Device
Operating
Temperature Range
Package
LM2576
EASY SWITCHER
TM
3.0 A STEPDOWN
VOLTAGE REGULATOR
ORDERING INFORMATION
LM2576TXX
LM2576TVXX
TJ = 40
to +125
C
Straight Lead
Vertical Mount
D2T SUFFIX
PLASTIC PACKAGE
CASE 936A
(D2PAK)
Order this document by LM2576/D
T SUFFIX
PLASTIC PACKAGE
CASE 314D
TV SUFFIX
PLASTIC PACKAGE
CASE 314B
LM2576D2TXX
Surface Mount
XX = Voltage Option, i.e. 3.3, 5, 12, 15 V; and ADJ for
Adjustable Output.
SEMICONDUCTOR
TECHNICAL DATA
1
5
1
5
1
5
DEVICE TYPE/NOMINAL OUTPUT VOLTAGE
LM25763.3
LM25765
LM257612
LM257615
LM2576ADJ
3.3 V
5.0 V
12 V
15 V
1.23 V to 37 V
Pin 1. Vin
2. Output
3. Ground
4. Feedback
5. ON/OFF
Heatsink surface
connected to Pin 3.
Heatsink surface (shown as terminal 6 in case outline
drawing) is connected to Pin 3.
1
MOTOROLA ANALOG IC DEVICE DATA
Advance Information
Easy Switcher
TM
3.0 A
Step-Down Voltage Regulator
The LM2576 series of regulators are monolithic integrated circuits ideally
suited for easy and convenient design of a stepdown switching regulator
(buck converter). All circuits of this series are capable of driving a 3.0 A load
with excellent line and load regulation. These devices are available in fixed
output voltages of 3.3 V, 5.0 V, 12 V, 15 V, and an adjustable output version.
These regulators were designed to minimize the number of external
components to simplify the power supply design. Standard series of
inductors optimized for use with the LM2576 are offered by several different
inductor manufacturers.
Since the LM2576 converter is a switchmode power supply, its efficiency
is significantly higher in comparison with popular threeterminal linear
regulators, especially with higher input voltages. In many cases, the power
dissipated is so low that no heatsink is required or its size could be reduced
dramatically.
A standard series of inductors optimized for use with the LM2576 are
available from several different manufacturers. This feature greatly simplifies
the design of switchmode power supplies.
The LM2576 features include a guaranteed
4% tolerance on output
voltage within specified input voltages and output load conditions, and
10%
on the oscillator frequency (
2% over 0
C to 125
C). External shutdown is
included, featuring 80
A (typical) standby current. The output switch
includes cyclebycycle current limiting, as well as thermal shutdown for full
protection under fault conditions.
Features
3.3 V, 5.0 V, 12 V, 15 V, and Adjustable Output Versions
Adjustable Version Output Voltage Range, 1.23 to 37 V
4% Maximum
Over Line and Load Conditions
Guaranteed 3.0 A Output Current
Wide Input Voltage Range
Requires Only 4 External Components
52 kHz Fixed Frequency Internal Oscillator
TTL Shutdown Capability, Low Power Standby Mode
High Efficiency
Uses Readily Available Standard Inductors
Thermal Shutdown and Current Limit Protection
Applications
Simple HighEfficiency StepDown (Buck) Regulator
Efficient PreRegulator for Linear Regulators
OnCard Switching Regulators
Positive to Negative Converter (BuckBoost)
Negative StepUp Converters
Power Supply for Battery Chargers
This document contains information on a new product. Specifications and information herein
are subject to change without notice.
Motorola, Inc. 1997
Rev 0
LM2576
2
MOTOROLA ANALOG IC DEVICE DATA
Figure 1. Block Diagram and Typical Application
7.0 V 40 V
Unregulated
DC Input
L1
100
H
Gnd
+Vin
1
Cin
100
F
3
ON/OFF
5
Output
2
Feedback
4
D1
1N5822
Cout
1000
F
Typical Application (Fixed Output Voltage Versions)
Representative Block Diagram and Typical Application
Unregulated
DC Input
+Vin
1
Cout
Feedback
4
Cin
L1
D1
R2
R1
1.0 k
Output
2
Gnd
3
ON/OFF
5
Reset
Latch
Thermal
Shutdown
52 kHz
Oscillator
1.235 V
BandGap
Reference
Freq
Shift
18 kHz
Comparator
Fixed Gain
Error Amplifier
Current
Limit
Driver
1.0 Amp
Switch
ON/OFF
3.1 V Internal
Regulator
Regulated
Output
Vout
Load
Output
Voltage Versions
3.3 V
5.0 V
12 V
15 V
R2
(
)
1.7 k
3.1 k
8.84 k
11.3 k
For adjustable version
R1 = open, R2 = 0
LM2576
5.0 V Regulated
Output 3.0 A Load
ABSOLUTE MAXIMUM RATINGS
(Absolute Maximum Ratings indicate limits beyond
which damage to the device may occur.)
