UMW
R
UMW LM2576
Description
The LM2576 series of regulators are monolithic integrated circuits that provide all the active functions for a step-down (buck) switching
regulator, capable of driving 3A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3V,
5V, 12V, 15V, and an adjustable output versions. Requiring a minimum number of external components, these regulators are simple to
use and include internal frequency compensation and a fixed-frequency oscillator. The LM2576
series offers a
high-efficiency replacement for popular three-terminal linear regulators. It substantially reduces the size of the heat sink, and in some
cases no heat sink is required. A standard series of inductors optimized for use with the LM2576 are available from several different
manufacturers. This feature greatly simplifies the design of switch-mode power supplies. Other features include a guaranteed ± 4%
tolerance on output voltage within specified input voltages and output load conditions, and ±10% on the oscillator frequency. External
shutdown is included, featuring 50µA (typical) standby current. The output switch includes cycle-by-cycle current limiting, as well as
thermal shutdown for full protection under fault conditions.
Note: TheLM2576HV is not produced yet.
Applications
Features
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
3.3V, 5V, 12V, 15V, and adjustable output versions
Adjustable version output voltage range
1.23V to 37V (57V for HV version) ±4% max over line
and load conditions
Guaranteed 3A output current
Wide input voltage range, 40V up to57V for HV
version
Requires only 4 external components
52 kHz fixed frequency oscillator
TTL shutdown capability, low power standby mode
High efficiency
Uses readily available standard inductors
Thermal shutdown and current limit protection
Typical application
7V - 40V
(57V for HV)
UNREGULATED
DC INPUT
Figure 1.(Fixed Output Voltage Versions)
LM2576/
FEEDBACK
LM2576HV - 4
L1
OUTPUT
5.0
+VIN
1
2
+
GND
Simple high-efficiency step-down (buck) regulator
Efficient pre-regulator for linear regulators
On-card switching regulators
Positive to negative converter (Buck-Boost)
3
5 ON/OFF
100
H
D1
CIN
1N5822
+
COUT
1000
F
+5V
REGULATED
OUTPUT
3A
LOAD
Package Types
TO220B-5L
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TO220-5L
1
TO263-5L
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UMW LM2576
Pin Descriptions
Pin Assignments
5 ON/OFF
4 Feedback
3 Gnd
2 Output
1 Vin
TO220B-5L/TO220-5L
5 ON/OFF
4 Feedback
3 Gnd
2 Output
1 Vin
Name
Description
Vin
Input supply voltage
Output
Switching output
Gnd
Ground
Feedback
Output voltage feedback
ON/OFF
ON/OFF shutdown
Active is “Low” or floating
TO263-5L
Block Diagram
VIN
UNREGULATED
DC INPUT
ON/OFF
INTERNAL
REGULATOR
1
ON/OFF
5
+
4
CIN
FEEDBACK
R2
R1
1.0k
FIXED GAIN
ERROR AMP
+
-
COMPARATOR
DRIVER
3 AMP
SWITCH
+
-
OUTPUT
L1
VOUT
2
+
3
1.23V
52kHZ
BAND-GAP
REFERENCE OSCILLATOR
D1
COUT
RESET
THERMAL
SHUTDOWN
CURRENT
LIMIT
L
O
A
D
GND
3.3V, R2 =1.7K
5V, R2 = 3.1K
12V, R2 = 8.84K
15V, R2 =11.3K
For ADJ, Version
R1 = Open, R2 =0Ω
Ordering information
Temperature
Range
-40°C ≤ TA
≤ 125°C
Output Voltage, V
3.3
5.0
12
Package Type
15
ADJ
LM2576HVS - 3.3 LM2576HVS -5.0 LM2576HVS -12 LM2576HVS -15 LM2576HVS -ADJ
LM2576S -3.3
LM2576S - 5.0
LM2576S -12
LM2576S -15
LM2576HVT -3.3 LM2576HVT -5.0 LM2576HVT -12 LM2576HVT - 15 LM2576HVT - ADJ
LM2576T -3.3
MIK2576T-3.3
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LM2576T - 5.0
MIK2576T-5.0
LM2576T -12
MIK2576T-12
LM2576T -15
MIK2576T-15
2
TO-263
LM2576S -ADJ
TO-220
LM2576T -ADJ
MIK2576T-ADJ
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UMW LM2576
Absolute Maximum Ratings (Note 1)
Parameter
Maximum
Units
45
57
V
Maximum Suppl y Voltage
LM2576
LM2576HV
-0.3V ≤ V ≤ +VIN
-1
Internally Limited
-65 to +150
150
2
260
ON/OFF Pin Input Voltage
Output Voltage to Ground (Steady State)
Power Dissipation
Storage Temperature Range
Maximum Junction Temperature
Minimum ESD Rating (C= 100pF, R = 1.5 kΩ)
Lead Temperature (Soldering, 10 Seconds)
V
W
°C
°C
kV
°C
Operating Ratings
Parameter
Temperature Range
LM2576/LM2576HV
Supply Voltage
Value
-40 ≤ TJ ≤ +125
Units
°C
40
57
V
LM2576
LM2576HV
Electrical Characteristics LM2576 - 3.3,LM2576HV -3.3
Specifications with standard type face are for T J = 25°C, and those with boldface type apply over full Operating Temperature Range.
