Order this document by LM2576/D
LM2576
Easy Switcher
™
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 step–down 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 switch–mode power supply, its efficiency
is significantly higher in comparison with popular three–terminal 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 switch–mode 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
µA
(typical) standby current. The output switch
includes cycle–by–cycle current limiting, as well as thermal shutdown for full
protection under fault conditions.
Features
EASY SWITCHER™
3.0 A STEP–DOWN
VOLTAGE REGULATOR
SEMICONDUCTOR
TECHNICAL DATA
T SUFFIX
PLASTIC PACKAGE
CASE 314D
Pin 1.
2.
3.
4.
5.
Vin
Output
Ground
Feedback
ON/OFF
1
5
TV SUFFIX
PLASTIC PACKAGE
CASE 314B
Heatsink surface
connected to Pin 3.
1
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
5
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
D2T SUFFIX
PLASTIC PACKAGE
CASE 936A
(D2PAK)
1
5
Heatsink surface (shown as terminal 6 in case outline
drawing) is connected to Pin 3.
Applications
Simple High–Efficiency Step–Down (Buck) Regulator
Efficient Pre–Regulator for Linear Regulators
On–Card Switching Regulators
Positive to Negative Converter (Buck–Boost)
Negative Step–Up Converters
Power Supply for Battery Chargers
DEVICE TYPE/NOMINAL OUTPUT VOLTAGE
LM2576–3.3
LM2576–5
LM2576–12
LM2576–15
LM2576–ADJ
3.3 V
5.0 V
12 V
15 V
1.23 V to 37 V
ORDERING INFORMATION
Device
LM2576T–XX
LM2576TV–XX
Operating
Temperature Range
Package
Straight Lead
TJ = –40° to +125°C Vertical Mount
Surface Mount
LM2576D2T–XX
XX = Voltage Option, i.e. 3.3, 5, 12, 15 V; and ADJ for
Adjustable Output.
©
Motorola, Inc. 1999
Rev 1, 07/1999
MOTOROLA ANALOG IC DEVICE DATA
1
LM2576
Figure 1. Block Diagram and Typical Application
Typical Application
(Fixed Output Voltage Versions)
Feedback
7.0 V – 40 V
Unregulated
DC Input
+Vin
Cin
100
µF
1
3 Gnd 5
LM2576
4
Output
2
ON/OFF
L1
100
µH
D1
1N5822
5.0 V Regulated
Output 3.0 A Load
Cout
1000
µF
Representative Block Diagram and Typical Application
+Vin
1
Cin
4
Feedback
R2
Fixed Gain
Error Amplifier Comparator
Current
Limit
Unregulated
DC Input
3.1 V Internal
Regulator
ON/OFF
ON/OFF
5
Output
Voltage Versions
3.3 V
5.0 V
12 V
15 V
For adjustable version
R1 = open, R2 = 0
Ω
R2
(Ω)
1.7 k
3.1 k
8.84 k
11.3 k
R1
1.0 k
Driver
Freq
Shift
18 kHz
52 kHz
Oscillator
Latch
Output
1.0 Amp
Switch
Reset
Thermal
Shutdown
2
Gnd
3
D1
L1
Regulated
Output
Vout
Cout
Load
1.235 V
Band–Gap
Reference
ABSOLUTE MAXIMUM RATINGS
(Absolute Maximum Ratings indicate limits beyond
which damage to the device may occur.)
Rating
Maximum Supply Voltage
ON/OFF Pin Input Voltage
Output Voltage to Ground (Steady–State)
Power Dissipation
Case 314B and 314D (TO–220, 5–Lead)
Thermal Resistance, Junction–to–Ambient
Thermal Resistance, Junction–to–Case
Case 936A (D2PAK)
Thermal Resistance, Junction–to–Ambient
Thermal Resistance, Junction–to–Case
Storage Temperature Range
Minimum ESD Rating (Human Body Model:
C = 100 pF, R = 1.5 kΩ)
Lead Temperature (Soldering, 10 seconds)
Maximum Junction Temperature
NOTE:
ESD data available upon request.
