LM2576 Basics
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.
LM2596 Basics
The LM2596 series regulator is a monolithic integrated circuit with all the functions of a step-down switching regulator, capable of driving a 3A load through the excellent line and load regulation. These devices provide fixed output voltages of 3.3V, 5V, and 12V. These regulators require a minimum number of external components, are easy to use, and have internal frequency compensation and a fixed-frequency oscillator.
The LM2596 series operates at a switching frequency of 150kHz and requires fewer filter components than low-frequency switching regulators. Available in a standard 5-pin TO-220 package with several different lead bend options, and a 5-pin TO-263 surface-mount package.
LM2576 vs LM2596: Pinout and Configuration
| Pin Number | Pin Name | Description |
| 1 | V IN | The voltage which has to be regulated is provided as input to this pin |
| 2 | Output | The regulated output can be obtained through this pin |
| 3 | Ground | Connected to system ground |
| 4 | Feedback | This pin is provided with the feedback voltage based on which the output is regulated |
| 5 | ON/OFF | Connect to the ground to activate the regulator or connect to Vcc to disable the regulator. |
| Pin Number | Pin Name | Description |
| 1 | V IN | This is the positive input power of the IC switching regulator. There must be a suitable input bypass capacitor on this pin to minimize voltage transients andto supply the switching currents required by the regulator. |
| 2 | Output | This pin is an internal switch. The voltage on this pin is switched between approximately (+V IN -V SAT ) and approximately -0.5 V, and the duty cycle is V OUT /V IN. In order to minimize coupling with sensitive circuits, the copper area of the PCB connected to this pin must be kept to a minimum. |
| 3 | Ground | Circuit ground |
| 4 | Feed Back | Senses the regulated output voltage to complete the feedback loop |
| 5 | ON/OFF | Enable pin, should be grounded for normal operation |
LM2576 vs LM2596: Datasheet
LM2576 vs LM2596: Features
LM2576 Features
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This voltage regulator includes fixed frequency voltage with 52kHz of the internal oscillator of frequency.
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Available packages are TO-220 &TO-263
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This voltage regulator provides permanent o/p voltages like 3.3V, 5V, 12V & 15V.
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In-built current limit protection & thermal shutdown
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The o/p voltage can be changed from 1.23V to 37V by connecting exterior components.
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Input voltage max is 40V
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It can resist a ±4% of tolerance on o/p voltage once the i/p voltage is in the specified range & output load conditions are satisfied & ±10% tolerance on the frequency of the oscillator.
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For variable type voltage regulator, output voltage ranges from 1.23V – 37V
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The specified output current is up to 3A
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It includes an under–voltage lockout circuit that maintains the i/p voltage within a range & maintains the regulator off till it reaches a fixed threshold level.
LM2596 Features
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3A Step Down Voltage Regulator IC
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Available as 3.3V regulator, 5V Regulator, 12V Regulator, and Variable regulator
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Input Supply Voltage: 4.5V to 40V
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Minimum Output Voltage: 3.16V
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Continuous Output Current: 3A
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Peak Output Current: 6.9A
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Switching Frequency: 150KHz
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Available in To-220 and To-263 Package
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