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microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 1 copyright ? 2000 rev. 1.1b, 2005-03-03 www. microsemi . com lx1741 high efficiency high voltage boost controller p roduction d a ta s heet integrated products description the lx1741 is a compact high efficiency step-up boost controller. featuring a pseudo-hysteretic pulse frequency modulation topology, the lx1741 was designed for maximum efficiency, reduced board size, and minimal cost. utilizing an external n-channel mosfet, the lx1741 offers designers maximum flexibility with respect to efficiency and cost. the lx1741 provides several design enhancements that improve overall performance under very light load currents by implementing control circuitry that is optimized for portable systems - thus providing a quiescent supply current of only 80a (typ) and a shutdown current of less than 1a. the input voltage ranges from 1.6v to 6.0v, allowing for a wide selection of system battery voltages. start-up operation is guaranteed at 1.6v input the output voltage is programmed easily using two external resistors in conjunction with the feedback pin. depending on the mosfet selected, the lx1741 is capab le of achieving output voltages much higher than 40v. the lx1741 has an additional feature for simple dynamic adjustment of the output voltage (i.e., up to 15% of the nominal output voltage). voltage adjustment is achieved via an analog reference signal or a direct pwm input signal applied to the adj pin. any pwm amplitude is easily accom- modated with a single external resistor. the lx1741 is available in both the 8- pin msop, and the miniature 8-pin mlp requiring minimal pcb area. important: for the most current data, consult microsemi ?s website: http://www.microsemi.com key features ? > 85% maximum efficiency ? 80a typical quiescent supply current ? externally programmable peak inductor current limit for maximum efficiency ? logic controlled shutdown ? < 0.5 a shutdown current (typ) ? dynamic output voltage adjustment via analog reference or direct pwm input ? 8-pin msop package or 8-pin mlp applications/benefits ? pagers ? wireless phones ? pdas ? handheld computers ? general lcd bias applications ? led driver product highlight c 1 4.7 f r cs 1k ? l 1 47 h 1206 case size v bat = 1.6v to 6.0v on off v lcd = 18v 15% lx1741 gnd shdn in adj fb cs ndrv src package order info lm plastic mlp 8-pin du plastic msop 8-pin t a ( c) rohs compliant / pb-free transition dc: 0452 rohs compliant / pb-free transition dc: 0432 0 to 70 lx1741clm lx1741cdu note: available in tape & reel. append the letters ?tr? to the part number. (i.e. LX1741CDU-TR) l l x x 1 1 7 7 4 4 1 1
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 2 copyright ? 2000 rev. 1.1b, 2005-03-03 www. microsemi . com lx1741 high efficiency high voltage boost controller p roduction d a ta s heet integrated products absolute maximum ratings supply voltage (v cc ) .................................................................................... -0.3v to 7.0v feedback input voltage (v fb ) ..............................................................-0.3v to v in + 0.3v shutdown input voltage (v shdn ) ........................................................-0.3v to v in + 0.3v pwm input amplitude .........................................................................-0.3v to v in + 0.3v analog adjust input voltage (v adj ).................................................................-0.3v to v in source input current (i src ).................................................................................. 0.80 a rms operating junction temperature................................................................................ 150 c storage temperat ure rang e.........................................................................