Symbol
Vin
–
–
PD
R
θJA
R
θJC
PD
R
θJA
R
θJC
Tstg
–
–
TJ
Value
45
–0.3 V
≤
V
≤
+Vin
–1.0
Internally Limited
65
5.0
Internally Limited
70
5.0
–65 to +150
2.0
260
150
Unit
V
V
V
W
°C/W
°C/W
W
°C/W
°C/W
°C
kV
°C
°C
2
MOTOROLA ANALOG IC DEVICE DATA
LM2576
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
Operating Junction Temperature Range
Supply Voltage
Symbol
TJ
Vin
Value
–40 to +125
40
Unit
°C
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
LM2576–3.3
([Note 1] Test Circuit Figure 15)
Output Voltage (Vin = 12 V, ILoad = 0.5 A, TJ = 25°C)
Output Voltage (6.0 V
≤
Vin
≤
40 V, 0.5 A
≤
ILoad
≤
3.0 A)
TJ = 25°C
TJ = –40 to +125°C
Efficiency (Vin = 12 V, ILoad = 3.0 A)
LM2576–5
([Note 1] Test Circuit Figure 15)
Output Voltage (Vin = 12 V, ILoad = 0.5 A, TJ = 25°C)
Output Voltage (8.0 V
≤
Vin
≤
40 V, 0.5 A
≤
ILoad
≤
3.0 A)
TJ = 25°C
TJ = –40 to +125°C
Efficiency (Vin = 12 V, ILoad = 3.0 A)
LM2576–12
([Note 1] Test Circuit Figure 15)
Output Voltage (Vin = 25 V, ILoad = 0.5 A, TJ = 25°C)
Output Voltage (15 V
≤
Vin
≤
40 V, 0.5 A
≤
ILoad
≤
3.0 A)
TJ = 25°C
TJ = –40 to +125°C
Efficiency (Vin = 15 V, ILoad = 3.0 A)
LM2576–15
([Note 1] Test Circuit Figure 15)
Output Voltage (Vin = 30 V, ILoad = 0.5 A, TJ = 25°C)
Output Voltage (18 V
≤
Vin
≤
40 V, 0.5 A
≤
ILoad
≤
3.0 A)
TJ = 25°C
TJ = –40 to +125°C
Efficiency (Vin = 18 V, ILoad = 3.0 A)
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)
Feedback Voltage (8.0 V
≤
Vin
≤
40 V, 0.5 A
≤
ILoad
≤
3.0 A, Vout = 5.0 V)
TJ = 25°C
TJ = –40 to +125°C
Efficiency (Vin = 12 V, ILoad = 3.0 A, Vout = 5.0 V)
Vout
Vout
1.193
1.18
η
–
1.23
–
77
1.267
1.28
–
%
1.217
1.23
1.243
V
V
Vout
Vout
14.4
14.25
η
–
15
–
88
15.6
15.75
–
%
14.7
15
15.3
V
V
Vout
Vout
11.52
11.4
η
–
12
–
88
12.48
12.6
–
%
11.76
12
12.24
V
V
Vout
Vout
4.8
4.75
η
–
5.0
–
77
5.2
5.25
–
%
4.9
5.0
5.1
V
V
Vout
Vout
3.168
3.135
η
–
3.3
–
75
3.432
3.465
–
%
3.234
3.3
3.366
V
V
Symbol
Min
Typ
Max
Unit
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
MOTOROLA ANALOG IC DEVICE DATA
3
LM2576
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
ALL OUTPUT VOLTAGE VERSIONS
Feedback Bias Current (Vout = 5.0 V [Adjustable Version Only])
TJ = 25°C
TJ = –40 to +125°C
Oscillator Frequency [Note 3]
TJ = 25°C
TJ = 0 to +125°C
TJ = –40 to +125°C
Saturation Voltage (Iout = 3.0 A [Note 4])
