LM2574N-12/NOPB [TI]
具有 4 个外部组件的 8V 至 40V、500mA SIMPLE SWITCHER® 降压转换器 | P | 8 | -40 to 125;
| 型号： | LM2574N-12/NOPB |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | 具有 4 个外部组件的 8V 至 40V、500mA SIMPLE SWITCHER® 降压转换器 | P | 8 | -40 to 125 开关 光电二极管 转换器 |
| 文件： | 总35页 (文件大小：2714K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LM2574, LM2574HV
www.ti.com
SNVS104C –JUNE 1999–REVISED APRIL 2013
LM2574/LM2574HV SIMPLE SWITCHER™ 0.5A Step-Down Voltage Regulator
Check for Samples: LM2574, LM2574HV
1
FEATURES
DESCRIPTION
The LM2574 series of regulators are monolithic
23
•
3.3V, 5V, 12V, 15V, and Adjustable Output
Versions
integrated circuits that provide all the active functions
for a step-down (buck) switching regulator, capable of
driving a 0.5A 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.
•
Adjustable Version Output Voltage Range,
1.23V to 37V (57V for HV version) ±4% Max
Over Line and Load Conditions
•
•
Specified 0.5A Output Current
Wide Input Voltage Range, 40V, up to 60V for
HV Version
Requiring
a
minimum number of external
components, these regulators are simple to use and
include internal frequency compensation and a fixed-
frequency oscillator.
•
•
•
Requires Only 4 External Components
52 kHz Fixed Frequency Internal Oscillator
The LM2574 series offers
a
high-efficiency
TTL Shutdown Capability, Low Power Standby
Mode
replacement for popular three-terminal linear
regulators. Because of its high efficiency, the copper
traces on the printed circuit board are normally the
only heat sinking needed.
•
•
•
High Efficiency
Uses Readily Available Standard Inductors
Thermal Shutdown and Current Limit
Protection
A standard series of inductors optimized for use with
the LM2574 are available from several different
manufacturers. This feature greatly simplifies the
design of switch-mode power supplies.
APPLICATIONS
Other features include a specified ±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.
•
Simple High-Efficiency Step-Down (Buck)
Regulator
•
•
•
Efficient Pre-Regulator for Linear Regulators
On-Card Switching Regulators
Positive to Negative Converter (Buck-Boost)
Typical Application (Fixed Output Voltage Versions)
Note: Pin numbers are for 8-pin PDIP package.
Figure 1.
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
SIMPLE SWITCHER is a trademark of Texas Instruments.
2
3
All other trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 1999–2013, Texas Instruments Incorporated
LM2574, LM2574HV
SNVS104C –JUNE 1999–REVISED APRIL 2013
www.ti.com
Connection Diagram
* No internal connection, but should be
soldered to PC board for best heat transfer.
Figure 3. 14-Lead Wide (Top View)
Figure 2. 8-Lead PDIP (Top View)
See Package Number P0008E
SOIC (NPA)
See Package Number NPA0014A
2
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These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
Absolute Maximum Ratings(1)(2)
Maximum Supply Voltage
LM2574
45V
63V
LM2574HV
ON /OFF Pin Input Voltage
Output Voltage to Ground
Minimum ESD Rating
−0.3V ≤ V ≤ +VIN
−1V
(Steady State)
(C = 100 pF, R = 1.5 kΩ)
2 kV
Storage Temperature Range
Lead Temperature
−65°C to +150°C
260°C
(Soldering, 10 seconds)
Maximum Junction Temperature
Power Dissipation
150°C
Internally Limited
(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 ensure specific performance limits. For ensured specifications and test
conditions, see the LM2574-3.3, LM2574HV-3.3 Electrical Characteristics.
(2) If Military/Aerospace specified devices are required, please contact the TI Sales Office/ Distributors for availability and specifications.
Operating Ratings
Temperature Range
LM2574/LM2574HV
LM2574
−40°C ≤ TJ ≤ +125°C
Supply Voltage
40V
60V
LM2574HV
LM2574-3.3, LM2574HV-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
LM2574-3.3
Units
LM2574HV-3.3
(Limits)
(1)
Typ
Limit
SYSTEM PARAMETERS Test Circuit in Figure 23 and Figure 24,(2)
VOUT
Output Voltage
VIN = 12V, ILOAD = 100 mA
3.3
V
3.234
3.366
V(Min)
V(Max)
VOUT
Output Voltage
LM2574
4.75V ≤ VIN ≤ 40V, 0.1A ≤ ILOAD ≤ 0.5A
3.3
V
3.168/3.135
3.432/3.465
V(Min)
V(Max)
VOUT
Output Voltage
LM2574HV
4.75V ≤ VIN ≤ 60V, 0.1A ≤ ILOAD ≤ 0.5A
3.3
72
3.168/3.135
3.450/3.482
V(Min)
V(Max)
η
Efficiency
VIN = 12V, ILOAD = 0.5A
%
(1) All limits specified 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 specified via correlation using standard Statistical Quality Control
(SQC) methods. All limits are used to calculate Average Outgoing Quality Level.
(2) External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance.
When the LM2574 is used as shown in the Figure 24 test circuit, system performance will be as shown in system parameters section of
Electrical Characteristics.
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LM2574-5.0, LM2574HV-5.0 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
LM2574-5.0
LM2574HV-5.0
Limit
Units
(Limits)
(1)
Typ
SYSTEM PARAMETERS Test Circuit in Figure 23 and Figure 24,(2)
VOUT
Output Voltage
VIN = 12V, ILOAD = 100 mA
5
V
4.900
5.100
V(Min)
V(Max)
VOUT
Output Voltage
LM2574
7V ≤ VIN ≤ 40V, 0.1A ≤ ILOAD ≤ 0.5A
5
V
4.800/4.750
5.200/5.250
V(Min)
V(Max)
VOUT
Output Voltage
LM2574HV
7V ≤ VIN ≤ 60V, 0.1A ≤ ILOAD ≤ 0.5A
5
4.800/4.750
5.225/5.275
V(Min)
V(Max)
η
Efficiency
VIN = 12V, ILOAD = 0.5A
77
%
(1) All limits specified 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 specified via correlation using standard Statistical Quality Control
(SQC) methods. All limits are used to calculate Average Outgoing Quality Level.
(2) External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance.
When the LM2574 is used as shown in the Figure 24 test circuit, system performance will be as shown in system parameters section of
Electrical Characteristics.
LM2574-12, LM2574HV-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
LM2574-12
Units
LM2574HV-12
(Limits)
(1)
Typ
Limit
SYSTEM PARAMETERS Test Circuit in Figure 23 and Figure 24,(2)
VOUT
Output Voltage
VIN = 25V, ILOAD = 100 mA
12
V
11.76
12.24
V(Min)
V(Max)
VOUT
Output Voltage
LM2574
15V ≤ VIN ≤ 40V, 0.1A ≤ ILOAD ≤ 0.5A
12
V
11.52/11.40
12.48/12.60
V(Min)
V(Max)
VOUT
Output Voltage
LM2574HV
15V ≤ VIN ≤ 60V, 0.1A ≤ ILOAD ≤ 0.5A
12
88
11.52/11.40
12.54/12.66
V(Min)
V(Max)
η
Efficiency
VIN = 15V, ILOAD = 0.5A
%
(1) All limits specified 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 specified via correlation using standard Statistical Quality Control
(SQC) methods. All limits are used to calculate Average Outgoing Quality Level.