-65 c to 150 c lead temperature (solde ring 180 sec onds)............................................................... 235 c peak package solder reflow temp. (40 s econds max. exposure) ................ 260c (+0, -5) note: exceeding these ratings could cause damage to the device. all voltages are with respect to ground. currents are positive into, negative out of specified terminal . thermal data du plastic msop 8-pin thermal resistance - junction to a mbient , ja 206 c/w thermal resistance - junction to c ase , jc 39 c/w lm plastic mlp 8-pin thermal resistance - junction to a mbient , ja 41 c/w thermal resistance - junction to c ase , jc 5.2 c/w junction temperature calculation: t j = t a + (p d x jc ). the ja numbers are guidelines for the ther mal performance of the device/pc-board system. all of the above assume no ambient airflow. package pin out 1 2 4 3 5 6 8 7 src cs gnd in ndrv fb adj shdn du p ackage (top view) 4 3 2 1 5 6 7 8 src cs gnd shdn ndrv fb in adj lm p ackage (top view) rohs / pb-free 100% matte tin lead finish functional pin description n ame d escription in unregulated ic supply voltage i nput ? input range from +1.6v to 6.0v. bypass with a 1 f or greater capacitor for operation below 2.0v. fb feedback input ? connect to a resistive divider network between the output and gnd to set the voltage at v fb (see output voltage programming: application information). shdn active-low shutdown input ? a logic low shuts down the device and reduces the supply current to 0.1 a. connect shdn to v cc for normal operation. ndrv mosfet gate driver ? connects to an external n-channel mosfet. cs current-sense amplifier input ? connecting a resistor between cs and gnd sets the peak inductor current limit. gnd common terminal for ground reference. adj an applied pwm signal input becomes the internal reference, v ia an internal filter and gain resistor, thus allowing for a dynamic output voltage adjustment of 15% (i.e., corresponding to the duty cycle variance). connecting this pin to ground causes the device to revert to the internal voltage reference (note: refer to figure 8). src mosfet current sense input - connects to the external n-channel mosfet source. p p a a c c k k a a g g e e d d a a t t a a
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 3 copyright ? 2000 rev. 1.1b, 2005-03-03 www. microsemi . com lx1741 high efficiency high voltage boost controller p roduction d a ta s heet integrated products electrical characteristics unless otherwise specified, the following specifications apply over the operating ambient temperature 0 c t a 70 c except where otherwise noted and the following test conditions: v in = 3v, v out = 18.5v, v adj = 0v, r load = 9.25 k ? , shdn = v in lx1741 parameter symbol test conditions min typ max units operating voltage v in 1.6 6.0 v minimum start-up voltage v su t a = +25 c 1.6 v start-up voltage temperature coefficient k vst -2 mv/ c v fb = 1.5v 80 100 a quiescent current i q v shdn < 0.4v 0.2 0.5 a fb threshold voltage v fb v adj = gnd 1.264 1.290 1.316 v fb input bias current i fb v fb = 1.4v -200 200 na adj input voltage range 1 v adj 0 v in ? 100mv v adj input bias current i adj v adj = v fb = 1.29v 0.3 1.0 a src input current i src 0.8 a rms shutdown input bias current i shdn shdn = gnd -50 50 na shutdown high input voltage v shdn v in = 2v 1.6 v shutdown low input voltage v shdn v in = 2v 0.4 v current sense bias current i cs 3.0 5.0 7.0 a minimum peak current i min gbnt 2 145 ma comparator a delay t d gbnt 2 620 ns ndrv sink current i snk v in = 5v 50 ma ndrv source current i src v in = 5v 100 ma minimum off-time t off v fb = 1v 100 500 ns notes: 1. when using a dc source to adjust v out , the recommended v adj (range) is from 0.9v to 1.50v: see figure 3 and 8. 2. guaranteed typical value (not tested) @ t a = 25 o c (see section ?inductor selection and current limit programming?) simplified block diagram logic controller reference logic adj fb shutdown logic shdn cs driver gnd ndrv in 4 a src 2.5m ? 50pf a b 1.29v reference e e l l e e c c t t r r i i c c a a l l s s
