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| mar16-06 rev b sp7648 ultra-low quiescent current, high effciency boost regulator ? 2006 sipex corporation solved by tm sp7648 features true shutdown 700ma output current at 3.3v input; 4.2v output 92% efficiency from 2.7v in to 3.3v out wide input voltage range: 2.7v to 4.5v 5v fixed or adjustable output 0.3 1 switch integrated synchronous rectifier:0.3 1 anti-ringing switch technology programmable inductor peak current logic shutdown control low 0.8v or 0.288v reference voltage small 10 pin dfn or msop package low reference high efficiency boost regulator applications led driver camera flash handheld portable devices description the sp7648 is an ultra-low quiescent current, high efficiency step-up dc-dc converter ideal for single cell li-ion or dual cell alkaline battery applications to drive various leds. the sp7648 combines low quiescent current and excellent light-load efficiency of pfm control. the sp7648 features synchronous rectification, a 0.3 1 charging switch, an anti-ringing inductor switch, under- voltage lockout and programmable inductor peak current. the device can be shut down by a 1na active low shutdown pin. a very low 0.288v reference voltage is optimized for driving a constant current load. typical application circuit now available in lead free packaging sp7648 10 pin dfn 0 9 8 7 6 2 3 4 5 v out lx p gnd gnd fb flash shdn nc (test) r lim v batt ? 4.7 h v in sp7648 v batt flash fb lx v out nc 1.0k 1 on/off 0 f shdn gnd 0 f p gnd 0.33 1 r lim (2.7 - 4.5v) flash 470pf r lim 1k 1 r r 2 q d
2 mar16-06 rev b sp7648 ultra-low quiescent current, high effciency boost regulator ? 2006 sipex corporation lx, vo, v batt , flashout, fb to gnd pin ...................... -0.3 to 6.0v shdn, flash ..................................................... -0.3v to v batt +1.0v vo, gnd, lx current ............................................................... ........ 2a reverse v batt current .............................................................. 220ma forward v batt current .............................................................. 500ma storage temperature .................................................. -65 c to 150 c parameter min typ max units z conditions input voltage operating range, v batt 2.7 - 4.5 v z after startup output voltage range, v out 2.7 - 5.5 v z under voltage lock-out/uvlo 0.5 0.61 0.7 v z output voltage, v o 4.6 5.0 5.4 v z internal feedback divider shutdown current into v o, i sdo - 500 na z v s h d n = zerov shutdown current into v b a t t , i sdb - 250 750 na z v s h d n = zerov, v batt = 2.7v efficiency 92 - % - v batt = 2.7v, i o u t = 200ma, r l i m = 2k 1 inductor peak current limit, i pk 650 800 000 ma z r lim = 2k 1 , i pk = 1600/r l i m 600 ma z r lim = 1k 1 , i pk = 1600/r l i m output current (note 2) - 800 - ma - v batt = 2.7v, r l i m =1k 1 - 400 - ma - v batt = 2.7v, r l i m =2k 1 - 200 - ma - v batt = 2.7v, r l i m = 4k 1 minimum off-time constant k off 0.5 1.0 1.5 v* s z k off ) t o f f (v out - v batt ) maximum on-time constant k on 2.0 3.5 5.0 v* s z k on * t o n (v batt ) enable valid to output stable (note 3) - 300 500 s - i l o a d = ma nmos switch resistance - 0.30 0.6 1 z i nmos = 00ma pmos switch resistance - 0.30 0.6 1 z i pmos = 00ma fb set voltage, v fb 0.76 0.8 0.84 v z external feedback flash = 0 0.266 0.288 0.310 v z external feedback flash = 1 fb input current - 00 na z v fb =1.3v shdn input voltage (note 1) v il - - 0.5 v z v batt = 2.7v v ih 2.0 - - z v batt = 2.7v shdn input current - 00 na z lx pin leakage - - 3 a - flash threshold v i l - - 0.4 v v ih 1.0 - - v electrical specifications v b a t t =v shdn = 3.6v, v fb =zerov, i load = 0ma, t amb = -40 c to +85 c, v out = 5.0v, typical values at 27 c unless otherwise noted. the z denotes the specifications which apply over full operating temperature range -40oc to +85 c, unl ess otherwise specified. operating temperature ................................................ -40 c to +85 c esd rating ........................................................................ 