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SGM3142 6-channel charge pump white led driver with low dropout current source general description the SGM3142 is a high efficiency and cost effective charge pump white led driver. it supports up to 6 white leds and regulates a constant current for uniform intensity. the part maintains the high efficiency by utilizing a 1/1.5 fractional charge pump and low dropout current sources. the small equivalent 1 mode open loop resistance and ultra-low dropout voltage of current source extend the operating time of 1 mode and optimize the efficiency of li-ion battery in white led applications. user can easily configure each led current from 1.25ma to 20ma by a pulse dimming control. the dimming of white leds current can be achieved by applying a pulse signal to the en/set pin. there are totally 16 steps of current could be set by users. the operating voltage range is 2.7v to 5.5v. internal soft-start circuitry effectively reduces the in-rush current while both start-up and mode transition. the SGM3142 is available in green tqfn-44-16l package and is specified over an ambient temperature range of -40 to +85 . features input voltage range: 2.7v to 5.5v drives up to 6 leds at 20ma each 16-step brightness control high efficiency by fractional conversion with 1 and 1.5 modes automatic charge pump mode selection switching frequency: 1mhz 1% typical led current matching internal soft-start limits inrush current low input noise and low emi over-current and over-temperature protection output over-voltage protection under-voltage lockout with hysteresis available in green tqfn-44-16l package applications white led backlighting white photo-flash for dscs color (rgb) lighting programmable current source rev. a. 2 sg micro corp www.sg-micro.com
6-channel charge pump white led driver with low dropout current source 2 SGM3142 sg micro corp www.sg-micro.com package/ordering information model order number package description specified temperature range package option marking information SGM3142 SGM3142ytqe16g/tr tqfn-44-16l -40 to +85 tape and reel, 3000 SGM3142ytqe16 absolute maximum ratings vin to gnd?........................................................-0.3v to 6.0v the other pins to gnd?????...?????.. -0.3v to 6.0v package thermal resistance tqfn-44-16l, ja ???????.?..?????.?..50 /w storage temperature range...?.?...??.?...-65 to +150 junction temperature?................ ..................... .............. 150 operating temperature range...???...???-40 to +85 lead temperature (soldering 10 sec) ?......................................................................................260 esd susceptibility hbm??????????????????????.. 2000v mm?????????????????.????..??300v note: stresses beyond those listed under ?absolute maximum ratings? may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the s pecifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. caution this integrated circuit can be damaged by esd if you don?t pay attention to esd protection. sgmicro recommends that all integrated circuits be handled with appropriate precautions. failure to observe proper handling and installation procedures can cause damage. esd damage can range from subtle performance degradation to complete device failure. precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. sgmicro reserves the right to make any change in circuit design, specification or other related things if necessary without notice at any time. please contact sgmicro sales office to get the latest datasheet.
6-channel charge pump white led driver with low dropout current source 3 SGM3142 sg micro corp www.sg-micro.com pin configuration (top view) c2p vout c2n gnd 10 vin led4 5 6 7 8 2 3 4 1 9 11 12 13 14 15 16 c1p c1n n.c. n.c. en/ set led1 led5 led2 led3 led6 gnd tqfn-44-16l pin description pin name function 16 led1 output current for led1. 1 led2 output current for led2. 2 led5 output current for led5. 3 led6 output current for led6. 4 led3 output current for led3. 5 led4 output current for led4. 6 c1p positive input for the external flying capacitor c1. connect a ceramic 1 f capacitor close to the pins of the ic. 7 c1n negative input for the external flying capacitor c1. connect a ceramic 1 f capacitor close to the pins of the ic. 8,13 n.c. no internal connection. 9 vout output voltage source. 10 c2p positive input for the external flying capacitor c2. connect a ceramic 1 f capacitor close to the pins of the ic. 11 c2n negative input for the external flying capacitor c2. connect a ceramic 1 f capacitor close to the pins of the ic. 12 gnd ground. 14 vin power input voltage. 15 en/set chip enable (active high) and dimming control. exposed pad gnd exposed pad should be soldered to pcb board and connected to gnd.
