LM2575, NCV2575
1.0 A, Adjustable Output
Voltage, Step-Down
Switching Regulator
The LM2575 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 1.0 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 LM2575 are offered by several
different inductor manufacturers.
Since the LM2575 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 by the LM2575 regulator is so
low, that no heatsink is required or its size could be reduced
dramatically.
The LM2575 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
mA
typical standby current. The
output switch includes cycle−by−cycle current limiting, as well as
thermal shutdown for full protection under fault conditions.
Features
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1
5
TO−220
TV SUFFIX
CASE 314B
Heatsink surface connected to Pin 3
1
5
TO−220
T SUFFIX
CASE 314D
Pin
•
3.3 V, 5.0 V, 12 V, 15 V, and Adjustable Output Versions
•
Adjustable Version Output Voltage Range of 1.23 V to 37 V
±4%
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Maximum Over Line and Load Conditions
Guaranteed 1.0 A Output Current
Wide Input Voltage Range: 4.75 V to 40 V
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
Moisture Sensitivity Level (MSL) Equals 1
Pb−Free Packages are Available*
1.
2.
3.
4.
5.
V
in
Output
Ground
Feedback
ON/OFF
1
5
D
2
PAK
D2T SUFFIX
CASE 936A
Heatsink surface (shown as terminal 6 in
case outline drawing) is connected to Pin 3
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 25 of this data sheet.
Applications
Simple and High−Efficiency Step−Down (Buck) Regulators
Efficient Pre−Regulator for Linear Regulators
On−Card Switching Regulators
Positive to Negative Converters (Buck−Boost)
Negative Step−Up Converters
Power Supply for Battery Chargers
DEVICE MARKING INFORMATION
See general marking information in the device marking
section on page 26 of this data sheet.
*For additional information on our Pb−Free strategy and soldering details, please
download the ON Semiconductor Soldering and Mounting Techniques
Reference Manual, SOLDERRM/D.
©
Semiconductor Components Industries, LLC, 2009
June, 2009
−
Rev. 11
1
Publication Order Number:
LM2575/D
LM2575, NCV2575
Typical Application
(Fixed Output Voltage Versions)
Feedback
7.0 V - 40 V
Unregulated
DC Input
+V
in
C
in
100
mF
1
3 GND 5
LM2575
4
Output
2
ON/OFF
L1
330
mH
D1
1N5819
5.0 V Regulated
Output 1.0 A Load
C
out
330
mF
Representative Block Diagram and Typical Application
Unregulated
DC Input
C
in
4
Feedback
R2
Fixed Gain
Error Amplifier Comparator
Current
Limit
+V
in
1
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
W
R2
(W)
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
V
out
C
out
Load
1.235 V
Band-Gap
Reference
This device contains 162 active transistors.
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
Case 314B and 314D (TO−220, 5−Lead)
Thermal Resistance, Junction−to−Ambient
Thermal Resistance, Junction−to−Case
Case 936A (D
2
PAK)
Thermal Resistance, Junction−to−Ambient (Figure 34)
Thermal Resistance, Junction−to−Case
Storage Temperature Range
Minimum ESD Rating (Human Body Model: C = 100 pF, R = 1.5 kW)
Lead Temperature (Soldering, 10 s)
Maximum Junction Temperature
Symbol
V
in
−
−
P
D
R
qJA
R
qJC
P
D
R
qJA
R
qJC
T
stg
−
−
T
J
Value
45
−0.3
V
≤
V
≤
+V
in
−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
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
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LM2575, NCV2575
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
T
J
V
in
Value
−40
to +125
40
Unit
°C
V
SYSTEM PARAMETERS
([Note 1] Test Circuit Figure 14)
for the 12 V version, and V
in
= 30 V for the 15 V version. I
Load
= 200 mA. For typical values T
J
= 25°C, for min/max values T
J
is the
operating junction temperature range that applies [Note 2], unless otherwise noted.)
