View SGM3122_8018259.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

SGM3122 white led charge pump current source with pwm brightness control general description the SGM3122 is a charge pump with pwm brightness control for white led supplie s in lcd display backlight applications. the supply voltage ranges from 2.7v to 5.5v, it is ideally suited for all applications powered by a single li-ion battery cell or three to four nicd, nimh, or alkaline battery cells. the device provides a constant current for each led, and the initial current value can be set by an external resistor. high efficiency is achieved by utilizing a 1 /1.5 fractional conversion technique in combination with very low dropout current sources. the SGM3122 is capable of driving up to four channels of leds at 30ma per channel from a 2.7v to 5.5v input. additionally, the current controlled charge pump ensures low input current ripple and emi. a low external part count (two 0.47f flying capacitors and two small 1f capacitors at vin and vout) makes this part ideally suited for small, battery-powered applications. the SGM3122 is available in a green tqfn-33-16l package, and is rated over the -40c to +85c temperature range. features ? input voltage range: 2.7v to 5.5v ? drives up to 4 leds at 30ma each ? led brightness control through pwm control signal ? high efficiency by fractional conversion with 1 and 1.5 modes ? switching frequency: 1mhz ? regulated output current with 0.5% matching ? internal soft-start limits inrush current ? low input ripple and low emi ? over-current and over-temperature protected ? under-voltage lockout with hysteresis ? available in green tqfn-33-16l package applications cellular phones smart phones digital cameras handheld pcs camcorders pdas keypad backlight sg micro corp www.sg-micro.com rev. a. 2
white led charge pump current source with pwm brightness control 2 SGM3122 sg micro corp www.sg-micro.com SGM3122 package/ordering information order number package description specified temperature range package option marking information SGM3122ytq16g/tr tqfn-33-16l -40c to +85c tape and reel, 3000 3122tq absolute maximum ratings supply voltage???????.??????.??-0.3v to 6.0v voltage at en1, en2, vout, iset????..?.??-0.3v to v in output current at vout????.????...?????300ma storage temperature range???????....-65 to +150 maximum junction temperature???.?...??????160 operating temperature range...?........?.??. -40 to +85 lead temperature (soldering 10 sec) ?????????????????????.????260 esd susceptibility hbm??????????????...????????4000v mm????????????????????????400v 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.
white led charge pump current source with pwm brightness control 3 SGM3122 sg micro corp www.sg-micro.com SGM3122 pin configuration (top view) pgnd vout c2- c1- c1+ c2+ d4 iset nc d3 gnd d1 d2 en1 gnd en2 1234 5 6 7 8 9 10 12 11 13 15 14 16 vin tqfn-33-16l pin description pin name i/o function 1 iset i connect a resistor between this pin and gnd to set the maximum current through the leds. 2 nc - no internal connection. 3 - 6 d1 - d4 i current sink input. connect the cathode of the white leds to these inputs. 7 pgnd - power ground. 8 vout o connect the output capacitor and the anode of the leds to this pin. 9 c2+ - connect to the flying capacitor c2. 10 c1+ - connect to the flying capacitor c1. 11 c1- - connect to the flying capacitor c1. 12 c2- - connect to the flying capacitor c2. 13 vin i supply voltage input. 14 gnd - analog ground. 15 en1 i enable input. a logic high enables the converter, logic low forces the device into shutdown mode reducing the supply current to less than 1 a if en2 is tied to gnd. 16 en2 i an applied pwm signal reduces the led current as a function of the duty cycle of the pwm signal. en1 and en2 can be tied together for pwm dimming between 0ma and the maximum set with iset. en1 and en2 can also be used for digital dimming with 4 steps from 0ma to the maximum current set with iset. power pad connect with pgnd and gnd.