1.5kv hbm these are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. exposure to absolute maximum rating conditions for extended periods of time may affect reliability. absolute maximum ratings note 1: shdn must transition faster than 1v/100ms for proper operation. note 2: output current i = { vin } x e f f i c i e n c y x { i n d u c t o r p e a k c u r r e n t - i n d u c t o r r i p p l e c u r r e n t } vout 2 note 3: guaranteed by design. 3 mar16-06 rev b sp7648 ultra-low quiescent current, high effciency boost regulator ? 2006 sipex corporation pin description pin number pin name description 1 v batt battery voltage. the startup circuitry is powered by this pin. battery voltage is used to calculate switch off time: t off = k off / (v out - v batt ). when the battery voltage drops below 0.61v the sp7648 goes into an undervoltage lockout mode (uvlo), where the part is shut down. 2 flash reference control input. internal reference defaults to 0.8v if flash = low and 0.288v if flash = high. 3 nc (test) no connection. this pin is bonded out for test purposes only a nd must be left floating in all applications. 4 r lim current limit resistor. by connecting a resistor r lim from this pin to ground the inductor peak current is set by i peak =1600/r lim . the range for r lim is 9k 1 (for 180ma) to 1.k 1 (for 1.6a). 5 shdn shutdown not. tie this pin high to v batt, for normal operation. pull this pin to ground to disable all circuitry inside the chip. 6 fb feedback. connect this pin to gnd for fixed +5v operation. connect this pin to a resistor voltage divider between v out and gnd for adjustable output operation. 7 gnd ground. connect to ground plane. 8 pgnd power ground. the inductor charging current flows out of this p in. 9 lx inductor switching node. connect one terminal of the inductor to the positive terminal of the battery. connect the second terminal of the inductor to this pin. the inductor charging current flows into lx, through the internal charging n-channel fet, and out the pgnd pin. 10 v out output voltage. the inductor current flows out of this pin during switch off-time. it is also used as the internal regulator voltage supply. connect this pin to the positive terminal of the output capacitor. note that the thermal pad (pin 11) should be connected to ground. 4 mar16-06 rev b sp7648 ultra-low quiescent current, high effciency boost regulator ? 2006 sipex corporation functional diagram @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ 5 mar16-06 rev b sp7648 ultra-low quiescent current, high effciency boost regulator ? 2006 sipex corporation detailed description the sp7648 is a step-up dc-dc converter with an input voltage operation range from 2.7v to 4.7v. in addition to the main 0.3 1 internal nmosfet switch the sp7648 has an internal synchronous rectifier, thereby increasing efficiency and reducing the space and cost of an external diode. an in - ternal inductive-damping switch significantly reduces inductive ringing for low noise-high efficiency operation. if the supply voltage drops below 0.61v the sp7648 goes into under voltage lockout, thus opening both in - ternal switches. the inductor peak current is externally programmable to allow for a range of inductor values. circuit layout printed circuit board layout is a critical part of a power supply design. poor designs can result in excessive emi on the feedback paths and on the ground planes with applications involving high switching frequencies and large peak currents. excessive emi can result in instability or regulation errors. all power components should be placed on the pc board as closely as possible with the traces kept short, direct, and wide (>50mils or 1.25mm). extra copper on the pc board should be integrated into ground as a pseudo- ground plane. on a multilayer pc board, route the star ground using component- side copper fill, then connect it to the internal ground plane using vias. for the sp7648 theory of operation devices, the inductor and input & output filter capacitors should be soldered with their ground pins as close together as possible in a star-ground configuration. the v out pin must be bypassed directly