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 4 copyright ? 2000 rev. 1.1b, 2005-03-03 www. microsemi . com lx1741 high efficiency high voltage boost controller p roduction d a ta s heet integrated products application circuits typical lcd bias applications v bat = (1.6v to 6.0v) ? ? ? ? ? ? ? ? + = 2 1 ref out r r 1 v v r 1 r 2 c 1 4.7 f c 2 * 1nf r cs 1k ? l 1 * optional component used to reduce output voltage ripple. 47 h lx1741 ndrv shdn in src gnd fb cs adj figure 1 ? fixed output voltage operation v bat = (1.6v to 6.0v) ? ? ? ? ? ? ? ? + = 2 1 adj out r r 1 v v r 1 r 2 c 1 4.7 f c 2 * 1nf r cs 1k ? l 1 * optional component used to reduce output voltage ripple. 47 h r pwm 100khz v pwm = 3.0v 625k ? lx1741 ndrv shdn in src gnd fb cs adj figure 2 ? dynamic output voltag e operation via pwm input note : an in-series r pwm will attenuate the pwm amplitude to the prop er signal level at the adj pin. with the r pwm value shown, a pwm signal having a duty of 30% to 50% will generate 0.9v to 1.5v at the adj pin. a a p p p p l l i i c c a a t t i i o o n n s s
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 5 copyright ? 2000 rev. 1.1b, 2005-03-03 www. microsemi . com lx1741 high efficiency high voltage boost controller p roduction d a ta s heet integrated products application circuits (continued) typical lcd bias applications (cont) v bat = (1.6v to 6.0v) ? ? ? ? ? ? ? ? + = 2 1 adj out r r 1 v v r 1 r 2 c 1 4.7 f c 2 * 1nf r cs 1k ? l 1 * optional component used to reduce output voltage ripple. 47 h v adj = 0.9v to 1.5v + - lx1741 ndrv shdn in src gnd fb cs adj figure 3 ? dynamic output voltage oper ation via analog voltage input led driver application c 1 4.7 f r cs 1k ? l 1 47 h 1206 case size r 3 63.4? v bat = 1.6v to 6.0v on off r 1 1? r 2 59k ? v f = 3.6v typ. i led = 20ma to 0.25ma () ? ? ? ? ? ? ? ? ? ? ? ? ? ? + ? ? ? ? ? ? ? = 2 1 2 f adj 3 led r r r v 4 v r 1 i lx1741 ndrv shdn in src gnd fb cs adj figure 4 ? led driver with full-range dimming via pwm input note the component values shown are only examples for a worki ng system. actual values will vary greatly depending on desired parameters, efficiency, and layout constraints. a a p p p p l l i i c c a a t t i i o o n n s s a a p p p p l l i i c c a a t t i i o o n n s s
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 6 copyright ? 2000 rev. 1.1b, 2005-03-03 www. microsemi . com lx1741 high efficiency high voltage boost controller p roduction d a ta s heet integrated products application circuits (continued) rcs 20k r2 30.9k r1 1m l1 47h d1 b150/b 50v c2 1nf 50v c1 4.7uf 50v q1 3 x bss138 vbat = 3.2v vout = 40v 7 5 4 2 3 6 8 1 lx1741 figure 5 ? application of fixed output, 40v @ 20ma vbat +vout r8 4.02k r2 49.9k r1 787k l1 47h -vout d1 ups5819 c1 1uf 25v c3 1uf 25v d2 ups5819 d3 ups5819 d4 ups5819 c1 1000pf 50v c5 1uf 25v c6 1uf 25v c4 4.7uf 25v q1 fdv303n 7 5 4 2 3 6 8 1 lx1741 figure 6 ? application of dual output, 20v @ 2ma a a p p p p l l i i c c a a t t i i o o n n s s
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 7 copyright ? 