(2) External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance.
When the LM2574 is used as shown in the Figure 24 test circuit, system performance will be as shown in system parameters section of
Electrical Characteristics.
4
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LM2574-15, LM2574HV-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
LM2574-15
Units
LM2574HV-15
(Limits)
(1)
Typ
Limit
SYSTEM PARAMETERS Test Circuit in Figure 23 and Figure 24,(2)
VOUT
Output Voltage
VIN = 30V, ILOAD = 100 mA
15
V
14.70
15.30
V(Min)
V(Max)
VOUT
Output Voltage
LM2574
18V ≤ VIN ≤ 40V, 0.1A ≤ ILOAD ≤ 0.5A
15
V
14.40/14.25
15.60/15.75
V(Min)
V(Max)
VOUT
Output Voltage
LM2574HV
18V ≤ VIN ≤ 60V, 0.1A ≤ ILOAD ≤ 0.5A
15
88
14.40/14.25
15.68/15.83
V(Min)
V(Max)
η
Efficiency
VIN = 18V, ILOAD = 0.5A
%
(1) All limits specified 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 specified via correlation using standard Statistical Quality Control
(SQC) methods. All limits are used to calculate Average Outgoing Quality Level.
(2) External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance.
When the LM2574 is used as shown in the Figure 24 test circuit, system performance will be as shown in system parameters section of
Electrical Characteristics.
LM2574-ADJ, LM2574HV-ADJ 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, VIN = 12V, ILOAD = 100 mA.
Symbol
Parameter
Conditions
LM2574-ADJ
Units
LM2574HV-ADJ
(Limits)
(1)
Typ
Limit
SYSTEM PARAMETERS Test Circuit in Figure 23 and Figure 24(2)
VFB
VFB
VFB
Feedback Voltage
VIN = 12V, ILOAD = 100 mA
1.230
1.230
1.230
V
1.217
1.243
V(Min)
V(Max)
Feedback Voltage
LM2574
7V ≤ VIN ≤ 40V, 0.1A ≤ ILOAD ≤ 0.5A
VOUT Programmed for 5V. Circuit of Figure 24
V
1.193/1.180
1.267/1.280
V(Min)
V(Max)
Feedback Voltage
LM2574HV
7V ≤ VIN ≤ 60V, 0.1A ≤ ILOAD ≤ 0.5A
VOUT Programmed for 5V. Circuit of Figure 24
1.193/1.180
1.273/1.286
V(Min)
V(Max)
η
Efficiency
VIN = 12V, VOUT = 5V, ILOAD = 0.5A
77
%
(1) All limits specified 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 specified via correlation using standard Statistical Quality Control
(SQC) methods. All limits are used to calculate Average Outgoing Quality Level.
(2) External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance.
When the LM2574 is used as shown in the Figure 24 test circuit, system performance will be as shown in system parameters section of
Electrical Characteristics.
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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, VIN = 12V for the 3.3V, 5V, and Adjustable version, VIN = 25V for the 12V
version, and VIN = 30V for the 15V version. ILOAD = 100 mA.
Symbol
Parameter
Conditions
LM2574-XX
Units
LM2574HV-XX
(Limits)
(1)
Typ
Limit
DEVICE PARAMETERS
Ib
Feedback Bias
Current
Adjustable Version Only, VOUT = 5V
50
52
100/500
nA
(2)
fO
Oscillator Frequency
See
kHz
47/42
58/63
kHz(Min)
kHz(Max)
(3)
VSAT
DC
Saturation Voltage
Max Duty Cycle (ON)
Current Limit
IOUT = 0.5A
0.9
98
V
1.2/1.4
V(max)
(4)
See
%
%(Min)
93
(3)(2)
ICL
Peak Current
1.0
A
0.7/0.65
1.6/1.8
A(Min)
A(Max)
IL
Current
Output Leakage
Output = 0V
Output = −1V
Output = −1V
2
mA(Max)
mA
mA(Max)
7.5
5
(5) (6)
30
(5)
IQ
Quiescent Current
See
mA
10
mA(Max)
ISTBY
Standby Quiescent
Current
ON /OFF Pin= 5V (OFF)
50
μA
μA(Max)
200
(7)
θJA
θJA
θJA
θJA
Thermal Resistance
P Package, Junction to Ambient
P Package, Junction to Ambient
92
72
10
(8)
°C/W
(7)
(8)
NPA Package, Junction to Ambient
NPA Package, Junction to Ambient
2 78
ON /OFF CONTROL Test Circuit Figure 24
VIH
VIL
IH
ON /OFF Pin Logic
Input Level
VOUT = 0V
1.4
1.2
12
2.2/2.4
1.0/0.8
V(Min)
V(Max)
VOUT = Nominal Output Voltage
ON /OFF Pin = 5V (OFF)
ON /OFF Pin Input
Current
μA
μA(Max)
30
10
IIL
ON /OFF Pin = 0V (ON)
0
μA
μA(Max)
(1) All limits specified 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 specified via correlation using standard Statistical Quality Control
(SQC) methods. All limits are used to calculate Average Outgoing Quality Level.
(2) 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 power
dissipation of the IC by lowering the minimum duty cycle from 5% down to approximately 2%.Figure 9
(3) Output pin sourcing current. No diode, inductor or capacitor connected to output pin.
(4) Feedback pin removed from output and connected to 0V.
(5) 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.
(6) VIN = 40V (60V for high voltage version).
(7) Junction to ambient thermal resistance with approximately 1 square inch of printed circuit board copper surrounding the leads. Additional
copper area will lower thermal resistance further. See Application Hints in this data sheet and the thermal model in Switchers Made
Simple software.
(8) Junction to ambient thermal resistance with approximately 4 square inches of 1 oz. (0.0014 in. thick) printed circuit board copper
surrounding the leads. Additional copper area will lower thermal resistance further (See Note 7)
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Typical Performance Characteristics
(Circuit of Figure 24)
Normalized Output Voltage
Line Regulation
Figure 4.
Figure 5.
Dropout Voltage
Current Limit
Figure 6.
Figure 7.
Standby
Quiescent Current
Supply Current
Figure 8.
Figure 9.
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Typical Performance Characteristics (continued)
(Circuit of Figure 24)
Switch Saturation
Voltage
Oscillator Frequency
Figure 10.
Efficiency
Figure 11.
Minimum Operating Voltage
Figure 12.
Figure 13.
Supply Current
vs Duty Cycle
Feedback Voltage
vs Duty Cycle
Figure 14.
Figure 15.
8
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Typical Performance Characteristics (continued)
(Circuit of Figure 24)
Feedback
Pin Current
Junction to Ambient
Thermal Resistance
Figure 16.
Figure 17.