Symbol
Parameter
Conditions
LM2576 -3.3
LM2576HV -3.3
Typ
Units
(Limits)
Limit (Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
VOUT
VOUT
VOUT
η
VIN =12V, ILOAD =0.5A
Circuit of Figure 2
3.3
Output Voltage
MIK2576
6V ≤ VIN ≤ 40V, 0.5A ≤ ILOAD ≤
3A Circuit of Figure 2
3.3
Output Voltage
MIK2576HV
6V ≤ VIN ≤ 60V, 0.5A ≤ ILOAD ≤
3A Circuit of Figure 2
3.3
Efficiency
VIN =12V, ILOAD =3A
75
Output Voltage
3.234
3.366
V
V(Min)
V(Max)
3.168/3.135
3.432/3.465
V
V(Min)
V(Max)
3.168/3.135
3.450/3.482
V
V(Min)
V(Max)
%
Electrical CharacteristicsLM2576 -5.0,LM2576HV -5.0
Specifications with standard type face are for T J = 25°C, and those with boldface type apply over full Operating Temperature Range.
Symbol
Parameter
LM2576 -5.0
LM2576HV -5.0
Conditions
Typ
Units
(Limits)
Limit (Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
VOUT
VOUT
VOUT
η
Output Voltage
VIN =12V, ILOAD =0.5A
Circuit of Figure 2
5.0
Output Voltage
MIK2576
0.5A ≤ ILOAD ≤ 3A,
8V ≤ VIN ≤ 40V
Circuit of Figure 2
5.0
Output Voltage
MIK2576HV
0.5A ≤ ILOAD ≤ 3A,
8V ≤ VIN ≤ 60V
Circuit of Figure 2
5.0
Efficiency
VIN =12V, ILOAD =3A
77
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3
4.900
5.100
V
V(Min)
V(Max)
4.800/4.750
5.200/5.250
V
V(Min)
V(Max)
4.800/4.750
5.225/5.275
V
V(Min)
V(Max)
%
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UMW LM2576
Electrical Characteristics LM2576 -12, LM2576HV -12
Specifications with standard type face are for T J = 25°C, and those with boldface type apply over full Operating Temperature Range.
Symbol
Parameter
Conditions
LM2576 -12
LM2576HV -12
Typ
Units
(Limits)
Limit(Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
VOUT
VOUT
VOUT
η
VIN =25V, ILOAD =0.5A
Circuit of Figure 2
12
Output Voltage
MIK2576
0.5A ≤ ILOAD ≤ 3A,
15V ≤ VIN ≤ 40V
Circuit of Figure 2
12
Output Voltage
MIK2576HV
0.5A ≤ ILOAD ≤ 3A,
15V ≤ VIN ≤ 60V
Circuit of Figure 2
12
Efficiency
VIN =15V, ILOAD =3A
88
Output Voltage
11.76
12.24
V
V(Min)
V(Max)
11.52/11.40
12.48/12.60
V
V(Min)
V(Max)
11.52/11.40
12.54/12.66
V
V(Min)
V(Max)
%
Electrical Characteristics LM2576 -15,LM2576HV -15
Specifications with standard type face are for T J = 25°C, and those with boldface type apply over full Operating Temperature Range.
