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LM2574, LM2574HV

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SNVS104C –JUNE 1999–REVISED APRIL 2013

LM2574/LM2574HV SIMPLE SWITCHER™ 0.5A Step-Down Voltage Regulator

Check for Samples: LM2574, LM2574HV

FEATURES

DESCRIPTION

The LM2574 series of regulators are monolithic

• 3.3V, 5V, 12V, 15V, and Adjustable Output

integrated circuits that provide all the active functions

Versions

for a step-down (buck) switching regulator, capable of

• Adjustable Version Output Voltage Range,

driving a 0.5A load with excellent line and load

1.23V to 37V (57V for HV version) ±4% Max

regulation. These devices are available in fixed output

Over Line and Load Conditions

voltages of 3.3V, 5V, 12V, 15V, and an adjustable

output version.

• Specified 0.5A Output Current

• Wide Input Voltage Range, 40V, up to 60V for

Requiring a minimum number of external

HV Version components, these regulators are simple to use and

include internal frequency compensation and a fixed-

• Requires Only 4 External Components

frequency oscillator.

• 52 kHz Fixed Frequency Internal Oscillator

The LM2574 series offers a high-efficiency

• TTL Shutdown Capability, Low Power Standby

replacement for popular three-terminal linear

Mode

regulators. Because of its high efficiency, the copper

• High Efficiency

traces on the printed circuit board are normally the

only heat sinking needed.

• Uses Readily Available Standard Inductors

• Thermal Shutdown and Current Limit

A standard series of inductors optimized for use with

Protection

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

• Simple High-Efficiency Step-Down (Buck)

output voltage within specified input voltages and

Regulator

output load conditions, and ±10% on the oscillator

• Efficient Pre-Regulator for Linear Regulators

frequency. External shutdown is included, featuring

• On-Card Switching Regulators

50 μA (typical) standby current. The output switch

includes cycle-by-cycle current limiting, as well as

• Positive to Negative Converter (Buck-Boost)

thermal shutdown for full protection under fault

conditions.

Typical Application (Fixed Output Voltage Versions)

Note: Pin numbers are for 8-pin PDIP package.

Figure 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.

2SIMPLE SWITCHER is a trademark of Texas Instruments.

3All 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.

Summary of content (35 pages)