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Typical Performance Characteristics
(Circuit of Figure 24)
Continuous Mode Switching Waveforms
VOUT = 5V, 500 mA Load Current, L = 330 μH
Discontinuous Mode Switching Waveforms
VOUT = 5V, 100 mA Load Current, L = 100 μH
Notes:
Notes:
A: Output Pin Voltage, 10V/div
B: Inductor Current, 0.2 A/div
C: Output Ripple Voltage, 20 mV/div,
AC-Coupled
A: Output Pin Voltage, 10V/div
B: Inductor Current, 0.2 A/div
C: Output Ripple Voltage, 20 mV/div,
AC-Coupled
Horizontal Time Base: 5 μs/div
Horizontal Time Base: 5 μs/div
Figure 18.
Figure 19.
500 mA Load Transient Response for Continuous
250 mA Load Transient Response for Discontinuous
Mode Operation. L = 330 μH, COUT = 300 μF
Mode Operation. L = 68 μH, COUT = 470 μF
Notes:
Notes:
A: Output Voltage, 50 mV/div.
AC Coupled
A: Output Voltage, 50 mV/div.
AC Coupled
B: 100 mA to 500 mA Load Pulse
Horizontal Time Base: 200 μs/div
B: 50 mA to 250 mA Load Pulse
Horizontal Time Base: 200 μs/div
Figure 20.
Figure 21.
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Block Diagram
R1 = 1k
3.3V, R2 = 1.7k
5V, R2 = 3.1k
12V, R2 = 8.84k
15V, R2 = 11.3k
For Adj. Version
R1 = Open, R2 = 0Ω
Note: Pin numbers are for the 8-pin PDIP package.
Figure 22.
Test Circuit and Layout Guidelines
CIN — 22 μF, 75V
Aluminum Electrolytic
COUT — 220 μF, 25V
Aluminum Electrolytic
D1 — Schottky, 11DQ06
L1 — 330 μH, 52627
(for 5V in, 3.3V out, use
100 μH, RL-1284-100)
R1 — 2k, 0.1%
R2 — 6.12k, 0.1%
Figure 23. Fixed Output Voltage Versions
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Figure 24. Adjustable Output Voltage Version
As in any switching regulator, layout is very important. Rapidly switching currents associated with wiring
inductance generate voltage transients which can cause problems. For minimal inductance and ground loops, the
length of the leads indicated by heavy lines should be kept as short as possible. Single-point grounding (as
indicated) or ground plane construction should be used for best results. When using the Adjustable version,
physically locate the programming resistors near the regulator, to keep the sensitive feedback wiring short.
Table 1. Inductor Selection by Manufacturer's Part Number
Inductor Value
68 μH
Pulse Eng.
Renco
NPI
NP5915
NP5916
NP5917
NP5918/5919
NP5920/5921
NP5922
NP5923
*
*
RL-1284-68-43
RL-1284-100-43
RL-1284-150-43
RL-1284-220-43
RL-1284-330-43
RL-1284-470-43
RL-1283-680-43
RL-1283-1000-43
RL-1283-1500-43
RL-1283-2200-43
100 μH
*
150 μH
52625
52626
52627
52628
52629
52631
*
220 μH
330 μH
470 μH
680 μH
1000 μH
1500 μH
2200 μH
*
*
*
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LM2574 Series Buck Regulator Design Procedure
PROCEDURE (Fixed Output Voltage Versions)
EXAMPLE (Fixed Output Voltage Versions)
Given:
Given:
VOUT = 5V
VOUT = Regulated Output Voltage (3.3V, 5V, 12V, or 15V)
VIN(Max) = Maximum Input Voltage
ILOAD(Max) = Maximum Load Current
VIN(Max) = 15V
ILOAD(Max) = 0.4A
1. Inductor Selection (L1)
1. Inductor Selection (L1)
A. Select the correct Inductor value selection guide from Figure 25, A. Use the selection guide shown in Figure 26.
Figure 26, Figure 27, or Figure 28. (Output voltages of 3.3V, 5V, 12V
or 15V respectively). For other output voltages, see the design
procedure for the adjustable version.
B. From the selection guide, the inductance area intersected by the
15V line and 0.4A line is 330.
C. Inductor value required is 330 μH. From Table 1, choose Pulse
Engineering PE-52627, Renco RL-1284-330, or NPI NP5920/5921.
B. From the inductor value selection guide, identify the inductance
region intersected by VIN(Max) and ILOAD(Max).
C. Select an appropriate inductor from Table 1. Part numbers are
listed for three inductor manufacturers. The inductor chosen must be
rated for operation at the LM2574 switching frequency (52 kHz) and
for a current rating of 1.5 × ILOAD. For additional inductor information,
see INDUCTOR SELECTION in Application Hints of this data sheet.
2. Output Capacitor Selection (COUT
)
2. Output Capacitor Selection (COUT)
A. The value of the output capacitor together with the inductor A. COUT = 100 μF to 470 μF standard aluminum electrolytic.
defines the dominate pole-pair of the switching regulator loop. For
B. Capacitor voltage rating = 20V.
stable operation and an acceptable output ripple voltage,
(approximately 1% of the output voltage) a value between 100 μF
and 470 μF is recommended.
B. The capacitor's voltage rating should be at least 1.5 times greater
than the output voltage. For a 5V regulator, a rating of at least 8V is
appropriate, and a 10V or 15V rating is recommended.
Higher voltage electrolytic capacitors generally have lower ESR
numbers, and for this reason it may be necessary to select a
capacitor rated for a higher voltage than would normally be needed.
3. Catch Diode Selection (D1)
3. Catch Diode Selection (D1)
A. The catch-diode current rating must be at least 1.5 times greater A. For this example, a 1A current rating is adequate.
than the maximum load current. Also, if the power supply design
B. Use a 20V 1N5817 or SR102 Schottky diode, or any of the
must withstand a continuous output short, the diode should have a
suggested fast-recovery diodes shown in Table 2.
current rating equal to the maximum current limit of the LM2574. The
most stressful condition for this diode is an overload or shorted
output condition.
B. The reverse voltage rating of the diode should be at least 1.25
times the maximum input voltage.
4. Input Capacitor (CIN
An aluminum or tantalum electrolytic bypass capacitor located close A 22 μF aluminum electrolytic capacitor located near the input and
to the regulator is needed for stable operation. ground pins provides sufficient bypassing.
)
4. Input Capacitor (CIN)
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INDUCTOR VALUE SELECTION GUIDES
(For Continuous Mode Operation)
Figure 25. LM2574HV-3.3 Inductor Selection Guide Figure 26. LM2574HV-5.0 Inductor Selection Guide
Figure 27. LM2574HV-12 Inductor Selection Guide
Figure 28. LM2574HV-15 Inductor Selection Guide
Figure 29. LM2574HV-ADJ Inductor Selection Guide
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PROCEDURE (Adjustable Output Voltage Versions)
EXAMPLE (Adjustable Output Voltage Versions)
Given:
Given:
VOUT = Regulated Output Voltage
VIN(Max) = Maximum Input Voltage
ILOAD(Max) = Maximum Load Current
F = Switching Frequency (Fixed at 52 kHz)
VOUT = 24V
VIN(Max) = 40V
ILOAD(Max) = 0.4A
F = 52 kHz
1. Programming Output Voltage (Selecting R1 and R2, as shown 1. Programming Output Voltage (Selecting R1 and R2)
in Figure 24)
Use the following formula to select the appropriate resistor values.