Symbol
Parameter
Conditions
LM2576 -15
LM2576HV -15
Typ
Units
(Limits)
Limit (Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
VOUT
VOUT
VOUT
η
VIN =25, ILOAD =0.5A
Circuit of Figure 2
15
Output Voltage
MIK2576
0.5A ≤ ILOAD ≤ 3A,
18≤ VIN ≤ 40V
Circuit of Figure 2
15
Output Voltage
MIK2576HV
0.5A ≤ ILOAD ≤ 3A,
18 ≤ VIN ≤ 60V
Circuit of Figure 2
15
Efficiency
VIN =18V, ILOAD =3A
88
Output Voltage
14.70
15.30
V
V(Min)
V(Max)
14.40/14.25
15.60/15.75
V
V(Min)
V(Max)
14.40/14.25
15.68/15.83
V
V(Min)
V(Max)
%
Electrical Characteristics LM2576 -ADJ, LM2576HV -ADJ
Specifications with standard type face are for T J = 25°C, and those with boldface type apply over full Operating Temperature Range.
Symbol
Parameter
Conditions
LM2576 -ADJ
LM2576HV -ADJ
Typ
Units
(Limits)
Limit(Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
VOUT
VOUT
VOUT
η
Feedback Voltage
VIN =12V, ILOAD =0.5A,
VOUT =5V
Circuit of Figure 2
1.230
Feedback Voltage
MIK2576
0.5A ≤ ILOAD ≤ 3A , 8V ≤ VIN ≤
40V VOUT =5V
Circuit of Figure 2
1.230
Feedback Voltage
MIK2576HV
0.5A ≤ ILOAD ≤ 3A, 8V ≤ VIN ≤
60V, VOUT =5V
Circuit of Figure 2
1.230
Efficiency
VIN =12V, ILOAD =3A, VOUT =5V
77
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1.217
1.243
V
V(Min)
V(Max)
1.193/1.180
1.267/1.280
V
V(Min)
V(Max)
1.193/1.180
1.273/1.286
V
V(Min)
V(Max)
%
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UMW LM2576
All Output Voltage Versions
Electrical Characteristics
Specifications with standard type face are for T J = 25°C, and those with boldface type apply over full Operating Temperature Range.
Unless otherwise specified, V IN =12V for the 3.3V, 5V, and Adjustable version, V IN =25V for the 12V version, and V IN =30V for the 15V
version, , ILOAD =500mA.
Symbol
Parameter
Conditions
LM2576 -XX
LM2576HV -XX
Units
(Limits)
Typ
Limit (Note 2)
100/500
nA
47/42
58/63
kHz
kHz(Min)
kHz(Max)
1.8/2.0
V
V(Max)
93
%
%(Min)
4.2/3.5
6.9/7.5
A
A(Min)
A(Max)
DEVICE PARAMETERS
Ib
Feedback Bias Current
VOUT =5V (Adjustable Version Only)
50
fO
Oscillator Frequency
(Note 8)
52
VSAT
DC
Saturation Voltage
Max Duty Cycle (ON)
ICL
Current Limit
IL
Output Leakage Current
Output = 0V
IQ
Quiescent Current
ISTBY
Standby Quiescent Current
___
ON/OFF CONTROL
VIH
__
ON/OFF Pin
VIL
Logic Input Level
IIH
__
ON/OFF Pin Input
Current
IIL
Note
Note
Note
Note
Note
Note
Note
Note
IOUT =3A (Note 4)
1.4
(Note 5)
98
(Notes 4, 8)
5.8
2
(Notes 6, 7):
Output = -1V
Output = -1V
(Note 6)
30
mA(Max)
mA
mA(Max)
10
mA
mA(Max)
200
µA
µA(Max)
7.5
5
___
ON/OFF Pin = 5V (OFF)
50
VOUT = 0V
1.4
2.2/2.4
V(Min)
VOUT = Nominal Output Voltage
1.2
1.0/0.8
V(Max)
__
ON/OFF Pin = 5V (OFF)
12
30
µA
µA(Max)
__
ON/OFF Pin = 0V (ON)
0
10
µA
µA(Max)
1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating
Ratings indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits.
For guaranteed specifications and test conditions, see the Electrical Characteristics.
2: All limits guaranteed at room temperature (standa rd type face) and at temperature extremes (bold type face).
3: External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system
performance. When the LM2576/LM2576HV is used as shown in the Figure 2 test circuit, system performance will be as
shown in system parameters section of Electrical Characteristics.
4: Output pin sourcing current. No diode, inductor or capacitor connected to output.
5: Feedback pin removed from output and connected to 0V.
6: Feedback pin removed from output and connected to +12V for the Adjustable, 3.3V, and 5V, versions, and +25V for the 12V
and 15V versions, to force the output transistor OFF.
7: VIN =40V (60V for high voltage version).
8: The oscillator frequency reduces to approximately 11 kHz in the event of an output short or an overload which causes the
regulated output voltage to drop approximately 40% from the nominal output voltage. This self protections feature lowers the
average power dissipation of the IC by lowering the minimum duty cycle from 5% down to approximately 2%.
