LM2576T-ADJ P+
FEATURES
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3.3V, 5.0V, 12V and Adjustable Output Versions
Adjustable Version Output Voltage Range, 1.23 to 37V
+/- 4% maximum over line and load conditions
Guaranteed 3.0A Output Current
Wide Input Voltage Range
Requires Only 4 External Components
52kHz Fixed Frequency Internal Oscillator
TTL Shutdown Capability, Low Power Standby Mode
High Efficiency
Uses Readily Available Standard Inductors
Thermal Shutdown and Current Limit Protection
Moisture Sensitivity Level 3 for SMD packages
SOP8-PP PKG
TO-220 PKG
TO-263 PKG
APPLICATION
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
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DESCRIPTION
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The LM2576T-ADJ 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 3.0A load with excellent line and load regulation. These
devices are available in fixed output voltages of 3.3V, 5.0V, 12V 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 LM2576T-ADJ are offered by several different
inductor manufacturers.
Since the LM2576T-ADJ 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 LM2576T-ADJ are available from
several different manufacturers. This feature greatly simplifies the design of switch-mode power supplies. The
LM2576T-ADJ 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).
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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.
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LM2576T-ADJ P+
LM
2576
Output Voltage : ADJ / 3.3V / 5.0V /12V
Package Type
DP : SOP8-PP
T : TO220-5L
R : TO263-5L
Root Name
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Product Code
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LM2576T-ADJ P+
PIN CONFIGURATION
O N /O F F
FEEDBACK
GND
VOUT
V IN
O N /O F F
VIN 1
VOUT 2
FEEDBACK 3
ON/OFF
FEEDBACK
GND
8 N.C
Exposed
7 N.C
PAD
6 GND
4
VOUT
V IN
5 N.C.
SOP8-PP
TO220-5L
TO263-5L
PIN DESCRIPTION
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Package
Symbol
TO-220 5L
Description
SOP8-PP
TO-263 5L
1
VIN
2
2
VOUT
3
6
GND
4
3
FEEDBACK
5
4
ON/OFF
-
5, 7, 8
N.C.
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1
This pin is the positive input supply for the JSM2576
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).
This is the emitter of the internal switch. The saturation voltage
VSAT of this output switch is typically 1.5V. 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.
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.
It allows the switching regulator circuit to be shutdown using logic
level signals, thus dropping the total input supply current to
approximately 80uA.
The threshold voltage is typically 1.4V. 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
No Connect.
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* Exposed Pad of SOP8-PP package should be externally connected to GND.
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LM2576T-ADJ P+
Typical Application (Fixed Output Voltage Versions)
Figure 1. Block Diagram and Typical Application
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LM2576T-ADJ P+
ABSOLUTE MAXIMUM RATINGS
(Absolute Maximum Ratings indicate limits beyond which damage to the device may occur)
Rating
Value
UNIT
Maximum Supply Voltage
Vin
45
V
On/Off Pin Input Voltage
-
-0.3V ≤ V ≤ +Vin
V
Output Voltage to Ground (Steady-State)
Power Dissipation
SOP8-PP 8Lead
Thermal Resistance, Junction to Ambient
Thermal Resistance, Junction to Case
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=1.5kΩ
Lead Temperature (Soldering, 10seconds)
-
-1.0
V
PD
θJA
θJC
PD
θJA
θJC
PD
θJA
θJC
TSTG
Internally Limited
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Internally Limited
65
5
Internally Limited
70
5
-60 to +150
W
℃/W
℃/W
W
℃/W
℃/W
W
℃/W
℃/W
℃
-
2.0
kV
-
260
℃
TJ
150
℃
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Maximum Junction Temperature
OPERATING RATINGS (Operating Ratings indicate conditions for which the device is intended to be
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functional, but do not guarantee specific performance limits. For guaranteed specifications, see the
Electrical Characteristics.)
Symbol
Value.