R1 can be between 1k and 5k. (For best temperature coefficient and
stability with time, use 1% metal film resistors)
R2 = 1k (19.51−1) = 18.51k, closest 1% value is 18.7k
2. Inductor Selection (L1)
2. Inductor Selection (L1)
A. Calculate the inductor Volt • microsecond constant,
E • T (V • μs), from the following formula:
A. Calculate E • T (V • μs)
B. E • T = 185 V • μs
C. ILOAD(Max) = 0.4A
B. Use the E • T value from the previous formula and match it with
the E • T number on the vertical axis of the Inductor Value
Selection Guide shown in Figure 29.
D. Inductance Region = 1000
E. Inductor Value = 1000 μH Choose from Pulse Engineering Part
#PE-52631, or Renco Part #RL-1283-1000.
C. On the horizontal axis, select the maximum load current.
D. Identify the inductance region intersected by the E • T value and
the maximum load current value, and note the inductor value for that
region.
E. Select an appropriate inductor from the table shown in Table 1.
Part numbers are listed for three inductor manufacturers. The
inductor chosen must be rated for operation at the LM2574 switching
frequency (52 kHz) and for a current rating of 1.5 × ILOAD. For
additional inductor information, see INDUCTOR SELECTION in
Application Hints of this data sheet.
3. Output Capacitor Selection (COUT
)
3. Output Capacitor Selection (COUT)
A. The value of the output capacitor together with the inductor
defines the dominate pole-pair of the switching regulator loop. For
stable operation, the capacitor must satisfy the following
requirement:
However, for acceptable output ripple voltage select
OUT ≥ 100 μF
COUT = 100 μF electrolytic capacitor
C
The above formula yields capacitor values between 5 μF and 1000
μF that will satisfy the loop requirements for stable operation. But to
achieve an acceptable output ripple voltage, (approximately 1% of
the output voltage) and transient response, the output capacitor may
need to be several times larger than the above formula yields.
B. The capacitor's voltage rating should be at last 1.5 times greater
than the output voltage. For a 24V regulator, a rating of at least 35V
is recommended.
Higher voltage electrolytic capacitors generally have lower ESR
numbers, and for this reasion it may be necessary to select a
capacitor rate for a higher voltage than would normally be needed.
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PROCEDURE (Adjustable Output Voltage Versions)
4. Catch Diode Selection (D1)
EXAMPLE (Adjustable Output Voltage Versions)
4. Catch Diode Selection (D1)
A. The catch-diode current rating must be at least 1.5 times greater A. For this example, a 1A current rating is adequate.
than the maximum load current. Also, if the power supply design
B. Use a 50V MBR150 or 11DQ05 Schottky diode, or any of the
suggested fast-recovery diodes in Table 2.
must withstand a continuous output short, the diode should have a
current rating equal to the maximum current limit of the LM2574. The
most stressful condition for this diode is an overload or shorted
output condition. Suitable diodes are shown in Table 2.
B. The reverse voltage rating of the diode should be at least 1.25
times the maximum input voltage.
5. Input Capacitor (CIN
)
5. Input Capacitor (CIN)
An aluminum or tantalum electrolytic bypass capacitor located close A 22 μF aluminum electrolytic capacitor located near the input and
to the regulator is needed for stable operation.
ground pins provides sufficient bypassing. (See Table 2).
To further simplify the buck regulator design procedure, TI is making
available computer design software to be used with the Simple
Switcher line of switching regulators. Switchers Made Simple
(version 3.3) is available on a (3½″) diskette for IBM compatible
computers from a TI sales office in your area.
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Table 2. Diode Selection Guide
VR
1 Amp Diodes
Schottky
Fast Recovery
20V
1N5817
SR102
MBR120P
30V
40V
1N5818
SR103
11DQ03
MBR130P
10JQ030
The following diodes are all rated to 100V
11DF1
10JF1
MUR110
HER102
1N5819
SR104
11DQ04
11JQ04
MBR140P
50V
60V
90V
MBR150
SR105
11DQ05
11JQ05
MBR160
SR106
11DQ06
11JQ06
11DQ09
APPLICATION HINTS
INPUT CAPACITOR (CIN)
To maintain stability, the regulator input pin must be bypassed with at least a 22 μF electrolytic capacitor. The
capacitor's leads must be kept short, and located near the regulator.
If the operating temperature range includes temperatures below −25°C, the input capacitor value may need to be
larger. With most electrolytic capacitors, the capacitance value decreases and the ESR increases with lower
temperatures and age. Paralleling a ceramic or solid tantalum capacitor will increase the regulator stability at cold
temperatures. For maximum capacitor operating lifetime, the capacitor's RMS ripple current rating should be
greater than
(1)
INDUCTOR SELECTION
All switching regulators have two basic modes of operation: continuous and discontinuous. The difference
between the two types relates to the inductor current, whether it is flowing continuously, or if it drops to zero for a
period of time in the normal switching cycle. Each mode has distinctively different operating characteristics,
which can affect the regulator performance and requirements.
The LM2574 (or any of the Simple Switcher family) can be used for both continuous and discontinuous modes of
operation.
In many cases the preferred mode of operation is in the continuous mode. It offers better load regulation, lower
peak switch, inductor and diode currents, and can have lower output ripple voltage. But it does require relatively
large inductor values to keep the inductor current flowing continuously, especially at low output load currents.
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To simplify the inductor selection process, an inductor selection guide (nomograph) was designed (see Figure 25
through Figure 29). This guide assumes continuous mode operation, and selects an inductor that will allow a
peak-to-peak inductor ripple current (ΔIIND) to be a certain percentage of the maximum design load current. In the
LM2574 SIMPLE SWITCHER, the peak-to-peak inductor ripple current percentage (of load current) is allowed to
change as different design load currents are selected. By allowing the percentage of inductor ripple current to
increase for lower current applications, the inductor size and value can be kept relatively low.
INDUCTOR RIPPLE CURRENT
When the switcher is operating in the continuous mode, the inductor current waveform ranges from a triangular
to a sawtooth type of waveform (depending on the input voltage). For a given input voltage and output voltage,
the peak-to-peak amplitude of this inductor current waveform remains constant. As the load current rises or falls,
the entire sawtooth current waveform also rises or falls. The average DC value of this waveform is equal to the
DC load current (in the buck regulator configuration).
If the load current drops to a low enough level, the bottom of the sawtooth current waveform will reach zero, and
the switcher will change to a discontinuous mode of operation. This is a perfectly acceptable mode of operation.
Any buck switching regulator (no matter how large the inductor value is) will be forced to run discontinuous if the
load current is light enough.
The curve shown in Figure 30 illustrates how the peak-to-peak inductor ripple current (ΔIIND) is allowed to change
as different maximum load currents are selected, and also how it changes as the operating point varies from the
upper border to the lower border within an inductance region (see INDUCTOR SELECTION).
Figure 30. Inductor Ripple Current (ΔIIND) Range
Based on Selection Guides from Figure 25 through Figure 29.