TJ = 25°C
TJ = –40 to +125°C
Max Duty Cycle (“on”) [Note 5]
Current Limit (Peak Current [Notes 3 and 4])
TJ = 25°C
TJ = –40 to +125°C
Output Leakage Current [Notes 6 and 7], TJ = 25°C
Output = 0 V
Output = –1.0 V
Quiescent Current [Note 6]
TJ = 25°C
TJ = –40 to +125°C
Standby Quiescent Current (ON/OFF Pin = 5.0 V (“off”))
TJ = 25°C
TJ = –40 to +125°C
ON/OFF Pin Logic Input Level (Test Circuit Figure 15)
Vout = 0 V
TJ = 25°C
TJ = –40 to +125°C
Vout = Nominal Output Voltage
TJ = 25°C
TJ = –40 to +125°C
ON/OFF Pin Input Current (Test Circuit Figure 15)
ON/OFF Pin = 5.0 V (“off”), TJ = 25°C
ON/OFF Pin = 0 V (“on”), TJ = 25°C
Ib
–
–
fosc
–
47
42
Vsat
–
–
DC
ICL
4.2
3.5
IL
–
–
IQ
–
–
Istby
–
–
VIH
2.2
2.4
VIL
–
–
IIH
IIL
–
–
1.2
–
15
0
1.0
0.8
µA
30
5.0
1.4
–
–
–
80
–
200
400
V
5.0
–
9.0
11
µA
0.8
6.0
2.0
20
mA
5.8
–
6.9
7.5
mA
94
1.5
–
98
1.8
2.0
–
%
A
52
–
–
–
58
63
V
25
–
100
200
kHz
nA
Symbol
Min
Typ
Max
Unit
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.
4
MOTOROLA ANALOG IC DEVICE DATA
LM2576
TYPICAL PERFORMANCE CHARACTERISTICS
(Circuit of Figure 15)
Figure 2. Normalized Output Voltage
1.0
Vout , OUTPUT VOLTAGE CHANGE (%)
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
–50
Vin = 20 V
ILoad = 500 mA
Normalized at TJ = 25°C
Vout , OUTPUT VOLTAGE CHANGE (%)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
0
5.0
10
15
20
25
30
35
40
12 V and 15 V
3.3 V, 5.0 V and ADJ
ILoad = 500 mA
TJ = 25°C
Figure 3. Line Regulation
–25
0
25
50
75
100
125
TJ, JUNCTION TEMPERATURE (°C)
Vin, INPUT VOLTAGE (V)
Figure 4. Dropout Voltage
2.0
INPUT – OUTPUT DIFFERENTIAL (V)
I O, OUTPUT CURRENT (A)
ILoad = 3.0 A
1.5
6.5
Figure 5. Current Limit
Vin = 25 V
6.0
5.5
5.0
4.5
4.0
–50
1.0
ILoad = 500 mA
0.5
L1 = 150
µH
Rind = 0.1
Ω
0
–50
–25
0
25
50
75
100
125
–25
0
25
50
75
100
125
TJ, JUNCTION TEMPERATURE (°C)
TJ, JUNCTION TEMPERATURE (°C)
Figure 6. Quiescent Current
I stby , STANDBY QUIESCENT CURRENT (
µA)
20
I Q, QUIESCENT CURRENT (mA)
18
16
14
12
10
8.0
6.0
4.0
0
5.0
10
15
20
25
30
35
40
ILoad = 200 mA
ILoad = 3.0 A
Vout = 5.0 V
Measured at
Ground Pin
TJ = 25°C
200
180
160
140
120
100
80
60
40
20
0
–50
Figure 7. Standby Quiescent Current
VON/OFF = 5.0 V
Vin = 40 V
Vin = 12 V
–25
0
25
50
75
100
125
Vin, INPUT VOLTAGE (V)
TJ, JUNCTION TEMPERATURE (°C)
MOTOROLA ANALOG IC DEVICE DATA
5
