Ordering number : ENA1439 LA5757TP Monolithic Linear IC Separately-excited Step-down Switching Regulator (Variable Type) Overview The LA5757TP is a separately-excited step-down switching regulator (variable type). Features • Output smoothing condenser can use a Low ESR condenser for the reliability improvement • High efficiency • Four external parts • Time-base generator (300kHz) incorporated • Current limiter incorporated • Thermal shutdown circuit incorporated • Soft start circuit incorporated Specifications Maximum Ratings at Ta = 25°C Parameter Symbol Conditions Ratings Unit Input voltage VIN max 34 Output current IO max 1.5 A SW pin application reverse VSW -1 V Mounted on a specified board* V Allowable power dissipation Pd max 1.1 W Operating temperature Topr -30 to +125 °C Storage temperature Tstg -40 to +150 °C * Specified board: 114.3mm × 76.1mm × 1.6mm, glass epoxy board. Recommended Operating Conditions at Ta = 25°C Parameter Input voltage range Symbol VIN Conditions Ratings Unit 4.5 to 32 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. 40809 MS 20090326-S00004 No.A1439-1/6 LA5757TP Electrical Characteristics at Ta = 25°C, VO = 5V Parameter Symbol Ratings Conditions min Reference voltage VOS Efficiency η Unit typ 1.230 max 1.255 1.280 V 83 Switching frequency f VIN = 15V, IO = 1.0A Line regulation ∆VOLINE VIN= 8 to 20V, IO=1.0A 240 Load regulation ∆VOLOAD VIN = 15V, IO = 0.5 to 1.5A Output voltage temperature coefficient ∆VO/∆Ta Designed target value* Ripple attenuation factor RREJ f = 100 to 120Hz Current limiter operating voltage IS VIN = 15V Thermal shutdown operating temperature TSD Thermal shutdown hysteresis width ∆TSD % 300 360 kHz 40 100 mV 10 30 ±0.5 mV mV/°C 45 dB Designed target value* 165 °C Designed target value* 15 °C 1.6 A * Designed target value: No measurement made. Package Dimensions unit : mm (typ) 3332 Pd max -- Ta 6.5 2.3 1.5 5.0 2.5 1.2 0.8 (5.5) 7.0 0.5 0.2 0.6 (0.65) 1.3 1 2 0.5 0.5 1.2 Allowable power dissipation, Pd max -- W 1.4 1.2 1.1 Specified board: 114.3×76.1×1.6mm3 glass epoxy board. With specified board 1 0.8 0.6 0.4 0 --30--20 5 0.22 0.2 0 20 40 60 80 100 120 140 Ambient temperature, Ta -- °C SANYO : TP5HFA Pin Assignment (1)VIN (2)SWOUT (3)GND (4)VOS (5)SS No.A0951-2/5 LA5757TP Block Diagram VIN 1 2 SWOUT Constnt Current Circuit OCP Reg. RESET OSC DRIVE Comp. TSD 2 VOS Amp. ON/OFF Comp. 0.4V VREF 5 SS 3 GND Application Circuit Example L1 VIN SWOUT LA5757TP C2 D1 C1 VOS SS GND R2 R1 C3 Notes: C3 is for the soft start function. Delete C3 and keep the SS pin open when the soft function is not necessary. 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 1.255V (typ). The equation to set the output voltage is as follows: R2 VO = 1+ × 1.255V(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. No.A0951-3/5 LA5757TP 2. Start delay function The SS pin has the internally-connected 10µA (typ) constant-current supply. When the voltage of SS pin exceeds the threshold voltage, the regulator starts operation. As the threshold is 0.62V(typ), the start delay time can be calculated as follows: ex. For setting at 1µF Td = C × V 1µ × 0.62 = = 28.2 msec 22µ 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 = 15V to 3.3V output to be made, for example, the PWM-ON duty has the value as shown below. VOUT + VF PWMduty = = 25% VIN - Vsat + VF 1.5V 0.62V PWM wave (Note that calculation is made with Vsat = 1V and VF = 0.2V) The output voltage of error amplifier, which is 3.3V, is the value with PWM = 25%, as calculated in the above equation, so that this voltage is determined as follows: Ver = (∆VPWM) × PWMduty + VPWML = 0.88V × 0.25 + 0.62V = 0.84V (∆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 strt time is calculated as follows: Tss = C × ∆VPWM × PWMduty C × 0.88 × PWMduty = 22µA i For the set conditions of C = 1µF and PWMduty = 25%: Tss = 1µ × 0.88V × 0.25 = 10msec 22µA No.A0951-4/5 LA5757TP Timing Chart VIN SWOUT VOUT Tss Td Overcurrent protection characteristic 8 6 85 Efficiency -- % Output voltage, VO -- V 7 Efficiency -- VIN 90 VIN = 12V VO = 5V CIN = 1000µF COUT = 470µF L = 68µH 5 4 3 IO = 0.5 A 80 1.5A 1.0A 75 70 2 65 1 0 0 0.4 0.8 1.2 1.6 60 2.0 0 10 Load current, IL -- A VOsat -- ISW 30 40 30 40 ISTB -- VIN 250 1.4 Standby current, ISTB -- µA Output saturation voltage, VOsat -- V 1.6 20 Input voltage, VIN -- V 1.2 1.0 0.8 0.6 0.4 200 150 100 50 0.2 0 0 0.25 0.5 0.75 1.0 Switch current, ISW -- A 1.25 1.5 0 0 10 20 Input voltage, VIN -- V No.A0951-5/5 LA5757TP LR -- IL 1.0 INR -- VIN 2.5 Input regulation, INR -- % Load regulation, LR -- % 2.0 0.5 0 -0.5 1.5 1.0 0.5 0 -1.0 0 0.25 0.5 0.75 1.0 Load current, IL -- A 1.25 1.5 -0.5 0 5 10 15 20 25 30 Input voltage, VIN -- V 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. 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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 April, 2009. Specifications and information herein are subject to change without notice. PS No.A1439-6/6