RT9052 1 ds9052-01 april 2011 www.richtek.com ordering information note : richtek products are : ` rohs compliant and compatible with the current require- ments of ipc/jedec j-std-020. ` suitable for use in snpb or pb-free soldering processes. pin configurations (top view) applications z z z z z led backlight applications z z z z z current source z z z z z transistor driver sot-23-6 single channel led current source controller general description the RT9052 is a low cost, single channel led current source controller with a specific fault detector. the part can drive an external npn-bjt for various applications. the RT9052 is operated with vcc power ranging from 3.8v to 13.5v. with such a topology, it's very flexible and cost effective. the RT9052 comes in a small sot-23-6 package. features z z z z z 3.8v to 13.5v operation voltage z z z z z voltage reference 0.8v with 2% high accuracy z z z z z fault indicator with delay z z z z z dimming control by pwm z z z z z small footprint package sot-23-6 z z z z z rohs compliant and halogen free marking information eu=dnn eu= : product code dnn : date code typical application circuit dim gnd iset vcc dri 4 23 5 6 fault dri iset gnd vcc dim 5 3 2 6 4 1 wled r iset 5v 12v 1f v led RT9052 r b c in 100k r1 fault package type e : sot-23-6 RT9052 lead plating system g : green (halogen free and pb free)
RT9052 2 ds9052-01 april 2011 www.richtek.com functional pin description pin no. pin name pin function 1 dim pwm dimming control input. 2 gnd ground. 3 iset current setting input. 4 fault fault signal open drain output. 5 dri driver output. 6 vcc power supply input. function block diagram reference voltage dim + - + - 3ms delay vcc gnd dri iset driver v ref 0.9 x v ref fault
RT9052 3 ds9052-01 april 2011 www.richtek.com electrical characteristics (v cc = 5v/12v, t a = 25 c, unless otherwise specified) absolute maximum ratings (note 1) supply input voltage, v cc ---------------------------------------------------------------------------------------------- 15v dim voltage ---------------------------------------------------------------------------------------------------------------- 7v fault output voltage --------------------------------------------------------------------------------------------------- 7v power dissipation, p d @ t a = 25 c sot-23-6 -------------------------------------------------------------------------------------------------------------------- 0.4w package thermal resistance (note 2) sot-23-6, ja -------------------------------------------------------------------------------------------------------------- 250 c/w lead temperature (soldering, 10 sec.) ------------------------------------------------------------------------------ 260 c junction temperature ---------------------------------------------------------------------------------------------------- 150 c storage temperature range -------------------------------------------------------------------------------------------- ? 65 c to 150 c esd susceptibility (note 3) hbm (human body mode) ---------------------------------------------------------------------------------------------- 2kv mm (machine mode) ----------------------------------------------------------------------------------------------------- 200v recommended operating conditions (note 4) supply input voltage, v cc ---------------------------------------------------------------------------------------------- 3.8v to 13.5v dim voltage ---------------------------------------------------------------------------------------------------------------- 0v t o 5.5v junction temperature range ------------------------------------------------------------------------------------------- ? 40 c to 125 c ambient temperature range ------------------------------------------------------------------------------------------- ? 40 c to 85 c parameter symbol test conditions min typ max unit uvlo threshold v cc rising 3.15 3.4 3.65 v uvlo hysteresis 0.1 0.2 0.3 v v cc supply current i cc v cc = 12v -- 0.3 0.8 ma driver source current v cc = 12v, v dri = 6v 5 -- -- ma driver sink current v cc = 12v, v dri = 6v 5 -- -- ma iset reference voltage v ref v cc = 12v, v dri = 5v 0.784 0.8 0.816 v iset line regulation v cc = 4.5v to 13.5v -- 3 6 mv amplifier voltage gain v cc = 12v, no load -- 70 -- db fault rising threshold v cc = 12v 85 90 95 %v ref fault hysteresis v cc = 12v -- 15 -- %v ref sink capability v cc = 12v @ 1ma -- 0.2 0.4 v delay time t delay v cc = 12v 1 3 10 ms falling delay v cc = 12v -- 15 20 s dim dim rising threshold dim th v cc = 12v -- 0.7 1 v dim hysteresis v cc = 12v -- 30 -- mv standby current i standby v cc = 12v, v dim = 0v -- -- 5 a
RT9052 4 ds9052-01 april 2011 www.richtek.com note 1. stresses listed as the above " absolute maximum ratings " may cause permanent damage to the device. these are for stress ratings. functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. note 2. ja is measured in natural convection at t a = 25 c on a low effective thermal conductivity test board of jedec 51-3 thermal measurement standard. note 3. devices are esd sensitive. handling precaution is recommended. note 4. the device is not guaranteed to function outside its operating conditions.
