specifications of any and all sanyo semiconductor co.,l td. products described or contained herein stipulate the performance, characteristics, and functions of the described products in the independent state, and are not guarantees of the performance, characteristics, and functions of the described products as mounted in the customer ' s products or equipment. to verify symptoms and states that cannot be evaluated in an independent device, the customer should always evaluate and test devices mounted in the customer ' sproductsor equipment. any and all sanyo semiconductor co.,ltd. products described or contained herein are, with regard to "standard application", intended for the use as general electronics equipment (home appliances, av equipment, communication device, office equipment, industrial equ ipment etc.). the products mentioned herein shall not be intended for use for any "special application" (medica l equipment whose purpose is to sustain life, aerospace instrument, nuclear control device, burning appliances, t ransportation machine, traffic signal system, safety equipment etc.) that shall require extremely high level of re liability and can directly threaten human lives in case of failure or malfunction of the product or may cause har m to human bodies, nor shall they grant any guarantee thereof. if you should intend to use our products for app lications outside the standard applications of our customer who is considering such use and/or outside the scope of our intended standard applications, please consult with us prior to the intended use. if there is n o consultation or inquiry before the intended use, our customer shall be solely responsible for the use. 42007 ms pc 20070420-s00001 / 11707 ms pc 20061204-s00012 no.a0647-1/5 LA5744TP overview the LA5744TP is a separately-excited step-d own switching regulator (variable type). functions ? high efficiency. ? time-base generator (300khz) incorporated. ? current limiter incorporated. ? thermal shutdown circuit incorporated. ? soft start circuit incorporated. specifications maximum ratings at ta = 25 c parameter symbol conditions ratings unit input voltage v in 30 v maximum output current i o max 2a sw pin application reverse voltage v sw -1 v allowable power dissipation pd max mounted on a circuit board.* 1.1 w operating temperature topr -30 to +125 c storage temperature tstg -40 to +150 c * specified circuit board : 76.1 114.3 1.6mm 3 , glass epoxy. recommended operating conditions at ta = 25 c parameter symbol conditions ratings unit input voltage range v in 4.5 to 28 v monolithic linear ic separately-excited step-down switching regulator (variable type) orderin g numbe r : ena0647a
LA5744TP no.a0647-2/5 electrical characteristics at ta = 25 c, v o = 5v ratings parameter symbol conditions min typ max unit reference voltage v os v in = 15v, i o = 1.0a 1.20 1.23 1.26 v efficiency v in = 15v, i o = 1.0a 83 % switching frequency f v in = 15v, i o = 1.0a 240 300 360 khz line regulation ? v o line v in = 8 to 20v, i o = 1.0a 40 100 mv load regulation ? v o load v in = 20v, i o = 0.5 to 1.5a 10 30 mv output voltage temperature coefficient ? v o / ? ta designed target value. * 0.5 mv/ c ripple attenuation factor rrej f = 100 to 120hz 45 db current limiter operating voltage i s v in = 15v 3.1 a thermal shutdown operating temperature tsd designed target value. * 165 c thermal shutdown hysteresis width ? tsd designed target value. * 15 c * design target value : no measurement made. package dimensions unit : mm (typ) 3332 pin assignment (1) v in (2) sw out (3) gnd (4) v os (5) ss pd max -- ta ambient temperature, ta ? c allowable power dissipation, pd max ? w 0 0.2 0.4 0.6 0.8 1 1.1 1.4 1.2 --30--20 0 20 40 60 0.22 14 0 80 100 120 specified board : 114.3 76.11.6mm 3 glass epoxy sanyo : tp5hfa 6.5 0.5 5.0 7.0 (5.5) 1.2 1.2 0.5 0.5 0.6 1.5 2.3 12 5 0.2 2.5 0.8 1.3 (0.65)
LA5744TP no.a0647-3/5 block diagram application circuit example notes : 1. c3 is for the soft start function. delete c3 and keep the ss pin open when the soft start function is not necessary. 2. in some cases, the output may not turn on if power is applied wh en a load is connected. if this is a problem, increase the valu e of the inductor. 1 v in reg. constant current circuit osc reset drive ocp tsd vref amp. comp. 2 sw out 4 v os 3 5 gnd ss on/off comp. 0.4v v in sw out v os gnd ss l1 22h c1 470f /50v r1 r2 c2 390f d1 sbd LA5744TP c3 1f
