Ordering number : ENA0586 Monolithic Linear IC LA5724M Separately-Excited Step-Down Switching Regulator (Variable Type) Overview The LA5724M is a separately-excited step-down switching regulator (variable type). Functions • Time-base generator (160kHz) incorporated. • Current limiter incorporated. • Thermal shutdown circuit incorporated. Specifications Absolute Maximum Ratings at Ta = 25°C Parameter Input voltage Maximum output current SW pin application reverse voltage Symbol Conditions Ratings Unit VIN 30 IO max 0.6 A VSW -1 V VOS pin application voltage VVOS Allowable power dissipation Pd max Mounted on a circuit board.* V -0.2 to 7 V 0.8 W Operating temperature Topr -30 to +125 °C Storage temperature Tstg -40 to +150 °C * Specified circuit board : 114.3×76.1×1.6mm3, glass epoxy board. Recommended Operating Conditions at Ta = 25°C Parameter Input voltage range Symbol VIN Conditions Ratings Unit 4.5 to 28 V Any and all SANYO Semiconductor products described or contained herein do not have specifications that can handle applications that require extremely high levels of reliability, such as life-support systems, aircraft's control systems, or other applications whose failure can be reasonably expected to result in serious physical and/or material damage. Consult with your SANYO Semiconductor representative nearest you before using any SANYO Semiconductor products described or contained herein in such applications. SANYO Semiconductor assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all SANYO Semiconductor products described or contained herein. 11707 MS PC 20061002-S00008 No.A0586-1/5 LA5724M Electrical Characteristics at Ta = 25°C, VIN = 15V Parameter Symbol Ratings Conditions min Reference voltage VOS Reference pin bias current IFB Switching frequency fosc η Efficiency Short-circuit protection circuit IO = 0.3A Unit typ 1.20 128 VOUT = 5V, IO = 0.3A fscp max 1.23 1.26 V 1 2 µA 160 192 kHz 82 % 30 kHz operating switching frequency Saturation voltage Vsat IOUT = 0.3A, VOS = 0V 1.2 V Maximum on duty D max VOS = 0V 100 % Minimum on duty D min VOS = 5V 0 % Output leakage current Ilk SWOUT = -1V Supply current Iin VOS = 2V Current limiter operating voltage IS VIN = 15V Thermal shutdown operating 5 200 µA 10 mA 0.7 A TSD Designed target value. * 165 °C ∆TSD Designed target value. * 15 °C temperature Thermal shutdown Hysteresis width * Design target value : No measurement made. Package Dimensions unit : mm (typ) 3032D 5.0 5 0.63 4.4 6.4 8 0.15 0.35 1.7max 1.27 (1.5) (0.65) 4 0.8 Pd max -- Ta Designated board : 114.3×76.1×1.6mm3 glass epoxy Mounted on a board 0.6 0.4 0.2 0 --30--20 0.16 0 20 40 60 80 100 120 140 Ambient temperature, Ta – °C 0.1 1 Allowable power dissipation, Pd max – W 1 SANYO : MFP8(225mil) No.A0586-2/5 LA5724M Pin Assignment NC NC GND NC VIN NC SWOUT VOS Block Diagram VIN 3 SWOUT 1 Reg. OCP Reset OSC Drive NC 2 NC 5 NC 7 NC 8 Comp. TSD 4 VOS Amp. VREF 6 GND Note : Since the NC pins are not connected within the IC package, they can be used as connection points. Application Circuit Example L1 47µH VIN SWOUT LA5724M C3 1000pF + + C2 100µF D1 SBD C1 470µF /50V VOS R2 GND R1 No.A0586-3/5 LA5724M Protection Circuit Functional Descriptions 1. Overcurrent protection function The overcurrent protection function detects, on a cycle-by-cycle basis, the output transistor current and turns off that output transistor current if it exceeds 0.7A in a cycle-by-cycle manner. Limit current Inductor current SWOUT voltage 2. Short circuit protection function This IC prevents the current from increasing when the outputs are shorted by setting the switching frequency to 30kHz if the VOS pin voltage falls below 0.8V. Note : Since the switching frequency becomes 30kHz when the VOS pin voltage falls under 0.8V, the current capacity is reduced. If a load is applied with the VOS pin voltage over 0.8V, the inductance value operates at 47µH. 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 VOS pin voltage becomes 1.23V (typ). The equation to set the output voltage is as follows : R2 VO = 1+ × 1.23V(typ) R1 The VOS pin has the inrush current of 1µA (typ). Therefore, the error becomes larger when R1 and R2 resistance values are large. No.A0586-4/5 LA5724M Timing Chart VIN voltage 30kHz 160kHz SWOUT voltage 1.23V 0.8V VOS voltage 0V Specifications of any and all SANYO Semiconductor 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's products or equipment. SANYO Semiconductor Co., Ltd. strives to supply high-quality high-reliability products. However, any and all semiconductor products fail with some probability. It is possible that these probabilistic failures could give rise to accidents or events that could endanger human lives, that could give rise to smoke or fire, or that could cause damage to other property. When designing equipment, adopt safety measures so that these kinds of accidents or events cannot occur. Such measures include but are not limited to protective circuits and error prevention circuits for safe design, redundant design, and structural design. In the event that any or all SANYO Semiconductor products (including technical data,services) described or contained herein are controlled under any of applicable local export control laws and regulations, such products must not be exported without obtaining the export license from the authorities concerned 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 information storage or retrieval system, or otherwise, without the prior written permission of SANYO Semiconductor Co., Ltd. Any and all information described or contained herein are subject to change without notice due to product/technology improvement, etc. When designing equipment, refer to the "Delivery Specification" for the SANYO Semiconductor product that you intend to use. Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed for volume production. SANYO Semiconductor believes information herein is accurate and reliable, but no guarantees are made or implied regarding its use or any infringements of intellectual property rights or other rights of third parties. This catalog provides information as of January, 2007. Specifications and information herein are subject to change without notice. PS No.A0586-5/5