10kohm, ichx is set to 120ma. ovp 3 7 output over-voltage feedback input. connect ovp to the tap point of the resistor divider between output and ground. fset 4 8 boost switching frequency program pin. program the boost frequency by different external resistance, and the boost converter frequency set by formula: fsw=50000/r fset (k ). if setting fset=100k, boost frequency is 50 0khz. en 5 9 the device enable pin. a logic high signal turns on the internal ldo and enables the ic. connect en to vcc and make eup2588 always on. ics 6 10 current sense input. during normal operation, this pin senses the voltage across the external inductor current sensing resistor for peak current mode control and also to limit the inductor current during every switching cycle. drv 7 11 external n-ch power device gate driver output. this pin provides the boost converter power device gate drive signal. vcc 8 12 5v linear regulator output to power internal circuitry. bypass vcc to gnd with a ceramic capacitor of 1f or greater. if 4.5v eup2588 ds2588 ver1.2 dec. 2011 3 ordering information order number package type markin g operating temperature range eup2588dir1 sop-16 xxxxx p2588 -40 c to +85c EUP2588XIR1 tssop-16 (ep) xxxxx eup2588 -40 c to +85c eup2588 lead free code 1: lead free, halogen free packi n g r: tape & reel operating temperature range i: industry standard package type d: sop x: tssop (ep) block di agram figure 2. block diagram n~n?t?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
eup2588 ds2588 ver1.2 dec. 2011 4 absolute maximum ratings (1) ics, ch (n) to gnd ------ ---------------------------------------------------- --------------- -0.3v to 65v vin to gnd --------------------------------------------------- ------------------------------- -0.3v to 30v ovp, en, pwmi, fault, vcc to gnd ------ ------------------------------------------ -0.3v to +6v comp, drv, iset, fset to gnd ------ ------------------------------------------ - 0.3v to (vcc+0.3)v continuous power dissipation (t a = +70c) 16-pin sop [derate 12.5mw/c (jedec high-k 2s2p) above +70c] --------------------- 1000mw 16-pin tssop [derate 25mw/c (jedec high-k 2s2p) above +70c] -------------------- 2000mw operating temperature range ------ ---------------------------------------------------- -- -40c to +85c maximum junction temperature ------ ---------------------------------------------------- ------- +150c storage temperature range ------ ---------------------------------------------------- ---- -60c to +150c lead temperature (soldering, 10s) ----- - ---------------------------------------------------- ------- +300c operating conditions (2) operating temperature range ------------------------------------------------------------- -40c to +85c supply voltage , vin----------------------------------------------------------------------------- 4.5v to 28v maximum led current, ichn ------------------------------------------------------------- 60ma to 180ma maximum led pulse current=1ms -------------------------------------------------------------------200ma note ( 1): stress beyond those listed under absolute maximum ratings may damage the device. note (2): the device is not guaranteed to function outside the recommended operating conditions. electr ical characteristics (circuit of figure 1, vin=12v, gnd=0v, r iset =10k , r fset =10 0k ,v pwmi = 5v , t a = 40c to +85c , un le ss otherwise noted. typical values are at t a = +25c.) eup2588 symbol parameter conditions min. typ. max. unit vin vin supply voltage 4.5 28 v i_vin vin supply current pwmi=5v 1 2 ma i_off vin shutdown current pwmi=en=0,vin=12v 6 a i_standby vin standby current en=5v, pwmi=0v, vin=12v 750 1200 a vcc vcc output voltage ven=5v, 6v100ns (drv=hi time>100ns) 450 500 550 mv gm comp transconductance ? icomp=10 a 60 s dmax maximum duty cycle 90 93 96 % led current regulation rch chn sink resistance iledn=120ma 5 n~n?t?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
eup2588 ds2588 ver1.2 dec. 2011 5 electrical characteristics (continued) (circuit of figure 1, vin=12v, gnd=0v, r iset =10k , r fset =100 k ,v pwmi = 5v , t a = 40c to +85c , un le ss otherwise noted. typical values are at t a = +25c.) eup2588 symbol parameter conditions min. typ. max. unit led current regulation viset iset regulation voltage 1 v iled output led current riset=10k 115.2 120 124.8 ma imatch chn current matching iled=120ma -1.5 1.5 % dimming controls tpwmimin minimum pwm pulse in external pwm dimming mode 0.5 s vpwmh pwmi input high level 2.4 vcc v vpwml pwmi input low level 0 0.7 v ipwmi pwmi pull down current v pwmi =5v -1 +1 a fault detections vovp over-voltage threshold on ovp rising edge 1.9 2.0 2.1 v vhys-ovp ovp hysteresis falling edge 70 mv vchx_ov chx over voltage threshold v in >5.5v 6.5 7 7.5 v r fault fault sink resistance 10 tsd thermal shutdown threshold 150 oc tsd_hys thermal shutdown hysteresis 30 oc n~n?t?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