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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 FEATURES DESCRIPTION • The LM2574 series of regulators are monolithic 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.
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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 2. 8-Lead PDIP (Top View) See Package Number P0008E 2 Submit Documentation Feedback Figure 3.
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LM2574, LM2574HV www.ti.com SNVS104C – JUNE 1999 – REVISED APRIL 2013 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 LM2574HV 63V −0.3V ≤ V ≤ +VIN ON /OFF Pin Input Voltage Output Voltage to Ground (Steady State) −1V Minimum ESD Rating (C = 100 pF, R = 1.
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LM2574, LM2574HV SNVS104C – JUNE 1999 – REVISED APRIL 2013 www.ti.com 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 Units (Limits) LM2574HV-5.0 Typ SYSTEM PARAMETERS Test Circuit in Figure 23 and Figure 24, VOUT Output Voltage VIN = 12V, ILOAD = 100 mA 7V ≤ VIN ≤ 40V, 0.1A ≤ ILOAD ≤ 0.
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LM2574, LM2574HV www.ti.com SNVS104C – JUNE 1999 – REVISED APRIL 2013 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 LM2574HV-15 Typ SYSTEM PARAMETERS Test Circuit in Figure 23 and Figure 24, VOUT Output Voltage VIN = 30V, ILOAD = 100 mA 15 18V ≤ VIN ≤ 40V, 0.1A ≤ ILOAD ≤ 0.5A VOUT Output Voltage LM2574HV 18V ≤ VIN ≤ 60V, 0.
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LM2574, LM2574HV SNVS104C – JUNE 1999 – REVISED APRIL 2013 www.ti.com 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.
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LM2574, LM2574HV www.ti.com SNVS104C – JUNE 1999 – REVISED APRIL 2013 Typical Performance Characteristics (Circuit of Figure 24) Normalized Output Voltage Line Regulation Figure 4. Figure 5. Dropout Voltage Current Limit Figure 6. Figure 7. Supply Current Standby Quiescent Current Figure 8. Figure 9.
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LM2574, LM2574HV SNVS104C – JUNE 1999 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) (Circuit of Figure 24) 8 Oscillator Frequency Switch Saturation Voltage Figure 10. Figure 11. Efficiency Minimum Operating Voltage Figure 12. Figure 13. Supply Current vs Duty Cycle Feedback Voltage vs Duty Cycle Figure 14. Figure 15.
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LM2574, LM2574HV www.ti.com SNVS104C – JUNE 1999 – REVISED APRIL 2013 Typical Performance Characteristics (continued) (Circuit of Figure 24) Feedback Pin Current Junction to Ambient Thermal Resistance Figure 16. Figure 17.
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LM2574, LM2574HV SNVS104C – JUNE 1999 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (Circuit of Figure 24) Continuous Mode Switching Waveforms VOUT = 5V, 500 mA Load Current, L = 330 μH Notes: 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 Figure 18. Notes: A: Output Pin Voltage, 10V/div B: Inductor Current, 0.
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LM2574, LM2574HV www.ti.com SNVS104C – JUNE 1999 – REVISED APRIL 2013 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.
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LM2574, LM2574HV SNVS104C – JUNE 1999 – REVISED APRIL 2013 www.ti.com 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.
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LM2574, LM2574HV www.ti.com SNVS104C – JUNE 1999 – REVISED APRIL 2013 LM2574 Series Buck Regulator Design Procedure PROCEDURE (Fixed Output Voltage Versions) EXAMPLE (Fixed Output Voltage Versions) Given: VOUT = Regulated Output Voltage (3.3V, 5V, 12V, or 15V) VIN(Max) = Maximum Input Voltage ILOAD(Max) = Maximum Load Current Given: VOUT = 5V VIN(Max) = 15V ILOAD(Max) = 0.4A 1. Inductor Selection (L1) A.
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LM2574, LM2574HV SNVS104C – JUNE 1999 – REVISED APRIL 2013 www.ti.com 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.
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LM2574, LM2574HV www.ti.com SNVS104C – JUNE 1999 – REVISED APRIL 2013 PROCEDURE (Adjustable Output Voltage Versions) Given: VOUT = Regulated Output Voltage VIN(Max) = Maximum Input Voltage ILOAD(Max) = Maximum Load Current F = Switching Frequency (Fixed at 52 kHz) EXAMPLE (Adjustable Output Voltage Versions) Given: VOUT = 24V VIN(Max) = 40V ILOAD(Max) = 0.4A F = 52 kHz 1. Programming Output Voltage (Selecting R1 and R2, as shown 1.
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LM2574, LM2574HV SNVS104C – JUNE 1999 – REVISED APRIL 2013 www.ti.com PROCEDURE (Adjustable Output Voltage Versions) EXAMPLE (Adjustable Output Voltage Versions) 4. Catch Diode Selection (D1) A. The catch-diode current rating must be at least 1.5 times greater than the maximum load current. Also, if the power supply design must withstand a continuous output short, the diode should have a current rating equal to the maximum current limit of the LM2574.
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LM2574, LM2574HV www.ti.com SNVS104C – JUNE 1999 – REVISED APRIL 2013 Table 2.
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LM2574, LM2574HV SNVS104C – JUNE 1999 – REVISED APRIL 2013 www.ti.com 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.
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LM2574, LM2574HV www.ti.com SNVS104C – JUNE 1999 – REVISED APRIL 2013 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.
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LM2574, LM2574HV SNVS104C – JUNE 1999 – REVISED APRIL 2013 www.ti.com 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).
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LM2574, LM2574HV www.ti.com SNVS104C – JUNE 1999 – REVISED APRIL 2013 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.
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LM2574, LM2574HV SNVS104C – JUNE 1999 – REVISED APRIL 2013 www.ti.com 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.
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LM2574, LM2574HV www.ti.com SNVS104C – JUNE 1999 – REVISED APRIL 2013 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.
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LM2574, LM2574HV SNVS104C – JUNE 1999 – REVISED APRIL 2013 www.ti.com 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 stepdown switching regulator.
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LM2574, LM2574HV www.ti.com SNVS104C – JUNE 1999 – REVISED APRIL 2013 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.
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LM2574, LM2574HV SNVS104C – JUNE 1999 – REVISED APRIL 2013 www.ti.com REVISION HISTORY Changes from Revision B (April 2013) to Revision C • 26 Page Changed layout of National Data Sheet to TI format ..........................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (°C) Device Marking (4/5) LM2574HVN-15/NOPB ACTIVE PDIP P 8 40 Green (RoHS & no Sb/Br) SN | CU SN Level-1-NA-UNLIM -40 to 125 LM2574HVN -15 P+ LM2574HVN-5.0 NRND PDIP P 8 40 TBD Call TI Call TI -40 to 125 LM2574HVN -5.0 P+ LM2574HVN-5.
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PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (°C) Device Marking (4/5) LM2574N-12 NRND PDIP P 8 40 TBD Call TI Call TI -40 to 125 LM2574N -12 P+ LM2574N-12/NOPB ACTIVE PDIP P 8 40 Green (RoHS & no Sb/Br) SN | CU SN Level-1-NA-UNLIM -40 to 125 LM2574N -12 P+ LM2574N-3.
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PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 (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.
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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 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant LM2574HVMX-12/NOPB SOIC NPA 14 1000 330.0 16.4 10.9 9.5 3.2 12.0 16.0 Q1 LM2574HVMX-15/NOPB SOIC NPA 14 1000 330.0 16.4 10.9 9.5 3.2 12.0 16.0 Q1 LM2574HVMX-3.3/NOPB SOIC NPA 14 1000 330.0 16.4 10.9 9.5 3.2 12.0 16.
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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 SOIC NPA 14 1000 367.0 367.0 38.0 LM2574HVMX-15/NOPB SOIC NPA 14 1000 367.0 367.0 38.0 LM2574HVMX-3.3/NOPB SOIC NPA 14 1000 367.0 367.0 38.0 LM2574HVMX-5.0 SOIC NPA 14 1000 367.0 367.0 38.0 LM2574HVMX-5.0/NOPB SOIC NPA 14 1000 367.0 367.0 38.
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MECHANICAL DATA NPA0014B www.ti.
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