Unit
Operating Junction Temperature Range
TJ
-40 to +125
℃
Vin
40
V
Supply Voltage
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Rating
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LM2576T-ADJ P+
ELECTRICAL CHARACTERISTICS / SYSTEM PARAMETERS ([Note 1] Test Circuit Figure 15)
(Unless otherwise specified, Vin = 12V for the 3.3V, 5.0V, and Adjustable version, Vin = 25V for the 12V 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
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JSM2576-3.3V ([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)
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JSM2576-5.0V ([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)
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
4.8
4.75
-
5.0
77
5.2
5.25
-
V
%
Vout
11.76
12
12.24
V
Vout
11.52
11.4
-
12
88
12.48
12.6
-
V
%
η
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JSM2576-12V ([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)
Symbol
Feedback Voltage (8.0V≤Vin≤40V, 0.5A≤ILOAD≤3.0A, Vout=5.0V)
TJ=25℃
TJ= -40℃ ~ +125℃
Efficiency (Vin=12V, ILOAD=3.0A, Vout=5.0V)
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JSM2576T-ADJ ([Note 1] Test Circuit Figure 2)
Feedback Voltage (Vin=12V, ILOAD=0.5A, TJ=25℃)
η
Vout
1.217
1.23
1.243
V
Vout
1.193
1.18
-
1.23
77
1.267
1.28
-
V
η
%
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1. External components such as the catch diode, inductor, input and output capacitors can affect switching
regulator system performance.
When the JSM2576 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 JSM2576: Tlow = –40°C Thigh = +125°C
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LM2576T-ADJ P+
ELECTRICAL CHARACTERISTICS / Device Parameters
(Unless otherwise specified, Vin = 12V for the 3.3V, 5.0V, and Adjustable version, Vin = 25V for the 12V 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
Ib
-
25
-
100
200
nA
47
42
52
-
58
63
VSAT
-
1.5
-
1.8
2
V
DC
94
98
-
%
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
µA
2.2
2.4
1.4
-
-
-
1.2
-
1
0.8
V
-
15
0
30
0.5
µA
All Output Voltage Versions
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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℃
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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℃
FOSC
VIH
VIL
IIH
IIL
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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℃
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ON/OFF Pin Logic Input Level (Test circuit Figure 15)
Vout=0V
TJ=25℃
TJ= -40 to +125℃
Vout=Nominal Output Voltage
TJ=25℃
kHz
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 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 sourcing current. No diode, inductor or capacitor connected to output pin.
5. Feedback removed from output and connected to 0V.
6. Feedback removed from output and connected to +12V for the Adjustable, 3.3V, and 5.0V versions, and +25V for the 12V
version, to force the output transistor “off”.
7. Vin = 40V.
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LM2576T-ADJ P+
TYPICAL PERFORMANCE CHARACTERISTICS (Circuit of Figure 15)
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Figure 2. Normalized Output Voltage
Figure 3. Line Regulation
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Figure 4. Dropout Voltage
Figure 5. Current Limit
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Figure 6. Quiescent Current
Figure 7. Standby Quiescent Current
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LM2576T-ADJ P+
TYPICAL PERFORMANCE CHARACTERISTICS (Circuit of Figure 15)
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Figure 8. Standby Quiescent Current
Figure 9. Switch Saturation Voltage
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Figure 10. Oscillator Frequency
Figure 11. Minimum Operating Voltage
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Figure 12. Feedback Pin Current
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LM2576T-ADJ P+
TYPICAL PERFORMANCE CHARACTERISTICS
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Figure 13. Switching Waveforms
Figure 14. Load Transient Response
Vout = 15V
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A : Output Pin Voltage, 10V/DIV
B: Inductor Current, 2.0A/DIV
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C: Inductor Current, 2.0A/DIV
D: Output Ripple Voltage, 50mV/DIV, AC-Coupled
TO220-5
A
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D2
A1
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B
G
Horizontal Time Base : 5.0 µs/DIV
q
D1
D
F
d
a
UNIT:mm
DIM.
A
A1
B
a
b
D
b
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MIN
4.520
1.250
10.030
1.680
0.710
28.600
TYP
4.570
1.270
10.130
1.700
0.810
28.700
MAX
4.620
1.290
10.330
1.770
0.910
28.850
DIM.
MIN
TYP
D1
22.420 22.520
D2
8.690 8.740
d
0.365 0.380
q
3.790 3.840
F
7.800
G
12.620
MAX
22.620
8.790
0.395
3.890
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