white led charge pump current source with pwm brightness control 4 SGM3122 sg micro corp www.sg-micro.com SGM3122 electrical characteristics (v in = 3.6v, en1 = en2 = v in , t a = 25c, unless otherwise noted.) parameter symbol conditions min typ max units supply voultage and current input voltage range v in i led = 25ma 2.7 5.5 v v in = 4.2v, 1 mode, en1 = en2 = 1 i set = 0 a 100 a v in = 4.2v, 1 mode, en1 = en2 = 1 i set = 20 a 200 a quiescent power supply current i q i out = 0ma, 1.5 mode 2 ma shutdown supply current i sd en1 = en2 = gnd 0.1 1 a charge pump stage overvoltage limit v out led1 unconnected v in = 4.2v 5.3 v start-up time c out = 1 f, i dx 0.9 i dx_set 150 s soft-start duration 130 s switching frequency f 0.6 1 1.4 mhz efficiency v in = 3.7v, i led = 15ma each, v dx = 3.1v 83 % shutdown temperature temperature rising 160 shutdown temperature hysteresis 20 input current limit en1 = en2 = 1, i set = 100 a 300 ma current sinks recommended maximum current per current sink i dx 3.2v v in 5.5v 30 ma current into each current sink when iset is shorted to gnd i dx 3.0v v in 5.5v iset shorted to gnd 45 ma current matching between any two outputs v dx = 3.1v, t a = 25 -3 0.5 3 % line regulation 3v < v in < 5.5v, v led = 3.1v, en1 = en2 = 1, i set = 80 a 0.8 % en2 = 0, en1 = 1 200 en2 = 1, en1 = 0 400 reference voltage for current set v iset en2 = 1, en1 = 1 580 600 620 mv recommended iset pin current range i set 2 130 a i dx to iset current ratio k en1 = en2 = 1, iset = 80 a 230 255 280 en2 = 0, en1 = 1 200 en2 = 1, en1 = 0 300 voltage at d x to gnd v source en2 = 1, en1 = 1 400 mv en1, en2 en1,en2 high level input voltage v ih 1.3 v en1,en2 low level input voltage v il 0.3 v en1,en2 trip point hysteresis 75 mv en2 input leakage current i ikg en1, en2 = gnd or en1, en2 = v in = 5.5v 0.1 1 a en1 input leakage current i ikg en1, en2 = gnd or en1, en2 = v in = 5.5v 0.1 1 a under-voltage lockout threshold v (uvlo) input voltage falling 2.1 v under-voltage lockout hysteresis 20 mv frequency range at pwm 0 50 khz recommended on-time for pwm signal 2.5 s shutdown delay time 0.85 ms
white led charge pump current source with pwm brightness control 5 SGM3122 sg micro corp www.sg-micro.com SGM3122 typical application + - li-ion battery c in 1 f vin d1 en1 iset gnd pgnd d2 d3 vout c2+ c1+ c1- c2- rset c out 1 f c2 0.47 f en2 c1 0.47 f SGM3122 d4 functional block diagram 1f vout 1f d1 d2 d3 iset r set gnd pgnd charge pump current sinks reference control en1 en2 vin c1+ c1- 0.47f c2+ c2- 0.47f d4
white led charge pump current source with pwm brightness control 6 SGM3122 sg micro corp www.sg-micro.com SGM3122 typical performance characteristics table of graphs figure 1 efficiency ( ) vs input voltage (i led = 25ma, 20ma, 15ma, 10ma, 5ma per led), en2 = en1 = 1 the curve with higher efficiency is for input voltage from high to low. 2 led current, i led vs duty cycle on pwm (i led max set to 20ma), for f = 32khz, and f = 1khz, dc = 1% to 100%, v in = 3.6v. 3 switching frequency (f s ) vs free-air temperature (t a = -40 to 85 , v in = 3.6v) 4 quiescent current (i q ) vs input voltage (t a = 25 ) (measured with i d1 = 5ma) 5 led current regulation vs input voltage 4 20ma 6 maximum output current from charge pump stage vs input voltage (t a = 25c) 7, 8 dimming response pwm signal and current at d1 vs time-on scope f = 32khz and f = 1khz, v in = 3.6v, duty cycle = 50%, en1 = en2 = pwm 9, 10 startup timing v in = 3.6v, 4 20ma, en1 = en2 = 00 changed to en2 = en1 = 11 11 input and output ripple v in = 3.6v, 4 20ma, en1 = en2 = 1 12 line transient response v in and i d1 vs time-on scope led current at d1 with v in = 4.2v to 3.6v to 4.2v with en2 = en1 = 11, 4 20ma
white led charge pump current source with pwm brightness control 7 SGM3122 sg micro corp www.sg-micro.com SGM3122 typical performance characteristics efficiency vs. input voltage 30 40 50 60 70 80 90 2.5 3 3.5 4 4.5 5 5.5 input voltage (v) efficiency (%) en1 = en2 = 1 5ma 10ma 15ma 20ma 25ma the curve with higher efficiency is for input voltage from high to low figure 1 switching frequency vs. temperature 900 920 940 960 980 1000 1020 -55 -35 -15 5 25 45 65 85 temperature ( ) switching frequency (khz) v in = 3.6v figure 3 led current regulation vs. input voltage 24.5 24.7 24.9 25.1 25.3 25.5 3.2 3.6 4 4.4 4.8 5.2 input voltage (v) led current (ma) 5.5 figure 5 d1 led current vs duty cycle 0 5 10 15 20 25 0 102030405060708090100 duty cycle (%) i led(d1) - d1 led current (ma) en1 = en2 = 1 f = 32khz f = 1khz i led max set to 20ma figure 2 quiescent current vs. input voltage 0 0.5 1 1.5 2 2.5 3 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 input voltage (v) quiescent current (ma) t a = 25 figure 4 maximum output current vs. input voltage 40 60 80 100 120 140 160 180 2.7 3.2 3.7 4.2 4.7 5.2 input voltage (v) maximum output current (ma) 5.5 v led = 3.1v t a = 25 figure 6
