LM2575 Simple switcher 1A step down voltage regulator

The LM2575 circuit is a simple step down dc regulated switching IC that can use to output current of 1A and voltage of 3.3V, 5V, 12V,15V ,and also an adjustable output. We love LM1575/LM2575/LM2575 National Semiconductor it why it is amazing since as step down voltage( Buck dc converter) switching regulator like 78xx series IC. But so well than it. We see a design to take advantaged of advanced circuit techniques, as following.


Figure 1 connection Diagrams of LM2575xx IC on TO-220( xx indicates output voltage output to select. See information on part number.)

1. There is fixed voltage output of 3.3V may be use to power supply 3 volts of digital camera AC adapter.
2. Not heat, High effciency so use a smaller heat sink.
3. Output current of 1A load with excellent line and load regulation
4. Wide input voltage range 40V to 60V( HV-IC types) better than LM317.
5. Needs only 4 outside parts. see in Figure 1
6. Output voltage in adjustable styes 1.23V to 37V like LM317 but has HV vertion up to 57V.
7. It has a -/+ 4% max over line and load conditions.
8. 52 kHz fixed frequency internal oscillator
9. Uses readily available standard inductors.
10. Thermal shutdown and current limit protection.
11. Uses readily available standard inductors.
12. Thermal shutdown and current limit protection.


Figure 2 is the basic typical application as Fixed voltage output)

Cin-100uF, 75V Aluminum electrolyte
Cout-330uF 25V Aluminum electrolyte
D1 – schottky,11DQ06
L1-330uH( for 5V in and 3.3V out, use 100uH)

Read also: How to use 7805 voltage regulator

Simple 5V 1A Switching Regulator using LM2575-5.0

The switching regulator circuit using LM2575-5.0. It is fixed voltage regulator same LM7805 IC, But it has the good efficiency. No hot and full output current at 1A.

You can make the stable voltage by using the 3 terminal regulator like LM317. However, because the output electric current and the inputted electric current are the same approximately, the difference between the input electric power (The input voltage x The input electric current) and the output power (The output voltage x The output current) is consumed as the heat with the regulator. Because it is, the efficiency isn’t good.


Data sheet for LM2575


LM2575 Pins

SIMPLE SWITCHER 1A Step-Down Voltage Regulator


Figure 3 is Adjustable output voltage we buy one number use for many projects.

Where Vreff = 1.23V.
R1 = 1k to 5K resistance
R2 6.12K

How to use its in various projects Applications
The LM2575 is simple high-efficiency step-down (buck) swithcing regulator, Efficien pre-regulator for linear regulators, Positive to negative converter (Buck-Boost) and etc.

We use products of National semiconductor, since they ver high-efficiency and top quality on so cheap We love it our life so well up when use them.
Related Circuits

What’s more? You can look other power supply circuits: Click Here

Get Ebook: Simple Electronics Vol-03


I always try to make Electronics Learning Easy.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.