to ground as close to the sp7648 devices as possible (within 0.2in or 5mm). the dc-dc converter and any digital circuitry should be placed on the opposite corner of the pc board as far away from sensitive rf and analog input stages. noisy traces, such as from the lx pin, should be kept away from the voltage- feedback v fb node and separated from it using grounded copper to minimize emi. see the sp7648eb evaluation board manual for pc board layout design details. control scheme a minimum off-time, current limited pulse frequency modulation (pfm) control scheme combines the high output power and efficiency of a pulse width modulation (pwm) device with the ultra low quiescent current of the traditional pfm. at low to mod - erate output loads the pfm control provides higher efficiency than traditional pwm con - verters are capable of delivering. at these loads the switching frequency is determined by a minimum off-time (t off , min) and a maximum on-time (t on , max) where: t off < k off / (v out - v b a t t ) t on > k on / v b a t t k off = 1.0v s k on = 3.5 v s 6 mar16-06 rev b sp7648 ultra-low quiescent current, high effciency boost regulator ? 2006 sipex corporation theory of operation figure 1. inductor current vs. load at light loads (as shown in plot a in figure 1) the charge cycle will last the maximum value for t on : for a 3v battery this would be as follows: t on = k on / v batt = 3.5v s/ 3v = 1.17 s. the current built up in the coil during the charge cycle gets fully discharged in the discontinuous conduction mode (dcm). when the current in the coil has reached zero, the synchronous rectifier switch is opened and the voltage across the coil (from v batt to lx) is shorted internally to eliminate inductive ringing. with increasing load (as shown in plot b in figure 1) this inductor damping time becomes shorter, because the output will quickly drop below its regula- tion point due to heavier load. if the load current increases further, the sp7648 en- ters continuous conduction mode (ccm) where there is always current flowing in the inductor. the charge time remains at maxi- mum t on as long as the inductor peak current limit is not reached as shown in plot c in figure 1. the inductor peak current limit can be programmed by tying a resistor r lim from the r lim pin to ground where: i peak = 1600 / r lim when the peak current limit is reached the charge time is short-cycled. in plot d of figure 1, the switch current reaches the peak current limit during the charge period which ends the charge cycle and starts the discharge cycle. however, full load is not yet achieved because at the end of the minimum discharge time the output was still within regulation. maximum load is reached when this discharge time has shrunk to the minimum allowed value t off as shown in plot e of figure 1. component selection selection of capacitors for sp7648 power supply circuits can be made through the use of the component selection table. capa- citor equivalent series resistance (esr) in the range of 0.2 to 0.3 1 is a requirement for obtaining sufficient output voltage ripple for the sp7648 to properly regulate under its load. for example, in the sp7648 application circuit a 0 f, 10v, x5r, surface mount ceramic output filter capacitor is used. ceramic capa- citors have an esr too low to produce enough output ripple for the sp7648 to regulate the output; therefore, a 0.33 1 resistor is added in series with the 0 f capacitor at the v out pin. designers should select input and output capacitors with a rating exceeding the inductor current ripple, which is typically set by the inductor value and the k on value as given in the following relationship: i l(ripple) = k on /l, where k on = 3.5v* s inductor current vs. load ton max. toff min. e. iripple=toff* (vo - vi)/l llim llim llim llim llim ton max. ton max. ton max. ton max. toff min. toff min. toff min. toff min. d. toff*= (vo - vi)/l 8 mar16-06 rev b sp7648 ultra-low quiescent current, high effciency boost regulator ? 