2009/04/20 ver.2 page 1 SP1820 four channels constant current led driver description applications the SP1820 is a four channels constant current driver white led. the device can drive up to 20ma load current per channel from single cell lithium ion battery. SP1820 can provide lowest cost led driver for various applications. it does not require any external components. internal thermal protection automatically adjusts led current to prevent overheating. the dimming control can be achieved by feeding a pwm or analog signal into th e iset pin. the device can be shut down by enable low. z battery powered devices z digital camera z pda, mp3/4 z gps z mobile phone z keyboard/display backlight features pin configuration(sop ? 8p) part marking z low cost led driver z constant current output z four channels led driver provides matching led current z low quiescent current z disconnects leds in shutdown mode z thermal shut down protection z current adjustable via external resistor z dimming control thru either enable or iset
2009/04/20 ver.2 page 2 SP1820 four channels constant current led driver typical applcation circuit pin description pin symbol description 1 vcc supply voltage input 2 gnd ground 3 en high enable pin 4 iset current set input 5 led1 led 1 6 led2 led 2 7 led3 led 3 8 led4 led 4 ordering information part number package part marking SP1820s8rgb sop- 8p SP1820 SP1820s8rgb : 13? tape reel ; pb ? free ; halogen ? free
2009/04/20 ver.2 page 3 SP1820 four channels constant current led driver block diagram absoulte maximum ratings (t a =25 unless otherwise specified) parameter symbol value unit dc supply voltage v in 5.5 v output led current i led 20 ma operating temperature t opr -40 85 maximum junction temperature t j(max) 125 storage temperature t s -65 150 the ic has a protection circuit against static electricity. do not apply high static electricity or high voltage that exceeds the performance of the protection circuit to the ic. electrical characteristics (t a =25 , v in =3.6v, r set =7.5kohm, v led =0.5v, unless otherwise specified) parameter conditions min. typ. max. unit operating voltage 2.7 5.5 v led current 18.5 20 21.5 ma current matching ch to ch +/-1.5 +/-3.5 % quiescent current i led = 0a, rset = open 250 a line regulation iled change pe r volt vcc change 0.15 0.6 %/v load regulation v led <5v, i led = 20ma 3 6 %/v i set voltage 1.5 v enable voltage high 3.6v vin 4.2v 3.6 v enable voltage low 3.6v vin 4.2v 0.4 v thermal shutdown threshold 130 thermal shutdown hysteresis 20 current off mode 0.2 a
2009/04/20 ver.2 page 4 SP1820 four channels constant current led driver performance characteristics (t a =25 , unless otherwise specified.) iled vs. vled 0 2 4 6 8 10 12 14 16 18 20 0 0.2 0.4 0.6 0.8 1 vle d(v) il e d (m a ) iled vs. power supply 0 2 4 6 8 10 12 14 16 18 20 3.6 3.8 4 4.2 4.4 4.6 4.8 5 power supply(v) il e d (m a ) quiescent current vs. power supply 100 105 110 115 120 125 3.6 3.8 4 4.2 4.4 4.6 4.8 5 power supply(v) iq (u a ) led current vs. set resister 0 5 10 15 20 25 30 8 121620242832 rset(k ) ? il e d (m a )
2009/04/20 ver.2 page 5 SP1820 four channels constant current led driver application information circuit description SP1820 is a four channels white-led driver with matching current output. the matching current regulator has a 460:1 ratio between iled and iset. SP1820 is capable to supply 25ma for each channel with proper selection of external resistor. the design has a band gap regulator , voltage to current converter and mirror drivers. thermal protection SP1820 has a thermal comparator to shut down th e device when the internal temperature reaches 150 . it will remain shut down until the temperature drops to 130 . enable SP1820 has an enable pin that is designed for ttl input. the device will be active at voltage high. this pin can also be used to control the brightness of led with a pw m signal. the brightness is proportional to the duty cycle of the pwm signal. when duty cycle is zero, leds are tu rned off. for 50% duty cycl e, it will result an average iled to be half the programmed led current which is set by rset. iset the iset pin is a voltage input to set the current of led. an external resistor is used to set the output current, as approximated with the following equation: rset = 460 * (1.2v/iled) however, the rset shall not be selected to exceed the maximum current delivery capability of the device, 25ma. a pwm signal or analog signal can also be applied at iset pin to control the led brightness.
2009/04/20 ver.2 page 6 SP1820 four channels constant current led driver sop- 8 package outline
2009/04/20 ver.2 page 7 SP1820 four channels constant current led driver information provided is alleged to be exact and consistent. sync power corporation presumes no responsibility for the penalties of use of such information or for any violation of pa tents or other rights of third parties which may result from its use. no license is granted by allegation or otherwise under any pate nt or patent rights of sync power corporation. conditions mentioned in this publication ar e subject to change without notice. this p ublication surpasses and replaces all information previously supplied. sync power corporation products are not authorized for use as critical components in life support devices or systems without express written approval of sync power corporation. ?the sync power logo is a registered trademark of sync power corporation ?2004 sync power corporation ? printed in taiwan ? all rights reserved sync power corporation 7f-2, no.3-1, park street nankang district (nksp), taipei, taiwan 115 phone: 886-2-2655-8178 fax: 886-2-2655-8468 http://www.syncpower.com
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