Ordering number : ENA1683
LA5759
Overview
Monolithic Linear IC
Separately-excited Step-down
Switching Regulator (Variable Type)
The LA5759 is a separately-excited step-down switching regulator (variable type).
Features
•
Output smoothing condenser can use a Low ESR condenser for the reliability improvement
•
High efficiency
•
Four external parts
•
Time-base generator (80kHz) incorporated
•
Current limiter incorporated
•
Thermal shutdown circuit incorporated
•
Soft start circuit incorporated
Specifications
Maximum Ratings
at Ta = 25°C
Parameter
Input voltage
SW pin application reverse
Allowable power dissipation
Symbol
VIN max
VSW
Pd max1
Pd max2
Operating temperature
Storage temperature
Topr
Tstg
Infinite heat sink.
No heat sink.
Conditions
Ratings
34
-1
7.5
1.75
-30 to +125
-40 to +150
Unit
V
V
W
W
°C
°C
Recommended Operating Conditions
at Ta = 25°C
Parameter
Input voltage range
Symbol
VIN
Conditions
Ratings
4.5 to 32
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
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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.
51210 SY 20100308-S00001 No.A1683-1/4
LA5759
Electrical Characteristics
at Ta
=
25°C, VO = 3.3V
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
Symbol
VOS
η
f
ΔV
OLINE
ΔV
OLOAD
ΔV
O/ΔTa
RREJ
IS
TSD
ΔTSD
VIN = 15V, IO = 1.0A
VIN= 8 to 20V, IO=1.0A
VIN = 15V, IO = 0.5 to 1.5A
Designed target value*
f = 100 to 120Hz
VIN = 15V
Designed target value*
Designed target value*
5.4
165
15
60
Conditions
min
1.235
Ratings
typ
1.26
78
80
40
10
±0.5
45
100
100
30
max
1.285
V
%
kHz
mV
mV
mV/°C
dB
A
°C
°C
Unit
* Designed target value: No measurement made.
Package Dimensions
unit : mm (typ)
3376
10.0
Pd max -- Ta
3.6
2.7
10.4 MAX
10.0
4.5
1.3
Allowable power dissipation, Pd max -- W
8.0
7.5
100×100×1.5mm
3
Infinite heat sink
θjc=5°C
15.0
6.0
5.6
50×50×1.5mm
3
Al heat
sink
mounting
torque
39N⋅cm
silicone
grease
applied
40
60
80
100
120
140
160
MSG07021
(8.8)
15.5
21.3
4.0
3.3
2.0
1.75
30×30×1.5mm
3
No heat sink
0.9
1 2
(1.6)
5
0.8
1.7
0.4
3.15
7.05
0
-30 -20
0
20
Ambient temperature, Ta --
°C
SANYO : 220-5HMDB
Pin Assignment
(1)VIN (2)SWOUT (3)GND (4)VOS (5)SS
No.A1683-2/4
LA5759
Block Diagram
VIN 1
Constnt
Current
Circuit
Reg.
OCP
2 SWOUT
OSC
RESET
DRIVE
Comp.
TSD
4 VOS
Amp.
ON/OFF Comp.
0.4V
VREF
5
SS
3
GND
Application Circuit Example
L1
VIN
SWOUT
LA5759
C1
D1
C2
VOS
SS
C3
GND
R2
R1
Notes: C3 is for the soft start function. Delete C3 and keep the SS pin open when the soft function is not necessary.
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 1.26V (typ).
The equation to set the output voltage is as follows:
VO = 1+
R2
× 1.26V(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.A1683-3/4
LA5759
2. Start delay function
The SS pin has the internally-connected 10μA (typ) constant-current supply. When the voltage of SS pin exceeds
the threshold voltage, the regulator starts operation. As the threshold is 0.62V(typ), the start delay time can be
calculated as follows:
ex. For setting at 1μF
Td =
C
×
V 1μ
×
0.4
=
=
40 msec
i
10μ
Timing Chart
VIN
SWOUT
VOUT
Td
Tss
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products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition
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This catalog provides information as of May, 2010. Specifications and information herein are subject
to change without notice.
PS No.A1683-4/4
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