Ordering number : ENA0490 Monolithic Linear IC LA5774MP Separately-excited Step-down Switching Regulator (Variable Type) Overview The LA5774MP is a Separately-excited step-down switching regulator (variable type). Functions • Low-ESR capacitor with increased reliability applicable as the output smoothing capacitor. • High efficiency. • Four external parts. • Time-base generator (160kHz) incorporated. • Current limiter incorporated. • Thermal shutdown circuit incorporated. • Soft start circuit incorporated. Specifications Absolute Maximum Ratings at Ta = 25°C Parameter Symbol Maximum Input voltage VIN max Maximum Output current SW pin application reverse voltage Allowable power dissipation Conditions Ratings Unit 30 V IO max 3 A VSW -1 V 3.9 W Pd max Mounted on a substrate.* Operating temperature Topr -30 to +125 °C Storage temperature Tstg -40 to +150 °C * Specified substrate : 76.1×114.3×1.6mm3 : Copper foil ratio 60％ FR4 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. 72606 MS PC B8-9089 No.A0490-1/5 LA5774MP Electrical Characteristics at Ta = 25°C, VO = 3.3V Parameter Symbol Reference voltage Efficiency Switching frequency Ratings Conditions VOS VIN = 15V, IO = 1.0A η VIN = 15V, IO = 1.0A f min typ 1.235 Unit max 1.26 1.285 V 78 VIN = 15V, IO = 1.0A 160 192 kHz Line regulation ∆VOLINE VIN = 8 to 20V, IO = 1A 40 100 mV Load regulation ∆VOLOAD VIN = 15V, IO = 0.5 to 1.5A 10 30 ∆VO/∆Ta Output voltage temperature 128 % ±0.5 Designed target value. * mV mV/°C coefficient Ripple attenuation factor RREJ Current limiter operating voltage f = 100 to 120Hz IS Thermal shutdown operating 45 VIN = 15V dB 3.1 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) 3275 Pd max - Ta 4.5 (1.6) 1.5 0.9 1.7 0.2 0.4 1 1.3 9.9 4.5 (8.8) 1.2 10.0 Allowable power dissipation, Pd max - W 4.5 5 2.7 4.0 3.90 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 -30 -20 SANYO : SMP5 Specified sbstrate: 76.1×114.3×1.6mm3 Copper foil ratio 60% FR4 0 20 40 60 80 100 Ambient temperature, Ta - °C 120 140 160 MSG06072 Pin Assignment (1) VIN (2) SWOUT (3) GND (4) VOS (5) SS No.A0490-2/5 LA5774MP Block Diagram VIN 1 2 SWOUT Reg. OCP Reset OSC Drive Comp. THD 4 VOS Amp. VREF 5 3 SS GND Application Circuit Example L1 68µH VIN SWOUT LA5774MP C2 390µF D1 SBD C1 470µF /50V VOS SS GND R2 R1 C3 1µF Notes: C3 is for the soft start function. Delete C3 and keep the SS pin open when the soft start function is not necessary. No.A0490-3/5 LA5774MP 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 1.26V (typ). The equation to set the output voltage is as follows: R2 VO = 1+ × 1.26V(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. 2. Start delay function The SS pin has the internally-connected 22µA (typ) constant-current supply. When the voltage of SS pin exceeds the threshold voltage, the regulator starts operation. As the threshold voltage is 0.62V (typ), the start delay time can be calculated as follows: ex. For setting at 1µF Td = C × V 1µF × 0.62 = = 28.2 ms i 22µA 3. Soft start function The internal PWM waveform has the voltage value as shown in the right. If down-conversion from the voltage of VIN = 15 V to VIN = 3.3V is to be made, for example, the PWM-ON duty has the value as shown below. 1.5V 0.62V PWM wave VOUT PWMduty = V − Vsat + VF = 23 % IN (Note that calculation is made with Vsat = 1V and VF = 0.2V) The output voltage of error amplifier, which is 3.3 V, is the value with PWM = 23%, as calculated in the above equation, so that this voltage is determined as follows: Ver = (∆VPWM) × PWMduty + VPWML = 0.88V × 0.23 + 0.62V = 0.82V (∆VPWM is the PWM amplitude value or 0.88V(typ) while VPWML is the lower limit voltage of PWM waveform or 0.62V(typ)) SS pin and error amplifier output voltages are designed to prefer the lower voltages, so that VOUT will reach the designed regulation voltage in timing when the SS pin voltage exceeds the error amplifier output. Therefore, the soft start time is calculated as follows: Tss = C × ∆VPWM × PWMduty C × 0.88 × PWMduty = 22µA i For the set conditions of C = 1µF and PWMduty = 23%: Tss = 1µF × 0.88V × 0.23 = 9.2ms 22µA No.A0490-4/5 LA5774MP Timing Chart VIN SWOUT VOUT Td Tss 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, of 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 June, 2006. Specifications and information herein are subject to change without notice. PS No.A0490-5/5