NSC LM2576-ADJMDC Datasheet

LM2576/LM2576HV Series SIMPLE SWITCHER
®
3A Step-Down Voltage Regulator
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 aminimumnumber of external components, these regulators are simple to use and include internal frequency compensation and a fixed-frequency oscillator.
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 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.
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)
±
4%max over
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
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)
SIMPLE SWITCHER®is a registered trademark of National Semiconductor Corporation.
DS011476-1
FIGURE 1.
June 1999
LM2576/LM2576HV Series SIMPLE SWITCHER 3A Step-Down Voltage Regulator
© 1999 National Semiconductor Corporation DS011476 www.national.com
Block Diagram
Ordering Information
Temperature
Range
Output Voltage NS Package Package
Type
3.3 5.0 12 15 ADJ Number
−40˚C T
A
125˚C
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
Tape & Reel
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
DS011476-2
3.3V R2=1.7k 5V, R2=3.1k 12V, R2=8.84k 15V, R2=11.3k For ADJ. Version R1=Open, R2=0 Patent Pending
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Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.
Maximum Supply Voltage
LM2576 45V LM2576HV 63V
ON /OFF Pin Input Voltage
−0.3V V +V
IN
Output Voltage to Ground
(Steady State) −1V Power Dissipation Internally Limited Storage Temperature Range −65˚C to +150˚C Maximum Junction Temperature 150˚C
Minimum ESD Rating
(C=100 pF, R=1.5 k)2kV
Lead Temperature
(Soldering, 10 Seconds) 260˚C
Operating Ratings
Temperature Range
LM2576/LM2576HV −40˚C T
J
+125˚C
Supply Voltage
LM2576 40V LM2576HV 60V
LM2576-3.3, LM2576HV-3.3 Electrical Characteristics
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 Units
(Limits)
LM2576HV-3.3
Typ Limit
(Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit
Figure 2
V
OUT
Output Voltage V
IN
=
12V, I
LOAD
=
0.5A 3.3 V
Circuit of
Figure 2
3.234 V(Min)
3.366 V(Max)
V
OUT
Output Voltage 6V VIN≤ 40V, 0.5A ≤ I
LOAD
3A 3.3 V
LM2576 Circuit of
Figure 2
3.168/3.135 V(Min)
3.432/3.465 V(Max)
V
OUT
Output Voltage 6V VIN≤ 60V, 0.5A ≤ I
LOAD
3A 3.3 V
LM2576HV Circuit of
Figure 2
3.168/3.135 V(Min)
3.450/3.482 V(Max)
η Efficiency V
IN
=
12V, I
LOAD
=
3A 75
%
LM2576-5.0, LM2576HV-5.0 Electrical Characteristics
Specifications with standard type face are for T
J
=
25˚C, and those with
Figure 2
boldface type apply over full Operating
Temperature Range.
Symbol Parameter Conditions LM2576-5.0 Units
(Limits)
LM2576HV-5.0
Typ Limit
(Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit
Figure 2
V
OUT
Output Voltage V
IN
=
12V, I
LOAD
=
0.5A 5.0 V
Circuit of
Figure 2
4.900 V(Min)
5.100 V(Max)
V
OUT
Output Voltage 0.5A I
LOAD
3A, 5.0 V
LM2576 8V V
IN
40V 4.800/4.750 V(Min)
Circuit of
Figure 2
5.200/5.250 V(Max)
V
OUT
Output Voltage 0.5A I
LOAD
3A, 5.0 V
LM2576HV 8V V
IN
60V 4.800/4.750 V(Min)
Circuit of
Figure 2
5.225/5.275 V(Max)
η Efficiency V
IN
=
12V, I
LOAD
=
3A 77
%
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LM2576-12, LM2576HV-12 Electrical Characteristics
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 Units
(Limits)
LM2576HV-12
Typ Limit
(Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit
Figure 2
V
OUT
Output Voltage V
IN
=
25V, I
LOAD
=
0.5A 12 V
Circuit of
Figure 2
11.76 V(Min)
12.24 V(Max)
V
OUT
Output Voltage 0.5A I
LOAD
3A, 12 V
LM2576 15V V
IN
40V 11.52/11.40 V(Min)
Circuit of
Figure 2
12.48/12.60 V(Max)
V
OUT
Output Voltage 0.5A I
LOAD
3A, 12 V
LM2576HV 15V V
IN
60V 11.52/11.40 V(Min)
Circuit of
Figure 2
12.54/12.66 V(Max)
η Efficiency V
IN
=
15V, I
LOAD
=
3A 88
%
LM2576-15, LM2576HV-15 Electrical Characteristics
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 Units
(Limits)
LM2576HV-15
Typ Limit
(Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit
Figure 2
V
OUT
Output Voltage V
IN
=
25V, I
LOAD
=
0.5A 15 V
Circuit of
Figure 2
