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LM2576: Introduction & Information

Author: Irene Date: 6 Mar 2021  2065

LM2576 Datasheet

The LM2576 series of monolithic integrated circuits provide all the active functions for a step-down (buck) switching regulator. LM2576 series are capable of driving a 3A load with excellent line and load regulation. The regulators are simple to use because they require a minimum number of external components and include internal frequency compensation and a fixed-frequency oscillator.


Catalog

LM2576 Description

LM2576 Pinout

LM2576 Features

LM2576 Applications

LM2576 Circuit Diagram

LM2576 Package 

LM2576 Parameters

Electrical Characteristics: All Output Voltage Versions

LM2576 Manufacturer

Component Datasheet

FAQ

Ordering & Quantity


LM2576 Description

The LM2576 series of monolithic integrated circuits provide all the active functions for a step-down (buck) switching regulator. Fixed versions are available with a 3.3V, 5V, or 12V fixed output. Adjustable versions have an output voltage range from 1.23V to 37V. Both versions are capable of driving a 3A load with excellent line and load regulation.

These regulators are simple to use because they require a minimum number of external components and include internal frequency compensation and a fixed-frequency oscillator.

The LM2576 series offers a high efficiency replacement for popular three-terminal adjustable linear regulators. It substantially reduces the size of the heat sink, and in many cases no heat sink is required.

A standard series of inductors available from several different manufactures are ideal for use with the LM2576 series. This feature greatly simplifies the design of switch-mode power supplies.

The feedback voltage is guaranteed to ±2% tolerance for adjustable versions, and the output voltage is guaranteed to ±3% for fixed versions, within specified input voltages and output load conditions. The oscillator frequency is guaranteed to ±10%. external shutdown is included, featuring less than 200μA standby current. The output switch includes cycle-by-cycle current limiting and thermal shutdown for full protection under fault conditions.


LM2576 Pinout 

Pin Function Decription

  Symbol Description
1 VIN This pin is the positive input supply for the LM2576 step-down switching regulator. In order to minimize voltage transients and to supply the switching currents needed by the regulator, a suitable input bypass capacitor must be present.
2 Output This is the emitter of the internal switch. The saturation voltage Vast of this output switch is typically 1.5 V. it should be kept in mind that the PCB area connected to this pin should be kept to a minimum in order to minimize coupling to sensitive circuitry.
3 Gnd Circuit ground pin. See the information about the printed circuit board layout.
4 Feedback This pin senses regualted output voltage to complete the feedback loop. Ths signal is divided by the internal resistor divider network R2, R1 and applied to the non-inverting input of the internal error amplifier. In the Adjustable version of the LM2576 switching regualtor this pin is the direct input pf the error amplifier and the resistor network R2, R1 is connected externally to allow programming of the output voltage.
5 ON/OFF It allows the switching regulator circuit to be shut down using logic level signals, thus dropping the total input supply current to approximately 80 mA. The threshold voltage is typically 1.4 V. Applying a voltage above this value (up to+Vin) shuts the regulator off. If the voltage applied to this pin is lower than 1.4 V or if this pin is left open, the regualtor will be in the “on” condition.

LM2576 Features

  • 3V, 5V, 12V, 15V, and adjustable output versions

  • Adjustable version output voltage range: 1.23 V to 37 V (57 V for HV version) ±4% maximum over line and load conditions

  • Specified 3A output current

  • Wide input voltage range: 4 V to 40 V

  • Requires only four external components

  • 52kHz Fixed-frequency internal oscillator

  • Low-power standby modeIQ typically < 200 μA

  • High efficiency

  • Uses readily available standard inductors

  • Thermal shutdown and current limit protection

  • 100% electrical thermal limit burn-in


LM2576 Applications

  • Simple high-efficiency step-down (buck) regulator

  • Efficient pre-regulator for linear regulators

  • On-card switching regulators

  • Positive to negative converter (inverting Buck-Boost)

  • Isolated Flyback Converter using minimum number of external components

  • Negative Boost Converter


LM2576 Circuit Diagram


LM2576 Package 


LM2576 Parameters

Vin (Min) (V) 4
Vin (Max) (V) 40
Vout (Min) (V) 3.3
Vout (Max) (V) 37
Iout (Max) (A) 3
Iq (Typ) (mA) 5
Switching frequency (Min) (kHz) 42
Switching frequency (Max) (kHz) 63
Features Enable, Over Current Protection
Operating temperature range (C) -40 to 125
Rating Catalog
Approx. price (US$) 1ku | 1.05
Regulated outputs (#) 1
Pin Number 5
Maximum current 3A

Electrical Characteristics: All Output Voltage Versions


LM2576  Manufacturer

Texas Instruments Inc. (TI)  is an American technology company that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globally. Its headquarters are in Dallas, Texas, United States. TI is one of the top ten semiconductor companies worldwide, based on sales volume. Texas Instruments's focus is on developing analog chips and embedded processors, which accounts for more than 80% of their revenue. TI also produces TI digital light processing (DLP) technology and education technology products including calculators, microcontrollers and multi-core processors. To date, TI has more than 43,000 patents worldwide.