white led charge pump current source with pwm brightness control 8 SGM3122 sg micro corp www.sg-micro.com SGM3122 typical performance characteristics figure 7 figure 9 figure 11 figure 8 figure 10 figure 12
white led charge pump current source with pwm brightness control 9 SGM3122 sg micro corp www.sg-micro.com SGM3122 detailed description operation the SGM3122 uses a fractional conversion charge pump to generate a supply voltage for the integrated current sinks. these current sinks are used to ensure a constant current for each led. depending on the input voltage and programmed led current, the charge pump either operates in the 1 mode or in the 1.5 mode. by switching automatically between these two modes, the circuit optimizes power conversion efficiency as well as extends operating time by allowing the discharge of the battery completely. the charge pump can generate 120ma of output current, so each of the 4-led outputs can be powered with up to 30ma of current. the maximum led current is set by a resistor connected to the iset pin. this resistor programs a reference current, which is current mirrored to set the led current. applying a pwm signals to the en1 pin and/or the en2 pin controls the led brightness. see a detailed description in the section analog dimming using iset pin. led current adjustment (iset) a resistor programs a reference current, which is current mirrored to set the led current. the voltage at the iset pin depends on the status of en1 and en2. the current in each led is typically 255 times the current through the resistor at iset (see table 2). r iset = led iset i v k v iset ? voltage from iset pin (0.2v, 0.4v or 0.6v) to gnd, see table 1. i led ? current per led from d x pin to gnd. k ? d x to iset current ratio (typically 255). the led current varies linearly from 0ma to i led (max) by applying a pmw signal with 0% to 100% duty cycle. the led brightness can however also be controlled by an analog control signal that is fed into the iset pin. soft-start the SGM3122 has an internal soft-start circuit to limit the inrush current during startup. this prevents possible voltage drops of the input voltage if a high impedance power source is connected to the input of the SGM3122. when the device starts up with an output voltage that is below the input voltage, the output capacitor is charged directly from the input with a current source. the output current increases linearly until the output reaches within 300mv of the input voltage. when the programmed output current can be reached with the 1 mode, the SGM3122 terminates the soft-start and begins normal operation. when the desired output current cannot be reached, the charge pump begins operation in 1.5 mode and pumps the output voltage up to the needed level to reach the programmed output current. enable (en1, en2) the enable pins en1 and en2 are used to enable the device or set it into shutdown. the SGM3122 is enabled if one of the enable pins is pulled higher than the enable trip point of 1.3v. the device starts up by going through the soft-start routine as described in the section soft-start. pulling both pins to gnd, after a delay, programs the device to shutdown. in shutdown, the charge pump, current sources, voltage reference, oscillator, and all other func tions are turned off and the supply current is reduced to 0.1a. en1 and en2 can also be used for dimming. the logic levels at en1 and en2 set the minimum voltage at the current mirrors and the voltage at the iset pin to gnd. this sets the current at the leds to be either the full current or a fraction of the full current. see table 1 for further details. the maximum current through the leds is set by a resistor connected between iset and gnd. en1 and en2 can also be used for pwm dimming. the pwm signal can either be applied to en1 or en2, or both inputs can be tied together and the pwm signal can be applied to both pins. depending on the configuration, the current during pwm dimming is switched between 0ma and its maximum (en1 and en2 connected to the pwm signal) or between 0ma and 1/3 of the full led current if en2 = 0 and en1 is toggled. when en1 = 0 and en2 is toggled, the output current can be changed between 0ma and 2/3 of the full range.