RT9052 5 ds9052-01 april 2011 www.richtek.com typical operating characteristics iset voltage vs. vcc input voltage 0.780 0.785 0.790 0.795 0.800 0.805 0.810 0.815 0.820 3.5 5.0 6.5 8.0 9.5 11.0 12.5 14.0 vcc input voltage (v) iset voltage (v) v dim = 3v dim threshold voltage vs. vcc input voltage 0.4 0.5 0.6 0.7 0.8 0.9 1.0 3.5 5.0 6.5 8.0 9.5 11.0 12.5 14.0 vcc input voltage (v) dim threshold voltage (v) rising falling standby current vs. vcc input voltage 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 3.5 5.0 6.5 8.0 9.5 11.0 12.5 14.0 vcc input voltage (v) standby current ( a) 1 v dim = 0v supply current vs. vcc input voltage 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 3.5 5.0 6.5 8.0 9.5 11.0 12.5 14.0 vcc input voltage (v) supply current (ma ) v dim = 3v supply current vs. temperature 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 -50-25 0 25 50 75100125 temperature (c) supply current (ma ) v dim = 3v dim threshold voltage vs. temperature 0.4 0.5 0.6 0.7 0.8 0.9 1.0 -50 -25 0 25 50 75 100 125 temperature (c) dim threshold voltage (v) rising falling v cc = 12v
RT9052 6 ds9052-01 april 2011 www.richtek.com dri sink current vs. dri voltage 0 5 10 15 20 25 01234567 dri voltage (v) dri sink current (ma) v cc = 12v, v iset = 1v, v dim = 3v dri source current vs. dri voltage 35 37 39 41 43 45 47 49 51 53 55 01234567 dri voltage (v) dri source current (ma) v cc = 12v, v iset 0.6v, v dim = 3v led current vs. pwm duty 0 20 40 60 80 100 120 140 160 180 0 102030405060708090100 pwm duty (%) led current (ma) v cc = 12v, r iset = 5.1 , v dim = 0 to 5v/250hz 8leds dim pwm dimming time (1ms/div) v dim (5v/div) v iset (500mv/div) v led (2v/div) i led (100ma/div) v cc = 12v, r iset = 5.1 , v led = 3v iset voltage vs. temperature 0.760 0.765 0.770 0.775 0.780 0.785 0.790 0.795 0.800 0.805 0.810 0.815 0.820 -50-25 0 255075100125 temperature (c) iset voltage (v) v cc = 12v dri source current vs. temperature 0 10 20 30 40 50 60 70 -50 -25 0 25 50 75 100 125 temperature (c) dri source current (ma) v cc = 12v, v iset 0.6v, v dri = 6v
RT9052 7 ds9052-01 april 2011 www.richtek.com application information the RT9052 is a low cost single channel led current source controller with a specific fault indicating scheme. this device can drive an external npn-bjt for various applications. the RT9052 is operated with vcc power ranging from 3.8v to 13.5v. with such a topology, it is very flexible and cost effective. capacitors selection careful selection of the external capacitors for the RT9052 is necessary to maintain high stability and performance. a capacitor 1 f must be connected between vcc and ground to improve supply voltage stability for proper operation. fault function the RT9052 has a fault function with delay. the fault output is an open drain output. connect a 100k pull up resistor to external 5v source to obtain an output voltage. when the iset voltage reaches 90% of normal value, fault will become active and be pulled high by external circuits with a typical 3ms delay. led current setting the RT9052 includes a 0.8v reference voltage for easy setting of the led current source. as shown in application circuit, the led current is easily set via an r iset resistor. ) led iset 0.8 (v) i = r ( ( a) pwm dimming operation for controlling the led brightness, the RT9052 can perform dimming control by applying a pwm signal to the dim pin. the average led current is proportional to the pwm signal duty cycle. note that the magnitude of the pwm signal needs to be higher than the maximum dimming voltage of the dim pin, in order to have correct dimming control. npn transistor selection the RT9052 drives the npn transistor via the dri pin (source base current i b ). when making an npn transistor selection, the