c o p y r igh t @ w i n s em i microelectronics c o . , lt d . , a l l ri g h t r e s er v ed . rev. 1.0 july .201 1 ws ws ws ws 3 3 3 3 2 2 2 2 15 15 15 15 features features features features simple low parts count wide input voltage range 8v to 40v up to 1.5a output current output current limit protection over temperature protection single pin on/off and brightness control using dc voltage or pwm typical 5% output current accuracy inherent open-circuit led protection high efficiency (up to 97% ) adjustable led constant current applications applications applications applications mr16 leds automotive lighting low voltage industrial lighting i lluminated signs typical typical typical typical application application application application circuit circuit circuit circuit description description description description the WS3215 is a continuous conduction mode inductive step-down converter . designed for driving single or multiple series led efficiently from a voltage source higher than the total led chain voltage. the device operates from an input supply between 8v and 30v and provides an external adjustable output current of up to 1.5a . depending upon supply voltage and external components, the WS3215 can provide more than 10 watts of output power. the WS3215 includes the power switch and a high-side output current sensing circuit . which uses an external resistor to set the nominal average output current, and a dedicated dim input accepts either a dc voltage or a wide range of pulsed dimming. applying a voltage of 0.3v or lower to the dim pin turns the output off and switches the device into a low current standby state. WS3215 using sot89-5 package . 40v/1.5a 40v/1.5a 40v/1.5a 40v/1.5a step-down step-down step-down step-down high high high high brightness brightness brightness brightness led led led led driver driver driver driver
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 2 / 9 ws ws ws ws 3 3 3 3 2 2 2 2 15 15 15 15 pin pin pin pin definition definition definition definition and and and and device device device device marking marking marking marking pin pin pin pin function function function function description description description description pin pin pin pin name name name name pin pin pin pin no. no. no. no. pin pin pin pin type type type type function function function function description description description description sw 1 output drain terminal of internal power mosfet. gnd 2 power signal and power gnd. dim 3 floating used for enabling switch and dimming with either a dc voltage or pwm input signal . csn 4 current monitoring used for high-side output current sensing with an external sensing resistance between csn and vin. vin 5 frequency setting power supply input. bypass with capacitor as close to the device as possible . exposed pad 6 floating connected to gnd for thermal considerations and pasted on pcb for reducing thermal resistance. block block block block diagram diagram diagram diagram
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 3 / 9 ws ws ws ws 3 3 3 3 2 2 2 2 15 15 15 15 ordering ordering ordering ordering information information information information package package package package ic ic ic ic marking marking marking marking information information information information purchasing purchasing purchasing purchasing device device device device name name name name sot89-5 pb-free WS3215 tp ws32 15 recommended recommended recommended recommended operating operating operating operating condition condition condition condition s s s s ymbol ymbol ymbol ymbol p p p p arameter arameter arameter arameter v v v v alue alue alue alue u u u u nit nit nit nit v in input voltage 8~40 v t a operating temperature -20~85 absolute absolute absolute absolute maximum maximum maximum maximum ratings ratings ratings ratings ( ( ( ( note note note note 1) 1) 1) 1) s s s s ymbol ymbol ymbol ymbol p p p p arameter arameter arameter arameter value value value value unit unit unit unit v in dc supply voltage -0.3~50 v sw drain voltage of internal power mosfet -0.3~50 v csn output current sensing voltage ( relative tov in ) 0.3~-6.0 v dim switch enable and dimming voltage -0.3~6.0 v isw maximum output current 1.8 a p dmax power dissipation ( note 2 ) 1.5 w p tr thermal resistance , sot89-5 ( ja ) 45 /w t j junction operating temperature -40 to 150 t stg storage temperature -55 to 150 note 1 absolute maximum ratings are limits beyond which damage to the device may occur. operating ratings are conditions for which the device is intended to be functional, but device parameter specifications may not be guaranteed. for guaranteed specifications and test conditions, see the electrical characteristics. note 2 higher temperature leads to the necessary decreasing of maximum power dissipation. it also decided by both t jmax , ja , and ambient temperature t a . the maximum accepted power is formulated as p dmax = (t jmax -t a )/ ja or the value among the lower ones in the absolute maximum rating. esd esd esd esd information information information information s s s s ymbol ymbol ymbol ymbol p p p p arameter arameter arameter arameter v v v v alue alue alue alue u u u u nit nit nit nit v esd-hbm human body model on all pins ( discharge with a 100pf capacitor through a 1.5k resistance . ) 4 kv v esd-mm machine model on all pins 4 00 v
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 4 / 9 ws ws ws ws 3 3 3 3 2 2 2 2 15 15 15 15 electrical electrical electrical electrical characteristics characteristics characteristics characteristics ( ( ( ( vin=12v,t=25 . (unless otherwise specified) ) note 3 4 symbol symbol symbol symbol parameter parameter parameter parameter test test test test conditions conditions conditions conditions min min min min typ typ typ typ max max max max unit unit unit unit v in supply voltage - 8 40 v v uvlo v in uvlo threshold v in dscreasing 6.8 v v uvlo,hys v in uvlo hysteresis v in increasing 500 mv f sw maximal oscillating frequency 1 mhz sensing current v csn average sensing voltage v in - v csn 95 100 105 mv v csn_hys sensing voltage hysteresis 10 % i csn input current from csn v in - v csn =50mv 8 ua turn-off current i off turn-off current v dim <0.3v 50 ua dim input v dim internal supply voltage dim floating 5 v v dim_h high level for dim input voltage 2.5 v v dim_l low level for dim input voltage 0.3 v v dim_dc dimming rang with a dc voltage 0.5 2.5 v f dim maximal pwm dimming frequency f osc =500khz 50 khz d pwm_lf duty range of pwm dimming at low frequency f dim =100hz 0.02% 1 pwm dimming ratio at low frequency 5000:1 d pwm_hf duty range of pwm dimming at high frequency f dim =20khz 4% 1 pwm dimming ratio at high frequency 25:1 r dim pull-up resistance between dim and internal supply voltage 1.2 m i dim_l leakage current v dim = 0 4.2 ua switching r sw sw turn-on resistance v in =24v 0. 5 v in =12v 0. 5 i swmean sw continuous current 1.5 a i leak sw leakage current 0.5 5 ua thermal protection t sd otp threshold 160 t sd_hys otp hysteresis 20 note 3 typical numbers are measured at 25 c as standard parameter. note 4 in this datasheet, design methods, measurement and statistical analysis guarantee the typical value while measurement guarantees the range between the minimum and maximum.