Characteristics
LM2575−3.3
(Note 1 Test Circuit Figure 14)
Output Voltage (V
in
= 12 V, I
Load
= 0.2 A, T
J
= 25°C)
Output Voltage (4.75 V
≤
V
in
≤
40 V, 0.2 A
≤
I
Load
≤
1.0 A)
T
J
= 25°C
T
J
=
−40
to +125°C
Efficiency (V
in
= 12 V, I
Load
= 1.0 A)
LM2575−5
([Note 1] Test Circuit Figure 14)
Output Voltage (V
in
= 12 V, I
Load
= 0.2 A, T
J
= 25°C)
Output Voltage (8.0 V
≤
V
in
≤
40 V, 0.2 A
≤
I
Load
≤
1.0 A)
T
J
= 25°C
T
J
=
−40
to +125°C
Efficiency (V
in
= 12 V, I
Load
= 1.0 A)
LM2575−12
(Note 1 Test Circuit Figure 14)
Output Voltage (V
in
= 25 V, I
Load
= 0.2 A, T
J
= 25°C)
Output Voltage (15 V
≤
V
in
≤
40 V, 0.2 A
≤
I
Load
≤
1.0 A)
T
J
= 25°C
T
J
=
−40
to +125°C
Efficiency (V
in
= 15V, I
Load
= 1.0 A)
LM2575−15
(Note 1 Test Circuit Figure 14)
Output Voltage (V
in
= 30 V, I
Load
= 0.2 A, T
J
= 25°C)
Output Voltage (18 V
≤
V
in
≤
40 V, 0.2 A
≤
I
Load
≤
1.0 A)
T
J
= 25°C
T
J
=
−40
to +125°C
Efficiency (V
in
= 18 V, I
Load
= 1.0 A)
LM2575 ADJUSTABLE VERSION
(Note 1 Test Circuit Figure 14)
Feedback Voltage (V
in
= 12 V, I
Load
= 0.2 A, V
out
= 5.0 V, T
J
= 25°C)
Feedback Voltage (8.0 V
≤
V
in
≤
40 V, 0.2 A
≤
I
Load
≤
1.0 A, V
out
= 5.0 V)
T
J
= 25°C
T
J
=
−40
to +125°C
Efficiency (V
in
= 12 V, I
Load
= 1.0 A, V
out
= 5.0 V)
V
FB
V
FB
1.217
1.193
1.18
−
1.23
1.23
−
77
1.243
1.267
1.28
−
%
V
V
V
out
V
out
14.7
14.4
14.25
−
15
15
−
88
15.3
15.6
15.75
−
%
V
V
V
out
V
out
11.76
11.52
11.4
−
12
12
−
88
12.24
12.48
12.6
−
%
V
V
V
out
V
out
4.9
4.8
4.75
−
5.0
5.0
−
77
5.1
5.2
5.25
−
%
V
V
V
out
V
out
3.234
3.168
3.135
−
3.3
3.3
−
75
3.366
3.432
3.465
−
%
V
V
Symbol
Min
Typ
Max
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, V
in
= 12 V for the 3.3 V, 5.0 V, and Adjustable version, V
in
= 25 V
Unit
η
η
η
η
η
1. External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance.
When the LM2575 is used as shown in the Figure 14 test circuit, system performance will be as shown in system parameters section.
2. Tested junction temperature range for the LM2575 and the NCV2575:
T
low
=
−40°C
T
high
= +125°C
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3
LM2575, NCV2575
DEVICE PARAMETERS
for the 12 V version, and V
in
= 30 V for the 15 V version. I
Load
= 200 mA. For typical values T
J
= 25°C, for min/max values T
J
is the
operating junction temperature range that applies [Note 2], unless otherwise noted.)