2006 sipex corporation current to avoid saturating the inductor, which would result in a loss in efficiency and could damage the inductor. the sp7648 evaluation board uses a r lim value of 1k 1 for an i peak = 1.6a to allow the circuit to deliver up to 700ma for v in = 3.3v and v out = 4.2v. other values could be selected using the above relationships. using the flash control pin the sp7648 will regulate the output by the equations above depending on the state of the flash pin. when the flash pin is low (<0.4v), the internal reference voltage is defined as 0.8v. when the flash pin is high (>0.4v), the internal reference voltage is defined as 0.288v. this allows the use of smaller values for the sense resistor for current regulation mode. this improves ef - ficiency and reduces the physical size of the sense resistor. an external mosfet switch can be used to change the sense resistor when changing to the flash mode. high brightness white led for the high brightness lumiled white led application, the sp7648 is generally pro - grammed as a current source. the bias resistors r1 and r2 are used to set the operating current of the white led with the equation: r = v fb /i f where v fb is 0.8v in torch mode and 0.288v in flash mode, i f is the operating current of theory of operation the led. to set the operating current to be about 200ma in torch mode, the flash pin is forced low, r2 is selected as 0.8v/ 0.2 = 4 1 , as shown in the typical application circuit. to set the operating current to 700ma in flash mode, the flash pin is forced high, r is selected as 0.288v/0.41 1 = 700ma. in real - ity r in flash includes the series mosfet r d son and the parallel combination of r 2 = 4 1 shown by the formula: r in flash = { r x (r 2 + q r dson ) } {r + r 2 + q r dson } if the sp7648 is powered up before the led is plugged in, the circuit will bring the feed - back pin to zerov and the sp7648 has a feature to set the output voltage to be 5v. once the led is plugged in, the feedback pin will go up to 0.8v in torch mode or 0.288v in flash mode and begin to regulate. the output voltage will go from 5v to v f +v fb , where v f is the forward voltage of the led. when the led is open, the feedback pin voltage will go to zerov and the output voltage will go to 5v which will protect the part from overvoltage at the output. one approach to control led brightness is to apply a pwm signal to the shdn input of the sp7648. in this case, the output current will be equal to the product of v ref /r1 and the average duty cycle at the shdn pin. an optional 10k 1 potentiometer may also be used for dimming the led current by varying the potentiometer between low brightness and full brightness. if the fb pin is pulled below 150mv the output will default to 5v defined by an inter - nal resistor divider. 9 mar16-06 rev b sp7648 ultra-low quiescent current, high effciency boost regulator ? 2006 sipex corporation typical performance characteristics sp7648 for luxeon i 0 100 200 300 400 500 600 700 800 3.0 3.2 3.4 3.6 3.8 4.0 4.2 vin (v) output current (ma) flash mode, vf=3.6v torch mode, vf=3.2v sp7648 for luxeon i 50 60 70 80 90 100 3.0 3.2 3.4 3.6 3.8 4.0 4.2 vin (v) efficiency (%) flash mode, vf=3.6v torch mode, vf=3.2v sp7648 for aot(2015hpw1915b) 0 100 200 300 400 500 600 700 800 3.0 3.2 3.4 3.6 3.8 4.0 4.2 vin (v) output current (ma) flash mode, vf=3.9v torch mode, vf=3.3v sp7648 for aot(2015hpw1915b) 50 60 70 80 90 100 3.0 3.2 3.4 3.6 3.8 4.0 4.2 vin (v) efficiency (%) flash mode, vf=3.9v torch mode,vf=3.3v sp7648 for aot(6060hpw0305bd) 0 100 200 300 400 500 600 3.0 3.2 3.4 3.6 3.8 4.0 4.2 vin (v) output current (ma) flash mode, vf=4.2v torch mode, vf=3.5v sp7648 for aot(6060hpw0305bd) 50 60 70 80 90 100 3.0 3.2 3.4 3.6 3.8 4.0 4.2 vin (v) efficiency (%) flash mode, vf=4.2v torch mode, vf=3.5v 0 mar16-06 rev b sp7648 ultra-low quiescent current, high effciency boost regulator ? 2006 sipex corporation startup 700ma flash, vin = 3.6v, vout = 3.65v startup 200ma torch, vin = 3.6v, vout = 3.9v ripple 700ma flash, vin = 3.6v, vout = 3.65v ripple 200ma torch, vin = 3.6v, vout = 3.9v typical performance characteristics ch1 = shdn (5v/div) ch2 = vout (1v/div) ch4 = iin (1a/div) ch1 = vin (ac) 100mv/div ch2 = vout (ac) 100mv/div mar16-06 rev b sp7648 ultra-low quiescent current, high effciency boost regulator ? 