1. Lm2596 Step Down Power Converter
2. Dc To Dc Converter Schematic

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I Description

Lm2596 Buck Converter Circuit Diagram. Lm2596 Dc Dc Buck Converter Step Down Power Module Output 1 25v 35v Lm2596 Typical Application Reference Design Dc To Dc.

What is LM2596? LM2596 is a switching voltage regulator for step-down power management monolithic integrated circuits, capable of outputting 3A drive current, while having good linearity and load regulation characteristics. The fixed output versions of LM2596 are 3.3V, 5V and 12V, and the adjustable version can output various voltages less than 37V.

With only a few external components, we can use this voltage regulator! Moreover, the LM2596 switching frequency is 150KHz, which means that compared with low-frequency switching regulators, we can use smaller specifications of filter components. In addition, LM2596 integrates frequency compensation and fixed frequency generator.

This blog will introduce 4 typical application circuits of LM2596.

Figure 1. LM2596

Catalog

II Circuit of LM2596 Output 3.3V, 5V

Have you noticed that in the design below, all LM2596 chips choose a supply voltage of 5V, 3.3V or 1.8V? This is because, in the design of the whole control system, if the power supply system is too complex and redundant, it will not only cause electromagnetic interference to other parts of the circuit, but also the economic benefit is not good. Therefore, the selection of 5 V, 3.3 V or 1.8 V supply voltage is beneficial to the experimental design.

What are the other benefits ? In this way, the 24 V voltage can be directly converted into the desired voltage by using 3 LM2596 and some capacitors, inductors, diodes and so on. This kind of design circuit is not only simple and convenient, but also very economical. The power supply circuit is shown in Figure 2.

When we use it, we can choose the chips of LM2596 + 5V, LM2596 + 3.3V and LM2596 + 1.8V according to our needs:

Lm2596 Step Down Power Converter

• To obtain the connection of graph (a) when + 1.8V and + 5V,
• To obtain the connection of graph (b) when + 3.3V.

Figure 2. LM2596 Circuit Diagram

Dc To Dc Converter Schematic

III Circuit of Step-Down Voltage Regulators

When you think aoout the voltage regulator and step-down module in the single-chip microcomputer system, will you think of common chips such as LM7805 and AMS117? Since LM7805 and AMS117 are low in cost and can be used directly without external expansion of other components, they have been widely used.

But don't forget that LM7805 has a fatal disadvantage: high heat generation and low output current. In the microcontroller system, if the external device current is very small, then it’s OK to choose LM7805. However, once we need to drive modules with larger currents such as relays, LM7805 appears to be powerless, because high heat generation means power loss. In addition, if the input voltage of LM7805 is about 15V, even if the current required for the output load is small, its heat generation is about 85 ℃ (I think this should be able to fry an egg), so a heat sink or a cooling fan must be added to it . This means that cost and PCB layout will be affected.

The LM2596 series of regulators are monolithic integrated circuits that provide all the active functions for a step-down (buck) switching regulator, capable of driving a 3-A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3 V, 5 V, 12 V, and an adjustable output version. However, it should be noted that because LM2596 is a switching voltage regulator, its own calorific value is very small. This means that the wide input voltage range compared with the LM7805, LM2596 needs to add several external components.

Figure 3. LM2596 Step-Down Voltage Regulators

From the above figure, we can see that compared with LM7805, LM2596 has 4 more external components, and its output current can reach 3A at most, which is enough to deal with common single-chip microcomputer systems, at the same time, the input voltage range is wide and the maximum input voltage is 40V. LM2596 also has an adjustable version. If the adjustable version is used to make a 0-30v high-current adjustable power supply, it is completely feasible.

Figure 4. Adjustable LM2596

The above figure is a circuit diagram of an adjustable version of LM2596, which can output a DC voltage of 0-37v, which is much better than LM317.

IV LM2596 Application Circuit

LM2596 supports adjustable output. When the input is 40V, the output can be continuously adjusted to 0～37V. The typical application circuit is as follows:

Figure 5. LM2596 Application Circuit

Note: The feedback wire should be far away from the inductance, and the thick wire in the circuit must be short. Here we'd better shield it with a ground wire. The resistors R1 and R2 that regulate the output voltage should be close to the 4 pins of the LM2596.

V LM2596 Adjustable Current Limiting Regulator

LM2596 does not have the function of current limiting, but in some electronic designs and auxiliary equipment, there is a certain demand for the function of current limiting. Although the standard application circuit given by the manufacturer cannot accomplish this function, we can add a function circuit to make it realize the current limiting function. As shown in Figure 6:

Figure 6. LM2596 Adjustable Current Limiting Regulator

FAQ