National Semiconductor LM2576HV Technical data
LM2576/LM2576HV Series
SIMPLE SWITCHER
®
3A Step-Down Voltage Regulator
LM2576/LM2576HV Series SIMPLE SWITCHER 3A Step-Down Voltage Regulator
August 2004
General 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 version.
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
put voltage within specified input voltages and output load
conditions, and
shutdown is included, featuring 50 µA (typical) standby current. The output switch includes cycle-by-cycle current limiting, as well as thermal shutdown for full protection under
fault conditions.
±
10% on the oscillator frequency. External
4% tolerance on out-
Features
n 3.3V, 5V, 12V, 15V, and adjustable output versions
n Adjustable version output voltage range,
1.23V to 37V (57V for HV version)
line and load conditions
n Guaranteed 3A output current
n Wide input voltage range, 40V up to 60V for
HV version
n Requires only 4 external components
n 52 kHz fixed frequency internal oscillator
n TTL shutdown capability, low power standby mode
n High efficiency
n Uses readily available standard inductors
n Thermal shutdown and current limit protection
n P+ Product Enhancement tested
±
4% max over
Applications
n Simple high-efficiency step-down (buck) regulator
n Efficient pre-regulator for linear regulators
n On-card switching regulators
n Positive to negative converter (Buck-Boost)
Typical Application (Fixed Output Voltage
Versions)
01147601
FIGURE 1.
SIMPLE SWITCHER®is a registered trademark of National Semiconductor Corporation.
© 2004 National Semiconductor Corporation DS011476 www.national.com
Block Diagram
LM2576/LM2576HV
3.3V R2 = 1.7k
5V, R2 = 3.1k
12V, R2 = 8.84k
15V, R2 = 11.3k
For ADJ. Version
R1 = Open, R2 = 0Ω
Patent Pending
Ordering Information
Temperature
Range
−40˚C ≤ T
≤ 125˚C
A
3.3 5.0 12 15 ADJ Number
LM2576HVS-3.3 LM2576HVS-5.0 LM2576HVS-12 LM2576HVS-15 LM2576HVS-ADJ TS5B TO-263
LM2576S-3.3 LM2576S-5.0 LM2576S-12 LM2576S-15 LM2576S-ADJ
LM2576HVSX-3.3 LM2576HVSX-5.0 LM2576HVSX-12 LM2576HVSX-15 LM2576HVSX-ADJ TS5B
LM2576SX-3.3 LM2576SX-5.0 LM2576SX-12 LM2576SX-15 LM2576SX-ADJ
LM2576HVT-3.3 LM2576HVT-5.0 LM2576HVT-12 LM2576HVT-15 LM2576HVT-ADJ T05A TO-220
LM2576T-3.3 LM2576T-5.0 LM2576T-12 LM2576T-15 LM2576T-ADJ
LM2576HVT-3.3 LM2576HVT-5.0 LM2576HVT-12 LM2576HVT-15 LM2576HVT-ADJ T05D
Flow LB03 Flow LB03 Flow LB03 Flow LB03 Flow LB03
LM2576T-3.3 LM2576T-5.0 LM2576T-12 LM2576T-15 LM2576T-ADJ
Flow LB03 Flow LB03 Flow LB03 Flow LB03 Flow LB03
01147602
Output Voltage NS Package Package
Type
Tape & Reel
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LM2576/LM2576HV
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Minimum ESD Rating
(C = 100 pF, R = 1.5 kΩ)2kV
Lead Temperature
(Soldering, 10 Seconds) 260˚C
Maximum Supply Voltage
LM2576 45V
Operating Ratings
LM2576HV 63V
ON /OFF Pin Input Voltage
−0.3V ≤ V ≤ +V
Output Voltage to Ground
(Steady State) −1V
Power Dissipation Internally Limited
Storage Temperature Range −65˚C to +150˚C
IN
Temperature Range
LM2576/LM2576HV −40˚C ≤ T
≤ +125˚C
J
Supply Voltage
LM2576 40V
LM2576HV 60V
Maximum Junction Temperature 150˚C
LM2576-3.3, LM2576HV-3.3 Electrical Characteristics
Specifications with standard type face are for TJ= 25˚C, and those with boldface type apply over full Operating Temperature
Range.
Symbol Parameter Conditions LM2576-3.3 Units
(Limits)
SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
V
OUT
Output Voltage VIN= 12V, I
LOAD
Circuit of Figure 2 3.234 V(Min)
V
OUT
Output Voltage 6V ≤ VIN≤ 40V, 0.5A ≤ I
LM2576 Circuit of Figure 2 3.168/3.135 V(Min)
V
OUT
Output Voltage 6V ≤ VIN≤ 60V, 0.5A ≤ I
LM2576HV Circuit of Figure 2 3.168/3.135 V(Min)
η Efficiency V
= 12V, I
IN
LOAD
LM2576HV-3.3
Typ Limit
(Note 2)
= 0.5A 3.3 V
3.366 V(Max)
≤ 3A 3.3 V
LOAD
3.432/3.465 V(Max)
≤ 3A 3.3 V
LOAD
3.450/3.482 V(Max)
=3A 75 %
LM2576-5.0, LM2576HV-5.0 Electrical Characteristics
Specifications with standard type face are for TJ= 25˚C, and those with Figure 2 boldface type apply over full Operating Temperature Range.
