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Ordering number : ENA0490
Monolithic Linear IC
LA5774MP
Overview
Separately-excited Step-down
Switching Regulator (Variable Type)
The LA5774MP is a Separately-excited step-down switching regulator (variable type).
Functions
* Low-ESR capacitor with increased reliability applicable as the output smoothing capacitor. * High efficiency. * Four external parts. * Time-base generator (160kHz) incorporated. * Current limiter incorporated. * Thermal shutdown circuit incorporated. * Soft start circuit incorporated.
Specifications
Absolute Maximum Ratings at Ta = 25C
Parameter Maximum Input voltage Maximum Output current SW pin application reverse voltage Allowable power dissipation Operating temperature Storage temperature Symbol VIN max IO max VSW Pd max Topr Tstg Mounted on a substrate.* Conditions Ratings 30 3 -1 3.9 -30 to +125 -40 to +150 Unit V A V W C C
* Specified substrate : 76.1x114.3x1.6mm3 : Copper foil ratio 60 FR4
Recommended Operating Conditions at Ta = 25C
Parameter Input voltage range Symbol VIN Conditions Ratings 4.5 to 28 Unit V
Any and all SANYO Semiconductor products described or contained herein do not have specifications
SANYO Semiconductor assumes no responsibility for equipment failures that result from using products
that can handle applications that require extremely high levels of reliability, such as life-support systems, aircraft's control systems, or other applications whose failure can be reasonably expected to result in serious physical and/or material damage. Consult with your SANYO Semiconductor representative nearest you before using any SANYO Semiconductor products described or contained herein in such applications. 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 products described or contained herein.
72606 MS PC B8-9089 No.A0490-1/5
LA5774MP
Electrical Characteristics at Ta = 25C, VO = 3.3V
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 * Design target value: No measurement made. TSD Designed target value. * 15 C RREJ IS TSD f = 100 to 120Hz VIN = 15V Designed target value. * 3.1 165 45 dB A C Symbol VOS f VOLINE VOLOAD VO/Ta Conditions VIN = 15V, IO = 1.0A VIN = 15V, IO = 1.0A VIN = 15V, IO = 1.0A VIN = 8 to 20V, IO = 1A VIN = 15V, IO = 0.5 to 1.5A Designed target value. * 128 Ratings min 1.235 typ 1.26 78 160 40 10 0.5 192 100 30 max 1.285 Unit V % kHz mV mV mV/C
Package Dimensions
unit : mm (typ) 3275
4.5
Pd max - Ta
1.2
10.0
4.5
Allowable power dissipation, Pd max - W
1.3
4.0 3.90 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 -30 -20
Specified sbstrate: 76.1x114.3x1.6mm3 Copper foil ratio 60% FR4
(8.8)
9.9
(1.6)
1.7
0.9 0.4
4.5
1
5
SANYO : SMP5
1.5
0.2 2.7
0
20
40
60
80
100
120
140
160
Ambient temperature, Ta - C
MSG06072
Pin Assignment
(1) VIN (2) SWOUT (3) GND (4) VOS (5) SS
No.A0490-2/5
LA5774MP
Block Diagram
VIN 1 Reg. OCP
2 SWOUT
OSC
Reset
Drive
Comp.
THD 4 VOS VREF
Amp.
5 SS
3 GND
Application Circuit Example
L1 68H
VIN
SWOUT
LA5774MP
C1 470F /50V D1 SBD C2 390F
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 start function is not necessary.
No.A0490-3/5
LA5774MP
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+ x 1.26V(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. 2. 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 voltage is 0.62V (typ), the start delay time can be calculated as follows: ex. For setting at 1F
Td = C x V 1F x 0.62 = = 28.2 ms i 22A
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.
VOUT PWMduty = V - Vsat + VF = 23 % IN
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 3.3 V, is the value with PWM = 23%, as calculated in the above equation, so that this voltage is determined as follows: Ver = (VPWM) x PWMduty + VPWML = 0.88V x 0.23 + 0.62V = 0.82V (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 start time is calculated as follows:
Tss = C x VPWM x PWMduty C x 0.88 x PWMduty = 22A i
For the set conditions of C = 1F and PWMduty = 23%:
Tss = 1F x 0.88V x 0.23 = 9.2ms 22A
No.A0490-4/5
LA5774MP
Timing Chart
VIN
SWOUT
VOUT
Td
Tss
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This catalog provides information as of June, 2006. Specifications and information herein are subject to change without notice. PS No.A0490-5/5

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