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Ordering number : ENA0952
Monolithic Linear IC
LA5754MP
Overview
Separately-excited Step-down
Switching Regulator (Variable Type)
The LA5754MP is a separately-excited step-down switching regulator (variable type).
Features
* High efficiency * Four external parts * Time-base generator (125kHz) incorporated * Current limiter incorporated * Thermal shutdown circuit incorporated * Soft start circuit incorporated
Specifications
Absolute Maximum Ratings at Ta = 25C
Parameter Input voltage Output current SW pin application reverse voltage Allowable power dissipation Symbol VIN max IO max Vsw Pd max1 Pd max2 Junction temperature Operating temperature Storage temperature Tj max Topr Tstg Infinite heat sink. No heat sink. Conditions Ratings 30 3 -1 7.5 1.75 150 -30 to +125 -40 to +150 Unit V A V W W C C C
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.
91907 MS PC B8-8724 No.A0952-1/5
LA5754MP
Recommended Operating Conditions at Ta = 25C
Parameter Input voltage range Operating junction temperature range VIN Tj op Symbol Conditions Ratings 5.5 to 28 -30 to +150 Unit V C
Electrical Characteristics at Ta = 25C
Parameter Output voltage 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 VO f VOLINE VOLOAD VO/Ta RREJ IS TSD TSD f = 100 to 120Hz VIN = 15V Designed target value* Designed target value* 3.1 165 15 Symbol Conditions min VIN = 15V, IO = 1.0A VIN = 15V, IO = 1.0A VIN= 8 to 20V, IO=1.0A VIN = 15V, IO = 0.5 to 1.5A 2.53 100 Ratings typ 2.66 125 25 10 0.5 45 max 2.76 150 80 30 V kHz mV mV mV/C dB A C C Unit
* Designed target value: No measurement made.
Package Dimensions
unit : mm (typ) 3275
4.5
Pd max -- Ta
Mounted on a specified board: 114.3x76.1x1.6mm3 Copper foil ratio 60% FR4
1.2
10.0
4.5 1.3
Allowable power dissipation, Pd max -- W
4.0 3.90 3.5 3.0 2.5 2.0 1.5 1.0
(8.8)
9.9
(1.6)
1.7
0.9 0.4
4.5
1.5 0.2 2.7
0.78 0.5 0 -30 -20
1
5
SANYO : SMP5
0
20
40
60
80
100
120
140
160
Ambient temperature, Ta -- C
MSG07022
Pin Assignment
(1)VIN (2)SWOUT (3)GND (4)VOS (5)SS
No.A0952-2/5
LA5754MP
Block Diagram
VIN 1
2 SWOUT
Reg.
OCP
OSC
Reset Drive
Comp. TSD 4 VOS
Amp.
VREF
5 SS
3 GND
Application Circuit Example
L1 47H
VIN
SWOUT
LA5754MP
C1 1000F D1 SBD C2 1000F
VOS SS
C3 1F
GND
R2 R1
Notes: C3 is for the soft start function. Delete C3 and keep the SS pin open when the soft function is not necessary. Calculation equation to set the output voltage This IC controls the switching output so that the VOS pin voltage becomes 2.66V (typ). The equation to set the output voltage is as follows:
R2 VO = 1+ x 2.66V(typ) R1
The VOS pin has the inrush current of 1A (typ). Therefore, the error becomes larger when R1 and R2 resistance values are large.
No.A0952-3/5
LA5754MP
Description of Functional Settings
1.Start delay function The SS pin has the internally-connected 22A (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 1F
Td = C x V 1 x 0.62 = = 28.2 msec 22 i
1.5V
2.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.
PWMduty = VOUT + VF = 25% VIN - Vsat + VF
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) x PWMduty + VPWML = 0.88V x 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 x VPWM x PWMduty C x 0.88 x PWMduty = 22A i 1 x 0.88V x 0.25 = 10msec 22A
For the set conditions of C = 1F and PWMduty = 25%:
Tss =
No.A0952-4/5
LA5754MP
Timing Chart
VIN
SWOUT
VOUT
Td
Tss
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This catalog provides information as of September, 2007. Specifications and information herein are subject to change without notice. PS No.A0952-5/5

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