2000 rev. 1.1b, 2005-03-03 www. microsemi . com lx1741 high efficiency high voltage boost controller p roduction d a ta s heet integrated products application information f unctional d escription the lx1741 is a pulse frequency modulated (pfm) boost converter that is optimized for large step up voltage applications like lcd biasing. it operates in a pseudo- hysteretic mode with a fixed switch ?off time? of 300ns. converter switching is enabled when the feedback voltage, v fb , falls below the 1.29v reference or vadj (see block diagram). when this occurs, comparator a activates the off-time controller. the off-time controller and the current limiter circuit activate comparator b which toggles the ndrv output circuit. the ndrv output is switched ?on? (and remains ?on?) until the inductor current ramps up to the peak current level. this current level is set via the external r cs resistor and monitored through the cs and src inputs. the load is powered from en ergy stored in the output capacitor during the in ductor charging cycl e. once the peak inductor current value is ac hieved, the ndrv output is turned off (off-time is typically 300ns) allowing a portion of the energy stored in the inductor to be delivered to the load. this causes the output voltage to continue to rise at the input to the feedback circuit (i.e., comparator a). if the voltage at the fb input is still less than 1.29v at the end of the off-time period, the ndrv output switches the external fet ?on? and the inductor charging cycle repeats until v fb is greater than the internal reference. this switching behavior is shown in figure 9 and 11. the application of an extern al voltage source at the adj pin allows for output voltage adjustment over a typical range of approximately 15%. the designer can select one of two possible methods. one option is to vary the reference voltage directly at the adj pin by applying a dc voltage from 0.9 to 1.5v. the second option is to connect a pwm logic signal to the adj pin (e.g., see figure 2). the lx1741 includes an internal 50pf capacitor to ground that works with an external resistor to create a low-pass filter (i.e., filter out the ac co mponent of a pulse width modulated input of f pwm 100khz). the adjustment voltage level is selectable (with limited accuracy) by implementing the voltage divider created between the external series re sistor and the internal 2.5m ? resistor. if the dc voltage at the adj pin drops below 0.6v, the device will revert to the internal reference voltage level of 1.29v. a typical adjustment curve is shown in figure 8 (see section titled: characteristic curves). disabling the lx1741 is achieved by driving the shdn pin with a low-level logic signal thus reducing the device power consumption to less than 1 a. o utput v oltage p rogramming selecting the appropriate valu es for r1 and r2 in the voltage divider connected to the feedback pin programs the output voltage. using a value of 49.9k for r2 works well in most applications. r1 can be determined by the following equation (where v ref = 1.29v nominal): () v v - v r2 r1 ref ref out = d esign e xample : let r2 equals 49.9k and the required vout equal to 18v. () ? = ? = k 4 . 646 49.9k r1 1.29v 1.29v - 18v i nductor s election and c urrent l imit p rogramming setting the level of peak inductor current to, at least, 1.5x the expected maximum dc input current will minimize the inductor size, the input ripple current, and the output ripple voltage. the designer is encouraged to use inductors that will not saturate at the peak inductor current level. an inductor value of 47 h is recommended. choosing a lower value emphasizes peak current overshoot while choosing a higher value emphasizes output ripple voltage. the peak switch current is defined using a resistor placed between the cs terminal and ground and the i peak equation is: cs scale d in min peak r i t l v i i ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? + + = the maximum i peak value is limited by the i src value (max. = 0.8a rms ). the minimum i peak value is defined when r cs is zero. a typical va lue for the mi nimum peak current (i min ) at 25 o c is 145ma. the parameter t d is related to internal operation of compar ator a. a typical value at 25 o c is 620ns. a typical value of i scale at 25 o c is 31ma per k ? . all of these parameters have an effect on the final i peak value. d esign e xample : determine i peak where v in equals 3.0v and r cs equals 4.02k ? using nominal values for all other parameters. 4.02k ? k ? 31ma 620ns h 47 3.0v 145ma i peak + + = ? ? ? ? ? ? ? ? ? ? ? ? ? ? the result of this example yields a nominal i peak equal to 145ma + 39.6ma + 124.6ma = 309.2ma. a a p p p p l l i i c c a a t t i i o o n n s s