6-channel charge pump white led driver with low dropout current source 4 SGM3142 sg micro corp www.sg-micro.com electrical characteristics (v in = 2.7v to 5.5v, c in = c out = c1 = c2 = 1 f, t a = +25 , unless otherwise noted.) parameter symbol conditions min typ max units input power supply input supply voltage v in 2.7 5.5 v under-voltage lockout threshold v in rising 1.8 2.2 2.5 v under-voltage lockout hysteresis 100 mv i q 1 mode, v in = 4v 0.3 1 quiescent power supply current i q 1.5 mode, v in = 3.3v 1 3.5 ma shutdown current i shdn v en = 0.4v 0.1 10 a 1 mode to 1.5 mode transition voltage (v in falling) v ts_1.5 v f = 3.25v, i out = 120ma, i ledx = 20ma 3.68 v hysteresis of mode transition 350 mv output output current i ledx v in = 3.5v,100% setting 18 20 22 ma current matching v in = 3.5v,100% setting -4 1 4 % en/set logic logic-high voltage v ih 1.5 v threshold logic-low voltage v il 0.4 v low time for dimming t lo 0.5 75 ? s high time for dimming t hi 0.25 ? s high current i ih v ih = v in 0.01 1 a en/set current low current i il v il = gnd 0.01 1 a low time for shutdown t shdn pwm dimming 0.3 0.5 ms frequency oscillator frequency f osc 1000 khz
6-channel charge pump white led driver with low dropout current source 5 SGM3142 sg micro corp www.sg-micro.com typical performance characteristics c in = c out = c1 = c2 = 1 f, t a = +25 , unless otherwise noted. efficiency vs. input voltage (620ma) 40 50 60 70 80 90 100 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 input voltage (v) efficiency (%) v diode = 3.25v efficiency vs. input voltage (610ma) 40 50 60 70 80 90 100 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 input voltage (v) efficiency (%) v diode = 3.1v
6-channel charge pump white led driver with low dropout current source 6 SGM3142 sg micro corp www.sg-micro.com typical performance characteristics c in = c out = c1 = c2 = 1 f, t a = +25 , unless otherwise noted. i diode vs. input voltage (620ma) 100 105 110 115 120 125 130 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 input voltage (v) i diode (ma) v diode = 3.25v enable voltage vs. input voltage 0.4 0.6 0.8 1.0 1.2 1.4 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 input voltage (v) en voltage threshold (v) rising falling i diode vs. input voltage (610ma) 50 55 60 65 70 75 80 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 input voltage (v) i diode (ma) v diode = 3.1v
6-channel charge pump white led driver with low dropout current source 7 SGM3142 sg micro corp www.sg-micro.com function block diagram 1/1.5 charge pump c1p c1n c2p c2n led1 led2 led3 led4 led driver en/set 1mhz osc voltage reference vout soft start control vin current reference led6 led5 16 steps pulse dimming interface uvlo ovp dimming dac
6-channel charge pump white led driver with low dropout current source 8 SGM3142 sg micro corp www.sg-micro.com typical application + c in 1f led4 led3 led2 led1 c1n c2p c1p c2n SGM3142 vin en/set gnd v battery 15 12 led5 led6 vout c out 1f 16 1 4 5 2 3 14 9 c1 1f c2 1f 6 7 10 11 en/set figure 1. for 6-wleds application circuit en i ledx shutdown 100% 15/16 3/16 4/16 5/16 1/16 shutdown 0 1 2 3 4 5 14 15 0 1 30s < t ready 0.5s < t hi 0.5s < t lo < 75s 500s < t shdn 2/16 2/16 1/16 figure 2. brightness control by pulse dimming
6-channel charge pump white led driver with low dropout current source 9 SGM3142 sg micro corp www.sg-micro.com typical application circuits + c in 1f led4 led3 led2 led1 c1n c2p c1p c2n SGM3142 vin en/set gnd v battery 15 12 led5 led6 vout c out 1f 14 9 c1 1f c2 1f 6 7 10 11 en/set 16 1 4 5 2 3 r b r b r b resistor r is optional r b r b r b resistor r is optional figure 3. driving two groups of paralleled white led's + c in 1f led4 led3 led2 led1 c1n c2p c1p c2n SGM3142 vin en/set gnd v battery 15 12 led5 led6 vout c out 1f 14 9 c1 1f c2 1f 671011 en/set 16 1 4 5 2 3 r b r b r b resistor r is optional r b r b r b photo flash led in some applications, white led forward voltages (v f ) can vary significantly. ballast resistors between the led cathodes and ground are recommended for balancing the forward voltage differences. t he ballast resistor value may be approximated by the following equation: f f source b i v v r ? ? figure 4. driving high current photo-flash led
6-channel charge pump white led driver with low dropout current source 10 SGM3142 sg micro corp www.sg-micro.com application information the SGM3142 is a high efficiency charge pump white led driver. it provides 6 channels low dropout voltage current source to regulated 6 white leds current. for high efficiency, the SGM3142 implements a smart mode transition for charge pump operation. the SGM3142 provides pulse dimming function for led brightness control. soft-start the SGM3142 includes a soft-start circuit to limit the inrush current at power on and mode switching. soft-start circuit limits the input current before output voltage reaching a desired voltage level. input uvlo the input operating voltage range of the SGM3142 is 2.7v to 5.5v. an input capacitor at the vin pin could reduce ripple voltage. it is recommended to use a ceramic 1f or larger capacitance as the input capacitor. this ic provides an under-voltage lockout (uvlo) function to prevent it from unstable issue when startup. the uvlo threshold of input rising voltage is set at 2.2v typically with a hysteresis 100mv. thermal protection the SGM3142 has a thermal protection circuit that will shut down the internal ldo and charge pump