LM2575S-3.3

Manufacturer Part NumberLM2575S-3.3
DescriptionIC REG SIMPLE SWITCHER TO-263-5
ManufacturerNational Semiconductor
SeriesSIMPLE SWITCHER®
TypeStep-Down (Buck)
LM2575S-3.3 datasheet
 


Specifications of LM2575S-3.3

Internal Switch(s)YesSynchronous RectifierNo
Number Of Outputs1Voltage - Output3.3V
Current - Output1AFrequency - Switching52kHz
Voltage - Input4 ~ 40 VOperating Temperature-40°C ~ 125°C
Mounting TypeSurface MountPackage / CaseD²Pak, TO-263 (5 leads + tab)
Lead Free Status / RoHS StatusContains lead / RoHS non-compliantPower - Output-
Other names*LM2575S-3.3  
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LM1575/LM2575/LM2575HV
SIMPLE SWITCHER
General Description
The LM2575 series of regulators are monolithic integrated
circuits that provide all the active functions for a step-down
(buck) switching regulator, capable of driving a 1A load with
excellent line and load regulation. These devices are avail-
able in fixed output voltages of 3.3V, 5V, 12V, 15V, and an
adjustable output version.
Requiring a minimum number of external components, these
regulators are simple to use and include internal frequency
compensation and a fixed-frequency oscillator.
The LM2575 series offers a high-efficiency replacement for
popular three-terminal linear regulators. It substantially re-
duces the size of the heat sink, and in many cases no heat
sink is required.
A standard series of inductors optimized for use with the
LM2575 are available from several different manufacturers.
This feature greatly simplifies the design of switch-mode pow-
er supplies.
Other features include a guaranteed ±4% tolerance on output
voltage within specified input voltages and output load con-
ditions, and ±10% on the oscillator frequency. External shut-
down 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 con-
ditions.
Typical Application
(Fixed Output Voltage Versions)
Note: Pin numbers are for the TO-220 package.
SIMPLE SWITCHER
®
is a registered trademark of National Semiconductor Corporation
© 2007 National Semiconductor Corporation
®
1A Step-Down Voltage Regulator
Features
3.3V, 5V, 12V, 15V, and adjustable output versions
Adjustable version output voltage range,
1.23V to 37V (57V for HV version) ±4% max over
line and load conditions
Guaranteed 1A output current
Wide input voltage range, 40V up to 60V for HV version
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
P
+
Product Enhancement tested
Applications
Simple high-efficiency step-down (buck) regulator
Efficient pre-regulator for linear regulators
On-card switching regulators
Positive to negative converter (Buck-Boost)
11475
April 2007
1147501
www.national.com

LM2575S-3.3 Summary of contents

  • Page 1

    ... Typical Application (Fixed Output Voltage Versions) Note: Pin numbers are for the TO-220 package. SIMPLE SWITCHER ® registered trademark of National Semiconductor Corporation © 2007 National Semiconductor Corporation ® 1A Step-Down Voltage Regulator Features ■ 3.3V, 5V, 12V, 15V, and adjustable output versions ■ ...

  • Page 2

    Block Diagram and Typical Application 3.3V 1.7k 5V 3.1k 12V 8.84k 15V 11.3k For ADJ. Version R1 = Open 0Ω Note: Pin numbers are for the TO-220 package. www.national.com FIGURE ...

  • Page 3

    ... Internal Connection LM2575M-XX or LM2575HVM-XX See NS Package Number M24B TO-263(S) 5-Lead Surface-Mount Package 1147529 Top View 1147530 Side View LM2575S-XX or LM2575HVS-XX See NS Package Number TS5B 3 1147524 Side View LM2575T-XX Flow LB03 or LM2575HVT-XX Flow LB03 See NS Package Number T05D 1147526 Top View ...