2006 sipex corporation package: 10 pin msop pin #1 designator to be within this index area (d/2 * e1/2) front view l gauge plane seating plane l2 c ? ?1 ?1 r1 r e1 e e/2 e1 e d 1 2 top view (l1) 1 2 3 4 5 10 9 8 7 6 d/2 min nom max min nom max a1 0.00 - 0.15 0.000 - 0.006 c 0.08 - 0.23 0.004 - 0.009 r 0.07 - - 0.003 - - r1 0.07 - - 0.003 - - ? 0o - 8o 0o - 8o ?1 5o - 15o 5o - 15o a - - 1.10 - 0.043 a2 0.75 0.85 0.95 0.030 0.034 0.038 b 0.17 - 0.33 0.007 - 0.013 d e e1 e e1 l 0.40 0.60 0.80 0.016 0.024 0.032 l1 l2 symbol 0.118 bsc 0.193 bsc 0.118 bsc 0.079 bsc 0.037 ref 0.010 bsc 0.020 bsc sipex pkg signoff date/rev: jl aug09-05 reva 0.50 bsc 2.00 bsc 0.95 ref 0.25 bsc 3.00 bsc 4.90 bsc 3.00 bsc 10 pin msop jedec mo-187 variation ba dimensions in millimeters: controlling dimension dimensions in inches conversion factor: 1 inch = 25.40 mm side view a a2 a1 seating plane b 12 mar16-06 rev b sp7648 ultra-low quiescent current, high effciency boost regulator ? 2006 sipex corporation package: 10 pin dfn package: 10 pin dfn min nom max min nom max a 0.80 0.90 1.00 0.032 0.036 0.039 a1 0.00 0.02 0.05 0.000 0.001 0.002 a3 k 0.20 - - 0.008 - - ? 0o - 14o 0o - 14o b 0.18 0.25 0.30 0.008 0.010 0.012 d d2 2.20 - 2.70 0.087 - 0.106 e e2 1.40 - 1.75 0.056 - 0.069 e l 0.30 0.40 0.50 0.012 0.016 0.020 3x3 10 pin dfn jedec mo-229 variation veed-5 dimensions in millimeters: controlling dimension dimensions in inches conversion factor: 1 inch = 25.40 mm 3.00 bsc 0.119 bsc symbol sipex pkg signoff date/rev: jl aug09-05 / reva 0.20 ref 0.008 ref 0.119 bsc 3.00 bsc 0.020 bsc 0.50 bsc ? (a3) a1 a seating plane side view 10 1 2 3 4 5 9 8 7 6 index area (d/2 x e/2) bottom view b e l k d2 e2 e2/2 d2/2 pin1 designator to be within this index area (d/2 x e/2) top view d e e/2 d/2 note that thermal pad (pin 11) should be connected to ground. 13 mar16-06 rev b sp7648 ultra-low quiescent current, high effciency boost regulator ? 2006 sipex corporation typical performance characteristics sp7648 for luxeon i 0 100 200 300 400 500 600 700 800 3.0 3.2 3.4 3.6 3.8 4.0 4.2 vin (v) output current (ma) flash mode, vf=3.6v torch mode, vf=3.2v sp7648 for luxeon i 50 60 70 80 90 100 3.0 3.2 3.4 3.6 3.8 4.0 4.2 vin (v) efficiency (%) flash mode, vf=3.6v torch mode, vf=3.2v sp7648 for aot(2015hpw1915b) 0 100 200 300 400 500 600 700 800 3.0 3.2 3.4 3.6 3.8 4.0 4.2 vin (v) output current (ma) flash mode, vf=3.9v torch mode, vf=3.3v sp7648 for aot(2015hpw1915b) 50 60 70 80 90 100 3.0 3.2 3.4 3.6 3.8 4.0 4.2 vin (v) efficiency (%) flash mode, vf=3.9v torch mode,vf=3.3v sp7648 for aot(6060hpw0305bd) 0 100 200 300 400 500 600 3.0 3.2 3.4 3.6 3.8 4.0 4.2 vin (v) output current (ma) flash mode, vf=4.2v torch mode, vf=3.5v sp7648 for aot(6060hpw0305bd) 50 60 70 80 90 100 3.0 3.2 3.4 3.6 3.8 4.0 4.2 vin (v) efficiency (%) flash mode, vf=4.2v torch mode, vf=3.5v sipex corporation headquarters and sales offce 233 south hillview drive milpitas, ca 95035 tel: (408) 934-7500 fax: (408) 935-7600 sipex corporation reserves the right to make changes to any products described herein. sipex does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others. part number operating temperature range package type sp7648er .................................................. -40 c to +85 c ........................................................... 10 pin dfn sp7648er/tr ............................................ -40 c to +85 c .......................................................... 10 pin dfn sp7648eu .................................................. -40 c to +85 c ........................................................ 10 pin msop sp7648eu/tr ............................................ -40 c to +85 c ....................................................... 10 pin msop ordering information available in lead free packaging. to order add -l suffix to part number. example: sp7648er/tr = standard; sp7648er-l/tr = lead free /tr = tape and reel pack quantity is 3,000 for dfn, and 2,500 for msop. solved by tm |
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