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 5 / 9 ws ws ws ws 3 3 3 3 2 2 2 2 15 15 15 15 typical typical typical typical operating operating operating operating characteristics characteristics characteristics characteristics 75.00 80.00 85.00 90.00 95.00 100.00 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 vin/v vin/v vin/v vin/v eff./% eff.1 led eff.1 led eff.1 led eff.1 led eff.3 led eff.3 led eff.3 led eff.3 led eff.7 led eff.7 led eff.7 led eff.7 led l=47uh,rs=0.27ohm l=47uh,rs=0.27ohm l=47uh,rs=0.27ohm l=47uh,rs=0.27ohm efficiency efficiency efficiency efficiency 75.00 80.00 85.00 90.00 95.00 100.00 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 vin/v vin/v vin/v vin/v eff./% eff.1 led eff.1 led eff.1 led eff.1 led eff.3 led eff.3 led eff.3 led eff.3 led eff.7 led eff.7 led eff.7 led eff.7 led l=47uh,rs=0.27ohm l=47uh,rs=0.27ohm l=47uh,rs=0.27ohm l=47uh,rs=0.27ohm efficiency efficiency efficiency efficiency vdim vs vin vdim vs vin vdim vs vin vdim vs vin 0 1 2 3 4 5 0 5 10 15 20 25 30 35 40 vin/v vin/v vin/v vin/v vdim/v vdim/v vdim/v vdim/v vdim vs vin vdim vs vin vdim vs vin vdim vs vin 0 1 2 3 4 5 0 5 10 15 20 25 30 35 40 vin/v vin/v vin/v vin/v vdim/v vdim/v vdim/v vdim/v
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 6 / 9 ws ws ws ws 3 3 3 3 2 2 2 2 15 15 15 15
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 7 / 9 ws ws ws ws 3 3 3 3 2 2 2 2 15 15 15 15
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 8 / 9 ws ws ws ws 3 3 3 3 2 2 2 2 15 15 15 15 operation operation operation operation description description description description applying WS3215 with inductor (l) and current sensing resistance rs forms a self-oscillating step-down continuous current mode inductive led controller. when vin increases at the beginning, led output current are zero initially through inductor, sensing resistance. meanwhile, the cs comparator turns high, the voltage of sw is low and the internal power mosfet is conductible. through the external components and internal power mosfet to gnd, output current gets greater with a constant rate determined by the voltage difference between inductor s two terminals, then generate a sensing voltage on the rs. if (vin-vcsn)>110mv, cs comparator turns low and internal power mosfet turn off, the state can not change until (vin-vcsn)<90mv. as a result, the average led output current can be caculated by the following equation: high-side current sensing circuit is applied for less external components. with 1% accuracy of sensing resistance, the led output current can be controlled within 5% variation. a dedicated dim input accepts a wide range of a dc voltage or pulsed dimming. applying a voltage of 2.5v or higher to the dim pin will turn on the power mosfet completely, however, 0.3v or lower will turn the output off. therefore, it is available to receive a pwm dimming frequency range from 100hz to 20khz. otherwise, an external resistance can be used to set the led output current. linking with the internal pull-up resistance (typically 1.2 mohm) , which is connected to the inner regulated 5v, a voltage applied to the dim can be achieved. by changing the ratio between the outer and inner resistance, the dimming voltage can be different and brightness of led can be adjustable. during the turn-off phase, the quiescent current is only 60ua although the inner reference module is still at work.. for the consideration of reliability, over-temperature protection in WS3215 is necessary. it avoids the WS3215 suffering over-temperature damage and guarantees the maximum led output current after recovery to normal. rs rs iout 1 . 0 2 11 . 0 09 . 0 = + =
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 9 / 9 ws ws ws ws 3 3 3 3 2 2 2 2 15 15 15 15 sot sot sot sot 89 89 89 89 - - - - 5 5 5 5 packa packa packa packa ge ge ge ge dimension dimension dimension dimension a a a a 1.40 1.50 1.60 a1 a1 a1 a1 0.30 0.40 0.50 b b b b 0.36 0.42 0.48 b1 b1 b1 b1 0.41 0.47 0.53 c c c c 0.38 0.40 0.43 d d d d 4.40 4.50 4.60 e e e e 4.25 e1 e1 e1 e1 2.40 2.50 2.60 e e e e 1.40 1.50 1.60 l l l l 0.80
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