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Typical Performance Characteristics (Circuit of Figure 2)
Normalized Output Voltage
VIN =20V
I L OA D = 500mA
Normalized at
TJ =25°C
Line Regulation
Dropout Voltage
I L OA D = 500mA
TJ =25°C
L1 = 150
H
I L OA D = 3A
3.3V, 5V & ADJ
12V & 15V
I L OA D = 1A
I L OA D = 200mA
RIND = 0.1Ω
JUNCTION TEMPERATURE (°C)
Standby
Quiescent Current
INPUT VOLTAGE (V)
JUNCTION TEMPERATURE (°C)
Quiescent Current
Current Limit
VIN = 25V
VIN = 40V
VOUT = 5V
Measured at
Ground Pin
TJ =25°C
VON/OFF = 5V
VIN =12 V
ILOAD = 3A
ILOAD = 200mA
JUNCTION TEMPERATURE (°C)
Switch Saturation
Voltage
INPUT
VOLTAGE (V)
JUNCTION TEMPERATURE (°C)
Efficiency
Oscilator Frequency
Normalized at 25°C
I L OA D = 3A
TJ =25°C
I L OA D = 200mA
15V OUT
-55°C
25°C
150°C
VIN = 40V
5V
IL OA D = 3A
VIN = 12V
IL OA D = 200mA
SWITCH CURRENT (A)
Minimum Operating Voltage
Adjustable Version Only
INPUT VOLTAGE (V)
JUNCTION TEMPERATURE (°C)
Quiescent Current
vs Duty Cycle
Feedback Voltage
vs Duty Cycle
Adjustable Version Only
Adjustable Version Only
I LOAD = 500mA
VIN = 7V
VIN = 40V
VIN = 40V
VOUT ≈ 1.23V
I LOAD = 500mA
JUNCTION TEMPERATURE (°C)
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VIN = 7V
I LOAD = 500mA
DUTY CYCLE (%)
6
DUTY CYCLE (%)
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Maximum Power Dissipation
(TO-263)
Feedback Pin Current
Adjustable Version Only
θJA = 32°C/W
θJ A = 37°C/W
θJ A = 50°C/W
θJ A = 73°C/W
AMBIENT TEMPERATURE (°C)
JUNCTION TEMPERATURE (°C)
Switching Waveforms
Response
Load Transient
A
Output
Voltage
Change
B
Load
Current
C
D
5
s/div
100
s/div
VOUT =15V
A: Output Pin Voltage, 50V/div
B: Output Pin Current, 2A/div
C: Inductor Current, 2A/div
D: Output Ripple Voltage, 50mV/div,
AC-Coupled
Horizontal Time Base: 5µs/div
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Test Circuit and Layout Guidelines
As in any switching regulator, layout is very important. Rapidly switching currents associated with wiring inductance generate voltage
transients which can cause problems. For minimal inductance and ground loops, the length of the leads indicated by heavy lines should
be kept as short as possible.
Single-point grounding (as indicated) or ground plane construction should be used for best results. When using the Adjustable version,
physically locate the programming resistors near the regulator, to keep the sensitive feedback wiring short.
Fixed Output Voltage Versions
(Figure 2a)
FEEDBACK
+VIN
1
LM2576HVFIXED OUTPUT
4
2
+
VIN
UNREGULATED
DC INPUT
1 00
GN
F
D
3
ON/OFF
5
L1
VOUT
OUTPUT
100
H
+
D1
MBR360
L
O
A
D
COUT
1000
F
CIN — 100µF, 75V, Aluminum Electrolytic
COUT — 1000µF, 25V, Aluminum Electrolytic
D1 — Schottky, MBR360
L1 — 100µH, Pulse Eng. PE-92108
R1 — 2k, 0.1%
R2 — 6.12k, 0.1%
Adjustable Output Voltage Version
+VIN
1
LM2576HVADJ
FEEDBACK
4
L1
OUTPUT
2
7V -60V
UNREGULATED
DC INPUT
VOUT
=
R2
+
100
CIN
F
GND
3
ON/OFF
5
(Figure 2b)
VOUT
5.00V
100
H
MBR360
COUT
+
1000
F
R2
L
O
A
D
R1
R
VREF 1
( +2
)
R
V
R 1 (V OUT− )1
REF
where VREF = 1.23V, R1 between 1k and 5k
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Package Information
(1) TO220-5L
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UMW LM2576
Package Information
(2) TO263-5L
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