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1 LT1572 100khz, 1.25a switching regulator with catch diode boost converter efficiency l0ad current (ma) 0 efficiency (%) 80 90 100 200 LT1572 ?ta01 70 60 50 50 100 150 250 boost converter v in = 5v v out = 12v d u escriptio s f ea t u re n catch diode included in package n wide input voltage range: 3v to 30v n low quiescent current: 6ma n internal 1.25a switch n very few external parts required n self-protected against overloads n operates in nearly all switching topologies n shutdown mode draws only 50 m a typical current n can be externally synchronized the lt ? 1572 is a 1.25a 100khz monolithic switching regulator with on-board switch and catch diode included in one package. it combines an lt1172 with a 1a schottky catch diode. the LT1572 can be operated in all standard switching configurations, including boost, buck, sepic, flyback, forward, inverting and cuk. all necessary con- trol, oscillator and protection circuitry is included on the die with the high efficiency switch. this makes the part extremely easy to use and provides bustproof operation similar to that obtained with 3-pin linear regulators. the LT1572 operates with supply voltages from 3v to 30v and draws only 6ma quiescent current. it can deliver load power up to 15w with no external power devices. by utilizing a current mode switching technique, the LT1572 achieves excellent response to load and line transients. the LT1572 has many unique features not found on the more difficult to use control chips presently available. it uses adaptive anti-sat switch drive to allow very wide ranging load currents with no loss in efficiency. an exter- nally activated shutdown mode reduces total supply cur- rent to 50 m a typical for standby operation. external syn- chronizing of switching frequency is possible, with a range of 120khz to 160khz. u s a o pp l ic at i n 3.3v-to-5v and 5v-to-12v boost converters n negative-to-positive converter n sepic converter (input can be greater or less than output) n battery charger , ltc and lt are registered trademarks of linear technology corporation. u a o pp l ic at i ty p i ca l LT1572 ?ta01 r1 10.7k 1% + c1 1 m f r2 1.24k 1% LT1572 gnd e2 e1 v in l1* 50 m h v sw anode ? 15 14 3 2 11 9 r3 1k 5 4, 13 12 10 coiltronics ctx50-2 avx tps or sprague 593d always connect both anode (2, 15) and cathode (3, 14) pins * ** ? cathode ? fb v c 12v 0.25a v in 4.5v to 10v c3 100 m f 10v + c2** 100 m f 16v 5v-to-12v boost converter
2 LT1572 a u g w a w u w a r b s o lu t exi t i s wu u package / o rder i for atio supply voltage (note 4).......................................... 40v switch output voltage (note 4) .............................. 60v feedback pin voltage (transient, 1ms) ................ 15v operating junction temperature range operating .............................................. 0 c to 100 c short circuit ......................................... 0 c to 125 c storage temperature range ............... C 65 c to 150 c lead temperature (soldering, 10 sec)................. 300 c diode average forward current .......................................... 1a peak repetitive forward current .............................. 2a peak non-repetitive forward current ....................... 3a peak repetitive reverse voltage ............................. 20v continuous (average) reverse voltage .................. 15v operating junction temperature ......................... 125 c note 1: minimum effective switch on time for the LT1572 (in current limit only) is ? 0.6 m s. this limits the maximum safe input voltage during an output shorted condition. buck mode and inverting mode input voltage during an output shorted condition is limited to: v in (max, output shorted) = 15v + buck and inverting mode r = inductor dc resistance i l = 2.5a v f = output catch diode forward voltage at i l t = 0.6 m s, f = 100khz switching frequency order part number LT1572cs r i l + v f t f maximum input voltage can be increased by increasing r or v f . external current limiting such as that shown in an19, figure 39, will provide protection up to the full supply voltage rating. c1 in figure 39 should be reduced to 200pf. transformer designs will tolerate much higher input voltages because leakage inductance limits rate of rise of current in the switch. these designs must be evaluated individually to assure that