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 8 copyright ? 2000 rev. 1.1b, 2005-03-03 www. microsemi . com lx1741 high efficiency high voltage boost controller p roduction d a ta s heet integrated products application information (continued) o utput r ipple c apacitor s election output voltage ripple is a function of the inductor value (l), the output capacitor value (c out ), the peak switch current setting (i peak ), the load current (i out ), the input voltage (v in ) and the output voltage (v out ) for a this boost converter regulation scheme. when the switch is first turned on, the peak-to-peak voltage ripple is a function of the output droop (as the inductor current charges to i peak ), the feedback transition error (i.e., typically 10mv), and the output overshoot (when the stored energy in the inductor is delivered to the load at the end of the charging cycle). therefore the total ripple voltage is v ripple = ? v droop + ? v overshoot + 10mv the initial droop can be estimated as follows where the 0.5v value in the denominator is an estimate of the voltage drop across the inductor and the fet?s r ds_on : () () 0.5 v i i c l ? v in out pk out droop ? = ? ? ? ? ? ? ? ? the output overshoot can be estimated as follows where the 0.5 value in the denominator is an estimate of the voltage drop across the diode: () () in out 2 out pk out 2 1 overshoot v 0.5 v i i c l ? v ? + ? ? ? ? ? ? ? ? ? = d esign e xample : determine the v ripple where i pk equals 200ma, i out equals 35ma, l equals 47 h, c out equals 4.7 f, v in equals 3.0v, and v out equals 18.0v: () () mv 8 2 0.5 3.0 35ma 200ma f 4.7 h 47 ? v droop = ? ? ? ? ? ? ? = () () mv 4 . 9 0 . 3 0.5 0 . 8 1 ma 5 3 ma 200 f 4.7 h 47 ? v 2 2 1 overshoot = ? + ? ? ? ? ? ? ? ? ? = therefore, for c out equals 4.7 f: v ripple = 28mv + 9.4mv + 10mv = 47.4mv increasing the output capacitor value results in the reduction of the output voltage ripple voltage. low esr capacitors are recommended to reduce ripple caused by the switching current. multi-layer ceramic capacitors with x5r or x7r dielectric are a supe rior choice featuring small size, very low esr, and a temp erature stable dielectric. low esr electrolytic capacitors such as solid tantalum or os-con types are also accep table. moreover, adding a capacitor from the output to the feedback pin (c2) allows the internal feedback circuitry to respond faster which further minimizes output voltage ripple and reduces noise coupling into the high impedance feedback input. d iode s election a schottky diode is recommended for most applications (e.g. microsemi ups5819). the low forward voltage drop and fast recovery time associ ated with this device supports the switching demands associated with this circuit topology. the designer is encouraged to consider the diode?s average and peak current ratings with respect to the application?s output and peak inductor curren t requirements. further, the diode?s reverse breakdown voltage characteristic must be capable of withstanding a negative voltage transition that is greater than v out . t ransistor s election the lx1741 can drive up to 100ma of gate drive current. an n-channel mosfet with a relatively low threshold voltage, low gate charge and low r ds(on) is required to optimize overall circuit performance. the lxe1741 evaluation board uses a fairchild fdv303. this nmos device was chosen because it demonstrates an r ds_on of 0.33 ? and a total gate charge q g of 1.64nc (typ.). pcb l ayout the lx1741 produces high slew-rate voltage and current waveforms hence; the designer should take this into consideration when laying out the circuit. minimizing trace lengths from the ic to the inductor, transistor, diode, input and output capacitors, and feedback connection (i.e., pin 6) are typical considerations. moreover, the designer should maximize the dc input and output trace widths to accommodate peak current leve ls associated with this circuit. a a p p p p l l i i c c a a t t i i o o n n s s