Consider the following example:
VOUT = 5V @ 0.4A
VIN = 10V minimum up to 20V maximum
The selection guide in Figure 26 shows that for a 0.4A load current, and an input voltage range between 10V and
20V, the inductance region selected by the guide is 330 μH. This value of inductance will allow a peak-to-peak
inductor ripple current (ΔIIND) to flow that will be a percentage of the maximum load current. For this inductor
value, the ΔIIND will also vary depending on the input voltage. As the input voltage increases to 20V, it
approaches the upper border of the inductance region, and the inductor ripple current increases. Referring to the
curve in Figure 30, it can be seen that at the 0.4A load current level, and operating near the upper border of the
330 μH inductance region, the ΔIIND will be 53% of 0.4A, or 212 mA p-p.
This ΔIIND is important because from this number the peak inductor current rating can be determined, the
minimum load current required before the circuit goes to discontinuous operation, and also, knowing the ESR of
the output capacitor, the output ripple voltage can be calculated, or conversely, measuring the output ripple
voltage and knowing the ΔIIND, the ESR can be calculated.
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From the previous example, the Peak-to-peak Inductor Ripple Current (ΔIIND) = 212 mA p-p. Once the ΔIND value
is known, the following three formulas can be used to calculate additional information about the switching
regulator circuit:
1. Peak Inductor or peak switch current
(2)
2. Minimum load current before the circuit becomes discontinuous
(3)
3. Output Ripple Voltage = (ΔIIND) × (ESR of COUT
)
The selection guide chooses inductor values suitable for continuous mode operation, but if the inductor value
chosen is prohibitively high, the designer should investigate the possibility of discontinuous operation. The
computer design software Switchers Made Simple will provide all component values for discontinuous (as well
as continuous) mode of operation.
Inductors are available in different styles such as pot core, toroid, E-frame, bobbin core, etc., as well as different
core materials, such as ferrites and powdered iron. The least expensive, the bobbin core type, consists of wire
wrapped on a ferrite rod core. This type of construction makes for an inexpensive inductor, but since the
magnetic flux is not completely contained within the core, it generates more electro-magnetic interference (EMI).
This EMl can cause problems in sensitive circuits, or can give incorrect scope readings because of induced
voltages in the scope probe.
The inductors listed in the selection chart include powdered iron toroid for Pulse Engineering, and ferrite bobbin
core for Renco.
An inductor should not be operated beyond its maximum rated current because it may saturate. When an
inductor begins to saturate, the inductance decreases rapidly and the inductor begins to look mainly resistive (the
DC resistance of the winding). This can cause the inductor current to rise very rapidly and will affect the energy
storage capabilities of the inductor and could cause inductor overheating. Different inductor types have different
saturation characteristics, and this should be kept in mind when selecting an inductor. The inductor
manufacturers' data sheets include current and energy limits to avoid inductor saturation.
OUTPUT CAPACITOR
An output capacitor is required to filter the output voltage and is needed for loop stability. The capacitor should
be located near the LM2574 using short pc board traces. Standard aluminum electrolytics are usually adequate,
but low ESR types are recommended for low output ripple voltage and good stability. The ESR of a capacitor
depends on many factors, some which are: the value, the voltage rating, physical size and the type of
construction. In general, low value or low voltage (less than 12V) electrolytic capacitors usually have higher ESR
numbers.
The amount of output ripple voltage is primarily a function of the ESR (Equivalent Series Resistance) of the
output capacitor and the amplitude of the inductor ripple current (ΔIIND). See INDUCTOR RIPPLE CURRENT
(ΔIIND) in Application Hints.
The lower capacitor values (100 μF- 330 μF) will allow typically 50 mV to 150 mV of output ripple voltage, while
larger-value capacitors will reduce the ripple to approximately 20 mV to 50 mV.
Output Ripple Voltage = (ΔIIND) (ESR of COUT
)
To further reduce the output ripple voltage, several standard electrolytic capacitors may be paralleled, or a
higher-grade capacitor may be used. Such capacitors are often called “high-frequency,” “low-inductance,” or
“low-ESR.” These will reduce the output ripple to 10 mV or 20 mV. However, when operating in the continuous
mode, reducing the ESR below 0.03Ω can cause instability in the regulator.
Tantalum capacitors can have a very low ESR, and should be carefully evaluated if it is the only output capacitor.
Because of their good low temperature characteristics, a tantalum can be used in parallel with aluminum
electrolytics, with the tantalum making up 10% or 20% of the total capacitance.
The capacitor's ripple current rating at 52 kHz should be at least 50% higher than the peak-to-peak inductor
ripple current.
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CATCH DIODE
Buck regulators require a diode to provide a return path for the inductor current when the switch is off. This diode
should be located close to the LM2574 using short leads and short printed circuit traces.
Because of their fast switching speed and low forward voltage drop, Schottky diodes provide the best efficiency,
especially in low output voltage switching regulators (less than 5V). Fast-Recovery, High-Efficiency, or Ultra-Fast
Recovery diodes are also suitable, but some types with an abrupt turn-off characteristic may cause instability and
EMI problems. A fast-recovery diode with soft recovery characteristics is a better choice. Standard 60 Hz diodes
(e.g., 1N4001 or 1N5400, etc.) are also not suitable. See Table 2 for Schottky and “soft” fast-recovery diode
selection guide.
OUTPUT VOLTAGE RIPPLE AND TRANSIENTS
The output voltage of a switching power supply will contain a sawtooth ripple voltage at the switcher frequency,
typically about 1% of the output voltage, and may also contain short voltage spikes at the peaks of the sawtooth
waveform.
The output ripple voltage is due mainly to the inductor sawtooth ripple current multiplied by the ESR of the output
capacitor. (See INDUCTOR SELECTION in Application Hints.)
The voltage spikes are present because of the fast switching action of the output switch, and the parasitic
inductance of the output filter capacitor. To minimize these voltage spikes, special low inductance capacitors can
be used, and their lead lengths must be kept short. Wiring inductance, stray capacitance, as well as the scope
probe used to evaluate these transients, all contribute to the amplitude of these spikes.
An additional small LC filter (20 μH & 100 μF) can be added to the output (as shown in Figure 36) to further
reduce the amount of output ripple and transients. A 10 × reduction in output ripple voltage and transients is
possible with this filter.
FEEDBACK CONNECTION
The LM2574 (fixed voltage versions) feedback pin must be wired to the output voltage point of the switching
power supply. When using the adjustable version, physically locate both output voltage programming resistors
near the LM2574 to avoid picking up unwanted noise. Avoid using resistors greater than 100 kΩ because of the
increased chance of noise pickup.
ON /OFF INPUT
For normal operation, the ON /OFF pin should be grounded or driven with a low-level TTL voltage (typically
below 1.6V). To put the regulator into standby mode, drive this pin with a high-level TTL or CMOS signal. The
ON /OFF pin can be safely pulled up to +VIN without a resistor in series with it. The ON /OFF pin should not be
left open.
GROUNDING
The 8-pin molded PDIP and the 14-pin SOIC package have separate power and signal ground pins. Both ground
pins should be soldered directly to wide printed circuit board copper traces to assure low inductance connections
and good thermal properties.
THERMAL CONSIDERATIONS
The 8-pin PDIP (P) package and the 14-pin SOIC (NPA) package are molded plastic packages with solid copper
lead frames. The copper lead frame conducts the majority of the heat from the die, through the leads, to the
printed circuit board copper, which acts as the heat sink. For best thermal performance, wide copper traces
should be used, and all ground and unused pins should be soldered to generous amounts of printed circuit board
copper, such as a ground plane. Large areas of copper provide the best transfer of heat (lower thermal
resistance) to the surrounding air, and even double-sided or multilayer boards provide better heat paths to the
surrounding air. Unless the power levels are small, using a socket for the 8-pin package is not recommended
because of the additional thermal resistance it introduces, and the resultant higher junction temperature.