Characteristics
ALL OUTPUT VOLTAGE VERSIONS
Feedback Bias Current (V
out
= 5.0 V Adjustable Version Only)
T
J
= 25°C
T
J
=
−40
to +125°C
Oscillator Frequency Note 3
T
J
= 25°C
T
J
= 0 to +125°C
T
J
=
−40
to +125°C
Saturation Voltage (I
out
= 1.0 A Note 4)
T
J
= 25°C
T
J
=
−40
to +125°C
Max Duty Cycle (“on”) Note 5
Current Limit (Peak Current Notes 4 and 3)
T
J
= 25°C
T
J
=
−40
to +125°C
Output Leakage Current Notes 6 and 7, T
J
= 25°C
Output = 0 V
Output =
−1.0
V
Quiescent Current Note 6
T
J
= 25°C
T
J
=
−40
to +125°C
Standby Quiescent Current (ON/OFF Pin = 5.0 V (“off”))
T
J
= 25°C
T
J
=
−40
to +125°C
ON/OFF Pin Logic Input Level (Test Circuit Figure 14)
V
out
= 0 V
T
J
= 25°C
T
J
=
−40
to +125°C
V
out
= Nominal Output Voltage
T
J
= 25°C
T
J
=
−40
to +125°C
ON/OFF Pin Input Current (Test Circuit Figure 14)
ON/OFF Pin = 5.0 V (“off”), T
J
= 25°C
ON/OFF Pin = 0 V (“on”), T
J
= 25°C
I
b
nA
−
−
−
47
42
−
−
94
1.7
1.4
−
−
−
−
15
−
25
−
52
−
−
1.0
−
98
2.3
−
0.8
6.0
5.0
−
80
−
100
200
kHz
−
58
63
V
1.2
1.3
−
3.0
3.2
mA
2.0
20
mA
9.0
11
200
400
mA
%
A
Symbol
Min
Typ
Max
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, V
in
= 12 V for the 3.3 V, 5.0 V, and Adjustable version, V
in
= 25 V
Unit
f
osc
V
sat
DC
I
CL
I
L
I
Q
I
stby
V
V
IH
2.2
2.4
−
−
−
−
1.4
−
1.2
−
15
0
−
−
1.0
0.8
30
5.0
mA
V
IL
I
IH
I
IL
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. V
in
= 40 V.
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LM2575, NCV2575
TYPICAL PERFORMANCE CHARACTERISTICS
(Circuit of Figure 14)
0.6
Vout , OUTPUT VOLTAGE CHANGE (%)
Vout , OUTPUT VOLTAGE CHANGE (%)
0.4
0.2
0
-0.2
-0.4
-0.6
-50
V
in
= 20 V
I
Load
= 200 mA
Normalized at
T
J
= 25°C
1.0
0.8
0.6
0.4
0.2
0
-0.2
12 V and 15 V
I
Load
= 200 mA
T
J
= 25°C
3.3 V, 5.0 V and Adj
-25
0
25
50
75
100
125
0
5.0
10
15
20
25
30
35
40
T
J
, JUNCTION TEMPERATURE (°C)
V
in
, INPUT VOLTAGE (V)
Figure 2. Normalized Output Voltage
Figure 3. Line Regulation
1.2
Vsat , SATURATION VOLTAGE (V)
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0
125°C
25°C
-40°C
IO , OUTPUT CURRENT (A)
3.0
2.5
2.0
1.5
1.0
0.5
V
in
= 25 V
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0
-50
-25
0
25
50
75
100
125
SWITCH CURRENT (A)
T
J
, JUNCTION TEMPERATURE (°C)
Figure 4. Switch Saturation Voltage
Figure 5. Current Limit
2.0
INPUT-OUTPUT DIFFERENTIAL (V)
IQ , QUIESCENT CURRENT (mA)
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
-50
-25
0
25
50
75
100
125
I
Load
= 200 mA
I
Load
= 1.0 A
DV
out
= 5%
R
ind
= 0.2
W
20
18
16
14
12
10
8.0
6.0
4.0
0
5.0
10
15
20
25
30
35
40
I
Load
= 200 mA
I
Load
= 1.0 A
V
out
= 5.0 V
Measured at
Ground Pin
T
J
= 25°C
T
J
, JUNCTION TEMPERATURE (°C)
V
in
, INPUT VOLTAGE (V)
Figure 6. Dropout Voltage
Figure 7. Quiescent Current
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