current limit is well controlled up to maximum input voltage. boost mode designs are never protected against output shorts because the external catch diode and inductor connect input to output. e lectr ic al c c hara terist ics v in = 15v, v c = 0.5v, v fb = v ref , output pin open, unless otherwise noted. symbol parameter conditions min typ max units v ref reference voltage measured at feedback pin 1.224 1.244 1.264 v v c = 0.8v l 1.214 1.244 1.274 v i b feedback input current v fb = v ref 350 750 na l 1100 na g m error amplifier d i c = 25 m a 3000 4400 6000 m mho transconductance l 2400 7000 m mho error amplifier source or v c = 1.5v 150 200 350 m a sink current l 120 400 m a error amplifier clamp hi clamp, v fb = 1v 1.80 2.30 v voltage lo clamp, v fb = 1.5v 0.25 0.38 0.52 v reference voltage line 3v v in 40v l 0.03 %/v regulation v c = 0.8v a v error amplifier voltage gain 0.9v v c 1.4v 500 800 v/v minimum input voltage (note 3) l 2.6 3.0 v i q supply current 3v v in 40v, v c = 0.6v 6 9 ma consult factory for industrial and military grade parts. top view s package 16-lead plastic so *always connect both anode and both cathode pins t jmax (regulator) = 100 c t jmax (diode) = 125 c see thermal management section for q ja 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 nc anode* cathode* gnd v c fb nc nc nc anode* cathode* gnd e2 v sw e1 v in
3 LT1572 e lectr ic al c c hara terist ics v in = 15v, v c = 0.5v, v fb = v ref , output pin open, unless otherwise noted. symbol parameter conditions min typ max units control pin threshold duty cycle = 0 0.8 0.9 1.08 v l 0.6 1.25 v normal/flyback threshold 0.4 0.45 0.54 v on feedback pin v fb flyback reference voltage i fb = 50 m a 15.0 16.3 17.6 v (note 3) l 14.0 18.0 v change in flyback reference 0.05 i fb 1ma 4.5 6.8 9 v voltage flyback reference voltage i fb = 50 m a 0.01 0.03 %/v line regulation (note 3) 7v v in v max flyback amplifier d i c = 10 m a 150 300 500 m mho transconductance (g m ) flyback amplifier source v c = 0.6v, source l 15 32 70 m a and sink current i fb = 50 m a, sink l 25 40 70 m a bv output switch breakdown 3v v in 40v, i sw = 1.5ma l 60 80 v voltage (note 4) v sat output switch l 0.60 1.00 w on resistance (note 1) control voltage to switch 2a/v current transconductance i lim switch current limit duty cycle = 50%, t j 3 25 c l 1.25 3.0 a duty cycle = 50%, t j < 25 c l 1.25 3.5 a duty cycle = 80% (note 2) l 1.00 2.5 a d i in supply current increase 25 35 ma/a d i sw during switch on-time f switching frequency 88 100 112 khz l 85 115 khz dc max maximum switch duty cycle l 80 90 95 % shutdown mode 3v v in 40v 100 250 m a supply current v c = 0.05v shutdown mode 3v v in 40v 100 150 250 mv threshold voltage l 50 300 mv flyback sense delay time (note 3) 1.5 m s parameter conditions min typ max units forward voltage (note 5) i f = 200ma l 0.45 0.57 v i f = 500ma l 0.52 0.65 v i f = 1a l 0.55 0.70 v reverse leakage (note 5) v r = 5v, t j = 25 c15 m a v r = 5v, t j = 75 c 25 100 m a v r = 20v, t j = 25 c315 m a v r = 20v, t j = 75 c 70 300 m a diode thermal resistance (note 6) 90 c/w diode
4 LT1572 e lectr ic al c c hara terist ics v in = 15v, v c = 0.5v, v fb = v ref , output pin open, unless otherwise noted. the l denotes the specifications which apply over the full operating temperature range, 0 c to 100 c for the regulator chip and 0 c to 125 c for the diode. note 1: measured with v c in hi clamp, v fb = 0.8v. i sw = 1a. note 2: for duty cycles (dc) between 50% and 80%, minimum guaranteed switch current is given by i lim = 0.833 (2 C dc). note 3: minimum input voltage for isolated flyback mode is 7v. note 4: because the catch diode has a peak repetitive reverse voltage of 20v, diode breakdown may be the limiting factor on input voltage or switch voltage in many applications. note 5: see graphs for guaranteed forward voltage and reverse leakage current over temperature. parameters are 100% tested at 25 c and guaranteed at other temperatures by design and qa sampling. note 6: package soldered to fr4 board with 3 1oz copper and an internal or backside plane underneath the package to aid thermal transfer. diode is partly thermally coupled to regulator section. see application information section for details on thermal calculations. cc hara terist ics uw a t y p i ca lper f o r c e reference voltage vs temperature feedback bias current vs temperature minimum input voltage switch saturation voltage switch current limit vs duty cycle line regulation duty cycle (%) 0 switch current (a) 4 3 2 1 0 40 1572 g01 20 30 50 60 70 80 90 100 25 c 125 c ?5 c 10 temperature ( c) ?5 minimum input voltage (v) ?5 25 50 150 1572 g02 ?0 0 75 100 125 2.9 2.8 2.7 2.6 2.5 2.4 2.3 switch current = 0a switch current = 1.25a switch current (a) 0 switch saturation voltage (v) 2.00 1572 g03 0.25 0.50 0.75 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 1.00 1.25 1.50 1.75 25 c 150 c ?5 c 100 c input voltage (v) 0 reference voltage change (mv) 10 20 30 40 1572 g04 50 5 4 3 2 1 0 ? ? ? ? ? 