Ordering number : ENA0586
Monolithic Linear IC
LA5724M
Overview
Separately-Excited Step-Down
Switching Regulator
(Variable Type)
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
Input voltage
Maximum output current
SW pin application reverse voltage
VOS pin application voltage
Allowable power dissipation
Operating temperature
Storage temperature
Symbol
VIN
IO max
VSW
VVOS
Pd max
Topr
Tstg
Mounted on a circuit board.*
Conditions
Ratings
30
0.6
-1
-0.2 to 7
0.8
-30 to +125
-40 to +150
Unit
V
A
V
V
W
°C
°C
* Specified circuit board : 114.3×76.1×1.6mm
3
, glass epoxy board.
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
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
LA5724M
Electrical Characteristics
at Ta
=
25°C, VIN = 15V
Parameter
Reference voltage
Reference pin bias current
Switching frequency
Efficiency
Short-circuit protection circuit
operating switching frequency
Saturation voltage
Maximum on duty
Minimum on duty
Output leakage current
Supply current
Current limiter operating voltage
Thermal shutdown operating
temperature
Thermal shutdown Hysteresis
width
* Design target value : No measurement made.
∆TSD
Designed target value. *
15
°C
Vsat
D max
D min
Ilk
Iin
IS
TSD
IOUT = 0.3A, VOS = 0V
VOS = 0V
VOS = 5V
SWOUT = -1V
VOS = 2V
VIN = 15V
Designed target value. *
0.7
165
5
1.2
100
0
200
10
V
%
%
µA
mA
A
°C
Symbol
VOS
IFB
fosc
η
fscp
VOUT = 5V, IO = 0.3A
128
IO = 0.3A
Conditions
min
1.20
Ratings
typ
1.23
1
160
82
30
max
1.26
2
192
V
µA
kHz
%
kHz
Unit
Package Dimensions
unit : mm (typ)
3032D
1
Pd max -- Ta
Designated board : 114.3×76.1×1.6mm
3
glass epoxy
Mounted on a board
5.0
8
5
Allowable power dissipation, Pd max – W
0.8
0.6
4.4
6.4
0.63
0.4
1
(0.65)
1.27
4
0.35
0.15
0.2
(1.5)
1.7max
0.16
0
--30--20
0
20
40
60
80
100
120
140
Ambient temperature, Ta – °C
0.1
SANYO : MFP8(225mil)
No.A0586-2/5
LA5724M
Pin Assignment
NC
NC
GND
NC
VIN
NC SWOUT VOS
Block Diagram
VIN
1
Reg.
OCP
3 SWOUT
OSC
NC
NC
NC
NC
2
Comp.
5
7
8
Reset
Drive
TSD
4 VOS
Amp.
VREF
6
GND
Note : Since the NC pins are not connected within the IC package, they can be used as connection points.
Application Circuit Example
L1
47µH
VIN
SWOUT
LA5724M
+
C1
470µF
/50V
VOS
GND
D1
SBD
C3
1000pF
+
C2
100µF
R2
R1
No.A0586-3/5
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
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 :
R2
VO = 1+
×
1.23V(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.
No.A0586-4/5
LA5724M
Timing Chart
VIN voltage
30kHz
160kHz
SWOUT voltage
1.23V
0.8V
VOS voltage
0V
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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.
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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
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This catalog provides information as of January, 2007. Specifications and information herein are subject
to change without notice.
PS No.A0586-5/5
电源技术