eup2588 ds2588 ver1.2 dec. 2011 6 86.0 87.0 88.0 89.0 90.0 91.0 92.0 93.0 94.0 95.0 6 11 16 21 26 input voltage(v) efficiency(%) 0 25 50 75 100 125 150 175 200 225 250 0 20 40 60 80 100 duty(%) iled(ma) 100hz 2khz typical operating characteristics (v in =12v, i set =20k, fset=330k, status=100k, l=47 h, c comp = 22nf, c out =47 f) efficien cy vs. input voltage current linearity fsw vs. rfset steady state 200hz pwmi dimming (duty cycle=50%) 2khz pwmi dimming (duty cycle=50%) 10 s/div 2ms/di v 200 s/div v sw 20v/div v out (ac) 1v/div 100 200 300 400 500 600 700 800 900 1000 40 80 120 160 200 240 280 320 360 rfset(k ) fsw(khz) v ch1 1v/div i led 200ma/div pwmi 5v/div v sw (ac) 20v/div v out 50v/div i led 200ma/div pwmi 5v/div v sw (ac) 20v/div v out 50v/div i led 200ma/div n~n?t?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
eup2588 ds2588 ver1.2 dec. 2011 7 typical operating characteristics (continued) (v in =12v, i set =20k, fset=330k, status=100k, l=47 h, c comp = 22nf, c out =47 f) v in startu p en startup protection of over thermal en from on to off vin from on to off protection of channel open (channel 1 open) 40ms/div 40ms/di v 40ms/div v in 10v/div en 5v/div v out 10v/div i led 100ma/div v in 10 v/div en 5v/div v out 10v/div i led 100ma/div v out 50v/div v ch2 20v/div v ch1 5v/div i ch2 500ma/div 10ms/div v sw 20v/div v out 20v/div v in 5v/div i led 200ma/div v sw 20v/div v out 20v/div v en 5v/div i led 200ma/div 10ms/div 1s/div v out 20v/div status 5v/div v ch1 10v/div i led 200ma/div n~n?t?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
eup2588 ds2588 ver1.2 dec. 2011 8 typical operating characteristics (continued) (v in =12v, iset=20k, fset=330k, status=100k, l=47 h, c comp = 22nf, c out =47 f) protec tion of channel short to vout (channel 1 short to vout) p rotection of vout short to gnd protection of inductor short 20ms/div v out 20v/div v ch2 5v/div v ch 1 10v/div i ch1 50ma/div v out 20v/div status 5v/div v ovp 1v/div i ch1 50ma/div 40ms/div 20ms/div v out 50v/div v sw (ac) 50v/div v ch1 50v/div i led 200 ma/div n~n?t?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
eup2588 ds2588 ver1.2 dec. 2011 9 detailed descriptions the eup2588 is a high-efficiency driver for arrays of white leds. it contains a fixed-frequency, current mode, pwm step-up controller, 5v linear regulator, dimming control circuit, and 4 regulated current sources (see figure 2). when enabled, the step-up controller boosts the output voltage to provide sufficient headroom for the current sources to regulate their respective string currents. the eup2588 features programmable switching frequency, which allows trade-offs between external component size and operating efficiency. the control architecture automatically skips pulses at light loads to improve efficiency and prevents overcharging the output capacitor. the eup2588 supports external digital control of the led current through a pwm logic input signal on pwmi. the eup2588 has multiple features to protect the controller from fault conditions. separate feedback loops limit the output voltage if one or more leds fail open or short. the controller features cycle-by-cycle current limit to provide consistent operation and soft-start capability. a thermal-shutdown circuit provides another level of protection. this part includes a 5v linear regulator that provides the internal bias and gate drive for the step-up controller. when an external 5v is available, the internal ldo can be overdriven to decrease power dissipation. otherwise, connect the vin pin to an input greater than 5.5v. an internal crude ldo keeps alive to provide power supply for internal logic and controller even en is low, which only dissipate 3ua quiescent current. 5v supply vcc and uvlo the eup2588 has built in 5v linear regulator vcc supply for internal control voltage. the eup2588 includes the power on reset (por) and under-voltage lockout (uvlo) features. por resets the fault latchs. por occurs when vcc rises above 2.8v (typ). the controller is disabled until vcc exceeds the uvlo threshold of 4.05v (typ). hysteresis on uvlo is approximately 150mv. the vcc should be bypassed to gnd with a 0.47 f or greater ceramic capacitor. system startup when the eup2588 is enabled, the chip checks the topol o gy connection first. and after 8ms delay, the chip monitors the ovp pin to see if the schottky diode is not connected or the boost output is short to gnd. if the ovp voltage is lower than 70mv, the chip will be disabled. it is recommended on the start up sequence that the enable signal comes after input voltage and pwm dimming signal established. step-up converter the converter operation frequency is programmable (from 150khz to 1.5mhz) with a external set resistor on fset pin, which is helpful for optimizing the external components sizes and improving the efficiency. an oscillator resistor on fset pin sets the internal oscillator frequency for the step-up converter according to the equation: for r fset = 1 00k , the switching frequency is set to 500kh z. the eup2588s fixed-frequency, current-mode, step-up controller automatically chooses the lowest active chx voltage to regulate the output voltage. when iled=180ma, a 0.85v is setting as the minimum chx feedback reference. the error signal is compared to the external switch current plus slope compensation to determine the switch on-time. as the load changes, the error amplifier sources or sinks current to the comp output to