LA5757TP Monolithic Linear Separately-excited Step-down

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LA5757TP Monolithic Linear Separately-excited Step-down

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Ordering number ENA1439
LA5757TP
Monolithic Linear
Separately-excited Step-down
Switching Regulator (Variable Type)
LA5757TP separately-excited step-down switching regulator (variable type).
Features
Output smoothing condenser condenser 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 25°C
Parameter Input voltage Output current application reverse Allowable power dissipation Operating temperature Storage temperature Symbol Topr Tstg Mounted specified board* Conditions Ratings +125 +150 Unit
Specified board: 114.3mm 76.1mm 1.6mm, glass epoxy board.
Recommended Operating Conditions 25°C
Parameter Input voltage range Symbol Conditions Ratings Unit
SANYO Semiconductor Co.,Ltd. products described contained herein are, with regard "standard application", intended general electronics equipment (home appliances, equipment, communication device, office equipment, industrial equipment etc.). products mentioned herein shall intended "special application" (medical equipment whose purpose sustain life, aerospace instrument, nuclear control device, burning appliances, transportation machine, traffic signal system, safety equipment etc.) that shall require extremely high level reliability directly threaten human lives case failure malfunction product cause harm human bodies, shall they grant guarantee thereof. should intend products applications outside standard applications customer considering such and/or outside scope intended standard applications, please consult with prior intended use. there consultation inquiry before intended use, customer shall solely responsible use. Specifications SANYO Semiconductor Co.,Ltd. products described contained herein stipulate performance, characteristics, functions described products independent state, guarantees performance, characteristics, functions described products mounted customer' products equipment. verify symptoms states that cannot evaluated independent device, customer should always evaluate test devices mounted customer' products equipment.
40809 20090326-S00004 No.A1439-1/6
LA5757TP
Electrical Characteristics 25°C,
Parameter Reference voltage Efficiency Switching frequency Line regulation Load regulation Output voltage temperature coefficient Ripple attenuation factor Current limiter operating voltage Thermal shutdown operating temperature Thermal shutdown hysteresis width Symbol VOLINE VOLOAD VO/Ta RREJ 15V, 1.0A VIN= 20V, IO=1.0A 15V, 1.5A Designed target value* 120Hz Designed target value* Designed target value* Conditions 1.230 Ratings 1.255 ±0.5 1.280 mV/°C Unit
Designed target value: measurement made.
Package Dimensions
unit (typ) 3332
Specified board: glass epoxy board. With specified board
Allowable power dissipation,
(5.5)
0.22
(0.65)
-30-20
Ambient temperature,
SANYO TP5HFA
Assignment
(1)VIN (2)SWOUT (3)GND (4)VOS (5)SS
No.A0951-2/5
LA5757TP
Block Diagram
Constnt Current Circuit Reg. SWOUT
RESET DRIVE
Comp.
Amp.
ON/OFF Comp. 0.4V
VREF
Application Circuit Example
SWOUT
LA5757TP
Notes: soft start function. Delete keep open when soft function necessary.
Description Functional Settings
Calculation equation output voltage This controls switching output that voltage becomes 1.255V (typ). equation output voltage follows:
1.255V(typ)
inrush current (typ). Therefore, error becomes larger when resistance values large.
No.A0951-3/5
LA5757TP
Start delay function internally-connected 10µA (typ) constant-current supply. When voltage exceeds threshold voltage, regulator starts operation. threshold 0.62V(typ), start delay time calculated follows: setting
0.62 28.2 msec
Soft start function internal waveform voltage value shown right. down-conversion from voltage 3.3V output made, example, PWM-ON duty value shown below.
VOUT PWMduty Vsat
1.5V
0.62V wave
(Note that calculation made with Vsat 0.2V) output voltage error amplifier, which 3.3V, value with 25%, calculated above equation, that this voltage determined follows: (VPWM) PWMduty VPWML 0.88V 0.25 0.62V 0.84V (VPWM amplitude value 0.88V(typ) while VPWML lower limit voltage waveform 0.62V(typ)) error amplifier output voltages designed prefer lower voltages, that VOUT will reach designed regulation voltage timing when voltage exceeds error amplifier output. Therefore, soft strt time calculated follows:
VPWM PWMduty 0.88 PWMduty 22µA
conditions PWMduty 25%:
0.88V 0.25 10msec 22µA
No.A0951-4/5
LA5757TP
Timing Chart
SWOUT
VOUT
Overcurrent protection characteristic
1000µF COUT 470µF 68µH
Efficiency
Output voltage,
Efficiency
1.5A
1.0A
Load current,
VOsat
Input voltage,
ISTB
Output saturation voltage, VOsat
Standby current, ISTB
0.25
0.75
1.25
Switch current,
Input voltage,
No.A0951-5/5
LA5757TP
Load regulation,
Input regulation,
-0.5
-1.0
0.25
0.75
1.25
-0.5
Load current,
Input voltage,
SANYO Semiconductor Co.,Ltd. assumes responsibility equipment failures that result from using products values that exceed, even momentarily, rated values (such maximum ratings, operating condition ranges, other parameters) listed products specifications SANYO Semiconductor Co.,Ltd. products described contained herein. SANYO Semiconductor Co.,Ltd. strives supply high-quality high-reliability products, however, semiconductor products fail malfunction with some probability. possible that these probabilistic failures malfunction could give rise accidents events that could endanger human lives, trouble that could give rise smoke fire, accidents that could cause damage other property. When designing equipment, adopt safety measures that these kinds accidents events cannot occur. Such measures include limited protective circuits error prevention circuits safe design, redundant design, structural design. event that SANYO Semiconductor Co.,Ltd. products described contained herein controlled under applicable local export control laws regulations, such products require export license from authorities concerned accordance with above law. part this publication reproduced transmitted form means, electronic mechanical, including photocopying recording, information storage retrieval system, otherwise, without prior written consent SANYO Semiconductor Co.,Ltd. information described contained herein subject change without notice product/technology improvement, etc. When designing equipment, refer "Delivery Specification" SANYO Semiconductor Co.,Ltd. product that intend use. Information (including circuit diagrams circuit parameters) herein example only; guaranteed volume production. Upon using technical information products described herein, neither warranty license shall granted with regard intellectual property rights other rights SANYO Semiconductor Co.,Ltd. third party. SANYO Semiconductor Co.,Ltd. shall liable claim suits with regard third party's intellctual property rights which resulted from technical information products mentioned above.
This catalog provides information April, 2009. Specifications information herein subject change without notice. No.A1439-6/6

LA5757TP Monolithic Linear Separately-excited Step-down

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