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 9 copyright ? 2000 rev. 1.1b, 2005-03-03 www. microsemi . com lx1741 high efficiency high voltage boost controller p roduction d a ta s heet integrated products evaluation board o verview the lxe1741 evaluation boa rd is available from microsemi for assessing overall circuit performance. the evaluation board, shown in figure 5, is 3 by 3 inches (i.e., 7.6 x 7.6cm) square and factory calibrated to provide a nominal 18v output from a 1.6v to 6.0v input. circuit designers can easily modify output voltage and current to suit their particular application by replacing the r1 and r cs values respectively. moreover, inductor, fet, and diodes are easily swapped out to promote design verification of a circuit that maximizes efficien cy and minimizes cost for any particular application. the input and output connections are described in table 1. e lectrical c onnections apply the dc input voltage to vbat ( not vcc ) however, the lx1741 ic may be driven from a separate dc source via the vcc input (if desi red). connect the test load to vout. primary output voltage adjustment is accomplished by selecting the appropriate value for r1. optional fine adjustment of the output voltage is achieved by applying either a dc voltage or a pwm-type signal to the vadj input. both low frequency (f < 100khz) and high frequency (f > 100khz) pwm signals are accommodated by choosing the appropriate jump er connection. further, the vadj circuit can be bypassed by selecting the appropriate jumper position (see table 2). the lx1741 exhibits a low quiescent current (i q < 1 a: typ) during shutdown mode. the shdn pin can be used to examine shutdown performan ce on the evaluation board. this pin is pulled-up to vcc via a 10k ? resistor. grounding the shdn pin shuts down the ic however, the load is still capable of drawing current through the inductor & diode circuit path. hence, v out during shutdown will be approximately v bat minus the inductor and diode forward voltage drop. the lx1741 can achieve outp ut voltages in excess of 25v. in certain applications, it is necessary to protect the load from excessive voltage excursions. the evaluation board provides a vlim jumper position for this purpose. engaging this jumper position ensures that the output voltage does not exceed 25v. the lxe1741 evaluation board provides an easy and cost effective solution for evalua tion on the lx1741. the factory installed component list for the evaluation board is provided in table 3 and the schematic is shown in figure 6. figure 7 ? lx1741 circuit evaluation board table 1: input and output pin assignments pin name allowable range description vbat 0 to 6v main power supply for outpu t. (set external current limit to 0.5a) vcc 1.6v to 6v lx1741 power. may be strapped to vbat or use a separate supply if vcc jumper is in the sep position. do not power output from vcc pin on board.. shdn 0 to vcc pulled up to vcc on board (10k ? ), ground to inhibit the lx1741. vout vcc to 25v programmed for 18v output, adjustable up to 25v. vadj in 0 to vcc apply a dc input or pwm input to adjust the output voltage. note: all pins are referenced to ground. e e v v a a l l b b o o a a r r d d
