Ordering number : ENA2191 LA5774MC Monolithic Linear IC Separately-excited Step-down http://onsemi.com Switching Regulator (Variable Type) Overview The LA5774MC is a Separately-excited step-down switching regulator (variable type). Function • High efficiency. • 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 Conditions Ratings Unit Maximum Input voltage VIN max 30 Maximum Output current IO max 3 A VSW -1 V 3.9 W SW pin application reverse voltage Allowable power dissipation VOS pin application reverse voltage Pd max Mounted on a substrate.* VVOS V -0.2 to +7 V 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 Caution 1) Absolute maximum ratings represent the value which cannot be exceeded for any length of time. Caution 2) Even when the device is used within the range of absolute maximum ratings, as a result of continuous usage under high temperature, high current, high voltage, or drastic temperature change, the reliability of the IC may be degraded. Please contact us for the further details. Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability. Recommended Operating Conditions at Ta = 25°C Parameter Input voltage range Symbol Conditions VIN Ratings Unit 4.5 to 28 V ORDERING INFORMATION See detailed ordering and shipping information on page 5 of this data sheet. Semiconductor Components Industries, LLC, 2013 May, 2013 52913NK 20130426-S00001 No.A2191-1/6 LA5774MC Electrical Characteristics at Ta = 25°C, VO = 3.3V Parameter Symbol Reference voltage Ratings Conditions min VOS typ 1.235 η Efficiency Switching frequency Unit max 1.26 1.285 78 fosc 128 V % 160 192 kHz Line regulation ΔVOLINE VIN = 8 to 20V 40 100 mV Load regulation ΔVOLOAD IO = 0.5 to 1.5A 10 30 ΔVO/ΔTa Output voltage temperature ±0.5 Designed target value. * mV mV/°C coefficient Ripple attenuation factor RREJ Current limiter operating voltage f = 100 to 120Hz 45 IS Thermal shutdown operating 3.1 dB A TSD Designed target value. * 165 °C ΔTSD Designed target value. * 15 °C temperature Thermal shutdown Hysteresis width * Design target value: No measurement made. PACKAGE DIMENSIONS D 2 PAK5 / SMP5J CASE 418AS ISSUE O E C A B SEATING PLANE NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M, 1994. 2. CONTROLLING DIMENSION: MILLIMETERS. 3. DIMENSIONS D AND E DO NOT INCLUDE MOLD FLASH, PROTRUSIONS, OR GATE BURRS. MOLD FLASH, PROTRUSIONS, OR GATE BURRS SHALL NOT EXCEED 0.15 MILLIMETERS PER SIDE. 4. DIMENSIONS D AND E ARE DETERMINED AT THE OUTERMOST EXTREMES OF THE PLASTIC BODY. 5. DATUMS A AND B ARE DETERMINED AT DATUM PLANE C. A c2 L3 D DETAIL A 1 2 3 4 DIM A A1 A3 b c c2 D E e L L1 L3 5 PIN 1 INDICATOR L1 e 5X TOP VIEW c b 0.13 M B A M BOTTOM VIEW SIDE VIEW RECOMMENDED SOLDERING FOOTPRINT* MILLIMETERS MIN MAX 4.20 4.80 0.00 0.30 2.40 3.00 0.75 1.05 0.25 0.55 1.10 1.50 9.50 10.30 9.80 10.20 1.70 BSC 1.20 1.80 3.80 4.40 1.00 1.40 A3 11.00 c L A1 DETAIL A 7.80 15.60 5X 2.50 5X 1.30 1.70 PITCH DIMENSIONS: MILLIMETERS *For additional information on our Pb−Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. No.A2191-2/6 LA5774MC Pin Assignment (1) VIN (2) SWOUT (3) GND (4) VOS (5) SS Allowable power dissipation derating curve Pd max - Ta Allowable power dissipation, Pd max - W 4.5 Specified sbstrate: 76.1×114.3×1.6mm3 Copper foil ratio 60% FR4 4.0 3.90 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 -30 -20 0 20 40 60 80 100 120 Ambient temperature, Ta - °C 140 160 MSG06072 Block Diagram VIN 1 2 SWOUT Reg. OCP Reset OSC Drive Comp. THD 4 VOS Amp. VREF 5 3 SS GND No.A2191-3/6 LA5774MC Application Circuit Example L1 VIN SWOUT C3 LA5774MC C2 D1 C1 SS GND VOS R2 R1 C4 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 22μA i 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 + VF PWMduty = V − Vsat + VF = 25 % 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 = 25%, as calculated in the above equation, so that this voltage is determined as follows: Ver = (ΔVPWM) × PWMduty + VPWML = 0.88V × 0.25 + 0.62V = 0.84V (ΔVPWM is the PWM amplitude value or 0.88V(typ) while VPWML is the lower limit voltage of PWM waveform or 0.62V(typ)) No.A2191-4/6 LA5774MC 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 × ΔVPWM × PWMduty C × 0.88 × PWMduty = 22μA i For the set conditions of C = 1μF and PWMduty = 25%: Tss = 1μF × 0.88V × 0.25 = 10ms 22μA Timing Chart VIN SWOUT VOUT Td Tss ORDERING INFORMATION Device LA5774MC-BE Package SMP5J (Pb-Free / Halogen Free) LA5774MC-E SMP5J (Pb-Free / Halogen Free) Shipping (Qty / Packing) 1000 / Tape & Reel 50 / Fan-Fold No.A2191-5/6 LA5774MC ON Semiconductor and the ON logo are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of SCILLC’s product/patent coverage may be accessed at www.onsemi.com/site/pdf/Patent-Marking.pdf. SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. 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This literature is subject to all applicable copyright laws and is not for resale in any manner. PS No.A2191-6/6