orderin g numbe r : ena1438b monolithic linear ic separately-excited step-down switching regulator (variable type) LA5756 overview the LA5756 is a separately-excited step-d own switching regulator (variable type). features ? output smoothing condenser can use a low esr condenser for the reliability improvement ? hi gh efficiency ? f our external parts ? tim e-base generator (80khz) incorporated ? curren t limiter incorporated ? t hermal shutdown circuit incorporated ? s oft start circ uit incorporated specifications maximum ratings at ta = 25 c parameter symbol conditions ratings unit input voltage v in ma x 34 v output current i o max 3.5 a sw pin application reverse v sw -1 v pd max1 infinite heat sink. 7.5 w allowable power dissipation pd max2 no heat sink. 1.75 w operating temperature topr -30 to +125 c storage temperature tstg -40 to +150 c recommended operating conditions at ta = 25 c parameter symbol conditions ratings unit input voltage range v in 4.5 to 32 v 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. 62409 sy 20090611-s00001 / 41509 ms / 40809 ms 20090326-s00003 no.a1438-1/4
LA5756 electrical characteristics at ta = 25 c, v o = 3.3v ratings parameter symbol conditions min typ max unit reference voltage v os 1.235 1.26 1.285 v efficiency 78 % switching frequency f v in = 15v, i o = 1.0a 60 80 100 khz line regulation v o li ne v in = 8 to 20v, i o =1.0a 40 100 mv load regulation v o lo ad v in = 15v, 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 4.2 a thermal shutdown operating temperature tsd designed target value* 165 c thermal shutdown hysteresis width tsd designed target value* 15 c * designed target value: no measurement made. package dimensions unit : mm (typ) 3376 140120100806040200-20-30 0 2.0 4.0 6.0 8.0 msg07021 160 10.0 7.5 5.6 3.3 1.75 ambient temperature, ta -- c pd max -- ta allowable power dissipation, pd max -- w 1001001.5mm 3 50501.5mm 3 30301.5mm 3 no heat sink infinite heat sink jc=5c al heat sink mounting torque 39n?cm silicone grease applied sanyo : 220-5hmdb 0.9 2.7 1.3 4.5 0.8 1.7 (1.6) 12 5 0.4 10.0 10.4 max (8.8) 15.0 21.3 15.5 3.6 7.05 3.15 pin assignment (1)v in (2)sw out (3)gnd (4)v os (5)ss no.a1438-2/4
LA5756 block diagram 2sw out drive ocp reset osc comp. reg. amp. tsd 4v os vref 0.4v on/off comp. 1v in 5 ss 3 gnd constnt current circuit application circuit example v in sw out v os gnd ss l1 c1 c2 d1 LA5756 c3 r2 r1 notes: c3 is for the soft start function. delete c3 and k eep the ss pin open when the soft function is not necessary. 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 1.26v (typ). the equation to set the output voltage is as follows: v o = 1+ 1.26v(typ) r2 r1 the v os pin has the inrush current of 1 a (typ). therefore, the error become s larger when r1 and r2 resistance values are large. no.a1438-3/4
LA5756 2. start delay function the ss pin has the internally-connected 10 a (typ) constant-current supply. when the voltage of ss pin exceeds the threshold voltage, the regulator starts operation. as th e threshold is 0.62v(typ), the start delay time can be calculated as follows: ex. for setting at 1 f td = = = 40 msec c v i 1 0.4 10 timing chart v in sw out v out td tss 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. this catalog provides information as of june, 2009. specifications and information herein are subject to change without notice. ps no.a1438-4/4
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