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Ordering number : ENA0586
LA5724M
Monolithic Linear IC
Separately-Excited Step-Down
Switching Regulator
(Variable Type)
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The LA5724M is a separately-excited step-down switching regulator (variable type).
Functions
Time-base generator (160kHz) incorporated.
Current limiter incorporated.
Thermal shutdown circuit incorporated.
Specifications
Absolute Maximum Ratings at Ta = 25°C
Parameter
Symbol
Conditions
Input voltage
Maximum output current
SW pin application reverse voltage
VOS pin application voltage
Allowable power dissipation
VIN
IO max
VSW
VVOS
Pd max
Mounted on a circuit board.*
Operating temperature
Topr
Storage temperature
Tstg
* Specified circuit board : 114.3×76.1×1.6mm3, glass epoxy board.
Recommended Operating Conditions at Ta = 25°C
Parameter
Input voltage range
Symbol
VIN
Conditions
Ratings
30
0.6
-1
-0.2 to 7
0.8
-30 to +125
-40 to +150
Ratings
4.5 to 28
Unit
V
A
V
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.
11707 MS PC 20061002-S00008 No.A0586-1/5

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LA5724M
Electrical Characteristics at Ta = 25°C, VIN = 15V
Parameter
Symbol
Reference voltage
Reference pin bias current
Switching frequency
VOS
IFB
fosc
Efficiency
η
Short-circuit protection circuit
operating switching frequency
Saturation voltage
fscp
Vsat
Maximum on duty
D max
Minimum on duty
D min
Output leakage current
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Ilk
Iin
Current limiter operating voltage
Thermal shutdown operating
temperature
Thermal shutdown Hysteresis
width
IS
TSD
TSD
* Design target value : No measurement made.
IO = 0.3A
Conditions
VOUT = 5V, IO = 0.3A
IOUT = 0.3A, VOS = 0V
VOS = 0V
VOS = 5V
SWOUT = -1V
VOS = 2V
VIN = 15V
Designed target value. *
Designed target value. *
min
1.20
128
Ratings
typ
1.23
1
160
82
30
1.2
100
0
5
0.7
165
15
max
1.26
2
192
Unit
V
µA
kHz
%
kHz
V
%
%
200 µA
10 mA
A
°C
°C
Package Dimensions
unit : mm (typ)
3032D
5.0
85
1
(0.65) 1.27
4
0.35
0.15
SANYO : MFP8(225mil)
Pd max -- Ta
1
Designated board : 114.3×76.1×1.6mm3
glass epoxy
Mounted on a board
0.8
0.6
0.4
0.2
0.16
0
--30--20
0 20 40 60 80 100 120 140
Ambient temperature, Ta – °C
No.A0586-2/5

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Pin Assignment
LA5724M
NC NC GND NC
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VIN NC SWOUT VOS
VIN 1
Reg.
OCP
3 SWOUT
NC 2
NC 5
NC 7
NC 8
OSC
Reset
Comp.
Drive
TSD
Amp.
6
GND
VREF
4 VOS
Note : Since the NC pins are not connected within the IC package, they can be used as connection points.
Application Circuit Example
VIN
SWOUT
L1
47µH
C1
470µF
/50V
+
LA5724M
GND
VOS
D1
SBD
C3
1000pF
R2
R1
+
C2
100µF
No.A0586-3/5

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LA5724M
Protection Circuit Functional Descriptions
1. Overcurrent protection function
The overcurrent protection function detects, on a cycle-by-cycle basis, the output transistor current and turns off that
output transistor current if it exceeds 0.7A in a cycle-by-cycle manner.
Limit current
Inductor current
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SWOUT voltage
2. Short circuit protection function
This IC prevents the current from increasing when the outputs are shorted by setting the switching frequency to 30kHz
if the VOS pin voltage falls below 0.8V.
Note : Since the switching frequency becomes 30kHz when the VOS pin voltage falls under 0.8V, the current capacity
is reduced. If a load is applied with the VOS pin voltage over 0.8V, the inductance value operates at 47µH. If a
load is to be applied when this voltage is under 0.8V, the inductance value must be increased.
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 1.23V (typ).
The equation to set the output voltage is as follows :
VO =
1+
R2
R1
× 1.23V(typ)
The VOS pin has the inrush current of 1µA (typ). Therefore, the error becomes larger when R1 and R2 resistance
values are large.
No.A0586-4/5

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Timing Chart
VIN voltage
SWOUT voltage
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1.23V
0.8V
VOS voltage 0V
LA5724M
30kHz
160kHz
Specifications of any and all SANYO Semiconductor 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.
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and all semiconductor products fail with some probability. It is possible that these probabilistic failures
could give rise to accidents or events that could endanger human lives, that could give rise to smoke or
fire, or that could cause damage to other property. When designing equipment, adopt safety measures
so that these kinds of accidents or events cannot occur. Such measures include but are not limited to
protective circuits and error prevention circuits for safe design, redundant design, and structural design.
In the event that any or all SANYO Semiconductor products (including technical data,services) described
or contained herein are controlled under any of applicable local export control laws and regulations, such
products must not be exported without obtaining the export license from the authorities concerned in
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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 January, 2007. Specifications and information herein are subject
to change without notice.
PS No.A0586-5/5