following criteria should be considered : dc current gain h fe , threshold voltage v be , collector- emitter voltage v ce , maximum collector current ic package thermal resistance (ja) . thermal considerations for continuous operation, do not exceed absolute maximum junction temperature. the maximum power dissipation depends on the thermal resistance of the ic package, pcb layout, rate of surrounding airflow, and difference between junction and ambient temperature. the maximum power dissipation can be calculated by the following formula : p d(max) = (t j(max) ? t a ) / ja where t j(max) is the maximum junction temperature, t a is the ambient temperature, and ja is the junction to ambient thermal resistance. for recommended operating condition specifications of the RT9052, the maximum junction temperature is 125 c and t a is the ambient temperature. the junction to ambient thermal resistance, ja , is layout dependent. for sot-23-6 packages, the thermal resistance, ja , is 250 c/w on a standard jedec 51-3 single-layer thermal test board. the maximum power dissipation at t a = 25 c can be calculated by the following formula : p d(max) = (125 c ? 25 c) / (250 c/w) = 0.400w for sot-23-6 package the maximum power dissipation depends on the operating ambient temperature for fixed t j(max) and thermal resistance, ja . for the RT9052 package, the derating curve in figure 1 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation.
RT9052 8 ds9052-01 april 2011 www.richtek.com 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0 25 50 75 100 125 ambient temperature (c) maximum power dissipation (w) 1 layout consideration there are three critical layout considerations. ` the current setting resistor should be located as close as possible to the RT9052 to avoid inducing any noise. ` the input capacitor have to put at near the ic for improved performance. ` the pass element operating under high power situation may raise the junction temperature above the package thermal resistance limit. (copper area can be added to improve power dissipation.) figure 1. derating curve for RT9052 package single-layer pcb dim gnd iset vcc dri 4 2 3 5 6 vcc c in 5v gnd dri r b r iset v led wled r1 place c in near the ic for improved performance the gnd plane should be connected to a strong ground plane for heat sinking and noise protection. iset node copper area should be minimized and kept far away from noise sources fault figure 2. pcb layout guide
RT9052 9 ds9052-01 april 2011 www.richtek.com information that is provided by richtek technology corporation is believed to be accurate and reliable. richtek reserves the ri ght to make any change in circuit design, specification or other related things if necessary without notice at any time. no third party intellectual property inf ringement of the applications should be guaranteed by users when integrating richtek products into any application. no legal responsibility for any said applications i s assumed by richtek. richtek technology corporation headquarter 5f, no. 20, taiyuen street, chupei city hsinchu, taiwan, r.o.c. tel: (8863)5526789 fax: (8863)5526611 richtek technology corporation taipei office (marketing) 5f, no. 95, minchiuan road, hsintien city taipei county, taiwan, r.o.c. tel: (8862)86672399 fax: (8862)86672377 email: marketing@richtek.com outline dimension a a1 e b b d c h l sot-23-6 surface mount package dimensions in millimeters dimensions in inches symbol min max min max a 0.889 1.295 0.031 0.051 a1 0.000 0.152 0.000 0.006 b 1.397 1.803 0.055 0.071 b 0.250 0.560 0.010 0.022 c 2.591 2.997 0.102 0.118 d 2.692 3.099 0.106 0.122 e 0.838 1.041 0.033 0.041 h 0.080 0.254 0.003 0.010 l 0.300 0.610 0.012 0.024
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