14.70 V(Min)
15.30 V(Max)
V
OUT
Output Voltage 0.5A I
LOAD
3A, 15 V
LM2576 18V V
IN
40V 14.40/14.25 V(Min)
Circuit of
Figure 2
15.60/15.75 V(Max)
V
OUT
Output Voltage 0.5A I
LOAD
3A, 15 V
LM2576HV 18V V
IN
60V 14.40/14.25 V(Min)
Circuit of
Figure 2
15.68/15.83 V(Max)
η Efficiency V
IN
=
18V, I
LOAD
=
3A 88
%
LM2576-ADJ, LM2576HV-ADJ Electrical Characteristics
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 Units
(Limits)
LM2576HV-ADJ
Typ Limit
(Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit
Figure 2
V
OUT
Feedback Voltage V
IN
=
12V, I
LOAD
=
0.5A 1.230 V
V
OUT
=
5V, 1.217 V(Min)
Circuit of
Figure 2
1.243 V(Max)
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LM2576-ADJ, LM2576HV-ADJ Electrical Characteristics
(Continued)
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 Units
(Limits)
LM2576HV-ADJ
Typ Limit
(Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit
Figure 2
V
OUT
Feedback Voltage 0.5A I
LOAD
3A, 1.230 V
LM2576 8V V
IN
40V 1.193/1.180 V(Min)
V
OUT
=
5V, Circuit of
Figure 2
1.267/1.280 V(Max)
V
OUT
Feedback Voltage 0.5A I
LOAD
3A, 1.230 V
LM2576HV 8V V
IN
60V 1.193/1.180 V(Min)
V
OUT
=
5V, Circuit of
Figure 2
1.273/1.286 V(Max)
η Efficiency V
IN
=
12V, I
LOAD
=
3A, V
OUT
=
5V 77
%
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. I
LOAD
=
500 mA.
Symbol Parameter Conditions LM2576-XX Units
(Limits)
LM2576HV-XX
Typ Limit
(Note 2)
DEVICE PARAMETERS
I
b
Feedback Bias Current V
OUT
=
5V (Adjustable Version Only) 50 100/500 nA
f
O
Oscillator Frequency (Note 11) 52 kHz
47/42 kHz
(Min)
58/63 kHz
(Max)
V
SAT
Saturation Voltage I
OUT
=
3A (Note 4) 1.4 V
1.8/2.0 V(Max)
DC Max Duty Cycle (ON) (Note 5) 98
%
93
%
(Min)
I
CL
Current Limit (Notes 4, 11) 5.8 A
4.2/3.5 A(Min)
6.9/7.5 A(Max)
I
L
Output Leakage Current (Notes 6, 7): Output=0V 2 mA(Max)
Output=−1V 7.5 mA Output=−1V 30 mA(Max)
I
Q
Quiescent Current (Note 6) 5 mA
10 mA(Max)
I
STBY
Standby Quiescent ON /OFF Pin=5V (OFF) 50 µA Current 200 µA(Max)
θ
JA
Thermal Resistance T Package, Junction to Ambient (Note 8) 65
θ
JA
T Package, Junction to Ambient (Note 9) 45 ˚C/W
θ
JC
T Package, Junction to Case 2
θ
JA
S Package, Junction to Ambient (Note 10) 50
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All Output Voltage Versions Electrical Characteristics
(Continued)
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. I
LOAD
=
500 mA.
Symbol Parameter Conditions LM2576-XX Units
(Limits)
LM2576HV-XX
Typ Limit
(Note 2)
ON /OFF CONTROL Test Circuit
Figure 2
V
IH
ON /OFF Pin V
OUT
=
0V 1.4 2.2/2.4 V(Min)
V
IL
Logic Input Level V
OUT
=
Nominal Output Voltage 1.2 1.0/0.8 V(Max)
I
IH
ON /OFF Pin Input ON /OFF Pin=5V (OFF) 12 µA Current 30 µA(Max)
I
IL
ON /OFF Pin=0V (ON) A
10 µA(Max)
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%produc- tion 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
IN
=
40V (60V for high voltage version).
Note 8: Junction to ambient thermal resistance (no external heat sink) for the 5 lead TO-220 package mounted vertically, with
1
⁄2inch leads in a socket, or on a PC
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
1
⁄4inch leads soldered to a PC board
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
JA
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.
Note 11: The oscillator frequency reduces to approximately 11kHz 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%.
Typical Performance Characteristics (Circuit of
Figure 2
)
Normalized Output Voltage
DS011476-27
Line Regulation
DS011476-28
Dropout Voltage
DS011476-29
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Typical Performance Characteristics (Circuit of
Figure 2
) (Continued)
Current Limit
DS011476-30
Quiescent Current
DS011476-31
Standby Quiescent Current
DS011476-32
Oscillator Frequency
DS011476-33
Switch Saturation Voltage
DS011476-34
Efficiency
DS011476-35
Minimum Operating Voltage
DS011476-36
Quiescent Current vs Duty Cycle
DS011476-37
Feedback Voltage vs Duty Cycle
DS011476-38
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