60 t j = 150 c t j = 55 c t j = 25 c temperature ( c) reference voltage (v) 1572 g05 1.250 1.248 1.246 1.244 1.242 1.240 1.238 1.236 1.234 ?5 25 25 50 150 ?0 0 75 100 125 temperature ( c) feedback bias current (na) 1572 g06 800 700 600 500 400 300 200 100 0 ?5 25 25 50 150 ?0 0 75 100 125
5 LT1572 cc hara terist ics uw a t y p i ca lper f o r c e supply current vs input voltage* feedback pin clamp voltage idle supply current vs temperature shutdown mode supply current error amplifier transconductance v c pin characteristics supply current vs supply voltage (shutdown mode) driver current* vs switch current supply voltage (v) 0 supply current ( m a) 10 20 30 40 160 140 120 100 80 60 40 20 0 1572 g07 v c = 50mv t j = 25 c v c = 0v switch current (a) 0 driver current (ma) 0.25 0.50 0.75 40 35 30 25 20 15 10 5 0 1.00 1.25 1572 g08 t j = 55 c t j = 3 25 c * average power supply current is found by multiplying driver current by duty cycle, then adding quiescent current. input voltage (v) 0 supply current (ma) 10 20 30 40 1572 g09 50 15 14 13 12 11 10 9 8 7 6 5 60 t j = 25 c note that this current does not include driver current, which is a function of load current and duty cycle. 90% duty cycle 50% duty cycle 10% duty cycle 0% duty cycle * under very low output current conditions, duty cycle for most circuits will approach 10% or less. v c pin voltage (mv) 0 supply current ( m a) 200 180 160 140 120 100 80 60 40 20 0 40 1572 g10 10 20 30 50 60 70 80 90 100 t j = 150 c ?5 c t j 125 c temperature ( c) transconductance ( m mho) 5000 4500 4000 3500 3000 2500 2000 1500 1000 500 0 1572 g11 ?5 25 25 50 150 ?0 0 75 100 125 g m = d i (v c pin) d v (fb pin) v c pin voltage (v) 300 200 100 0 100 200 300 400 1572 g12 v c pin current ( m a) 0 2.0 0.5 1.0 1.5 2.5 v fb = 1.5v (current into v c pin) v fb = 0.8v (current out of v c pin) t j = 25 c temperature ( c) idle supply current (ma) 11 10 9 8 7 6 5 4 3 2 1 1572 g13 ?5 25 25 50 150 ?0 0 75 100 125 v supply = 60v v supply = 3v v c = 0.6v feedback current (ma) 0 feedback voltage (mv) 500 450 400 350 300 250 200 150 100 50 0 0.4 1572 g14 0.1 0.2 0.3 0.5 0.6 0.7 0.8 0.9 1.0 ?5 c 25 c 150 c switch voltage (v) 0 switch current ( m a) 1000 900 800 700 600 500 400 300 200 100 0 40 1572 g15 10 20 30 50 60 70 80 90 100 v supply = 3v v supply = 15v v supply = 40v switch off characteristics
6 LT1572 cc hara terist ics uw a t y p i ca lper f o r c e shutdown thresholds isolated mode flyback reference voltage temperature ( c) v c pin voltage (mv) 1572 g16 400 350 300 250 200 150 100 50 0 ?5 25 25 50 150 ?0 0 75 100 125 400 350 300 250 200 150 100 50 0 v c pin current ( m a) current (out of v c pin) voltage v c voltage is reduced until regulator current drops below 300 m a junction temperature ( c) ?5 time ( m s) ?5 25 50 150 1572 g17 ?0 0 75 100 125 2.2 2.0 1.8 1.6 1.4 1.2 1.0 temperature ( c) flyback voltage (v) 1572 g18 23 22 21 20 19 18 17 16 15 ?5 25 25 50 150 ?0 0 75 100 125 r fb = 500 w r fb = 1k r fb = 10k flyback blanking time transconductance of error amplifier normal/flyback mode threshold on feedback pin frequency (hz) 1k transconductance ( m mho) 7000 6000 5000 4000 3000 2000 1000 0 1000 10k 100k 1572 g19 1m 10m 30 0 30 60 90 120 150 180 210 phase (deg) q g m temperature ( c) ?0 feedback pin voltage (mv) 500 490 480 470 460 450 440 430 420 410 400 0 50 75 1572 g20 ?5 25 100 125 150 24 22 20 18 16 14 12 10 ? ? ? feedback pin current ( m a) feedback pin current (at threshold) feedback pin voltage (at threshold)
