Ordering number : ENA0498 LA5779MP Monolithic Linear IC Separately-excited Step-down Switching Regulator (Variable Type) http://onsemi.com Overview The LA5779MP is a Separately-excited step-down switching regulator (variable type). Functions • High efficiency. • Six external parts. • Time-base generator (160kHz) incorporated. • Current limiter incorporated. • Thermal shutdown circuit incorporated. • ON/OFF function. Specifications Absolute Maximum Ratings at Ta = 25°C Parameter Symbol Maximum Input voltage VIN max 30 V IO max 3 A VSW -1 V Maximum Output current SW pin application reverse voltage Allowable power dissipation Pd max Operating temperature Storage temperature Conditions Ratings Mounted on a substrate.* Unit 3.9 W Topr -30 to +125 °C Tstg -40 to +150 °C 3 * Specified substrate : 76.1×114.3×1.6mm : Copper foil ratio 60％ FR4 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 VIN Semiconductor Components Industries, LLC, 2013 August, 2013 Conditions Ratings Unit 4.5 to 28 V N1306 MS PC 20060411-S00008 No.A0498-1/4 LA5779MP Electrical Characteristics at Ta = 25°C, VO = 3.3V Parameter Symbol Ratings Conditions min Reference voltage VOS Efficiency Switching frequency Switching frequency when VIN = 15V, IO = 1.0A Unit typ 1.20 max 1.23 1.26 V η VIN = 15V, IO = 1.0A, Set VO = 5V f VIN = 15V, IO = 1.0A 128 160 192 kHz fshort VIN = 15V, VOS = 0V 15 30 45 kHz 40 100 mV 10 30 84 % short-circuit protection is active Line regulation ΔVOLINE VIN = 8 to 20V, IO = 1.0A Load regulation ΔVOLOAD VIN = 15V, IO = 0.5 to 1.5A ΔVO/ΔTa Output voltage temperature ±0.5 Designed target value. * mV mV/°C coefficient Ripple attenuation factor RREJ f = 100 to 120Hz Output leak current IOleak VIN = 15V, SWOUT = -0.4V Current limiter operating voltage IS Operating current 45 VIN = 15V IVIN dB μA 50 3.1 A VIN = 15V 5.6 VIN = 15V, ENA = 5V 50 mA 100 μA 0.6 V Standby current ISTBY ENA pin LOW voltage range VENAL ENA pin HIGH voltage range VENAH Thermal shutdown operating TSD Designed target value. * 165 °C ΔTSD Designed target value. * 15 °C 2.4 VIN V temperature Thermal shutdown Hysteresis width * Design target value: No measurement made. Package Dimensions unit : mm (typ) 3275 Pd max - Ta 4.5 1.5 9.9 1.3 4.5 (8.8) 1.2 10.0 (1.6) 0.9 1.7 0.2 0.4 1 5 Allowable power dissipation, Pd max - W 4.5 2.7 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 4.0 3.90 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) ENA No.A0498-2/4 LA5779MP Block Diagram VIN 1 2 SWOUT Reg. OCP Reset OSC Drive Comp. THD 4 VOS Amp. VREF 5 3 ENA GND Application Circuit Example L1 47μH VIN SWOUT LA5779MP C2 390μF D1 SBD C1 470μF /50V VOS ENA GND R2 R1 No.A0498-3/4 LA5779MP Description of Functional Settings 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. 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. 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