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 10 copyright ? 2000 rev. 1.1b, 2005-03-03 www. microsemi . com lx1741 high efficiency high voltage boost controller p roduction d a ta s heet integrated products evaluation board (continued) table 2: jumper pin position assignments jumper / position function vcc/ vbat use this position when powering vbat and vcc from the same supply. do not connect power to the vcc input when using this jumper position. vcc/ sep use this position when using a separ ate vcc supply (different from vbat). ref/ ext use this position when using an exte rnal source to adjust the output voltage. ref/ int use this position when using the fixed output volt age mode. in this mode the output voltage can be varied by changing the value of r1 as described in the data sheet. adj/ hf use this position when adjusting the output with an exte rnal pwm that has a repetition rate in excess of 100khz. adj/ lf use this position when adjusting the output with an ex ternal pwm that has a repetition rate less than 100khz. or when using a dc adjustment voltage. vlim/ in use this position when adjusting the output voltage to prevent the output voltage from accidentally exceeding 25v. vlim/ out this position disables the output voltage adjustment clamp. this pos ition may be desired if maximizing efficiency when operating near 25v output level. note: always put jumpers in one of the two possible positions table 3: factory installed component list for the lx1741evaluation board ref description supplier part number c1 capacitor, cog, 1000pf, 0402, 50v murata grm36x7r102m050 c2 capacitor, x7r, 0.1uf, 0805, 50v murata grm40x7r104m050 c3 capacitor, y5v, 2.2uf, 0805, 16v avx 0805yg225zat c4,5 capacitor, x5r, 4.7uf, 1210, 25v taiyo yuden cetmk325bj475mn cr1 rectifier, schottky, 1a, 40v, powermite microsemi ups5819 l1 inductor, 47uh, 480ma, smt toko a920cy-470m jp1-7 3 term header, 0.1 in ctr 3m 929647-09-36-i sb1-4 jumper 3m 929955-06 q1 mosfet, n-chan, 25v, sot-23 fairchild fdv303n q2 transistor, npn, 40v, sot-23 on mmbt3904lt1 r1 resistor, 698k, 1/16w, 0603 panasonic erj3ekf6983 r2 resistor, 49.9k, 1/16w, 0603 panasonic erj3ekf4992 r3 resistor, 619k, 1/16w, 0603 panasonic erj3ekf6193 r4 resistor, 100k, 1/16w, 0603 panasonic erj3ekf1003 r5,r6 resistor, 1.00k, 1/16w, 0603 panasonic erj3ekf1001 r7 resistor, 10.0k, 1/16w, 0603 panasonic erj3ekf1002 r8 resistor, 4.02k, 1/16w, 0603 panasonic erj3ekf4021 u1 ic, boost controller microsemi lx1741 vr1 zener, 24v,225mw, sot-23 on bzx84c24lt1 note: the minimum part set for a working power supply co nsists of: c1, c2, c5, cr1, l1, q1, r1, r2, r8, u1 e e v v a a l l b b o o a a r r d d
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 11 copyright ? 2000 rev. 1.1b, 2005-03-03 www. microsemi . com lx1741 high efficiency high voltage boost controller p roduction d a ta s heet integrated products evaluation board (continued) vbat gnd vcc shdn vadj vout gnd c5 4.7f 25v c1 1000pf 50v c4 4.7f 25v c2 0.1f 50v c3 2.2f 16v r7 10k r8 4.02k r3 619k r4 100k r2 49.9k r1 698k r5 1k r6 1k jb1 v cc jb2 ref adj jb4 vlim q2 mmbt3904lt1 cr1 ups5819 lx1741 q1 fdv303n vr1 24v 225mw bzx84c24lt1 l1 47h x x figure 8 ? lx1741 boost evaluation board schematic characteristic curves channel 1 channel 2 figure 9 ? v out and inductor current waveforms channel 1: v out (ac coupled; 100mv/div) channel 2: inductor current (100ma/div.) configuration: v in = 1.6v, v out = 5.0v, i out = 20.0ma 0 5 10 15 20 25 30 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 adj ustment voltage output voltage f igure 10 ? typical v out versus v adj ? 0 ~ 0.6v : lx1741 uses internal 1.29v reference. ? 0.7v ~ 0.8v : transition from in ternal to external reference. ? 0.9 to 1.6v : lx1741 defaults to external voltage reference. c c h h a a r r t t s s