7 LT1572 w i dagra b l o c k 1.24v ref 1572 bd error amp 100khz osc 2.3v reg v in fb + + shutdown circuit v c comp logic driver anti- sat flyback error amp 16v switch out 5a, 75v switch current amp gain 6 ? 0.15v 0.16 w *always connect e1 to ground mode select e1* e2 lt1172 anode cathode operatio u the LT1572 is a current mode switcher. this means that switch duty cycle is directly controlled by switch current rather than by output voltage. referring to the block diagram, the switch is turned on at the start of each oscillator cycle. it is turned off when switch current reaches a predetermined level. control of output voltage is obtained by using the output of a voltage sensing error amplifier to set current trip level. this technique has several advantages. first, it has immediate response to input voltage variations, unlike ordinary switchers which have notoriously poor line transient response. second, it reduces the 90 phase shift at mid-frequencies in the energy storage inductor. this greatly simplifies closed- loop frequency compensation under widely varying input voltage or output load conditions. finally, it allows simple pulse-by-pulse current limiting to provide maximum switch protection under output overload or short conditions. a low dropout internal regulator provides a 2.3v supply for all internal circuitry on the LT1572. this low dropout design allows input voltage to vary from 3v to 40v with virtually no change in device performance. a 100khz oscillator is the basic clock for all internal timing. it turns on the output switch via the logic and driver circuitry. special adaptive anti-sat circuitry detects onset of satura- tion in the power switch and adjusts driver current instan- taneously to limit switch saturation. this minimizes driver dissipation and provides very rapid turn-off of the switch. a 1.2v bandgap reference biases the positive input of the error amplifier. the negative input is brought out for output voltage sensing. this feedback pin has a second function; when pulled low with an external resistor, it programs the LT1572 to disconnect the main error ampli- fier output and connects the output of the flyback amplifier
8 LT1572 operatio u to the comparator input. the LT1572 will then regulate the value of the flyback pulse with respect to the supply voltage. 1 this flyback pulse is directly proportional to output voltage in the traditional transformer coupled flyback topology regulator. by regulating the amplitude of the flyback pulse, the output voltage can be regulated with no direct connection between input and output. the output is fully floating up to the breakdown voltage of the trans- former windings. multiple floating outputs are easily ob- tained with additional windings. a special delay network inside the LT1572 ignores the leakage inductance spike at the leading edge of the flyback pulse to improve output regulation. the error signal developed at the comparator input is brought out externally. this pin (v c ) has four different functions. it is used for frequency compensation, current limit adjustment, soft starting, and total regulator shut- down. during normal regulator operation this pin sits at a voltage between 0.9v (low output current) and 2.0v (high output current). the error amplifiers are current output (g m ) types, so this voltage can be externally clamped for adjusting current limit. likewise, a capacitor coupled external clamp will provide soft start. switch duty cycle goes to zero if the v c pin is pulled to ground through a diode, placing the LT1572 in an idle mode. pulling the v c pin below 0.15v causes total regulator shutdown, with only 50 m a supply current for shutdown circuitry biasing. see an19 for full application details. e1 and e2 pins the LT1572 has the emitters of the power transistor brought out separately from the ground pin. this elimi- nates errors due to ground pin voltage drops and allows the user to reduce switch current limit 2:1 by leaving the second emitter (e2) disconnected. the first emitter (e1) should always be connected to the ground pin. note that switch on resistance doubles when e2 is left open, so efficiency will suffer somewhat when switch currents exceed 300ma. also, note that chip dissipation will actu- ally increase with e2 open during normal load operation, even though dissipation in current limit mode will de- crease . 