Ordering number : ENA0476A
Monolithic Linear IC
LA5779
Overview
Separately-excited Step-down
Switching Regulator
(Variable Type)
The LA5779 is a Separately-excited step-down switching regulator (variable type).
Functions
•
High efficiency.
•
Six external parts.
•
Time-base generator (160kHz) incorporated.
•
Current limiter incorporated.
•
Thermal shutdown circuit incorporated.
•
ON/OFF function.
Specifications
Absolute
Maximum Ratings
at Ta = 25°C
Parameter
Maximum Input voltage
Maximum Output current
SW pin application reverse voltage
Allowable power dissipation
Symbol
VIN max
IO max
VSW
Pd max1
Pd max2
Operating temperature
Storage temperature
Junction temperature
Topr
Tstg
Tj max
Infinitely large heat sink.
Independent IC.
Conditions
Ratings
30
3
-1
7.5
1.75
-30 to +125
-40 to +150
150
Unit
V
A
V
W
W
°C
°C
°C
Recommended Operating Conditions
at Ta = 25°C
Parameter
Input voltage range
Symbol
VIN
Conditions
Ratings
4.5 to 28
Unit
V
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"standard application", intended for the use as general electronics equipment (home appliances, AV equipment,
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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.
62707 MS PC 20070619-S00001 / N1306 MS PC 20060606-S00001 No.A0476-1/4
LA5779
Electrical Characteristics
at Ta
=
25°C, VO = 3.3V
Parameter
Reference voltage
Efficiency
Switching frequency
Switching frequency when
short-circuit protection is active
Line regulation
Load regulation
Output voltage temperature
coefficient
Ripple attenuation factor
Output leak current
Current limiter operating voltage
Operating current
Standby current
ENA pin LOW voltage range
ENA pin HIGH voltage range
Thermal shutdown operating
temperature
Thermal shutdown Hysteresis
width
* Design target value: No measurement made.
∆TSD
Designed target value. *
15
°C
RREJ
IOleak
IS
IVIN
ISTBY
VENAL
VENAH
TSD
Designed target value. *
2.4
165
f = 100 to 120Hz
VIN = 15V, SWOUT = -0.4V
VIN = 15V
VIN = 15V
VIN = 15V, ENA = 5V
3.1
5.6
200
0.6
VIN
45
50
dB
µA
A
mA
µA
V
V
°C
∆V
OLINE
∆V
OLOAD
∆V
O/∆Ta
VIN = 8 to 20V, IO = 1.0A
VIN = 15V, IO = 0.5 to 1.5A
Designed target value. *
40
10
±0.5
100
30
mV
mV
mV/°C
Symbol
VOS
η
f
fshort
Conditions
min
VIN = 15V, IO = 1.0A
VIN = 15V, IO = 1.0A, Set VO = 5V
VIN = 15V, IO = 1.0A
VIN = 15V, VOS = 0V
128
15
1.20
Ratings
typ
1.23
84
160
30
192
45
max
1.26
V
%
kHz
kHz
Unit
Package Dimensions
unit : mm (typ)
3079A
10.0
Pd max -- Ta
3.6
2.7
10.4max
10.0
4.5
1.3
Allowable pwer dissipation, Pd max -- W
8.0
7.5
100×100×1.5mm
3
Infinitely large heat sink
θjc=5°C/W
Al heat
sink plate
tightening
torque
39N.cm
With
silicone
grease
applied.
15.0
6.0
5.6
50×50×1.5mm
3
(8.8)
17.8
21.3
23.0
4.0
3.3
2.0
1.75
30×30×1.5mm
3
No heat sink
0.9
2.7
1
5
0.8
0.45
4.5
8.4
(1.6)
1.7
0
--30
0
20
40
60
80
100
120
140
160
Ambient temperature, Ta --
°C
PCA00833
SANYO : TO-220-5H
Pin Assignment
(1) VIN (2) SWOUT
(3) GND
(4) VOS
(5) ENA
No.A0476-2/4
LA5779
Block Diagram
VIN 1
Reg.
OCP
2 SWOUT
OSC
Reset
Drive
Comp.
THD
4 VOS
VREF
Amp.
5
ENA
3
GND
Application Circuit Example
L1
47µH
VIN
SWOUT
LA5779
C1
470µF
/50V
D1
SBD
C2
390µF
VOS
ENA
GND
R2
R1
No.A0476-3/4
LA5779
Description of Functional Settings
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.
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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.
products described or contained herein.
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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 June, 2007. Specifications and information herein are subject
to change without notice.
PS No.A0476-4/4
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