Symbol Parameter Conditions LM2576-5.0 Units
(Limits)
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SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
V
OUT
Output Voltage VIN= 12V, I
Circuit of Figure 2 4.900 V(Min)
V
OUT
Output Voltage 0.5A ≤ I
LM2576 8V ≤ V
LOAD
≤ 40V 4.800/4.750 V(Min)
IN
Circuit of Figure 2 5.200/5.250 V(Max)
V
OUT
Output Voltage 0.5A ≤ I
LM2576HV 8V ≤ V
LOAD
≤ 60V 4.800/4.750 V(Min)
IN
Circuit of Figure 2 5.225/5.275 V(Max)
LM2576HV-5.0
Typ Limit
(Note 2)
= 0.5A 5.0 V
LOAD
5.100 V(Max)
≤ 3A, 5.0 V
≤ 3A, 5.0 V
LM2576-5.0, LM2576HV-5.0
Electrical Characteristics
Specifications with standard type face are for TJ= 25˚C, and those with Figure 2 boldface type apply over full Operating Temperature Range.
Symbol Parameter Conditions LM2576-5.0 Units
LM2576/LM2576HV
SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
η Efficiency V
(Continued)
= 12V, I
IN
LM2576HV-5.0
Typ Limit
(Note 2)
=3A 77 %
LOAD
LM2576-12, LM2576HV-12 Electrical Characteristics
Specifications with standard type face are for TJ= 25˚C, and those with boldface type apply over full Operating Temperature
Range.
Symbol Parameter Conditions LM2576-12 Units
LM2576HV-12
Typ Limit
(Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
V
OUT
V
OUT
Output Voltage VIN= 25V, I
Output Voltage 0.5A ≤ I
LM2576 15V ≤ V
V
OUT
Output Voltage 0.5A ≤ I
LM2576HV 15V ≤ V
η Efficiency V
Circuit of Figure 2 11.76 V(Min)
LOAD
IN
Circuit of Figure 2 12.48/12.60 V(Max)
LOAD
IN
Circuit of Figure 2 12.54/12.66 V(Max)
= 15V, I
IN
= 0.5A 12 V
LOAD
12.24 V(Max)
≤ 3A, 12 V
≤ 40V 11.52/11.40 V(Min)
≤ 3A, 12 V
≤ 60V 11.52/11.40 V(Min)
=3A 88 %
LOAD
(Limits)
(Limits)
LM2576-15, LM2576HV-15 Electrical Characteristics
Specifications with standard type face are for TJ= 25˚C, and those with boldface type apply over full Operating Temperature
Range.
Symbol Parameter Conditions LM2576-15 Units
LM2576HV-15
Typ Limit
(Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
V
OUT
Output Voltage VIN= 25V, I
Circuit of Figure 2 14.70 V(Min)
V
OUT
Output Voltage 0.5A ≤ I
LM2576 18V ≤ V
LOAD
IN
Circuit of Figure 2 15.60/15.75 V(Max)
V
OUT
Output Voltage 0.5A ≤ I
LM2576HV 18V ≤ V
LOAD
IN
Circuit of Figure 2 15.68/15.83 V(Max)
η Efficiency V
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= 18V, I
IN
= 0.5A 15 V
LOAD
15.30 V(Max)
≤ 3A, 15 V
≤ 40V 14.40/14.25 V(Min)
≤ 3A, 15 V
≤ 60V 14.40/14.25 V(Min)
=3A 88 %
LOAD
(Limits)
LM2576-ADJ, LM2576HV-ADJ Electrical Characteristics
Specifications with standard type face are for TJ= 25˚C, and those with boldface type apply over full Operating Temperature
Range.