1 see note under block diagram. other application help more circuits and application help for the LT1572 can be found in the lt1172 data sheet, both in loose form and in the 1994 linear databook volume iii . extensive additional help is contained in application note 19. all application circuits using the lt1172 can also use the LT1572 as long as the 20v maximum reverse voltage of the diode is not exceeded. a cad program called switchercad is also available. this program can be used with the LT1572 by simply treating the LT1572 as an lt1172 and ignoring the predicted die temperature results obtained from switchercad itself. thermal management thermal management is particularly important with the LT1572 because both switch and diode power dissipation increase rapidly at low input voltage when using the popular boost topology. regulator and diode die tempera- ture must be calculated separately because they are not connected to an isothermal plane inside the package. diode plus regulator thermal resistance is approximately 70 c/w when the LT1572 is soldered to 1oz copper traces over an internal or backside copper plane using fr4 board material. however, individual calculation of die tempera- ture must take thermal coupling into account. to accom- plish this, thermal resistance is broken into two sections, a common (coupled) section and a second uncoupled section. die temperatures are calculated from: t reg = t a + p reg (90 c/w) + p diode (45 c/w) t diode = t a + p diode (90 c/w) + p reg (45 c/w) t a = ambient temperature t reg = regulator die temperature t diode = diode die temperature p reg = total regulator power dissipation p diode = diode power dissipation the following formulas can be used as a rough guide to calculate LT1572 power dissipation. for more details, the reader is referred to application note 19 (an19), effi- ciency calculations section.
9 LT1572 switch on resistance by 2:1, but reduces switch current limit by 2:1 also, resulting in a net 2:1 reduction in i 2 r switch dissipation under current limit conditions. the third approach is to clamp the v c pin to a voltage less than its internal clamp level of 2v. the lt1172 switch current limit is zero at approximately 1v on the v c pin and 2a at 2v on the v c pin. peak switch current can be externally clamped between these two levels with a diode. see an19 for details. diode characteristics the catch diode used in the LT1572 is a power schottky diode with a very low storage time and low forward voltage. this gives good efficiency in switching regulator applications, but some thought must be given to maxi- mum operating voltage and high temperature reverse leakage. peak repetitive reverse voltage rating on the diode is 20v . in a boost converter, maximum diode reverse voltage is equal to regulated output voltage, so this limits maximum output voltage to 20v. in a negative-to-positive converter, maximum diode voltage will be equal to the sum of output voltage plus input voltage. use the equa- tions in application note 19 or switchercad or calculate maximum diode voltage for other topologies. diode reverse leakage increases rapidly with temperature. this leakage is not high enough to significantly impact efficiency or diode power dissipation, but it can be of concern in shutdown mode if the diode is connected in such a way that the leakage adds to regulator shutdown current. use the graphs of diode leakage versus voltage and temperature to ensure proper high temperature sys- tem performance. the LT1572 diode is internally bonded to more than two package pins to reduce internal bond wire currents. all pins must be used to prevent excessive current in the individual internal bond wires . this is important in low load current applications because the LT1572 will draw high surge currents during start-up (to charge the output capacitor) even with no output load current. operatio u average supply current (including driver current) is: i in ? 6ma + i sw (0.004 + dc/40) i sw = switch current dc = switch duty cycle switch power dissipation is given by: p sw = (i sw ) 2 r sw dc r sw = LT1572 switch on resistance (1 w maximum) total power dissipation is the sum of supply current times input voltage plus switch power: p reg = i in v in + p sw in a typical example, using a boost converter to generate 12v at 0.12a from a 5v input, duty cycle is approximately 60%, and switch current is about 0.65a, yielding: i in = 6ma + 0.65(0.004 + dc/40) = 18ma p sw = (0.65) 2 1 w 0.6 = 0.25w p reg = 5v 0.018a + 0.25 = 0.34w approximate diode power dissipation for boost and buck converters is shown below. for other topologies or more accurate results, see application note 19 or use