Rating
Symbol
Value
Unit
Maximum Supply Voltage
Vin
45
V
ON/OFF Pin Input Voltage
0.3 V
V
+Vin
V
Output Voltage to Ground (SteadyState)
1.0
V
Power Dissipation
Case 314B and 314D (TO220, 5Lead)
PD
Internally Limited
W
Thermal Resistance, JunctiontoAmbient
R
JA
65
C/W
Thermal Resistance, JunctiontoCase
R
JC
5.0
C/W
Case 936A (D2PAK)
PD
Internally Limited
W
Thermal Resistance, JunctiontoAmbient
R
JA
70
C/W
Thermal Resistance, JunctiontoCase
R
JC
5.0
C/W
Storage Temperature Range
Tstg
65 to +150
C
Minimum ESD Rating (Human Body Model:
C = 100 pF, R = 1.5 k
)
2.0
kV
Lead Temperature (Soldering, 10 seconds)
260
C
Maximum Junction Temperature
TJ
150
C
NOTE: ESD data available upon request.
LM2576
3
MOTOROLA ANALOG IC DEVICE DATA
OPERATING RATINGS
(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.)
Rating
Symbol
Value
Unit
Operating Junction Temperature Range
TJ
40 to +125
C
Supply Voltage
Vin
40
V
SYSTEM PARAMETERS
([Note 1] Test Circuit Figure 15)
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, Vin = 12 V for the 3.3 V, 5.0 V, and Adjustable version, Vin = 25 V for
the 12 V version, and Vin = 30 V for the 15 V version. ILoad = 500 mA. For typical values TJ = 25
C, for min/max values TJ is the operating
junction temperature range that applies [Note 2], unless otherwise noted.)
Characteristics
Symbol
Min
Typ
Max
Unit
LM25763.3
([Note 1] Test Circuit Figure 15)
Output Voltage (Vin = 12 V, ILoad = 0.5 A, TJ = 25
C)
Vout
3.234
3.3
3.366
V
Output Voltage (6.0 V
Vin
40 V, 0.5 A
ILoad
3.0 A)
Vout
V
TJ = 25
C
3.168
3.3
3.432
TJ = 40 to +125
C
3.135
3.465
Efficiency (Vin = 12 V, ILoad = 3.0 A)
75
%
LM25765
([Note 1] Test Circuit Figure 15)
Output Voltage (Vin = 12 V, ILoad = 0.5 A, TJ = 25
C)
Vout
4.9
5.0
5.1
V
Output Voltage (8.0 V
Vin
40 V, 0.5 A
ILoad
3.0 A)
Vout
V
TJ = 25
C
4.8
5.0
5.2
TJ = 40 to +125
C
4.75
5.25
Efficiency (Vin = 12 V, ILoad = 3.0 A)
77
%
LM257612
([Note 1] Test Circuit Figure 15)
Output Voltage (Vin = 25 V, ILoad = 0.5 A, TJ = 25
C)
Vout
11.76
12
12.24
V
Output Voltage (15 V
Vin
40 V, 0.5 A
ILoad
3.0 A)
Vout
V
TJ = 25
C
11.52
12
12.48
TJ = 40 to +125
C
11.4
12.6
Efficiency (Vin = 15 V, ILoad = 3.0 A)
88
%
LM257615
([Note 1] Test Circuit Figure 15)
Output Voltage (Vin = 30 V, ILoad = 0.5 A, TJ = 25
C)
Vout
14.7
15
15.3
V
Output Voltage (18 V
Vin
40 V, 0.5 A
ILoad
3.0 A)
Vout
V
TJ = 25
C
14.4
15
15.6
TJ = 40 to +125
C
14.25
15.75
Efficiency (Vin = 18 V, ILoad = 3.0 A)
88
%
LM2576 ADJUSTABLE VERSION
([Note 1] Test Circuit Figure 15)
Feedback Voltage (Vin = 12 V, ILoad = 0.5 A, Vout = 5.0 V, TJ = 25
C)
Vout
1.217
1.23
1.243
V
Feedback Voltage (8.0 V
Vin
40 V, 0.5 A
ILoad
3.0 A, Vout = 5.0 V)
Vout
V
TJ = 25
C
1.193
1.23
1.267
TJ = 40 to +125
C
1.18
1.28
Efficiency (Vin = 12 V, ILoad = 3.0 A, Vout = 5.0 V)
77
%
NOTES: 1. External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the
LM2576 is used as shown in the
Figure 15 test circuit, system performance will be as shown in system parameters section.
2. Tested junction temperature range for the LM2576: Tlow = 40
C Thigh = +125
C
LM2576
4
MOTOROLA ANALOG IC DEVICE DATA
DEVICE PARAMETERS
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, Vin = 12 V for the 3.3 V, 5.0 V, and Adjustable version, Vin = 25 V for
the 12 V version, and Vin = 30 V for the 15 V version. ILoad = 500 mA. For typical values TJ = 25
C, for min/max values TJ is the operating
junction temperature range that applies [Note 2], unless otherwise noted.)