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Because of the 0.5A current rating of the LM2574, the total package power dissipation for this switcher is quite
low, ranging from approximately 0.1W up to 0.75W under varying conditions. In a carefully engineered printed
circuit board, both the P and the NPA package can easily dissipate up to 0.75W, even at ambient temperatures
of 60°C, and still keep the maximum junction temperature below 125°C.
A curve, Figure 17, displaying thermal resistance vs. pc board area for the two packages is shown in Typical
Performance Characteristics of this data sheet.
These thermal resistance numbers are approximate, and there can be many factors that will affect the final
thermal resistance. Some of these factors include board size, shape, thickness, position, location, and board
temperature. Other factors are, the area of printed circuit copper, copper thickness, trace width, multi-layer,
single- or double-sided, and the amount of solder on the board. The effectiveness of the pc board to dissipate
heat also depends on the size, number and spacing of other components on the board. Furthermore, some of
these components, such as the catch diode and inductor will generate some additional heat. Also, the thermal
resistance decreases as the power level increases because of the increased air current activity at the higher
power levels, and the lower surface to air resistance coefficient at higher temperatures.
The data sheet thermal resistance curves and the thermal model in Switchers Made Simple software (version
3.3) can estimate the maximum junction temperature based on operating conditions. ln addition, the junction
temperature can be estimated in actual circuit operation by using the following equation.
Tj = Tcu + (θj-cu × PD)
(4)
With the switcher operating under worst case conditions and all other components on the board in the intended
enclosure, measure the copper temperature (Tcu ) near the IC. This can be done by temporarily soldering a small
thermocouple to the pc board copper near the IC, or by holding a small thermocouple on the pc board copper
using thermal grease for good thermal conduction.
The thermal resistance (θj-cu) for the two packages is:
θj-cu = 42°C/W for the P-8 package
θj-cu = 52°C/W for the NPA-14 package
The power dissipation (PD) for the IC could be measured, or it can be estimated by using the formula:
where
•
IS is obtained from the typical supply current curve (adjustable version use the supply current vs. duty cycle
curve).
(5)
Additional Applications
INVERTING REGULATOR
Figure 31 shows a LM2574-12 in a buck-boost configuration to generate a negative 12V output from a positive
input voltage. This circuit bootstraps the regulator's ground pin to the negative output voltage, then by grounding
the feedback pin, the regulator senses the inverted output voltage and regulates it to −12V.
Note: Pin numbers are for the 8-pin PDIP package.
Figure 31. Inverting Buck-Boost Develops −12V
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For an input voltage of 8V or more, the maximum available output current in this configuration is approximately
100 mA. At lighter loads, the minimum input voltage required drops to approximately 4.7V.
The switch currents in this buck-boost configuration are higher than in the standard buck-mode design, thus
lowering the available output current. Also, the start-up input current of the buck-boost converter is higher than
the standard buck-mode regulator, and this may overload an input power source with a current limit less than
0.6A. Using a delayed turn-on or an undervoltage lockout circuit (described in the next section) would allow the
input voltage to rise to a high enough level before the switcher would be allowed to turn on.
Because of the structural differences between the buck and the buck-boost regulator topologies, the LM2574
Series Buck Regulator Design Procedure can not be used to select the inductor or the output capacitor. The
recommended range of inductor values for the buck-boost design is between 68 μH and 220 μH, and the output
capacitor values must be larger than what is normally required for buck designs. Low input voltages or high
output currents require a large value output capacitor (in the thousands of micro Farads).
The peak inductor current, which is the same as the peak switch current, can be calculated from the following
formula:
where
•
•
fosc = 52 kHz. Under normal continuous inductor current operating conditions,
the minimum VIN represents the worst case. Select an inductor that is rated for the peak current anticipated.
(6)
Also, the maximum voltage appearing across the regulator is the absolute sum of the input and output voltage.
For a −12V output, the maximum input voltage for the LM2574 is +28V, or +48V for the LM2574HV.
The Switchers Made Simple version 3.3) design software can be used to determine the feasibility of regulator
designs using different topologies, different input-output parameters, different components, etc.
NEGATIVE BOOST REGULATOR
Another variation on the buck-boost topology is the negative boost configuration. The circuit in Figure 32 accepts
an input voltage ranging from −5V to −12V and provides a regulated −12V output. Input voltages greater than
−12V will cause the output to rise above −12V, but will not damage the regulator.
Note: Pin numbers are for 8-pin PDIP package.
Figure 32. Negative Boost
Because of the boosting function of this type of regulator, the switch current is relatively high, especially at low
input voltages. Output load current limitations are a result of the maximum current rating of the switch. Also,
boost regulators can not provide current limiting load protection in the event of a shorted load, so some other
means (such as a fuse) may be necessary.
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UNDERVOLTAGE LOCKOUT
In some applications it is desirable to keep the regulator off until the input voltage reaches a certain threshold. An
undervoltage lockout circuit which accomplishes this task is shown in Figure 33 while Figure 34 shows the same
circuit applied to a buck-boost configuration. These circuits keep the regulator off until the input voltage reaches
a predetermined level.
VTH ≈ VZ1 + 2VBE (Q1)
Note: Complete circuit not shown (see Figure 31).
Note: Pin numbers are for 8-pin PDIP package.
Figure 33. Undervoltage Lockout for Buck Circuit
Note: Complete circuit not shown (see Figure 31 ).
Note: Pin numbers are for 8-pin PDIP package.
Figure 34. Undervoltage Lockout
for Buck-Boost Circuit
DELAYED STARTUP
The ON /OFF pin can be used to provide a delayed startup feature as shown in Figure 35. With an input voltage
of 20V and for the part values shown, the circuit provides approximately 10 ms of delay time before the circuit
begins switching. Increasing the RC time constant can provide longer delay times. But excessively large RC time
constants can cause problems with input voltages that are high in 60 Hz or 120 Hz ripple, by coupling the ripple
into the ON /OFF pin.
ADJUSTABLE OUTPUT, LOW-RIPPLE POWER SUPPLY
A 500 mA power supply that features an adjustable output voltage is shown in Figure 36. An additional L-C filter
that reduces the output ripple by a factor of 10 or more is included in this circuit.
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Note: Complete circuit not shown.
Note: Pin numbers are for 8-pin PDIP package.
Figure 35. Delayed Startup
Note: Pin numbers are for 8-pin PDIP package.
Figure 36. 1.2V to 55V Adjustable 500 mA Power Supply with Low Output Ripple
Definition of Terms
BUCK REGULATOR
A switching regulator topology in which a higher voltage is converted to a lower voltage. Also known as a step-
down switching regulator.
BUCK-BOOST REGULATOR
A switching regulator topology in which a positive voltage is converted to a negative voltage without a
transformer.
DUTY CYCLE (D)
Ratio of the output switch's on-time to the oscillator period.
(7)
CATCH DIODE OR CURRENT STEERING DIODE
The diode which provides a return path for the load current when the LM2574 switch is OFF.
