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 = 25°C
Parameter
Maximum Input voltage
Maximum Output current
SW pin application reverse voltage
Allowable power dissipation
Operating temperature
Storage temperature
3
Symbol
VIN max
IO max
VSW
Pd max
Topr
Tstg
Conditions
Ratings
30
3
-1
Unit
V
A
V
W
°C
°C
Mounted on a substrate.*
3.9
-30 to +125
-40 to +150
* Specified substrate : 76.1×114.3×1.6mm : Copper foil ratio 60％ FR4
Recommended Operating Conditions
at Ta = 25°C
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
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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
=
25°C, 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
η
f
∆V
OLINE
∆V
OLOAD
∆V
O/∆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: 76.1×114.3×1.6mm
3
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
68µH
VIN
SWOUT
LA5774MP
C1
470µF
/50V
D1
SBD
C2
390µF
VOS
SS
C3
1µF
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+
×
1.26V(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.
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
calculated as follows:
ex. For setting at 1µF
Td =
C
×
V 1µF
×
0.62
=
= 28.2 ms
i
22µA
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)
×
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 ×
PWMduty C
×
0.88
×
PWMduty
=
22µA
i
For the set conditions of C = 1µF and PWMduty = 23%:
Tss =
1µF
×
0.88V
×
0.23
= 9.2ms
22µA
No.A0490-4/5
LA5774MP
Timing Chart
VIN
SWOUT
VOUT
Td
Tss
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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
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and all semiconductor products fail with some probability. It is possible that these probabilistic failures
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so that these kinds of accidents or events cannot occur. Such measures include but are not limited to
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Any and all information described or contained herein are subject to change without notice due to
product/technology improvement, etc. When designing equipment, refer to the "Delivery Specification"
for the SANYO Semiconductor product that you intend to use.
Information (including circuit diagrams and circuit parameters) herein is for example only; it is not
guaranteed for volume production. SANYO Semiconductor believes information herein is accurate
and reliable, but no guarantees are made or implied regarding its use or any infringements of
intellectual property rights or other rights of third parties.
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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