Component Datasheet

LM2576 Datasheet


FAQ

  • Where is LM2576 used?

LM2576 is usually used as a voltage stabilizing device when the input and output voltage difference is large and the output current is also large. Because it is a switching regulator, it has a higher conversion efficiency and low heat generation than a linear regulator.

  • Whats the difference between LM2576T-ADJ and LM2576S-ADJ?

LM2576T-ADJ is the package of TO-220, LM2576S-ADJ is the package of TO-263-5, there is no difference in their functions.

  • What is the difference between LM2940 and LM2576? Which circuit are they applicable to?

LM2940 is a low-dropout linear stabilized integrated circuit. The linear stabilized power supply is characterized by a relatively simple circuit, high precision, and small ripple coefficient. It is suitable for precision power supplies with high voltage requirements. The disadvantage is that the efficiency is very low and the output The current is relatively small (relative to the switching power supply)

LM2576 is a switching power supply integrated circuit. Switching power supply, the circuit is more complicated, but the output current is large, the efficiency is high, the disadvantage is that the accuracy is lower and the ripple coefficient is larger.

  • Why do switching power supply chips LM2576 and LM2596 have diodes, inductors and capacitors behind the output pins?

The function of the diode and the inductance is that the output current can be continuous when the LM25XX is in the off state, and the function of the capacitor is to prevent the output voltage from sudden changes when the LM25XX is turned on and off. In fact, it is filtering.

  • Why the higher the switching frequency of LM2576 and LM2596, the smaller the output inductance and capacitance value?

Quite simply, the capacitive reactance of a capacitor decreases as the frequency increases, and the inductance of an inductor increases as the frequency increases. That is to say, the effect of using an inductance of 33uH in the case of 150Khz is basically the same as the effect of using an inductance of 100uH in the case of 52khz, and the principle of capacitance is the same. LM2596 is an upgraded version of LM2576. But LM2576 also has the advantage of less switching loss and less interference.

Ordering & Quality

Photo Mfr. Part # Company Description Package PDF Qty Pricing
(USD)
LM2576-12BT LM2576-12BT Company:Microchip Technology Remark:IC REG BUCK 12V 3A TO220-5 Package:TO-220-5
DataSheet
In Stock:On Order
Inquiry
Price:
400+: $2.59148
Inquiry
LM2576-12BU LM2576-12BU Company:Microchip Technology Remark:IC REG BUCK 12V 3A TO263-5 Package:TO-263-6, D²Pak (5 Leads + Tab), TO-263BA
DataSheet
In Stock:On Order
Inquiry
Price:
350+: $2.72486
Inquiry
LM2576-12WT LM2576-12WT Company:Microchip Technology Remark:IC REG BUCK 12V 3A TO220-5 Package:TO-220-5
DataSheet
In Stock:On Order
Inquiry
Price:
1+: $1.91000
25+: $1.59000
100+: $1.45000
Inquiry
LM2576-12WU LM2576-12WU Company:Microchip Technology Remark:IC REG BUCK 12V 3A TO263-5 Package:TO-263-6, D²Pak (5 Leads + Tab), TO-263BA
DataSheet
In Stock:80
Inquiry
Price:
1+: $2.28000
25+: $1.90000
100+: $1.73000
Inquiry
LM2576-3-3BT LM2576-3-3BT Company:Microchip Technology Remark:IC REG BUCK 3.3V 3A TO220-5 Package:TO-220-5
DataSheet
In Stock:On Order
Inquiry
Price:
400+: $2.59148
Inquiry
LM2576-3-3BU LM2576-3-3BU Company:Microchip Technology Remark:IC REG BUCK 3.3V 3A TO263-5 Package:TO-263-6, D²Pak (5 Leads + Tab), TO-263BA
DataSheet
In Stock:On Order
Inquiry
Price:
350+: $2.72486
Inquiry
LM2576-3-3WT LM2576-3-3WT Company:Microchip Technology Remark:IC REG BUCK 3.3V 3A TO220-5 Package:TO-220-5
DataSheet
In Stock:On Order
Inquiry
Price:
350+: $1.45000
Inquiry
LM2576-3-3WU LM2576-3-3WU Company:Microchip Technology Remark:IC REG BUCK 3.3V 3A TO263-5 Package:TO-263-6, D²Pak (5 Leads + Tab), TO-263BA
DataSheet
In Stock:182
Inquiry
Price:
1+: $2.30000
25+: $1.92000
100+: $1.75000
Inquiry
LM2576-3-3WU-TR LM2576-3-3WU-TR Company:Microchip Technology Remark:IC REG BUCK 3.3V 3A TO263-5 Package:TO-263-6, D²Pak (5 Leads + Tab), TO-263BA
DataSheet
In Stock:383
Inquiry
Price:
1+: $2.30000
25+: $1.92000
100+: $1.75000
750+: $1.75000
Inquiry
LM2576-5-0BT LM2576-5-0BT Company:Microchip Technology Remark:IC REG BUCK 5V 3A TO220-5 Package:TO-220-5
DataSheet
In Stock:On Order
Inquiry
Price:
400+: $2.59148
Inquiry

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