www. belling .com .cn 1 8 - channel wled linear driver b l8088 description the BL8088 is a cmos based white/blue led driver with stand - alone capability. the driver is primarily designed for led backlighting of lcd display powered by li - ion battery . with its high efficiency, low standby current and wide range of inp ut supply voltage, the BL8088 is suitable for applications such as portable device display and keypad backlighting. there are eight identical channels in BL8088 , each of which can drive one led by current rating of 20ma. BL8088 is available with qf n 3x3 - 1 6 package features ? 8 - channel output ? 2.7 to 5.5v input range ? pwm dimming control , suggested 1khz ? led sink current of 20ma ? independent current sink circuit for each led output ? low standby current ? high accuracy current match on each channel applications ? lcd screen b acklights d river ? mobile phone, portable d evi ce keypad b acklights d river typical application pin assignment block diagram bl8 0 88 l c 1 9 8 8 v i n e n g n d d 4 d 3 d 2 d 1 1 u f v i n e n d 5 d 6 d 7 d 8 1 6 1 5 1 4 1 3 1 2 3 4 1 2 1 1 1 0 9 5 6 7 8 k d l l n y w d 6 d 5 d 4 d 3 d 2 d 1 g n d n c e n n c n c n c d 8 d 7 v i n n c
www. b elling .com .cn 2 b l8088 marking information product classification BL8088 cjktr marking top view k c ll n yw k c : product code ll : lot no . n : fab code y : year no. w: week no. ordering information BL8088 1 2 3 code description 1 temp erature & rohs: c: - 40~85 ? c, pb free rohs std. 2 package type: jk : qfn 3x3 C 16 3 packing type: tr: tape&reel (standard) pin description name function description d1 - d 8 rgb or wled cathode connection pin en chip enable a nd dimming control . v in power supply gnd ground nc not connected absolute maximum rating supply voltage C 0.3v to 7v voltage of ledn, en pin C 0.3v to 7v maximum junction temperature 125c operating ambient temperature range C 40c to 85c storage temperature range C 40c to 150c lead temperature (soldering, 10 sec) 260c note: exceed these limits to damage to the device. note: exposure to absolute maximum rating conditions may affect device reliability . recommended operating conditions items mi n max unit supply voltage range 2.7 5.5 v operating temperature - 25 85 c 1 6 1 5 1 4 1 3 1 2 3 4 1 2 1 1 1 0 9 5 6 7 8 k d l l n y w d 6 d 5 d 4 d 3 d 2 d 1 g n d n c e n n c n c n c d 8 d 7 v i n n c
www. b elling .com .cn 3 b l8088 electrical characteristics vcc=3.7v, t a =25 c , no load, input: ven=3.7v. (unless otherwise noted) symbols parameters conditions spec unit min typ max v il en pin low lo gic 0.4 v v ih en pin high logic 1.7 v i il en pin low input current - 1 u a i ih en pin high input current 1 u a v ledl ledn dropout voltage 100 mv i led ledn sink current 18 20 22 ma i ledn ledn sink current deviation - 5 5 % i q qu iescent current 500 8 00 u a i stby standby supply current ven=0 0.5 u a detailed description BL8088 works with a wide range of supply voltage, from 2.7v to 6v. the forward voltage of commercial white/blue led is in the range of 2.9v to 3.5v at a current level of 20ma. proper selection of the led to match the supply voltage can fully utilize the li - ion battery. for example, there is 1% ~ 3 % power left in the li - ion battery when its voltage reaches 3.275v. so a led with a forward voltage value of 3 .2v can use up to 99% of the battery power under normal working condition. when the voltage of the battery drops below 3.2v, the current through the led (hence the brightness) starts to decrease. due to its uniquely designed current regulator, BL8088 offe r s low output dropout and provide superior efficiency performance over standard inductive boost type and capacitive charge pump type led driver. the en pin controls the on/off state of the device. a high level state turns on the device and a low level tur ns off the device, results in the low off state current. this pin needs to be terminated since a floating level of the en pin will cause the instability of the device. the sink current has a constant value of 20ma. the brightness of the led can be adjust ed by controlling the duty cycle of the BL8088 s ledn output. this can be accomplished by applying a pwm signal to the en pin. in BL8088 , the internal power on sequence presents a delay time of 6us from en pin to ledn pin. hence, i n order to modulate the o utput of ledn in every cycle normally , the width of dimming signal applied en pin have to be no less than 6us. for example, when a dimming signal of 20khz is applied, the minimum range of dimming is about 12%, that is, the average output current on each c hannel is 2.4ma.
www. b elling .com .cn 4 b l8088 typical performan ce characteristics quiescent current vs supply current (ta=25) 0 50 100 150 200 250 300 350 3.0 3.5 4.0 4.5 5.0 supply voltage (v) quiescent current (ua) quiescent current vs temperature (vcc=3.7v) 0 50 100 150 200 250 300 350 400 450 -40 -20 0 20 40 60 80 100 120 140 temperature ( ) quiescent current (ua) iled vs supply voltage (vcc=3.7v, vledn=3.2v) 10 12 14 16 18 20 22 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2 supply voltage (v) iled (ma) iled vs ledn dropout voltage (vcc=3.7v) 0 5 10 15 20 25 0.01 0.1 1 10 ledn dropout voltage (v) led current (ma) iled vs temperature (vcc=3.7v) 19.7 19.8 19.8 19.9 19.9 20.0 20.0 20.1 20.1 20.2 20.2 -50 -25 0 25 50 75 100 125 temperature ( ) iled (ma)
www. b elling .com .cn 5 b l8088 package information package qfn3x3 - 16 devices per reel 3000 unit mm
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