SANYO LA5744TP

Ordering number : ENA0647A
Monolithic Linear IC
Separately-Excited Step-Down
LA5744TP
Switching Regulator
(Variable Type)
Overview
The LA5744TP 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
Symbol
Conditions
Ratings
VIN
Maximum output current
SW pin application reverse voltage
Allowable power dissipation
Unit
30
V
IO max
2
A
VSW
-1
V
1.1
W
Operating temperature
Topr
-30 to +125
°C
Storage temperature
Tstg
-40 to +150
°C
* Specified circuit board :
76.1×114.3×1.6mm3,
Pd max
Mounted on a circuit board.*
glass epoxy.
Recommended Operating Conditions at Ta = 25°C
Parameter
Input voltage range
Symbol
VIN
Conditions
Ratings
Unit
4.5 to 28
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.
42007 MS PC 20070420-S00001 / 11707 MS PC 20061204-S00012 No.A0647-1/5
LA5744TP
Electrical Characteristics at Ta = 25°C, VO = 5V
Parameter
Symbol
Ratings
Conditions
min
Reference voltage
Efficiency
Switching frequency
VOS
VIN = 15V, IO = 1.0A
η
VIN = 15V, IO = 1.0A
f
Unit
typ
1.20
max
1.23
1.26
V
83
300
360
kHz
Line regulation
∆VOLINE
VIN = 8 to 20V, IO = 1.0A
40
100
mV
Load regulation
∆VOLOAD
VIN = 20V, IO = 0.5 to 1.5A
10
30
∆VO/∆Ta
Output voltage temperature
VIN = 15V, IO = 1.0A
240
%
±0.5
Designed target value. *
mV
mV/°C
coefficient
Ripple attenuation factor
RREJ
Current limiter operating voltage
IS
Thermal shutdown operating
f = 100 to 120Hz
45
VIN = 15V
dB
3.1
A
TSD
Designed target value. *
165
°C
∆TSD
Designed target value. *
15
°C
temperature
Thermal shutdown Hysteresis
width
* Design target value : No measurement made.
Package Dimensions
unit : mm (typ)
3332
Pd max -- Ta
6.5
2.3
1.5
5.0
2.5
1.2
0.8
(5.5)
7.0
0.5
0.2
0.6
(0.65)
1.3
1 2
0.5
0.5
1.2
5
Allowable power dissipation, Pd max – W
1.4
Specified board : 114.3×76.1×1.6mm3
glass epoxy
1.2
1.1
1
0.8
0.6
0.4
0.22
0.2
0
--30--20
0
20
40
60
80
100
120
140
Ambient temperature, Ta – °C
SANYO : TP5HFA
Pin Assignment
(1) VIN (2) SWOUT (3) GND (4) VOS (5) SS
No.A0647-2/5
LA5744TP
Block Diagram
VIN 1
2 SWOUT
Constant
current
circuit
Reg.
OCP
Reset
OSC
Drive
Comp.
TSD
4 VOS
Amp.
ON/OFF Comp.
0.4V
VREF
5
3
SS
GND
Application Circuit Example
L1
22µH
VIN
SWOUT
LA5744TP
C2
390µF
D1
SBD
C1
470µF
/50V
VOS
SS
GND
R2
R1
C3
1µF
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.A0647-3/5
LA5744TP
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.A0647-4/5
LA5744TP
Timing Chart
VIN voltage
30kHz
300kHz
SWOUT voltage
1.23V
0.8V
VOS voltage
0V
Td
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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.
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Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed
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This catalog provides information as of April, 2007. Specifications and information herein are subject
to change without notice.
PS No.A0647-5/5