  • Page 4

    ... LM2575T-ADJ Flow LB03 LM2575HVT-ADJ Flow LB03 LM2575N-5.0 LM2575HVN-5.0 LM2575N-12 LM2575HVN-12 LM2575N-15 LM2575HVN-15 LM2575N-ADJ LM2575HVN-ADJ LM2575M-5.0 LM2575HVM-5.0 LM2575M-12 LM2575HVM-12 LM2575M-15 LM2575HVM-15 LM2575M-ADJ LM2575HVM-ADJ LM2575S-3.3 LM2575HVS-3.3 LM2575S-5.0 LM2575HVS-5.0 LM2575S-12 LM2575HVS-12 LM2575S-15 LM2575HVS-15 LM2575S-ADJ LM2575HVS-ADJ LM1575J-3.3-QML LM1575J-5.0-QML LM1575J-12-QML LM1575J-15-QML LM1575J-ADJ-QML 4 High Temperature Voltage Rating ...

  • Page 5

    ... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Maximum Supply Voltage LM1575/LM2575 LM2575HV ON /OFF Pin Input Voltage Output Voltage to Ground (Steady State) Power Dissipation Storage Temperature Range Maximum Junction Temperature LM1575-3 ...

  • Page 6

    Symbol Parameter V Output Voltage 0.2A OUT LM2575HV 8V Circuit of Figure 2 η Efficiency V LM1575-12, LM2575-12, LM2575HV-12 Electrical Characteristics Specifications with standard type face are for T Range . Symbol Parameter SYSTEM PARAMETERS (Note 4) Test Circuit Figure ...

  • Page 7

    LM1575-ADJ, LM2575-ADJ, LM2575HV-ADJ Electrical Characteristics Specifications with standard type face are for T Range. Symbol Parameter SYSTEM PARAMETERS (Note 4) Test Circuit Figure 2 V Feedback Voltage V OUT IN V OUT Circuit of Figure 2 V Feedback Voltage 0.2A ...

  • Page 8

    Symbol Parameter θ Thermal Resistance T Package, Junction to Ambient (Note 9) JA θ T Package, Junction to Ambient (Note 10) JA θ T Package, Junction to Case JC θ N Package, Junction to Ambient (Note 11) JA θ M ...

  • Page 9

    Typical Performance Characteristics Normalized Output Voltage Dropout Voltage Quiescent Current (Circuit of Figure 2) 1147532 1147534 1147536 9 Line Regulation 1147533 Current Limit 1147535 Standby Quiescent Current 1147537 www.national.com ...

  • Page 10

    Oscillator Frequency Efficiency Quiescent Current vs Duty Cycle www.national.com 1147538 Minimum Operating Voltage 1147540 1147542 10 Switch Saturation Voltage 1147539 1147541 Feedback Voltage vs Duty Cycle 1147543 ...

  • Page 11

    Feedback Pin Current Switching Waveforms OUT A: Output Pin Voltage, 10V/div B: Output Pin Current, 1A/div C: Inductor Current, 0.5A/div D: Output Ripple Voltage, 20 mV/div, AC-Coupled Horizontal Time Base: 5 μs/div Maximum Power Dissipation (TO-263) (See ...

  • Page 12

    Test Circuit and Layout Guidelines As in any switching regulator, layout is very important. Rapidly switching currents associated with wiring inductance gener- ate voltage transients which can cause problems. For minimal inductance and ground loops, the length of the leads ...

  • Page 13

    LM2575 Series Buck Regulator Design Procedure PROCEDURE (Fixed Output Voltage Versions) Given Regulated Output Voltage (3.3V, 5V, 12V, or 15V) OUT V (Max) = Maximum Input Voltage IN I (Max) = Maximum Load Current LOAD 1. Inductor Selection ...

  • Page 14

    Inductor Value Selection Guides (For Continuous Mode Operation) FIGURE 3. LM2575(HV)-3.3 FIGURE 4. LM2575(HV)-5.0 www.national.com 1147510 FIGURE 5. LM2575(HV)-12 1147511 FIGURE 6. LM2575(HV)-15 1147514 FIGURE 7. LM2575(HV)-ADJ 14 1147512 1147513 ...

  • Page 15

    PROCEDURE (Adjustable Output Voltage Versions) Given Regulated Output Voltage OUT V (Max) = Maximum Input Voltage IN I (Max) = Maximum Load Current LOAD F = Switching Frequency (Fixed at 52 kHz) 1. Programming Output Voltage (Selecting R1 ...