LA5744TP no.a0647-4/5 protection circuit functional descriptions 1. overcurrent protection function the overcurrent protection functio n detects, on a cycle-by-cycle basis, the ou tput transistor current and turns off that output transistor curre nt if it exceeds 3.1a. 2. short circuit protection function this ic prevents the current from increasing when the ou tputs are shorted by setting the switching frequency to 30khz if the v os pin voltage falls below 0.8v. note 3 : if the soft start function is not used, the ic will st art up with the overcurrent protection function operating. at th is time, the switching frequency will be cut in half. this means that the switching frequency will be 15khz at startup. note 4 : since the switching frequency becomes 30khz when the v os pin voltage falls under 0.8v, the current capacity is reduced. if a load is applied with the v os pin voltage over 0.8v, the inductance value operates at 22 h. if a load is to be applied when this voltage is under 0.8v, the inductance value must be increased. description of functional settings 1. calculation equation to set the output voltage this ic controls the switching output so that the v os pin voltage becomes 1.23v (typ). the equation to set the output voltage is as follows : the v os pin has the inrush current of 1 a (typ). therefore, the error becomes larger when r1 and r2 resistance values are large. 2. startup delay function the output voltage rises when the internal voltage r eaches 0.4v (typical). until that point, a capacitor is charged from an internal 10 a (typical) constant-current supply. the start up delay time can be calculated as shown below example : assume a 1 f capacitor is used. v o = 1+ 1.23v(typ) r2 r1 td = = = 40 m s c v i 1f 0.4 10a limit current inductor current sw out voltage
LA5744TP ps no.a0647-5/5 sanyo semiconductor co.,ltd. assumes no responsib ility for equipment failures that result from using products at values that exceed, even momentarily, rate d values (such as maximum ra tings, operating condition ranges, or other parameters) listed in products specif ications of any and all sanyo semiconductor co.,ltd. products described or contained herein. sanyo semiconductor co.,ltd. strives to supply high-qual ity high-reliability products, however, any and all semiconductor products fail or malfunction with some probability. it is possible that these probabilistic failures or malfunction could give rise to acci dents or events that could endanger human lives, trouble that could give rise to smoke or fire, or accidents that could cause dam age to other property. when designing equipment, adopt safety measures so that these kinds of accidents or e vents cannot occur. such measures include but are not limited to protective circuits and error prevention c ircuits for safe design, redundant design, and structural design. upon using the technical information or products descri bed herein, neither warranty nor license shall be granted with regard to intellectual property rights or any other rights of sanyo semiconductor co.,ltd. or any third party. sanyo semiconductor co.,ltd. shall not be liable f or any claim or suits with regard to a third party's intellctual property rights which has resulted from the use of the technical information and products mentioned above. information (including circuit diagr ams and circuit parameters) herein is for example only; it is not guaranteed for volume production. any and all information described or contained herein are subject to change without notice due to product/technology improvement, etc. when designing equi pment, refer to the "delivery specification" for the sanyo semiconductor co.,ltd. product that you intend to use. in the event that any or all sanyo semiconductor c o.,ltd. products described or contained herein are controlled under any of applicable local export control laws and regulations, such products may require the export license from the authorities conc erned in accordance with the above law. no part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying and recording, or any in formation storage or retrieval system, or otherwise, without the prior written consent of sanyo semiconductor co.,ltd. timing chart 0v 0.8v 1.23v 30khz 300khz td v in voltage v os voltage sw out voltage this catalog provides information as of april, 2007. specifications and information herein are subject to change without notice.
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