EFFICIENCY (η)
The proportion of input power actually delivered to the load.
(8)
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CAPACITOR EQUIVALENT SERIES RESISTANCE (ESR)
The purely resistive component of a real capacitor's impedance (see Figure 37). It causes power loss resulting in
capacitor heating, which directly affects the capacitor's operating lifetime. When used as a switching regulator
output filter, higher ESR values result in higher output ripple voltages.
Figure 37. Simple Model of a Real Capacitor
Most standard aluminum electrolytic capacitors in the 100 μF–1000 μF range have 0.5Ω to 0.1Ω ESR. Higher-
grade capacitors (“low-ESR”, “high-frequency”, or “low-inductance”) in the 100 μF–1000 μF range generally have
ESR of less than 0.15Ω.
EQUIVALENT SERIES INDUCTANCE (ESL)
The pure inductance component of a capacitor (see Figure 37). The amount of inductance is determined to a
large extent on the capacitor's construction. In a buck regulator, this unwanted inductance causes voltage spikes
to appear on the output.
OUTPUT RIPPLE VOLTAGE
The AC component of the switching regulator's output voltage. It is usually dominated by the output capacitor's
ESR multiplied by the inductor's ripple current (ΔIIND). The peak-to-peak value of this sawtooth ripple current can
be determined by readingINDUCTOR RIPPLE CURRENT (ΔIIND) of Application Hints.
CAPACITOR RIPPLE CURRENT
RMS value of the maximum allowable alternating current at which a capacitor can be operated continuously at a
specified temperature.
STANDBY QUIESCENT CURRENT (ISTBY
)
Supply current required by the LM2574 when in the standby mode (ON/OFF pin is driven to TTL-high voltage,
thus turning the output switch OFF).
INDUCTOR RIPPLE CURRENT (ΔIIND
)
The peak-to-peak value of the inductor current waveform, typically a sawtooth waveform when the regulator is
operating in the continuous mode (vs. discontinuous mode).
CONTINUOUS/DISCONTINUOUS MODE OPERATION
Relates to the inductor current. In the continuous mode, the inductor current is always flowing and never drops to
zero, vs. the discontinuous mode, where the inductor current drops to zero for a period of time in the normal
switching cycle.
INDUCTOR SATURATION
The condition which exists when an inductor cannot hold any more magnetic flux. When an inductor saturates,
the inductor appears less inductive and the resistive component dominates. Inductor current is then limited only
by the DC resistance of the wire and the available source current.
OPERATING VOLT MICROSECOND CONSTANT (E•Top)
The product (in VoIt•μs) of the voltage applied to the inductor and the time the voltage is applied. This E•Top
constant is a measure of the energy handling capability of an inductor and is dependent upon the type of core,
the core area, the number of turns, and the duty cycle.
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REVISION HISTORY
Changes from Revision B (April 2013) to Revision C
Page
•
Changed layout of National Data Sheet to TI format .......................................................................................................... 25
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Product Folder Links: LM2574 LM2574HV
PACKAGE OPTION ADDENDUM
www.ti.com
25-Feb-2014
PACKAGING INFORMATION
Orderable Device
LM2574HVM-12
Status Package Type Package Pins Package
Eco Plan
Lead/Ball Finish
MSL Peak Temp
Op Temp (°C)
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
Device Marking
Samples
Drawing
Qty
(1)
(2)
(6)
(3)
(4/5)
NRND
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
PDIP
PDIP
NPA
14
14
14
14
14
14
14
14
14
14
14
14
14
14
14
8
50
TBD
Call TI
CU SN
Call TI
Call TI
LM2574HVM
-12 P+
LM2574HVM-12/NOPB
LM2574HVM-15
ACTIVE
NRND
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
P
50
50
Green (RoHS
& no Sb/Br)
Level-3-260C-168 HR
Call TI
LM2574HVM
-12 P+
TBD
LM2574HVM
-15 P+
LM2574HVM-15/NOPB
LM2574HVM-3.3/NOPB
LM2574HVM-5.0
ACTIVE
ACTIVE
NRND
50
Green (RoHS
& no Sb/Br)
CU SN
CU SN
Call TI
Level-3-260C-168 HR
Level-3-260C-168 HR
Call TI
LM2574HVM
-15 P+
50
Green (RoHS
& no Sb/Br)
LM2574HVM
-3.3 P+
50
TBD
LM2574HVM
-5.0 P+
LM2574HVM-5.0/NOPB
LM2574HVM-ADJ
ACTIVE
NRND
50
Green (RoHS
& no Sb/Br)
CU SN
Call TI
Level-3-260C-168 HR
Call TI
LM2574HVM
-5.0 P+
50
TBD
LM2574HVM
-ADJ P+
LM2574HVM-ADJ/NOPB
LM2574HVMX-12/NOPB
LM2574HVMX-15/NOPB
LM2574HVMX-3.3/NOPB
LM2574HVMX-5.0
ACTIVE
ACTIVE
ACTIVE
ACTIVE
NRND
50
Green (RoHS
& no Sb/Br)
CU SN
CU SN
CU SN
CU SN
Call TI
Level-3-260C-168 HR
Level-3-260C-168 HR
Level-3-260C-168 HR
Level-4-260C-72 HR
Call TI
LM2574HVM
-ADJ P+
1000
1000
1000
1000
1000
1000
40
Green (RoHS
& no Sb/Br)
LM2574HVM
-12 P+
Green (RoHS
& no Sb/Br)
LM2574HVM
-15 P+
Green (RoHS
& no Sb/Br)
LM2574HVM
-3.3 P+
TBD
LM2574HVM
-5.0 P+
LM2574HVMX-5.0/NOPB
LM2574HVMX-ADJ/NOPB
LM2574HVN-12
ACTIVE
ACTIVE
LIFEBUY
ACTIVE
Green (RoHS
& no Sb/Br)
CU SN
CU SN
Call TI
Level-3-260C-168 HR
Level-3-260C-168 HR
Call TI
LM2574HVM
-5.0 P+
Green (RoHS
& no Sb/Br)
LM2574HVM
-ADJ P+
TBD
LM2574HVN
-12 P+
LM2574HVN-12/NOPB
P
8
40
Green (RoHS
& no Sb/Br)
SN | CU SN
Level-1-NA-UNLIM
LM2574HVN
-12 P+
Addendum-Page 1
PACKAGE OPTION ADDENDUM
www.ti.com
25-Feb-2014
Orderable Device
Status Package Type Package Pins Package
Eco Plan
