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Ordering number : ENA0490
LA5774MP
Monolithic Linear IC
Separately-excited Step-down
Switching Regulator
(Variable Type)
Overview
www.DataSheet4UT.choemLA5774MP 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 = 25°C
Parameter
Maximum Input voltage
Maximum Output current
SW pin application reverse voltage
Allowable power dissipation
Symbol
VIN max
IO max
VSW
Pd max
Conditions
Mounted on a substrate.*
Operating temperature
Topr
Storage temperature
Tstg
* Specified substrate : 76.1×114.3×1.6mm3 : Copper foil ratio 60FR4
Ratings
30
3
-1
3.9
-30 to +125
-40 to +150
Recommended Operating Conditions at Ta = 25°C
Parameter
Input voltage range
Symbol
VIN
Conditions
Ratings
4.5 to 28
Unit
V
A
V
W
°C
°C
Unit
V
Any and all SANYO Semiconductor products described or contained herein do not have specifications
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.
SANYO Semiconductor 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
products described or contained herein.
72606 MS PC B8-9089 No.A0490-1/5

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LA5774MP
Electrical Characteristics at Ta = 25°C, VO = 3.3V
Parameter
Symbol
Conditions
Reference voltage
Efficiency
VOS
η
Switching frequency
f
Line regulation
Load regulation
Output voltage temperature
coefficient
Ripple attenuation factor
VOLINE
VOLOAD
VO/Ta
RREJ
Current limiter operating voltage
IS
Thermal shutdown operating
TSD
www.DataSheet4Ute.mcpoemrature
Thermal shutdown Hysteresis
TSD
width
* Design target value: No measurement made.
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. *
f = 100 to 120Hz
VIN = 15V
Designed target value. *
Designed target value. *
min
1.235
128
3.1
Ratings
typ
1.26
78
160
40
10
±0.5
45
165
15
max
1.285
192
100
30
Unit
V
%
kHz
mV
mV
mV/°C
dB
A
°C
°C
Package Dimensions
unit : mm (typ)
3275
10.0
4.5
1.3
(1.6)
1.7 0.9
0.4
0.2
2.7
1 5 SANYO : SMP5
Pd max - Ta
4.5
Specified sbstrate: 76.1×114.3×1.6mm3
4.0 Copper foil ratio 60% FR4
3.90
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
-30-20 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

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Block Diagram
LA5774MP
www.DataSheet4U.com
VIN 1
Reg.
OCP
OSC
Reset
Comp.
Drive
THD
Amp.
VREF
53
SS GND
2 SWOUT
4 VOS
Application Circuit Example
VIN
SWOUT
L1
68µH
C1
470µF
/50V
LA5774MP
SS GND
C3
1µF
VOS
D1
SBD
R2
R1
C2
390µF
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

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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:
VO =
1+
R2
R1
× 1.26V(typ)
The VOS pin has the inrush current of 1µA (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 22µA (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
www.DataSheet4U.cocmalculated as follows:
ex. For setting at 1µF
Td
=
C
×
i
V
=
1µF × 0.62
22µA
=
28.2
ms
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.
1.5V
0.62V
PWMduty
= VIN
VOUT
Vsat +
VF
=
23
%
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) × PWMduty + VPWML = 0.88V × 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
×
VPWM
i
×
PWMduty =
C
×
0.88 × PWMduty
22µA
For the set conditions of C = 1µF and PWMduty = 23%:
Tss
=
1µF
×
0.88V
22µA
×
0.23
=
9.2ms
No.A0490-4/5

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Timing Chart
VIN
SWOUT
www.DataSheet4U.com
VOUT
LA5774MP
Td Tss
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and are not guarantees of the performance, characteristics, and functions of the described products
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and reliable, but no guarantees are made or implied regarding its use or any infringements of
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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