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Ordering number : ENA0586
Monolithic Linear IC
LA5724M
Overview
Separately-Excited Step-Down
Switching Regulator (Variable Type)
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 = 25C
Parameter Input voltage Maximum output current SW pin application reverse voltage VOS pin application voltage Allowable power dissipation Operating temperature Storage temperature * Specified circuit board : 114.3x76.1x1.6mm3, Symbol VIN IO max VSW VVOS Pd max Topr Tstg glass epoxy board. Mounted on a circuit board.* Conditions Ratings 30 0.6 -1 -0.2 to 7 0.8 -30 to +125 -40 to +150 Unit V A V V W C C
Recommended Operating Conditions at Ta = 25C
Parameter Input voltage range Symbol VIN Conditions Ratings 4.5 to 28 Unit 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 = 25C, VIN = 15V
Parameter Reference voltage Reference pin bias current Switching frequency Efficiency Short-circuit protection circuit operating switching frequency Saturation voltage Maximum on duty Minimum on duty Output leakage current Supply current Current limiter operating voltage Thermal shutdown operating temperature Thermal shutdown Hysteresis width * Design target value : No measurement made. TSD Designed target value. * 15 C Vsat D max D min Ilk Iin IS TSD IOUT = 0.3A, VOS = 0V VOS = 0V VOS = 5V SWOUT = -1V VOS = 2V VIN = 15V Designed target value. * 0.7 165 5 1.2 100 0 200 10 V % % A mA A C Symbol VOS IFB fosc fscp VOUT = 5V, IO = 0.3A 128 IO = 0.3A Conditions min 1.20 Ratings typ 1.23 1 160 82 30 max 1.26 2 192 V A kHz % kHz Unit
Package Dimensions
unit : mm (typ) 3032D
1
Pd max -- Ta
Designated board : 114.3x76.1x1.6mm3 glass epoxy Mounted on a board
5.0 8 5
Allowable power dissipation, Pd max - W
0.8
0.6
4.4 6.4
0.63
0.4
1 (0.65) 1.27
4 0.35 0.15
0.2
(1.5)
1.7max
0.16
0 --30--20
0
20
40
60
80
100
120
140
Ambient temperature, Ta - C
0.1
SANYO : MFP8(225mil)
No.A0586-2/5
LA5724M
Pin Assignment
NC NC GND NC
VIN
NC SWOUT VOS
Block Diagram
VIN
1 Reg. OCP
3 SWOUT
OSC NC NC NC NC 2 Comp. 5 7 8
Reset Drive
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 47H VIN SWOUT
LA5724M
+ C1 470F /50V VOS GND D1 SBD
C3 1000pF
+ C2 100F
R2 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 47H. 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+ x 1.23V(typ) R1
The VOS pin has the inrush current of 1A (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

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