Lead/Ball Finish
MSL Peak Temp
Op Temp (°C)
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
Device Marking
Samples
Drawing
Qty
(1)
(2)
(6)
(3)
(4/5)
LM2574HVN-15/NOPB
LM2574HVN-5.0
ACTIVE
PDIP
PDIP
PDIP
PDIP
PDIP
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
P
8
40
Green (RoHS
& no Sb/Br)
SN | CU SN
Level-1-NA-UNLIM
LM2574HVN
-15 P+
LIFEBUY
ACTIVE
LIFEBUY
ACTIVE
NRND
P
8
40
40
TBD
Call TI
Call TI
LM2574HVN
-5.0 P+
LM2574HVN-5.0/NOPB
LM2574HVN-ADJ
P
8
Green (RoHS
& no Sb/Br)
SN | CU SN
Call TI
Level-1-NA-UNLIM
Call TI
LM2574HVN
-5.0 P+
P
8
40
TBD
LM2574HVN
-ADJ P+
LM2574HVN-ADJ/NOPB
LM2574M-12
P
8
40
Green (RoHS
& no Sb/Br)
SN | CU SN
Call TI
Level-1-NA-UNLIM
Call TI
LM2574HVN
-ADJ P+
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
14
14
14
14
14
14
14
14
14
14
14
14
14
50
TBD
LM2574M
-12 P+
LM2574M-12/NOPB
LM2574M-3.3/NOPB
LM2574M-5.0
ACTIVE
ACTIVE
NRND
50
Green (RoHS
& no Sb/Br)
CU SN
CU SN
Call TI
Level-3-260C-168 HR
Level-3-260C-168 HR
Call TI
LM2574M
-12 P+
50
Green (RoHS
& no Sb/Br)
LM2574M
-3.3 P+
50
TBD
LM2574M
-5.0 P+
LM2574M-5.0/NOPB
LM2574M-ADJ
ACTIVE
NRND
50
Green (RoHS
& no Sb/Br)
CU SN
Call TI
Level-3-260C-168 HR
Call TI
LM2574M
-5.0 P+
50
TBD
LM2574M
-ADJ P+
LM2574M-ADJ/NOPB
LM2574MX-12/NOPB
LM2574MX-3.3/NOPB
LM2574MX-5.0
ACTIVE
ACTIVE
ACTIVE
NRND
50
Green (RoHS
& no Sb/Br)
CU SN
CU SN
CU SN
Call TI
Level-3-260C-168 HR
Level-3-260C-168 HR
Level-4-260C-72 HR
Call TI
LM2574M
-ADJ P+
1000
1000
1000
1000
1000
1000
Green (RoHS
& no Sb/Br)
LM2574M
-12 P+
Green (RoHS
& no Sb/Br)
LM2574M
-3.3 P+
TBD
LM2574M
-5.0 P+
LM2574MX-5.0/NOPB
LM2574MX-ADJ
ACTIVE
NRND
Green (RoHS
& no Sb/Br)
CU SN
Call TI
Level-3-260C-168 HR
Call TI
LM2574M
-5.0 P+
TBD
LM2574M
-ADJ P+
LM2574MX-ADJ/NOPB
ACTIVE
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
LM2574M
-ADJ P+
Addendum-Page 2
PACKAGE OPTION ADDENDUM
www.ti.com
25-Feb-2014
Orderable Device
Status Package Type Package Pins Package
Eco Plan
Lead/Ball Finish
MSL Peak Temp
Op Temp (°C)
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
Device Marking
Samples
Drawing
Qty
(1)
(2)
(6)
(3)
(4/5)
LM2574N-12
LM2574N-12/NOPB
LM2574N-3.3/NOPB
LM2574N-5.0
LIFEBUY
PDIP
PDIP
PDIP
PDIP
PDIP
PDIP
PDIP
P
8
8
8
8
8
8
8
40
TBD
Call TI
SN | CU SN
SN | CU SN
Call TI
Call TI
LM2574N
-12 P+
ACTIVE
ACTIVE
LIFEBUY
ACTIVE
LIFEBUY
ACTIVE
P
P
P
P
P
P
40
40
40
40
40
40
Green (RoHS
& no Sb/Br)
Level-1-NA-UNLIM
Level-1-NA-UNLIM
Call TI
LM2574N
-12 P+
Green (RoHS
& no Sb/Br)
LM2574N
-3.3 P+
TBD
LM2574N
-5.0 P+
LM2574N-5.0/NOPB
LM2574N-ADJ
Green (RoHS
& no Sb/Br)
SN | CU SN
Call TI
Level-1-NA-UNLIM
Call TI
LM2574N
-5.0 P+
TBD
LM2574N
-ADJ P+
LM2574N-ADJ/NOPB
Green (RoHS
& no Sb/Br)
SN | CU SN
Level-1-NA-UNLIM
LM2574N
-ADJ P+
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
Addendum-Page 3
PACKAGE OPTION ADDENDUM
www.ti.com
25-Feb-2014
(6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish
value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 4
PACKAGE MATERIALS INFORMATION
www.ti.com
23-Sep-2013
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
B0
K0
P1
W
Pin1
Diameter Width (mm) (mm) (mm) (mm) (mm) Quadrant
(mm) W1 (mm)
LM2574HVMX-12/NOPB
LM2574HVMX-15/NOPB
SOIC
SOIC
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
14
14
14
14
14
14
14
14
14
14
14
14
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
330.0
330.0
330.0
330.0
330.0
330.0
330.0
330.0
330.0
330.0
330.0
330.0
16.4
16.4
16.4
16.4
16.4
16.4
16.4
16.4
16.4
16.4
16.4
16.4
10.9
10.9
10.9
10.9
10.9
10.9
10.9
10.9
10.9
10.9
10.9
10.9
9.5
9.5
9.5
9.5
9.5
9.5
9.5
9.5
9.5
9.5
9.5
9.5
3.2
3.2
3.2
3.2
3.2
3.2
3.2
3.2
3.2
3.2
3.2
3.2
12.0
12.0
12.0
12.0
12.0
12.0
12.0
12.0
12.0
12.0
12.0
12.0
16.0
16.0
16.0
16.0
16.0
16.0
16.0
16.0
16.0
16.0
16.0
16.0
Q1
Q1
Q1
Q1
Q1
Q1
Q1
Q1
Q1
Q1
Q1
Q1
LM2574HVMX-3.3/NOPB SOIC
LM2574HVMX-5.0 SOIC
LM2574HVMX-5.0/NOPB SOIC
LM2574HVMX-ADJ/NOPB SOIC
LM2574MX-12/NOPB
LM2574MX-3.3/NOPB
LM2574MX-5.0
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
LM2574MX-5.0/NOPB
LM2574MX-ADJ
LM2574MX-ADJ/NOPB
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
23-Sep-2013
*All dimensions are nominal
Device
Package Type Package Drawing Pins
SPQ
Length (mm) Width (mm) Height (mm)
LM2574HVMX-12/NOPB
LM2574HVMX-15/NOPB
LM2574HVMX-3.3/NOPB
LM2574HVMX-5.0
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
SOIC
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
NPA
14
14
14
14
14
14
14
14
14
14
14
14
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
367.0
38.0
38.0
38.0
38.0
38.0
38.0
38.0
38.0
38.0
38.0
38.0
38.0
LM2574HVMX-5.0/NOPB
LM2574HVMX-ADJ/NOPB
LM2574MX-12/NOPB
LM2574MX-3.3/NOPB
LM2574MX-5.0
LM2574MX-5.0/NOPB
LM2574MX-ADJ
LM2574MX-ADJ/NOPB
Pack Materials-Page 2
MECHANICAL DATA
NPA0014B
www.ti.com
IMPORTANT NOTICE
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changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest
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TI warrants performance of its components to the specifications applicable at the time of sale, in accordance with the warranty in TI’s terms
and conditions of sale of semiconductor products. Testing and other quality control techniques are used to the extent TI deems necessary
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