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 12 copyright ? 2000 rev. 1.1b, 2005-03-03 www. microsemi . com lx1741 high efficiency high voltage boost controller p roduction d a ta s heet integrated products characteristic curves channel 1 channel 2 figure 11 ? v out and inductor current waveforms (ma) channel 1: v out (ac coupled; 100mv/div) channel 2: inductor current (100ma/div.) configuration: v in = 3.0v, v out = 17.9v, i out = 11.0ma 50% 60% 70% 80% 90% 100% 1 2 3 4 5 6 7 8 9 101112131415 1617181920 output current efficiency (%) figure 12 ? efficiency vs. output current (ma) configuration: v in = 3.0v, v out = 17.9v, l1 = 47.0 h 50% 60% 70% 80% 90% 100% 1 2 3 4 5 6 7 8 9 10 111213141516 17181920 output current efficiency (%) figure 13 ? efficiency vs. output current (ma) configuration: v in = 5.2v, v out = 17.9v, l1 = 94.0 h 50% 60% 70% 80% 90% 100% 1 2 3 4 5 6 7 8 9 101112131415 1617181920 output current efficiency (%) figure 14 ? efficiency vs. output current (ma) configuration: v in = 3.0v, v out = 10.0v, l1 = 47.0 h c c h h a a r r t t s s
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 13 copyright ? 2000 rev. 1.1b, 2005-03-03 www. microsemi . com lx1741 high efficiency high voltage boost controller p roduction d a ta s heet integrated products characteristic curves 50% 60% 70% 80% 90% 100% 1 2 3 4 5 6 7 8 9 10 111213141516 17181920 output current efficiency (%) figure 15 ? efficiency vs. output current (ma) configuration: v in = 1.6v, v out = 5.0v, l1 = 47.0 h 50% 60% 70% 80% 90% 100% 1 2 3 4 5 6 7 8 9 10 11121314151617181920 output current efficiency (%) figure 16 ? efficiency vs. output current (ma) configuration: v in = 3.0v, v out = 5.0v, l1 = 47.0 h 50% 60% 70% 80% 90% 100% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 2 0 output current efficiency (%) figure 17 ? efficiency vs. output current (ma) configuration: v in = 3.0v, v out = 5.0v, l1 = 47.0 h 0 1 2 3 4 5 6 0 20 40 60 80 100 120 drive current (ma) gate drive voltage (v) figure 18 ? gate drive voltage vs. drive current (ma) c c h h a a r r t t s s
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 14 copyright ? 2000 rev. 1.1b, 2005-03-03 www. microsemi . com lx1741 high efficiency high voltage boost controller p roduction d a ta s heet integrated products package dimensions du 8-pin miniature shrink outline package (msop) n l p k m b d g h c a m illimeters i nches dim min max min max a 2.85 3.05 .112 .120 b 2.90 3.10 .114 .122 c ? 1.10 ? 0.043 d 0.25 0.40 0.009 0.160 g 0.65 bsc 0.025 bsc h 0.38 0.64 0.015 0.025 j 0.13 0.18 0.005 0.007 k 0.95 bsc 0.037 bsc l 0.40 0.70 0.016 0.027 m 3 3 n 0.05 0.15 0.002 0.006 p 4.75 5.05 0.187 0.198 lm 8-pin plastic mlp-micro exposed pad e d e b a3 internally connected together, but isolated from all other terminals l2 l2 d2 e2 l a2 a a1 k m illimeters i nches dim min max min max a 0.80 1.00 0.031 0.039 a1 0.00 0.05 0.000 0.002 a2 0.65 0.75 0.025 0.029 a3 0.15 0.25 0.005 0.009 b 0.28 0.38 0.011 0.015 d 2.90 3.10 0.114 0.122 e 2.90 3.10 0.114 0.122 e 0.65 bsc 0.025 bsc d2 1.52 2.08 0.060 0.082 e2 1.02 1.31 0.040 0.052 k 0.20 * 0.008 * l 0.20 0.60 0.008 0.023 l2 0 0.13 0 0.005 0 12 0 12 note: 1. dimensions do not include mold flash or protrusions; these shall not exceed 0.155mm(.006?) on any side. lead dimension shall not include solder coverage. m m e e c c h h a a n n i i c c a a l l s s
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 15 copyright ? 2000 rev. 1.1b, 2005-03-03 www. microsemi . com lx1741 high efficiency high voltage boost controller p roduction d a ta s heet integrated products notes production data ? information contained in this document is proprietary to microsemi and is current as of publication date. this document may not be modified in any way without the express written consent of microsemi. product processing does not necessarily include testing of all parameters. microsemi reserves the right to change the configuration and performance of the product and to discontinue product at any time. n n o o t t e e s s

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