Characteristics
Symbol
Min
Typ
Max
Unit
ALL OUTPUT VOLTAGE VERSIONS
Feedback Bias Current (Vout = 5.0 V [Adjustable Version Only])
Ib
nA
TJ = 25
C
25
100
TJ = 40 to +125
C
200
Oscillator Frequency [Note 3]
fosc
kHz
TJ = 25
C
52
TJ = 0 to +125
C
47
58
TJ = 40 to +125
C
42
63
Saturation Voltage (Iout = 3.0 A [Note 4])
Vsat
V
TJ = 25
C
1.5
1.8
TJ = 40 to +125
C
2.0
Max Duty Cycle ("on") [Note 5]
DC
94
98
%
Current Limit (Peak Current [Notes 3 and 4])
ICL
A
TJ = 25
C
4.2
5.8
6.9
TJ = 40 to +125
C
3.5
7.5
Output Leakage Current [Notes 6 and 7], TJ = 25
C
IL
mA
Output = 0 V
0.8
2.0
Output = 1.0 V
6.0
20
Quiescent Current [Note 6]
IQ
mA
TJ = 25
C
5.0
9.0
TJ = 40 to +125
C
11
Standby Quiescent Current (ON/OFF Pin = 5.0 V ("off"))
Istby
A
TJ = 25
C
80
200
TJ = 40 to +125
C
400
ON/OFF Pin Logic Input Level (Test Circuit Figure 15)
V
Vout = 0 V
VIH
TJ = 25
C
2.2
1.4
TJ = 40 to +125
C
2.4
Vout = Nominal Output Voltage
VIL
TJ = 25
C
1.2
1.0
TJ = 40 to +125
C
0.8
ON/OFF Pin Input Current (Test Circuit Figure 15)
A
ON/OFF Pin = 5.0 V ("off"), TJ = 25
C
IIH
15
30
ON/OFF Pin = 0 V ("on"), TJ = 25
C
IIL
0
5.0
NOTES: 3. The oscillator frequency reduces to approximately 18 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 protection feature lowers the average dissipation of the IC by lowering the
minimum duty cycle from 5% down to approximately 2%.
4. Output (Pin 2) sourcing current. No diode, inductor or capacitor connected to output pin.
5. Feedback (Pin 4) removed from output and connected to 0 V.
6. Feedback (Pin 4) removed from output and connected to +12 V for the Adjustable, 3.3 V, and 5.0 V versions, and +25 V for the 12 V and 15 V
versions, to force the output transistor "off".
7. Vin = 40 V.
LM2576
5
MOTOROLA ANALOG IC DEVICE DATA
I Q
, QUIESCENT
CURRENT
(mA)
40
TYPICAL PERFORMANCE CHARACTERISTICS
(Circuit of Figure 15)
V out
,
OUTPUT
VOL
T
AGE CHANGE (%)
V out
,
OUTPUT
VOL
T
AGE CHANGE (%)
, ST
ANDBY
QUIESCENT
CURRENT
(
TJ, JUNCTION TEMPERATURE (
C)
I O
, OUTPUT
CURRENT
(A)
TJ, JUNCTION TEMPERATURE (
C)
Vin, INPUT VOLTAGE (V)
Vin, INPUT VOLTAGE (V)
INPUT
OUTPUT
DIFFERENTIAL
(V)
TJ, JUNCTION TEMPERATURE (
C)
Figure 2. Normalized Output Voltage
TJ, JUNCTION TEMPERATURE (
C)
Figure 3. Line Regulation
Figure 4. Dropout Voltage
Figure 5. Current Limit
Figure 6. Quiescent Current
Figure 7. Standby Quiescent Current
ILoad = 200 mA
ILoad = 3.0 A
Vin = 12 V
Vin = 40 V
L1 = 150
H
Rind = 0.1
ILoad = 500 mA
ILoad = 3.0 A
Vout = 5.0 V
Measured at
Ground Pin
TJ = 25
C
VON/OFF = 5.0 V
A)
1.0
0.6
0.2
0
0.2
0.4
1.0
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0.2
0.4
0.6
2.0
1.5
1.0
0.5
0
6.5
6.0
5.5
5.0
4.5
4.0
20
18
16
14
12
10
8.0
6.0
4.0
200
180
160
140
120
100
80
60
20
0
125
100
75
50
25
0
25
50
40
35
30
25
20
15
10
5.0
0
125
100
75
50
25
0
25
50
125
100
75
50
25
0
25
50
40
35
30
25
20
15
10
5.0
0
125
100
75
50
25
0
25
50
0.8
0.6
0.4
0.8
Vin = 20 V
ILoad = 500 mA
Normalized at TJ = 25
C
ILoad = 500 mA
TJ = 25
C
3.3 V, 5.0 V and ADJ
12 V and 15 V
Vin = 25 V
I stby
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