LM2576
3.0A, 52kHz, Step-Down Switching Regulator
FEATURES
3.3V, 5.0V, 12V, 15V, and Adjustable Output Versions
TO-220 PKG
Adjustable Version Output Voltage Range, 1.23 to 37V
+/- 4% AG10Maximum Over Line and Load Conditions
Guaranteed 3.0A Output Current
Wide Input Voltage Range
Requires Only 4 External Components
1
52kHz Fixed Frequency Internal Oscillator
5
TTL Shutdown Capability, Low Power Standby Mode
TO-220V PKG
High Efficiency
Uses Readily Available Standard Inductors
1
Thermal Shutdown and Current Limit Protection
Moisture Sensitivity Level 3
5
Applications
Simple High-Efficiency Step-Down(Buck) Regulator
TO-263 PKG
Efficient Pre-Regulator for Linear Regulators
On-Card Switching Regulators
Positive to Negative Converter(Buck-Boost)
1
Negative Step-Up Converters
5
Power Supply for Battery Chargers
1. Vin 2. Output 3. Ground
4. Feedback 5. On/Off
DESCRIPTION
ORDERING INFORMATION
The LM2576 series of regulators are monolithic integrated
Device
Marking
Package
LM2576T-X.X
TO-220
circuits ideally suited for easy and convenient design of a
LM2576T-X.X
step-down switching regulator(buck converter).
LM2576TV-X.X
LM2576T-X.X
TO-220V
All circuits of this series are capable of driving a 3.0A load
LM2576R
LM2576R-X.X
TO-263
with excellent line and load regulation. These devices are
available in fixed output voltages of 3.3V, 5.0V,12V, 15V,
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 0oC to 125 oC).
External shutdown is included, featuring 80 ㎂(typical) standby current. The output switch includes
cycle-bycycle current limiting, as well as thermal shutdown for full protection under fault conditions.
HTC
2008 - Ver. 1.0
-1-
LM2576
3.0A, 52kHz, Step-Down Switching Regulator
Typical Application (Fixed Output Voltage Versions)
Figure 1. Block Diagram and Typical Application
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
TO-220 5Lead
Thermal Resistance, Junction to Ambient
Thermal Resistance, Junction to Case
TO-263 5Lead
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㏀)
Lead Temperature (Soldering,10seconds)
Maximum Junction Temperature
Symbol
Vin
-
Value
45
-0.3V ≤ V ≤ +Vin
- 1.0
Unit
V
V
V
PD
PθJA
PθJC
PD
PθJA
PθJC
Tstg
Internally Limited
65
5.0
Internally Limited
70
5.0
-60 to +150
W
℃/W
℃/W
W
℃/W
℃/W
℃
-
2.0
kV
TJ
260
150
℃
℃
HTC
-2-
LM2576
3.0A, 52kHz, Step-Down Switching Regulator
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, see the Electrical Characteristics.)
Rating
Operating Junction Temperature Range
Supply Voltage
Symbol
TJ
Value
-40 to +125
40
Vin
Unit
℃
V
ELECTRICAL CHARACTERISTICS / SYSTEM PARAMETERS ([Note 1] Test Circuit Figure 15)
(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
Vout
3.234
3.3
3.366
V
Vout
3.3
75
3.432
3.465
-
V
η
3.168
3.135
-
%
Vout
4.9
5.0
5.1
V
Vout
5.0
77
5.2
5.25
-
V
η
4.8
4.75
-
%
Vout
11.76
12
12.24
V
Vout
12
88
12.48
12.6
-
V
η
11.52
11.4
-
%
Vout
1.217
1.23
1.243
V
Vout
1.193
1.18
-
1.23
77
1.267
1.28
-
V
LM2576-3.3V ([Note 1] Test Circuit Figure 2)
Output Voltage (Vin = 12V, ILOAD=0.5A, TJ=25℃)
Output Voltage (6.0V≤Vin≤40V, 0.5A≤ILOAD≤3.0A
TJ=25℃
TJ= -40℃ ~ +125℃
Efficiency (Vin=12V, ILOAD=3.0A)
LM2576-5.0V ([Note 1] Test Circuit Figure 2)
Output Voltage (Vin = 12V, ILOAD=0.5A, TJ=25℃)
Output Voltage (8.0V≤Vin≤40V, 0.5A≤ILOAD≤3.0A
TJ=25℃
TJ= -40℃ ~ +125℃
Efficiency (Vin=12V, ILOAD=3.0A)
LM2576-12V ([Note 1] Test Circuit Figure 2)
Output Voltage (Vin = 25V, ILOAD=0.5A, TJ=25℃)
Output Voltage (15V≤Vin≤40V, 0.5A≤ILOAD≤3.0A
TJ=25℃
TJ= -40℃ ~ +125℃
Efficiency (Vin=25V, ILOAD=3.0A)
LM2576-ADJ ([Note 1] Test Circuit Figure 2)
Feedback Voltage (Vin=12V, ILOAD=0.5A, TJ=25℃)
Feedback Voltage(8.0V≤Vin≤40V, 0.5A≤ILOAD≤3.0A, Vout=5.0V)
TJ=25℃
TJ= -40℃ ~ +125℃
η
Efficiency (Vin=12V, ILOAD=3.0A, Vout=5.0V)