deliver the required peak-inductor current. the slope-compensation signal is added to the current-sense signal to improve stability at high duty cycles. at light-load or vout near to vin operation, the converter runs into the pulse-skipping mode, the fet is turned on for a minimum on-time of approximately 100ns, and then the converter discharges the power to the output in the remain period. the external mosfet will keep off until the output voltage needs to be boosted again. dimming control the eup2588 provides external pwm dimming for all 4 chann e ls led current adjustment. this pwm signal results in pwm chopping of the current in the leds for all 4 channels to provide led control. eup2588 accepts 100hz to 20khz external pwm signal, and this signal with low level less than 0.7v and high level above 2.4v. open string protection the open string protection is achieved through the over voltag e protection. if one or more strings are open, the respective chx pins are pulled to ground and the ic keeps charging the output voltage until it reach ovp threshold. then the part will mark-off the open strings whose chx pin voltage is less than 210mv. once the mark off operation completes, the remaining led strings will force the output voltage back into tight regulation. the string with the highest voltage drop is the ruling string during output regulation. the eup2588 always tries to light at least one string and if all strings in use are open, the eup2588 shuts down the step-up converter. the part will maintain mark-off information until the part shuts down. setting the over voltage protection the open string protection is achieved through the over volta g e protection (ovp). in some cases, an led string failure results in the feedback voltage always zero. the part then keeps boosting the output voltage higher and higher. if the output voltage reaches the programmed ovp threshold, the protection function will be triggered. to make sure the chip functions properly, the ovp setting resistor divider must be set with a proper value. the recommended ovp point is about 1.2 times higher than the output voltage for normal operation. fset sw 50000/r f = n~n?t?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
eup2588 ds2588 ver1.2 dec. 2011 10 short string protection the eup2588 monitors the chx pin voltage to judge if the sh ort string occurs. if one or more strings are shorted, the respective chx pins will be pulled up to the boost output and tolerate high voltage stress. if the chx pin voltage is higher than 7v, the short string condition is detected on the respective string. when the short string fault (chx over-voltage fault) continues for greater than 2ms, the string is marked off and disabled. once a string is marked off, its current regulation is forced to disconnect from the output voltage loop regulation. the marked-off led strings will be shut off totally until the part restarts. if all strings in used are short, the eup2588 will shut down the step-up converter. fault protection the eup2588 has multiple features to protect the device from f ault conditions. separate feedback loops limit the output voltage under any circumstance, ensuring safe operation. once an open string is detected, the string is disabled while other strings operate normally. the eup2588 also features short led detection. table 1 lists all the eup2588 fault protections control. table 1. eup2588 fault protection faults fault state boost dc-dc wled current chx short to gnd high, only 4chx off fault=lo only 4chx all off, controller will shutdown. otherwise, keep normal mark off the shorted chx, others keep normal chx over voltage high, only 4chx off fault =lo only 4chx all off, controller will shutdown. otherwise, keep normal mark off the led open chx, others keep normal ovp shorted to gnd or boost schottky diode malfunction (vovp<0.07v) fault =lo off off dc-dc boost output exceeds ovp threshold (vovp=2.0v) vovp>2.0v, fault =lo vovp<1.95v, fault =hi when vovp is greater than 2.0v, the boost controller will be turned off until vovp drops to 1.95v. on thermal fault (tj>+150oc) tj>150oc, fault =lo tj<120oc, fault =hi off first, then return to soft-start after tj falls below 120oc off first, then return to soft- start after tj falls below 120oc en low fault =hi off off ? ? ? ? ? ? ? ? + = 2 21 ovp r rr 0. 2v n~n?t?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
eup2588 ds2588 ver1.2 dec. 2011 11 packaging information sop-16 millimeters inches symbols min. max. min. max. a 1.35 1.75 0.053 0.069 a1 0.10 0.25 0.004 0.010 b 0.31 0.51 0.012 0.020 d 9.90 0.389 e1 3.90 0.153 e 5.79 6.20 0.228 0.244 e 1.27 0.050 l 0.38 1.27 0.015 0.050 n~n?t?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com
eup2588 ds2588 ver1.2 dec. 2011 12 tssop-16 (ep) millimeters inches symbols min. max. min. max. a - 1.20 - 0.047 a1 0.00 0.15 0.000 0.006 b 0.19 0.30 0.007 0.012 e1 4.40 0.173 d 5.00 0.197 d1 1.98 3.00 0.078 0.118 e 6.20 6.60 0.244 0.260 e2 1.98 3.00 0.078 0.118 e 0.65 0.026 l 0.45 0.75 0.018 0.030 n~n?t?m?w3^v?mw`r?y?b?g ?pqls? tel: 0755-8398 3377 / 135 9011 2223 http://www.gofotech.com v?mw`r?y?b? www.gofotech.com

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