white led charge pump current source with pwm brightness control 10 SGM3122 sg micro corp www.sg-micro.com SGM3122 detailed description table 1. enable levels enable level en2 en1 v iset led current 0 0 0 0 0 1 200 mv 1/3 1 0 400 mv 2/3 1 1 600 mv full table 2. r iset values set drive current (full) r iset computation value (k ? ) standard resistor value (k ? ) 30ma 5.1 5.1 25ma 6.12 6.19 20ma 7.65 7.68 10ma 15.3 15.4 5ma 30.6 30.9 under-voltage lockout the under-voltage lockout circuit shuts down the device when the voltage at vin drops below a typical threshold of 2.15v. this prevents damage to the device. the uvlo circuit allows the device to start up again after the voltage on the vin pin has increased by about 50mv above the uvlo lockout threshold. short-circuit and over-temperature protection the current at the vout pin is limited typically to 300ma. when the junction temperature exceeds 160c, the device shuts down to protect the device from damage. after the temperature decreases to about 140c, the device starts up again if it is enabled. over-voltage protection at vout the device uses the voltage at d1 to regulate voltage at vout. in case d1 is not connected, an overvoltage protection circuit ensures that the output voltage at vout does not exceed its limits. the connection of the leds must be started using d1 first. for all other leds there is no restriction in the sequence. for example, if there are only 2 leds used, the first led is connected to d1 and the other led can be connected to any other of the d2 to d4 pins.
white led charge pump current source with pwm brightness control 11 SGM3122 sg micro corp www.sg-micro.com SGM3122 theory of operation/design procedure capacitor selection ceramic capacitors such as x5r or x7r are recommended to be used with the SGM3122. for the two flying capacitors c1 and c2, it is important to use low esr capacitors to avoid unnecessary efficiency losses. low esr capacitors on vout reduce the ripple voltage on the supply of the current sources. table 3 lists capacitor types that have been tested with the SGM3122. table 3. capacitors part value voltage manufacturer size website c1608x5r1a105m c1608x5r1a474m c2012x7r1c105m 1 f 0.47 f 1 f 10v 10v 16v tdk 0603 0603 0805 www.componnent.tdk.com lmk107bj105ma lmk107bj474ma lmk212bj105mg 1 f 0.47 f 1 f 10v 10v 10v taiyo yuden 0603 0603 0805 www.t-yuden.com power dissipation the maximum power dissipation inside the SGM3122 can be calculated based on the following equation: p d max = [(1.5 v in ) - v o + 0.4v] i o the maximum power dissipation occurs when the input voltage is just low enough to operate in 1.5 mode, with a forward voltage of the white led at maximum. this is typically for v in = 4.2v and a forward voltage of 3.6v. this needs to be lower than the maximum allowed power dissipation of the package, which can be calculated using the following equation: p d_max, package = ja a max j r t t ? for example, the worst case power dissipation occurs at the input voltage level where the charge pump switches from the 1 mode to the 1.5 mode. at this operating point, the supply voltage to the current sources is at its maximum and the current sources must drop the most voltage in order to maintain a regulated output current. the worst case power dissipation occurs when all 4 led outputs are fully loaded with 30ma of led current. ? with: v in = 4.2v, v f = 3.6v, i o = 75ma (1.5 mode) ? p d_max = 0.203w power efficiency the power conversion efficiency of the SGM3122 can be calculated by adding up the products of each led current and voltage and dividing it by the product of the input voltage and current. with a fully charged battery where the input voltage is typically above the led forward voltage, the charge pump operates in the 1x mode and efficiency is very high. as the battery discharges, there is a point where the current sources no longer have enough voltage overhead to maintain a constant current regulation. at that point, the charge pump switches into the 1.5 mode. the conversion efficiency is lowest at the crossover. as the battery discharges further, the efficiency again increases until at about 3.2v where it reaches a second maximum. below 3.2v input voltage, the maximum current per led is less than 30ma.