%
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
HTC
-3-
LM2576
3.0A, 52kHz, Step-Down Switching Regulator
ELECTRICAL CHARACTERISTICS / Device Parameters
(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
Symbol
Min
TYP
Max
Unit
Ib
-
25
-
100
200
nA
47
42
52
-
58
63
94
1.5
98
1.8
2
-
ICL
4.2
3.5
5.8
-
6.9
7.5
A
IL
-
0.8
6
50
30
mA
IQ
-
5
-
9
11
mA
ISTBY
-
80
-
200
400
㎂
2.2
2.4
1.4
-
-
VIL
-
1.2
-
1
0.8
V
IIH
IIL
-
15
0
30
5.0
㎂
Feedback Bias Current (Vout=5.0V [Adjustable Version Only])
TJ=25℃
TJ= -40 to +125℃
Oscillator Frequency [Note 3]
TJ=25℃
TJ= 0 to +125℃
TJ= -40 to +125℃
Saturation Voltage (Iout=3.0A [note 4])
TJ=25℃
TJ= -40 to +125℃
Max Duty Cycle ("0") [Note 5]
Current Limit (Peak Current [Note 3 and 4])
TJ=25℃
TJ= -40 to +125℃
Output Leakage Current [Note 6 and 7], TJ=25℃
Output = 0V
Output = -1.0V
Quiescent Current [Note 6]
TJ=25℃
TJ= -40 to +125℃
Standby Quiescent Current (ON/OFF Pin = 5.0V ("off"))
TJ=25℃
TJ= -40 to +125℃
ON/OFF Pin Logic Input Level (Test circuit Figure 15)
Vout=0V
TJ=25℃
TJ= -40 to +125℃
Vout=Nominal Output Voltage
TJ=25℃
TJ= -40 to +125℃
ON/OFF Pin Input Current (Test Circuit Figure 15)
ON/OFF Pin = 5.0V (Regulator OFF), TJ=25℃
ON/OFF Pin = 0V (Regulator ON), TJ=25℃
Fosc
Vsat
DC
VIH
kHz
V
%
V
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
5.0V ersions, and +25 V for the 12 V and15 V versions, to force the output transistor “off”.
7. Vin = 40 V.
HTC
-4-
3.0A, 52kHz, Step-Down Switching Regulator
LM2576
TYPICAL PERFORMANCE CHARACTERISTICS (Circuit of Figure 15)
20
IQ, QUIESCENT CURRENT (mA)
18
16
14
12
10
8
6
4
HTC
-5-
3.0A, 52kHz, Step-Down Switching Regulator
LM2576
TYPICAL PERFORMANCE CHARACTERISTICS (Circuit of Figure 15)
HTC
-6-
3.0A, 52kHz, Step-Down Switching Regulator
LM2576
TYPICAL PERFORMANCE CHARACTERISTICS
HTC
-7-
3.0A, 52kHz, Step-Down Switching Regulator
LM2576
HTC
-8-
3.0A, 52kHz, Step-Down Switching Regulator
LM2576
PIN FUNCTION DESCRIPTION
Symbol
1
2
3
4
5
Vin
Description
This pin is the positive input supply for the LM2576 step–down switching
regulator.In order to minimize voltage transients and to supply the switching
currents needed by the regulator, a suitable input bypass capacitor must be
present .(Cin in Figure 1).
Output This is the emitter of the internal switch. The saturation voltage Vsat of this
output switch is typically 1.5 V. It should be kept in mind that the PCB area
connected to this pin should be kept to a minimum in order to minimize
coupling to sensitive circuitry.
Circuit ground pin. See the information about the printed circuit board layout.
Gnd
Feedback This pin senses regulated output voltage to complete the feedback loop.
The signal is divided by the internal resistor divider network R2, R1 and
applied to the non–inverting input of the internal error amplifier. In the
Adjustable version of the LM2576 switching regulator this pin is the direct
input of the error amplifier and the resistor network R2, R1 is connected
externally to allow programming of the output voltage.
ON/OFF It allows the switching regulator circuit to be shut down using logic level
signals, thus dropping the total input supply current to approximately 80 mA.
The threshold voltage is typically 1.4 V. Applying a voltage above this value
(up to +Vin) shuts the regulator off. If the voltage applied to this pin is lower
than 1.4V or if this pin is left open, the regulator will be in the "on" condition
HTC
-9-
3.0A, 52kHz, Step-Down Switching Regulator
LM2576
HTC
- 10 -
3.0A, 52kHz, Step-Down Switching Regulator
LM2576
HTC
- 11 -
3.0A, 52kHz, Step-Down Switching Regulator
LM2576
HTC
- 12 -
3.0A, 52kHz, Step-Down Switching Regulator
LM2576
HTC
- 13 -
3.0A, 52kHz, Step-Down Switching Regulator
LM2576
HTC
- 14 -