if the die temperature rises above the thermal limit. mode decision the SGM3142 uses a smart mode selection method to decide the working mode for optimizing the efficiency. mode decision circuit senses the output and led voltage for up/down selection. the SGM3142 automatically switches to 1.5 mode whenever the dropout condition is detected from the current source and returns to 1 mode whenever the dropout condition releases. brightness control the SGM3142 implements the pulse dimming method being used to control the brightness of white leds. the part implements a 4-bit dac for brightness control. users can easily configure the led current from 1.25ma to 20ma by a serial pulse. the maximum led current is up to 20ma that is sufficient for most application in backlight. the dimming of white leds' current can be achieved by applying a pulse signal to the en/set pin. there are totally 16 steps of current could be set by users. the detail operation of brightness dimming is showed in the figure 2. selecting capacitors careful selection of the four external capacitors c in , c1, c2, c out is important because they will affect some parameters such as input and output ripple, power efficiency, maximum supply current by charge pump, and start-up time. to reduce the input and output ripple effectively, the low esr ceramic capacitors are recommended. generally, to reduce the output ripple, increasing the output capacitance c out is necessary. however, this will increase the startup time of output voltage. for led driver applications, the input voltage ripple is more important than output ripple. input ripple is controlled by input capacitor c in , increasing the value of input capacitance can further reduce the ripple. practically, the input voltage ripple depends on the power supply?s impedance. if a single input capacitor c in cannot satisfy the requirement of application, it is necessary to add a low-pass filter. c-r-c filter used to reduce input ripple. the flying capacitor c1 and c2 determine the supply current capability of the charge pump. the lower value will limit the led? s current at low input voltage. for 6 20ma load over the entire input range of 2.7v to 5.5v, it is recommended to use a 1f ceramic capacitor on the flying capacitor c1 and c2.
6-channel charge pump white led driver with low dropout current source 11 SGM3142 sg micro corp www.sg-micro.com application information driving multiple led's, white led display module back lights the SGM3142 led1 to led6 outputs are true constant current sources capable of driving up to 20ma each over the operation input voltage range. since these outputs are true constant current sources, they may be connected in parallel to drive a single power output. any combination of outputs (led1 to led6) may be connected in parallel. the maximum total output current is a sum of how many current sources are parallel connected. this feature is particularly useful to power pre-manufactured display modules which are pre-wired with white led backlights connected in a parallel circuit configuration. any combination of outputs may be connected in parallel to drive groups of led's. the SGM3142 internal current source reference circuit bases feedback from current sensed on the led1 and led5 outputs. for best operation, the only requirement for this type of application is the output led1 and led5 should always be connected to the load circuit. the SGM3142 may be used to drive multiple led's having differing forward voltages. using feedback techniques, the current in led1 to led4 output currents sources are referenced to the current in the led connected to led1. the led5 and led6 output current sources are referenced to the current in led5, not to led1. if all six led's are of similar type, the diodes will be matched in current, maintaining uniform led brightness despite variations in manufacturer, production, etc.
6-channel charge pump white led driver with low dropout current source 12 SGM3142 sg micro corp www.sg-micro.com package outline dimensions tqfn-44-16l recommended land pattern (unit: mm) n9 k e1 e e n16 n5 n1 d d1 l b a1 a2 a side view bottom view top view 0.3 0.65 2.1 2.9 4.6 0.85 2.1 dimensions in millimeters dimensions in inches symbol min max min max a 0.700 0.800 0.028 0.031 a1 0.000 0.050 0.000 0.002 a2 0.203 ref 0.008 ref d 3.900 4.100 0.154 0.161 d1 2.000 2.200 0.079 0.087 e 3.900 4.100 0.154 0.161 e1 2.000 2.200 0.079 0.087 k 0.200 min 0.008 min b 0.250 0.350 0.010 0.014 e 0.650 typ 0.026 typ l 0.450 0.650 0.018 0.026
6-channel charge pump white led driver with low dropout current source 13 SGM3142 sg micro corp www.sg-micro.com tape and reel information note: the picture is only for reference. please make the object as the standard. key parameter list of tape and reel package type reel diameter reel width w1 (mm) a0 (mm) b0 (mm) k0 (mm) p0 (mm) p1 (mm) p2 (mm) w (mm) pin1 quadrant tqfn-44-16l 13 12.4 4.3 4.3 1.1 4.0 8.0 2.0 12.0 q1 reel width (w1) reel diameter reel dimensions tape dimensions direction of feed p2 p0 w p1 a0 k0 b0 q1 q2 q4 q3 q3 q4 q2 q1 q3 q4 q2 q1
6-channel charge pump white led driver with low dropout current source 14 SGM3142 sg micro corp www.sg-micro.com carton box dimensions note: the picture is only for reference. please make the object as the standard. key parameter list of carton box reel type length (mm) width (mm) height (mm) pizza/carton 13 386 280 370 5

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