Symbol Parameter Conditions LM2576-ADJ Units
LM2576HV-ADJ
(Limits)
Typ Limit
(Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
V
OUT
Feedback Voltage VIN= 12V, I
V
= 5V, 1.217 V(Min)
OUT
= 0.5A 1.230 V
LOAD
Circuit of Figure 2 1.243 V(Max)
V
OUT
V
OUT
η Efficiency V
Feedback Voltage 0.5A ≤ I
LM2576 8V ≤ V
V
OUT
Feedback Voltage 0.5A ≤ I
LM2576HV 8V ≤ V
V
OUT
= 12V, I
IN
≤ 3A, 1.230 V
LOAD
≤ 40V 1.193/1.180 V(Min)
IN
= 5V, Circuit of Figure 2 1.267/1.280 V(Max)
≤ 3A, 1.230 V
LOAD
≤ 60V 1.193/1.180 V(Min)
IN
= 5V, Circuit of Figure 2 1.273/1.286 V(Max)
LOAD
= 3A, V
=5V 77 %
OUT
All Output Voltage Versions Electrical Characteristics
Specifications with standard type face are for TJ= 25˚C, and those with boldface type apply over full Operating Temperature
Range. Unless otherwise specified, V
= 30V for the 15V version. I
LOAD
Symbol Parameter Conditions LM2576-XX Units
DEVICE PARAMETERS
I
b
f
O
V
SAT
Feedback Bias Current V
Oscillator Frequency (Note 11) 52 kHz
Saturation Voltage I
DC Max Duty Cycle (ON) (Note 5) 98 %
I
CL
I
L
I
Q
I
STBY
Current Limit (Notes 4, 11) 5.8 A
Output Leakage Current (Notes 6, 7): Output = 0V 2 mA(Max)
Quiescent Current (Note 6) 5 mA
Standby Quiescent ON /OFF Pin = 5V (OFF) 50 µA
Current 200 µA(Max)
= 12V for the 3.3V, 5V, and Adjustable version, VIN= 25V for the 12V version, and V
IN
= 500 mA.
LM2576HV-XX
Typ Limit
(Note 2)
= 5V (Adjustable Version Only) 50 100/500 nA
OUT
47/42 kHz
58/63 kHz
= 3A (Note 4) 1.4 V
OUT
1.8/2.0 V(Max)
93 %(Min)
4.2/3.5 A(Min)
6.9/7.5 A(Max)
Output = −1V 7.5 mA
Output = −1V 30 mA(Max)
10 mA(Max)
(Limits)
(Min)
(Max)
LM2576/LM2576HV
IN
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All Output Voltage Versions
Electrical Characteristics
Specifications with standard type face are for TJ= 25˚C, and those with boldface type apply over full Operating Temperature
Range. Unless otherwise specified, V
= 30V for the 15V version. I
Symbol Parameter Conditions LM2576-XX Units
LM2576/LM2576HV
DEVICE PARAMETERS
θ
JA
θ
JA
θ
JC
θ
JA
ON /OFF CONTROL Test Circuit Figure 2
V
IH
V
IL
I
IH
I
IL
Note 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.
Note 2: All limits guaranteed at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits are 100%
production tested. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods.
Note 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.
Note 4: Output pin sourcing current. No diode, inductor or capacitor connected to output.
Note 5: Feedback pin removed from output and connected to 0V.
Note 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.
Note 7: V
Note 8: Junction to ambient thermal resistance (no external heat sink) for the 5 lead TO-220 package mounted vertically, with
board with minimum copper area.
Note 9: Junction to ambient thermal resistance (no external heat sink) for the 5 lead TO-220 package mounted vertically, with
containing approximately 4 square inches of copper area surrounding the leads.
Note 10: If the TO-263 package is used, the thermal resistance can be reduced by increasing the PC board copper area thermally connected to the package. Using
0.5 square inches of copper area, θ
Note 11: 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 protection feature lowers the average power dissipation of the IC by lowering the minimum duty cycle
from 5% down to approximately 2%.
Thermal Resistance T Package, Junction to Ambient (Note 8) 65
ON /OFF Pin V
Logic Input Level V
ON /OFF Pin Input ON /OFF Pin = 5V (OFF) 12 µA
Current 30 µA(Max)
= 40V (60V for high voltage version).
IN
= 500 mA.
LOAD
is 50˚C/W, with 1 square inch of copper area, θJAis 37˚C/W, and with 1.6 or more square inches of copper area, θJAis 32˚C/W.
JA
(Continued)
= 12V for the 3.3V, 5V, and Adjustable version, VIN= 25V for the 12V version, and V
IN
LM2576HV-XX
Typ Limit
(Note 2)
T Package, Junction to Ambient (Note 9) 45 ˚C/W
T Package, Junction to Case 2
S Package, Junction to Ambient (Note 10) 50
= 0V 1.4 2.2/2.4 V(Min)
OUT
= Nominal Output Voltage 1.2 1.0/0.8 V(Max)
OUT
ON /OFF Pin = 0V (ON) 0µA
10 µA(Max)
1
⁄2inch leads in a socket, or on a PC
1
⁄4inch leads soldered to a PC board
IN
(Limits)
Typical Performance Characteristics
(Circuit of Figure 2)
Normalized Output Voltage Line Regulation
01147627 01147628
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Typical Performance Characteristics (Circuit of Figure 2) (Continued)
Dropout Voltage Current Limit
LM2576/LM2576HV
Quiescent Current
Oscillator Frequency
01147629
01147630
Standby
Quiescent Current
01147631 01147632
Switch Saturation
Voltage
01147633
01147634
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Typical Performance Characteristics (Circuit of Figure 2) (Continued)
Efficiency Minimum Operating Voltage
LM2576/LM2576HV
01147635
Quiescent Current
vs Duty Cycle
Minimum Operating Voltage
01147636
Feedback Voltage
vs Duty Cycle
01147637 01147638
Quiescent Current
vs Duty Cycle
01147636
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01147637
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