switchercad. boost: p diode = i out v f buck: p diode = i out v f (v in C v out )/v in v f = diode forward voltage at a current equal to i out for a buck converter and i out v out /v in for a boost converter. in most applications, full load current is used to calculate die temperature. however, if overload conditions must also be accounted for, three approaches are possible. first, if loss of regulated output is acceptable under overload conditions, the internal thermal limit of the LT1572 will protect the die in most applications by shut- ting off switch current. thermal limit is not a tested parameter , however, and should be considered only for noncritical applications with temporary overloads. the second approach for lower current applications is to leave the second switch emitter (e2) open. this increases
10 LT1572 operatio u synchronizing the LT1572 can be externally synchronized in the fre- quency range of 120khz to 160khz. this is accomplished as shown in the accompanying figures. synchronizing occurs when the v c pin is pulled to ground with an external transistor. to avoid disturbing the dc characteristics of the internal error amplifier, the width of the synchronizing pulse should be under 0.3 m s. c2 sets the pulse width at @ 0.2 m s. the effect of a synchronizing pulse on the LT1572 amplifier offset can be calculated from: d v kt q tfi v r i os ssc c c = ? ? ? ? ()() + ? ? ? ? 3 kt = 26mv at 25 c q t s = pulse width f s = pulse frequency i c = v c source current ( ? 200 m a) v c = operating v c voltage (1v to 2v) r3 = resistor used to set mid-frequency zero in frequency compensation network. with t s = 0.2 m s, f s = 150khz, v c = 1.5v, and r3 = 2k, offset voltage shift is ? 3.8mv. this is not particularly bother- some, but note that high offsets could result if r3 were reduced to a much lower value. also, the synchronizing transistor must sink higher currents with low values of r3, so larger drives may have to be used. the transistor must be capable of pulling the v c pin to within 200mv of ground to ensure synchronizing. synchronizing with bipolar transistor 1572 op01 c2 39pf r1 3k r2 2.2k LT1572 gnd v in v c c1 r3 2n2369 from 5v logic synchronizing with mos transistor 1572 op02 d1 1n4158 r2 2.2k LT1572 gnd v in v c c1 r3 from 5v logic c2 100pf d2 1n4158 *siliconix or equivalent vn2222*
11 LT1572 u s a o pp l ic at i ty p i ca l negative buck converter backlight ccfl supply (see an55 for details) gnd 2 m f 1572 ta04 d1 1n914 33pf 3kv 10 m f tant r3 10k 50k intensity adjust l1** 300 m h input voltage ? 4.5v to 20v q1,q2 = bcp56 or mps650/561 coiltronics ctx300-4 sumida 6345-020 or coiltronics 110092-1 a modification will allow operation down to 4.5v. consult factory. * ** *** ? c6 1 f m r1 560 w 1k LT1572 v in cathode v c v sw anode e2 e1 d2 1n914 lamp fb l2*** 0.02 m f a b q1* + + q2* information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. c3* 100 m f 5.2v 0.75a 1572 ta03 r3 l1** 50 m h r1 4.64k c2 200 m f c1 q1 2n3906 + v in cathode v c fb v sw anode e2 e1 LT1572 gnd v in 7v to 20v required if input leads 3 2" pulse engineering 92114 coiltronics 50-2-52 * ** r2 1.24k + r4 12k load
12 LT1572 linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7487 (408) 432-1900 l fax : (408) 434-0507 l telex : 499-3977 ? linear technology corporation 1995 u package d e sc r i pti o dimensions in inches (millimeters) unless otherwise noted. 0.016 ?0.050 0.406 ?1.270 0.010 ?0.020 (0.254 ?0.508) 45 0 ?8 typ 0.008 ?0.010 (0.203 ?0.254) 1 2 3 4 5 6 7 8 0.150 ?0.157* (3.810 ?3.988) 16 15 14 13 0.386 ?0.394* (9.804 ?10.008) 0.228 ?0.244 (5.791 ?6.197) 12 11 10 9 so16 0893 0.053 ?0.069 (1.346 ?1.752) 0.014 ?0.019 (0.355 ?0.483) 0.004 ?0.010 (0.101 ?0.254) 0.050 (1.270) typ *these dimensions do not include mold flash or protrusions. mold flash or protrusions shall not exceed 0.006 inch (0.15mm). s package 16-lead plastic soic related parts part number description comments lt1172 100khz, 1.25a high efficiency switching regulator LT1572 without diode lt1173 micropower dc/dc converter adjustable and fixed 5v, 12v operates down to 2v input lt1372 500khz high efficiency 1.5a step-up switching regulator latest technology, uses tiny inductors ltc1574 high efficiency step-down dc/dc converter ltc1174 with diode with internal schottky diode lt/gp 0595 10k ? printed in usa

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