  • Page 16

    ... An aluminum or tantalum electrolytic bypass capacitor located close to the regulator is needed for stable operation. To further simplify the buck regulator design procedure, National Semiconductor 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 National Semiconductor sales office in your area ...

  • Page 17

    V R 20V 1N5817 MBR120P SR102 30V 1N5818 MBR130P 11DQ03 SR103 40V 1N5819 MBR140P 11DQ04 SR104 50V MBR150 11DQ05 SR105 60V MBR160 11DQ06 SR106 Inductor Inductor Code Value L100 L150 L220 L330 L470 L680 H150 H220 H330 H470 H680 H1000 ...

  • Page 18

    Application Hints INPUT CAPACITOR ( maintain stability, the regulator input pin must be bypassed with at least a 47 μF electrolytic capacitor. The capacitor's leads must be kept short, and located near the regulator. If the operating ...

  • Page 19

    The capacitor's ripple current rating at 52 kHz should be at least 50% higher than the peak-to-peak inductor ripple cur- ...

  • Page 20

    SO package, and 30°C/W for the N package can be realized with a carefully engineered pc board. Included on the Switchers Made Simple design software is a more precise (non-linear) thermal model ...

  • Page 21

    NEGATIVE BOOST REGULATOR Another variation on the buck-boost topology is the negative boost configuration. The circuit in Figure 11 accepts an input voltage ranging from −5V to −12V and provides a regulated −12V output. Input voltages greater than −12V will ...

  • Page 22

    Note: Pin numbers are for the TO-220 package. FIGURE 15. 1.2V to 55V Adjustable 1A Power Supply with Low Output Ripple www.national.com 22 1147520 ...

  • Page 23

    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 ...

  • Page 24

    Physical Dimensions LM1575J-12/883, LM1575J-15/883, or LM1575J-ADJ/883 Order Number LM2575M-5.0, LM2575HVM-5.0, LM2575M-12, www.national.com inches (millimeters) unless otherwise noted 16-Lead Ceramic Dual-in-Line (J) Order Number LM1575J-3.3/883, LM1575J-5.0/883, NS Package Number J16A 24-Lead Wide Surface Mount (WM) LM2575HVM-12, LM2575M-15, LM2575HVM-15, LM2575M-ADJ or LM2575HVM-ADJ ...

  • Page 25

    Molded DIP (N) Order Number LM2575N-5.0, LM2575HVN-5.0, LM2575N-12, LM2575HVN-12, LM2575N-15, LM2575HVN-15, LM2575N-ADJ or LM2575HVN-ADJ NS Package Number N16A 5-Lead TO-220 (T) Order Number LM2575T-3.3, LM2575HVT-3.3, LM2575T-5.0, LM2575HVT-5.0, LM2575T-12, LM2575HVT-12, LM2575T-15, LM2575HVT-15, LM2575T-ADJ or LM2575HVT-ADJ NS Package Number T05A 25 ...

  • Page 26

    ... Order Number LM2575S-3.3, LM2575HVS-3.3, LM2575S-5.0, LM2575HVS-5.0, LM2575S-12, LM2575HVS-12, LM2575S-15, LM2575HVS-15, LM2575S-ADJ or LM2575HVS-ADJ www.national.com TO-263, Molded, 5-Lead Surface Mount NS Package Number TS5B 26 ...

  • Page 27

    Bent, Staggered 5-Lead TO-220 (T) Order Number LM2575T-3.3 Flow LB03, LM2575HVT-3.3 Flow LB03, LM2575T-5.0 Flow LB03, LM2575HVT-5.0 Flow LB03, LM2575T-12 Flow LB03, LM2575HVT-12 Flow LB03, LM2575T-15 Flow LB03, LM2575HVT-15 Flow LB03, LM2575T-ADJ Flow LB03 or LM2575HVT-ADJ Flow LB03 NS Package ...

  • Page 28

    ... National Semiconductor and the National Semiconductor logo are registered trademarks of National Semiconductor Corporation. All other brand or product names may be trademarks or registered trademarks of their respective holders. ...