ENA2191 D

Ordering number : ENA2191
LA5774MC
Monolithic Linear IC
Separately-excited Step-down
http://onsemi.com
Switching Regulator
(Variable Type)
Overview
The LA5774MC is a Separately-excited step-down switching regulator (variable type).
Function
• High efficiency.
• Time-base generator (160kHz) incorporated.
• Current limiter incorporated.
• Thermal shutdown circuit incorporated.
• Soft start circuit incorporated.
Specifications
Absolute Maximum Ratings at Ta = 25°C
Parameter
Symbol
Conditions
Ratings
Unit
Maximum Input voltage
VIN max
30
Maximum Output current
IO max
3
A
VSW
-1
V
3.9
W
SW pin application reverse voltage
Allowable power dissipation
VOS pin application reverse voltage
Pd max
Mounted on a substrate.*
VVOS
V
-0.2 to +7
V
Operating temperature
Topr
-30 to +125
°C
Storage temperature
Tstg
-40 to +150
°C
* Specified substrate : 76.1×114.3×1.6mm3 : Copper foil ratio 60% FR4
Caution 1) Absolute maximum ratings represent the value which cannot be exceeded for any length of time.
Caution 2) Even when the device is used within the range of absolute maximum ratings, as a result of continuous usage under high temperature, high current,
high voltage, or drastic temperature change, the reliability of the IC may be degraded. Please contact us for the further details.
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating
Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability.
Recommended Operating Conditions at Ta = 25°C
Parameter
Input voltage range
Symbol
Conditions
VIN
Ratings
Unit
4.5 to 28
V
ORDERING INFORMATION
See detailed ordering and shipping information on page 5 of this data sheet.
Semiconductor Components Industries, LLC, 2013
May, 2013
52913NK 20130426-S00001 No.A2191-1/6
LA5774MC
Electrical Characteristics at Ta = 25°C, VO = 3.3V
Parameter
Symbol
Reference voltage
Ratings
Conditions
min
VOS
typ
1.235
η
Efficiency
Switching frequency
Unit
max
1.26
1.285
78
fosc
128
V
%
160
192
kHz
Line regulation
ΔVOLINE
VIN = 8 to 20V
40
100
mV
Load regulation
ΔVOLOAD
IO = 0.5 to 1.5A
10
30
ΔVO/ΔTa
Output voltage temperature
±0.5
Designed target value. *
mV
mV/°C
coefficient
Ripple attenuation factor
RREJ
Current limiter operating voltage
f = 100 to 120Hz
45
IS
Thermal shutdown operating
3.1
dB
A
TSD
Designed target value. *
165
°C
ΔTSD
Designed target value. *
15
°C
temperature
Thermal shutdown Hysteresis
width
* Design target value: No measurement made.
PACKAGE DIMENSIONS
D 2 PAK5 / SMP5J
CASE 418AS
ISSUE O
E
C
A
B
SEATING
PLANE
NOTES:
1. DIMENSIONING AND TOLERANCING PER ASME
Y14.5M, 1994.
2. CONTROLLING DIMENSION: MILLIMETERS.
3. DIMENSIONS D AND E DO NOT INCLUDE MOLD
FLASH, PROTRUSIONS, OR GATE BURRS. MOLD
FLASH, PROTRUSIONS, OR GATE BURRS SHALL
NOT EXCEED 0.15 MILLIMETERS PER SIDE.
4. DIMENSIONS D AND E ARE DETERMINED AT THE
OUTERMOST EXTREMES OF THE PLASTIC BODY.
5. DATUMS A AND B ARE DETERMINED AT DATUM
PLANE C.
A
c2
L3
D
DETAIL A
1
2
3 4
DIM
A
A1
A3
b
c
c2
D
E
e
L
L1
L3
5
PIN 1
INDICATOR
L1
e
5X
TOP VIEW
c
b
0.13 M B A M
BOTTOM VIEW
SIDE VIEW
RECOMMENDED
SOLDERING FOOTPRINT*
MILLIMETERS
MIN
MAX
4.20
4.80
0.00
0.30
2.40
3.00
0.75
1.05
0.25
0.55
1.10
1.50
9.50
10.30
9.80
10.20
1.70 BSC
1.20
1.80
3.80
4.40
1.00
1.40
A3
11.00
c
L
A1
DETAIL A
7.80
15.60
5X
2.50
5X
1.30
1.70
PITCH
DIMENSIONS: MILLIMETERS
*For additional information on our Pb−Free strategy and soldering
details, please download the ON Semiconductor Soldering and
Mounting Techniques Reference Manual, SOLDERRM/D.
No.A2191-2/6
LA5774MC
Pin Assignment
(1) VIN (2) SWOUT
(3) GND
(4) VOS
(5) SS
Allowable power dissipation derating curve
Pd max - Ta
Allowable power dissipation, Pd max - W
4.5
Specified sbstrate: 76.1×114.3×1.6mm3
Copper foil ratio 60% FR4
4.0
3.90
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
-30 -20
0
20
40
60
80
100
120
Ambient temperature, Ta - °C
140
160
MSG06072
Block Diagram
VIN 1
2 SWOUT
Reg.
OCP
Reset
OSC
Drive
Comp.
THD
4 VOS
Amp.
VREF
5
3
SS
GND
No.A2191-3/6
LA5774MC
Application Circuit Example
L1
VIN
SWOUT
C3
LA5774MC
C2
D1
C1
SS
GND
VOS
R2
R1
C4
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:
R2
VO = 1+
× 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.
2. Start delay function
The SS pin has the internally-connected 22μA (typ) constant-current supply. When the voltage of SS pin exceeds the
threshold voltage, the regulator starts operation. As the threshold voltage is 0.62V (typ), the start delay time can be
calculated as follows:
ex. For setting at 1μF
Td =
C × V 1μF × 0.62
=
= 28.2 ms
22μA
i
3. Soft start function
The internal PWM waveform has the voltage value as shown in the right.
If down-conversion from the voltage of VIN = 15 V to VIN = 3.3V is to be
made, for example, the PWM-ON duty has the value as shown below.
1.5V
0.62V
PWM wave
VOUT + VF
PWMduty = V − Vsat + VF = 25 %
IN
(Note that calculation is made with Vsat = 1V and VF = 0.2V)
The output voltage of error amplifier, which is 3.3 V, is the value with PWM = 25%, as calculated in the above
equation, so that this voltage is determined as follows:
Ver = (ΔVPWM) × PWMduty + VPWML = 0.88V × 0.25 + 0.62V = 0.84V
(ΔVPWM is the PWM amplitude value or 0.88V(typ) while VPWML is the lower limit voltage of PWM
waveform or 0.62V(typ))
No.A2191-4/6
LA5774MC
SS pin and error amplifier output voltages are designed to prefer the lower voltages, so that VOUT will reach the
designed regulation voltage in timing when the SS pin voltage exceeds the error amplifier output.
Therefore, the soft start time is calculated as follows:
Tss =
C × ΔVPWM × PWMduty C × 0.88 × PWMduty
=
22μA
i
For the set conditions of C = 1μF and PWMduty = 25%:
Tss =
1μF × 0.88V × 0.25
= 10ms
22μA
Timing Chart
VIN
SWOUT
VOUT
Td
Tss
ORDERING INFORMATION
Device
LA5774MC-BE
Package
SMP5J
(Pb-Free / Halogen Free)
LA5774MC-E
SMP5J
(Pb-Free / Halogen Free)
Shipping (Qty / Packing)
1000 / Tape & Reel
50 / Fan-Fold
No.A2191-5/6
LA5774MC
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PS No.A2191-6/6
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