white led charge pump current source with pwm brightness control 12 SGM3122 sg micro corp www.sg-micro.com SGM3122 application information typical application of a smart phone displa y with resistors connected in parallel if more than 30ma of output current is needed, then the input pins to the current sinks can be connected in parallel as shown in the following application figure. this method can also be used to connect a lc display with only two connections for the white leds. c2- c1- c1+ c2+ iset vin en1 en2 gnd pgnd cin 1f 0.47f 0.47f c2 c1 d1 d2 d3 vout 1f li-ion battery SGM3122 d4
white led charge pump current source with pwm brightness control 13 SGM3122 sg micro corp www.sg-micro.com SGM3122 application information analog dimming using iset pin the iset pin can be used to connect an analog dc signal in the range of 0mv to 600mv (en1 = en2 = 1) for analog dimming of the white leds. for an input voltage of 0v at iset, the current is at its maximum, whereas at 600mv, the led current is zero. the maximum current is: ? for en2 = en1 = 1: i led = v set /r set k = 0.6v/6000 255 = 25.5ma per led. ? for en2 =1, en1 = 0: i led = v set /r se t k = 0.4v/6000 255 = 17ma per led. ? for en2 = 0, en1 = 1: i led = v set /r set k = 0.2v/6000 255 = 8.5ma per led. ? with en2, en1 set to 10 or 01, a voltage of 400mv or 200mv is required to set the led current to zero. li-ion battery c2- c1- c1+ c2+ iset vin en1 en2 gnd pgnd cin 1f 0.47f 0.47f c2 c1 d1 d2 d3 vout 6k v = 0mv to 600mv 1f SGM3122 d4
white led charge pump current source with pwm brightness control 14 SGM3122 sg micro corp www.sg-micro.com SGM3122 application information typical application using 3 white leds and 6 green leds for lcd backlight and keyboard lighting the SGM3122 can be used to power any kind of led. it is also possible to mix white leds with color leds which have a lower forward voltage. the led with the highest forward voltage (typically the white led) has to be connected to d1, because the output voltage of the charge pump is regulated in such a way to keep the voltage drop from d1 to gnd at 400mv (with en1 = en2 = 1). therefore the output voltage of the charge pump is regulated to: v out = v d1 + v fledd1 v out ? output voltage at vout v d1 ? voltage from d1 to gnd (v source at d1 pin, see electrical characteristics) v fledd1 ? forward voltage of the led connected to d1. resistor r g is used to provide current sharing between the 6 green leds. the upper value is calculated using: r g = g fg 1 fledd l v v ? 5.1k 1f r g = 220 3 white leds with 30ma each 6 green leds with 5ma each set current to 30ma per current sink (with en2 = en1 = 1) SGM3122 d4
white led charge pump current source with pwm brightness control 15 SGM3122 sg micro corp www.sg-micro.com SGM3122 package outline dimensions tqfn-33-16l 0.203 0.025 0.000-0.050 side view 3.000 0.050 top view 3.000 0.050 n9 0.400 0.050 bottom view n13 n1 n5 0.500 0.050 1.500 0.050 1.500 0.050 0.230 0.050 n16 0.750 0.050 1.5 1.5 0.5 0.23 0.7 2.1 3.5 recommended land pattern note: all linear dimensions are in millimeters.
white led charge pump current source with pwm brightness control 16 SGM3122 sg micro corp www.sg-micro.com SGM3122 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-33-16l 13 12.40 3.35 3.35 1.13 4.00 4.00 2.00 12.00 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
white led charge pump current source with pwm brightness control 17 SGM3122 sg micro corp www.sg-micro.com SGM3122 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

▲Up To Search▲

Price & Availability of SGM3122

	To Download SGM3122 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .