Ordering number : ENA0587A
Monolithic Linear IC
LA5744MP
Overview
Separately-Excited Step-Down
Switching Regulator
(Variable Type)
The LA5744MP is a separately-excited step-down switching regulator (variable type).
Functions
•
High efficiency.
•
Time-base generator (300kHz) incorporated.
•
Current limiter incorporated.
•
Thermal shutdown circuit incorporated.
•
Soft start circuit incorporated.
Specifications
Maximum Ratings
at Ta = 25°C
Parameter
Input voltage
Maximum output current
SW pin application reverse voltage
Allowable power dissipation
Operating temperature
Storage temperature
Symbol
VIN
IO max
VSW
Pd max
Topr
Tstg
Mounted on a circuit board.*
Conditions
Ratings
30
3
-1
3.9
-30 to +125
-40 to +150
Unit
V
A
V
W
°C
°C
* Specified circuit board : 76.1×114.3×1.6mm
3
: 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 Co.,Ltd. products described or contained herein are, with regard to
"standard application", intended for the use as general electronics equipment (home appliances, AV equipment,
communication device, office equipment, industrial equipment etc.). The products mentioned herein shall not be
intended for use for any "special application" (medical equipment whose purpose is to sustain life, aerospace
instrument, nuclear control device, burning appliances, transportation machine, traffic signal system, safety
equipment etc.) that shall require extremely high level of reliability and can directly threaten human lives in case
of failure or malfunction of the product or may cause harm to human bodies, nor shall they grant any guarantee
thereof. If you should intend to use our products for applications outside the standard applications of our
customer who is considering such use and/or outside the scope of our intended standard applications, please
consult with us prior to the intended use. If there is no consultation or inquiry before the intended use, our
customer shall be solely responsible for the use.
Specifications of any and all SANYO Semiconductor Co.,Ltd. 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.
31407 MS PC / 11707 MS PC 20060929-S00007 No.A0587-1/5
LA5744MP
Electrical Characteristics
at Ta
=
25°C, VO = 5V
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
min
VIN = 15V, IO = 1.0A
VIN = 15V, IO = 1.0A
VIN = 15V, IO = 1.0A
VIN = 8 to 20V, IO = 1.0A
VIN = 20V, IO = 0.5 to 1.5A
Designed target value. *
240
1.20
Ratings
typ
1.23
83
300
40
10
±0.5
360
100
30
max
1.26
V
%
kHz
mV
mV
mV/°C
Unit
Package Dimensions
unit : mm (typ)
3275
4.5
Pd max - Ta
1.2
10.0
4.5
1.3
Allowable power dissipation, Pd max - W
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
0.2
2.7
1
5
SANYO : SMP5
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.A0587-2/5
LA5744MP
Block Diagram
VIN 1
Constant
current
circuit
Reg.
OCP
2 SWOUT
OSC
Reset
Drive
Comp.
TSD
4 VOS
VREF
ON/OFF Comp.
0.4V
5
SS
3
Amp.
GND
Application Circuit Example
L1
22µH
VIN
SWOUT
LA5744MP
C1
470µF
/50V
D1
SBD
C2
390µF
VOS
SS
C3
1µF
GND
R2
R1
Notes :
1. C3 is for the soft start function. Delete C3 and keep the SS pin open when the soft start function is not necessary.
2.
In some cases, the output may not turn on if power is applied when a load is connected. If this is a problem, increase the value of
the inductor.
No.A0587-3/5
LA5744MP
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 3.1A.
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 3 : If the soft start function is not used, the IC will start up with the overcurrent protection function operating. At this
time, the switching frequency will be cut in half. This means that the switching frequency will be 15kHz at
startup.
Note 4 : 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 22µH. 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.
2. Startup Delay Function
The output voltage rises when the internal voltage reaches 0.4V (typical). Until that point, a capacitor is charged from
an internal 10µA (typical) constant-current supply. The startup delay time can be calculated as shown below
Example : Assume a 1µF capacitor is used.
Td =
C
×
V 1µF
×
0.4
=
= 40 ms
i
10µA
No.A0587-4/5
LA5744MP
Timing Chart
VIN voltage
30kHz
300kHz
SWOUT voltage
1.23V
0.8V
VOS voltage
0V
Td
SANYO Semiconductor Co.,Ltd. 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 Co.,Ltd.
products described or contained herein.
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semiconductor products fail or malfunction with some probability. It is possible that these probabilistic failures or
malfunction could give rise to accidents or events that could endanger human lives, trouble that could give rise
to smoke or fire, or accidents 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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No part of this publication may be reproduced or transmitted in any form or by any means, electronic or
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without the prior written consent of SANYO Semiconductor Co.,Ltd.
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 Co.,Ltd. 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.
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with regard to intellectual property rights or any other rights of SANYO Semiconductor Co.,Ltd. or any third
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above.
This catalog provides information as of March, 2007. Specifications and information herein are subject
to change without notice.
PS No.A0587-5/5
51单片机
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