Ordering number : ENA0742 Monolithic Linear IC LA5774 Separately-excited Step-down Switching Regulator (Variable Type) Overview The LA5774 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 1.75 W 7.5 W Pd max1 No heat sink Pd max2 Infinite heat sink Operating temperature Topr -30 to +125 °C Storage temperature Tstg -40 to +150 °C 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 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 equipment etc.). The products mentioned herein shall not be intended for use for any "special application" (medical equipment whose purpose is to sustain life, aerospace instrument, nuclear control device, burning appliances, transportation machine, traffic signal system, safety equipment etc.) that shall require extremely high level of reliability and can directly threaten human lives in case of failure or malfunction of the product or may cause harm to human bodies, nor shall they grant any guarantee thereof. If you should intend to use our products for applications 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 no consultation or inquiry before the intended use, our customer shall be solely responsible for the use. Specifications of any and all SANYO Semiconductor Co.,Ltd. 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. 31407 MS PC B8-9090 No.A0742-1/5 LA5774 Electrical Characteristics at Ta = 25°C, VO = 3.3V Parameter Symbol Ratings Conditions min Reference voltage VOS VIN = 15V, IO = 1.0A η VIN = 15V, IO = 1.0A Efficiency Switching frequency f Unit typ 1.235 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 % mV ±0.5 Designed target value. * 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) 3079C Pd max -- Ta 4.5 2.7 0.9 5 1 0.8 (1.6) 17.8 21.3 23.0 15.0 1.3 (8.8) 3.6 2.7 10.4max 10.0 Allowable power dissipation, Pd max -- W 10.0 0.45 1.7 4.5 8.0 7.5 100×100×1.5mm3 6.0 5.6 50×50×1.5mm3 4.0 3.3 2.0 1.75 Al heat sink mounting torque 39N⋅cm silicone grease applied 30×30×1.5mm3 No heat sink 0 -30 -20 8.4 Infinite heat sink θjc=5°C 0 20 40 60 80 100 Ambient temperature, Ta -- °C 120 140 160 MSG07021 SANYO : 220-5H Pin Assignment (1) VIN (2) SWOUT (3) GND (4) VOS (5) SS No.A0742-2/5 LA5774 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 LA5774 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.A0742-3/5 LA5774 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.A0742-4/5 LA5774 Timing Chart VIN SWOUT VOUT Td Tss SANYO Semiconductor Co.,Ltd. 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 Co.,Ltd. products described or contained herein. SANYO Semiconductor Co.,Ltd. strives to supply high-quality 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 accidents or events that could endanger human lives, trouble that could give rise to smoke or fire, or accidents 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 Co.,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 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 consent 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 Co.,Ltd. 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. Upon using the technical information or products described 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 for 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. This catalog provides information as of March, 2007. Specifications and information herein are subject to change without notice. PS No.A0742-5/5